1
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Baumgartner L, Ipsaro JJ, Hohmann U, Handler D, Schleiffer A, Duchek P, Brennecke J. Evolutionary adaptation of an HP1-protein chromodomain integrates chromatin and DNA sequence signals. eLife 2024; 13:RP93194. [PMID: 38995818 PMCID: PMC11245307 DOI: 10.7554/elife.93194] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/14/2024] Open
Abstract
Members of the diverse heterochromatin protein 1 (HP1) family play crucial roles in heterochromatin formation and maintenance. Despite the similar affinities of their chromodomains for di- and tri-methylated histone H3 lysine 9 (H3K9me2/3), different HP1 proteins exhibit distinct chromatin-binding patterns, likely due to interactions with various specificity factors. Previously, we showed that the chromatin-binding pattern of the HP1 protein Rhino, a crucial factor of the Drosophila PIWI-interacting RNA (piRNA) pathway, is largely defined by a DNA sequence-specific C2H2 zinc finger protein named Kipferl (Baumgartner et al., 2022). Here, we elucidate the molecular basis of the interaction between Rhino and its guidance factor Kipferl. Through phylogenetic analyses, structure prediction, and in vivo genetics, we identify a single amino acid change within Rhino's chromodomain, G31D, that does not affect H3K9me2/3 binding but disrupts the interaction between Rhino and Kipferl. Flies carrying the rhinoG31D mutation phenocopy kipferl mutant flies, with Rhino redistributing from piRNA clusters to satellite repeats, causing pronounced changes in the ovarian piRNA profile of rhinoG31D flies. Thus, Rhino's chromodomain functions as a dual-specificity module, facilitating interactions with both a histone mark and a DNA-binding protein.
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Affiliation(s)
- Lisa Baumgartner
- Institute of Molecular Biotechnology of the Austrian Academy of Sciences (IMBA), Vienna BioCenter (VBC), Vienna, Austria
- Vienna BioCenter PhD Program, Doctoral School of the University of Vienna and Medical University of Vienna, Vienna, Austria
| | - Jonathan J Ipsaro
- Howard Hughes Medical Institute, W.M. Keck Structural Biology Laboratory, Cold Spring Harbor Laboratory, Cold Spring Harbor, New York, United States
| | - Ulrich Hohmann
- Institute of Molecular Biotechnology of the Austrian Academy of Sciences (IMBA), Vienna BioCenter (VBC), Vienna, Austria
- Research Institute of Molecular Pathology (IMP), Vienna BioCenter (VBC), Vienna, Austria
| | - Dominik Handler
- Institute of Molecular Biotechnology of the Austrian Academy of Sciences (IMBA), Vienna BioCenter (VBC), Vienna, Austria
| | - Alexander Schleiffer
- Institute of Molecular Biotechnology of the Austrian Academy of Sciences (IMBA), Vienna BioCenter (VBC), Vienna, Austria
- Research Institute of Molecular Pathology (IMP), Vienna BioCenter (VBC), Vienna, Austria
| | - Peter Duchek
- Institute of Molecular Biotechnology of the Austrian Academy of Sciences (IMBA), Vienna BioCenter (VBC), Vienna, Austria
| | - Julius Brennecke
- Institute of Molecular Biotechnology of the Austrian Academy of Sciences (IMBA), Vienna BioCenter (VBC), Vienna, Austria
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2
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Ames A, Seman M, Larkin A, Raiymbek G, Chen Z, Levashkevich A, Kim B, Biteen JS, Ragunathan K. Epigenetic memory is governed by an effector recruitment specificity toggle in Heterochromatin Protein 1. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2023.11.28.569027. [PMID: 38077059 PMCID: PMC10705379 DOI: 10.1101/2023.11.28.569027] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/20/2023]
Abstract
HP1 proteins are essential for establishing and maintaining transcriptionally silent heterochromatin. They dimerize, forming a binding interface to recruit diverse chromatin-associated factors. HP1 proteins are specialized and rapidly evolve, but the extent of variation required to achieve functional specialization is unknown. To investigate how changes in amino acid sequence impacts epigenetic inheritance, we performed a targeted mutagenesis screen of the S. pombe HP1 homolog, Swi6. Substitutions within an auxiliary surface adjacent to the HP1 dimerization interface produced Swi6 variants with divergent maintenance properties. Remarkably, substitutions at a single amino acid position led to the persistent gain or loss of epigenetic inheritance. These substitutions increased Swi6 chromatin occupancy in vivo and altered Swi6-protein interactions that reprogram H3K9me maintenance. We show that relatively minor changes in Swi6 amino acid composition can lead to profound changes in epigenetic inheritance which provides a redundant mechanism to evolve novel effector specificity. .
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3
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Saab C, Stephan J, Akoury E. Structural insights into the binding mechanism of Clr4 methyltransferase to H3K9 methylated nucleosome. Sci Rep 2024; 14:5438. [PMID: 38443490 PMCID: PMC10914790 DOI: 10.1038/s41598-024-56248-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2023] [Accepted: 03/04/2024] [Indexed: 03/07/2024] Open
Abstract
The establishment and maintenance of heterochromatin, a specific chromatin structure essential for genomic stability and regulation, rely on intricate interactions between chromatin-modifying enzymes and nucleosomal histone proteins. However, the precise trigger for these modifications remains unclear, thus highlighting the need for a deeper understanding of how methyltransferases facilitate histone methylation among others. Here, we investigate the molecular mechanisms underlying heterochromatin assembly by studying the interaction between the H3K9 methyltransferase Clr4 and H3K9-methylated nucleosomes. Using a combination of liquid-state nuclear magnetic resonance spectroscopy and cryo-electron microscopy, we elucidate the structural basis of Clr4 binding to H3K9-methylated nucleosomes. Our results reveal that Clr4 engages with nucleosomes through its chromodomain and disordered regions to promote de novo methylation. This study provides crucial insights into the molecular mechanisms governing heterochromatin formation by highlighting the significance of chromatin-modifying enzymes in genome regulation and disease pathology.
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Affiliation(s)
- Christopher Saab
- Department of Natural Sciences, Lebanese American University, Beirut, 1102-2801, Lebanon
- Department of Chemistry, McGill University, 801 Sherbrooke St. West, Montreal, QC, H3AOB8, Canada
| | - Joseph Stephan
- School of Medicine, Lebanese American University, PO Box 36, Byblos, Lebanon
| | - Elias Akoury
- Department of Natural Sciences, Lebanese American University, Beirut, 1102-2801, Lebanon.
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4
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Weinzapfel EN, Fedder-Semmes KN, Sun ZW, Keogh MC. Beyond the tail: the consequence of context in histone post-translational modification and chromatin research. Biochem J 2024; 481:219-244. [PMID: 38353483 PMCID: PMC10903488 DOI: 10.1042/bcj20230342] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2023] [Revised: 01/29/2024] [Accepted: 01/31/2024] [Indexed: 02/16/2024]
Abstract
The role of histone post-translational modifications (PTMs) in chromatin structure and genome function has been the subject of intense debate for more than 60 years. Though complex, the discourse can be summarized in two distinct - and deceptively simple - questions: What is the function of histone PTMs? And how should they be studied? Decades of research show these queries are intricately linked and far from straightforward. Here we provide a historical perspective, highlighting how the arrival of new technologies shaped discovery and insight. Despite their limitations, the tools available at each period had a profound impact on chromatin research, and provided essential clues that advanced our understanding of histone PTM function. Finally, we discuss recent advances in the application of defined nucleosome substrates, the study of multivalent chromatin interactions, and new technologies driving the next era of histone PTM research.
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5
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Huang M, Hong M, Hou X, Zhu C, Chen D, Chen X, Guang S, Feng X. H3K9me1/2 methylation limits the lifespan of daf-2 mutants in C. elegans. eLife 2022; 11:74812. [PMID: 36125117 PMCID: PMC9514849 DOI: 10.7554/elife.74812] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2021] [Accepted: 09/16/2022] [Indexed: 11/29/2022] Open
Abstract
Histone methylation plays crucial roles in the development, gene regulation, and maintenance of stem cell pluripotency in mammals. Recent work shows that histone methylation is associated with aging, yet the underlying mechanism remains unclear. In this work, we identified a class of putative histone 3 lysine 9 mono/dimethyltransferase genes (met-2, set-6, set-19, set-20, set-21, set-32, and set-33), mutations in which induce synergistic lifespan extension in the long-lived DAF-2 (insulin growth factor 1 [IGF-1] receptor) mutant in Caenorhabditis elegans. These putative histone methyltransferase plus daf-2 double mutants not only exhibited an average lifespan nearly three times that of wild-type animals and a maximal lifespan of approximately 100 days, but also significantly increased resistance to oxidative and heat stress. Synergistic lifespan extension depends on the transcription factor DAF-16 (FOXO). mRNA-seq experiments revealed that the mRNA levels of DAF-16 Class I genes, which are activated by DAF-16, were further elevated in the daf-2;set double mutants. Among these genes, tts-1, F35E8.7, ins-35, nhr-62, sod-3, asm-2, and Y39G8B.7 are required for the lifespan extension of the daf-2;set-21 double mutant. In addition, treating daf-2 animals with the H3K9me1/2 methyltransferase G9a inhibitor also extends lifespan and increases stress resistance. Therefore, investigation of DAF-2 and H3K9me1/2 deficiency-mediated synergistic longevity will contribute to a better understanding of the molecular mechanisms of aging and therapeutic applications.
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Affiliation(s)
- Meng Huang
- Department of Obstetrics and Gynecology, University of Science and Technology of China, Hefei, China
| | - Minjie Hong
- Department of Obstetrics and Gynecology, University of Science and Technology of China, Hefei, China
| | - Xinhao Hou
- Department of Obstetrics and Gynecology, University of Science and Technology of China, Hefei, China
| | - Chengming Zhu
- Department of Obstetrics and Gynecology, University of Science and Technology of China, Hefei, China
| | - Di Chen
- State Key Laboratory of Pharmaceutical Biotechnology, Nanjing University, Nanjing, China
| | - Xiangyang Chen
- Department of Obstetrics and Gynecology, University of Science and Technology of China, Hefei, China
| | - Shouhong Guang
- Department of Obstetrics and Gynecology, University of Science and Technology of China, Hefei, China
| | - Xuezhu Feng
- Department of Obstetrics and Gynecology, University of Science and Technology of China, Hefei, China
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6
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Wang JL, Di DW, Luo P, Zhang L, Li XF, Guo GQ, Wu L. The roles of epigenetic modifications in the regulation of auxin biosynthesis. FRONTIERS IN PLANT SCIENCE 2022; 13:959053. [PMID: 36017262 PMCID: PMC9396225 DOI: 10.3389/fpls.2022.959053] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/01/2022] [Accepted: 07/15/2022] [Indexed: 06/01/2023]
Abstract
Auxin is one of the most important plant growth regulators of plant morphogenesis and response to environmental stimuli. Although the biosynthesis pathway of auxin has been elucidated, the mechanisms regulating auxin biosynthesis remain poorly understood. The transcription of auxin biosynthetic genes is precisely regulated by complex signaling pathways. When the genes are expressed, epigenetic modifications guide mRNA synthesis and therefore determine protein production. Recent studies have shown that different epigenetic factors affect the transcription of auxin biosynthetic genes. In this review, we focus our attention on the molecular mechanisms through which epigenetic modifications regulate auxin biosynthesis.
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Affiliation(s)
- Jun-Li Wang
- Ministry of Education (MOE) Key Laboratory of Cell Activities and Stress Adaptations, School of Life Sciences, Lanzhou University, Lanzhou, China
- Gansu Province Key Laboratory of Gene Editing for Breeding, School of Life Sciences, Lanzhou University, Lanzhou, China
| | - Dong-Wei Di
- State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing, China
| | - Pan Luo
- College of Life Science and Technology, Gansu Agricultural University, Lanzhou, China
| | - Li Zhang
- Basic Forestry and Proteomics Research Center, College of Life Sciences, Fujian Agriculture and Forestry University, Fuzhou, China
| | - Xiao-Feng Li
- Ministry of Education (MOE) Key Laboratory of Cell Activities and Stress Adaptations, School of Life Sciences, Lanzhou University, Lanzhou, China
- Gansu Province Key Laboratory of Gene Editing for Breeding, School of Life Sciences, Lanzhou University, Lanzhou, China
| | - Guang-Qin Guo
- Ministry of Education (MOE) Key Laboratory of Cell Activities and Stress Adaptations, School of Life Sciences, Lanzhou University, Lanzhou, China
- Gansu Province Key Laboratory of Gene Editing for Breeding, School of Life Sciences, Lanzhou University, Lanzhou, China
| | - Lei Wu
- Ministry of Education (MOE) Key Laboratory of Cell Activities and Stress Adaptations, School of Life Sciences, Lanzhou University, Lanzhou, China
- Gansu Province Key Laboratory of Gene Editing for Breeding, School of Life Sciences, Lanzhou University, Lanzhou, China
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7
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Schoelz JM, Riddle NC. Functions of HP1 proteins in transcriptional regulation. Epigenetics Chromatin 2022; 15:14. [PMID: 35526078 PMCID: PMC9078007 DOI: 10.1186/s13072-022-00453-8] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2022] [Accepted: 04/18/2022] [Indexed: 01/24/2023] Open
Abstract
In eukaryotes, DNA is packaged into chromatin, which presents significant barriers to transcription. Non-histone chromatin proteins such as the Heterochromatin Protein 1 (HP1) proteins are critical regulators of transcription, contributing to gene regulation through a variety of molecular mechanisms. HP1 proteins are highly conserved, and many eukaryotic genomes contain multiple HP1 genes. Given the presence of multiple HP1 family members within a genome, HP1 proteins can have unique as well as shared functions. Here, we review the mechanisms by which HP1 proteins contribute to the regulation of transcription. Focusing on the Drosophila melanogaster HP1 proteins, we examine the role of these proteins in regulating the transcription of genes, transposable elements, and piRNA clusters. In D. melanogaster, as in other species, HP1 proteins can act as transcriptional repressors and activators. The available data reveal that the precise impact of HP1 proteins on gene expression is highly context dependent, on the specific HP1 protein involved, on its protein partners present, and on the specific chromatin context the interaction occurs in. As a group, HP1 proteins utilize a variety of mechanisms to contribute to transcriptional regulation, including both transcriptional (i.e. chromatin-based) and post-transcriptional (i.e. RNA-based) processes. Despite extensive studies of this important protein family, open questions regarding their functions in gene regulation remain, specifically regarding the role of hetero- versus homodimerization and post-translational modifications of HP1 proteins.
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Affiliation(s)
- John M Schoelz
- Department of Biology, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Nicole C Riddle
- Department of Biology, University of Alabama at Birmingham, Birmingham, AL, USA.
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8
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Jeon YH, Kim GW, Kim SY, Yi SA, Yoo J, Kim JY, Lee SW, Kwon SH. Heterochromatin Protein 1: A Multiplayer in Cancer Progression. Cancers (Basel) 2022; 14:cancers14030763. [PMID: 35159030 PMCID: PMC8833910 DOI: 10.3390/cancers14030763] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2022] [Revised: 01/28/2022] [Accepted: 01/29/2022] [Indexed: 11/16/2022] Open
Abstract
Dysregulation of epigenetic mechanisms as well as genomic mutations contribute to the initiation and progression of cancer. In addition to histone code writers, including histone lysine methyltransferase (KMT), and histone code erasers, including histone lysine demethylase (KDM), histone code reader proteins such as HP1 are associated with abnormal chromatin regulation in human diseases. Heterochromatin protein 1 (HP1) recognizes histone H3 lysine 9 methylation and broadly affects chromatin biology, such as heterochromatin formation and maintenance, transcriptional regulation, DNA repair, chromatin remodeling, and chromosomal segregation. Molecular functions of HP1 proteins have been extensively studied, although their exact roles in diseases require further study. Here, we comprehensively review the studies that have revealed the altered expression of HP1 and its functions in tumorigenesis. In particular, the distinctive effects of each HP1 subtype, namely HP1α, HP1β, and HP1γ, have been thoroughly explored in various cancer types. We also highlight how HP1 can serve as a potential biomarker for cancer prognosis and therapeutic target for cancer patients.
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Affiliation(s)
- Yu Hyun Jeon
- College of Pharmacy, Yonsei Institute of Pharmaceutical Sciences, Yonsei University, Incheon 21983, Korea; (Y.H.J.); (G.W.K.); (S.Y.K.); (J.Y.); (J.Y.K.); (S.W.L.)
| | - Go Woon Kim
- College of Pharmacy, Yonsei Institute of Pharmaceutical Sciences, Yonsei University, Incheon 21983, Korea; (Y.H.J.); (G.W.K.); (S.Y.K.); (J.Y.); (J.Y.K.); (S.W.L.)
| | - So Yeon Kim
- College of Pharmacy, Yonsei Institute of Pharmaceutical Sciences, Yonsei University, Incheon 21983, Korea; (Y.H.J.); (G.W.K.); (S.Y.K.); (J.Y.); (J.Y.K.); (S.W.L.)
| | - Sang Ah Yi
- School of Pharmacy, Sungkyunkwan University, Suwon 16419, Korea;
| | - Jung Yoo
- College of Pharmacy, Yonsei Institute of Pharmaceutical Sciences, Yonsei University, Incheon 21983, Korea; (Y.H.J.); (G.W.K.); (S.Y.K.); (J.Y.); (J.Y.K.); (S.W.L.)
| | - Ji Yoon Kim
- College of Pharmacy, Yonsei Institute of Pharmaceutical Sciences, Yonsei University, Incheon 21983, Korea; (Y.H.J.); (G.W.K.); (S.Y.K.); (J.Y.); (J.Y.K.); (S.W.L.)
| | - Sang Wu Lee
- College of Pharmacy, Yonsei Institute of Pharmaceutical Sciences, Yonsei University, Incheon 21983, Korea; (Y.H.J.); (G.W.K.); (S.Y.K.); (J.Y.); (J.Y.K.); (S.W.L.)
| | - So Hee Kwon
- College of Pharmacy, Yonsei Institute of Pharmaceutical Sciences, Yonsei University, Incheon 21983, Korea; (Y.H.J.); (G.W.K.); (S.Y.K.); (J.Y.); (J.Y.K.); (S.W.L.)
- Correspondence: ; Tel.: +82-32-749-4513
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9
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Casale AM, Liguori F, Ansaloni F, Cappucci U, Finaurini S, Spirito G, Persichetti F, Sanges R, Gustincich S, Piacentini L. Transposable element activation promotes neurodegeneration in a Drosophila model of Huntington's disease. iScience 2022; 25:103702. [PMID: 35036881 PMCID: PMC8752904 DOI: 10.1016/j.isci.2021.103702] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2021] [Revised: 10/22/2021] [Accepted: 12/23/2021] [Indexed: 12/17/2022] Open
Abstract
Huntington's disease (HD) is an autosomal dominant disorder with progressive motor dysfunction and cognitive decline. The disease is caused by a CAG repeat expansion in the IT15 gene, which elongates a polyglutamine stretch of the HD protein, Huntingtin. No therapeutic treatments are available, and new pharmacological targets are needed. Retrotransposons are transposable elements (TEs) that represent 40% and 30% of the human and Drosophila genomes and replicate through an RNA intermediate. Mounting evidence suggests that mammalian TEs are active during neurogenesis and may be involved in diseases of the nervous system. Here we show that TE expression and mobilization are increased in a Drosophila melanogaster HD model. By inhibiting TE mobilization with Reverse Transcriptase inhibitors, polyQ-dependent eye neurodegeneration and genome instability in larval brains are rescued and fly lifespan is increased. These results suggest that TE activation may be involved in polyQ-induced neurotoxicity and a potential pharmacological target.
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Affiliation(s)
- Assunta Maria Casale
- Department of Biology and Biotechnology “C. Darwin”, Sapienza University of Rome, Rome, Italy
| | - Francesco Liguori
- Department of Biology and Biotechnology “C. Darwin”, Sapienza University of Rome, Rome, Italy
| | - Federico Ansaloni
- Area of Neuroscience, International School for Advanced Studies (SISSA), Trieste, Italy
| | - Ugo Cappucci
- Department of Biology and Biotechnology “C. Darwin”, Sapienza University of Rome, Rome, Italy
| | - Sara Finaurini
- Department of Health Sciences, Università del Piemonte Orientale, Novara, Italy
| | - Giovanni Spirito
- Area of Neuroscience, International School for Advanced Studies (SISSA), Trieste, Italy
| | | | - Remo Sanges
- Area of Neuroscience, International School for Advanced Studies (SISSA), Trieste, Italy
- Central RNA Laboratory, Istituto Italiano di Tecnologia, Genova, Italy
| | | | - Lucia Piacentini
- Department of Biology and Biotechnology “C. Darwin”, Sapienza University of Rome, Rome, Italy
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10
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Gibert JM, Peronnet F. The Paramount Role of Drosophila melanogaster in the Study of Epigenetics: From Simple Phenotypes to Molecular Dissection and Higher-Order Genome Organization. INSECTS 2021; 12:884. [PMID: 34680653 PMCID: PMC8537509 DOI: 10.3390/insects12100884] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/03/2021] [Revised: 09/24/2021] [Accepted: 09/26/2021] [Indexed: 01/06/2023]
Abstract
Drosophila melanogaster has played a paramount role in epigenetics, the study of changes in gene function inherited through mitosis or meiosis that are not due to changes in the DNA sequence. By analyzing simple phenotypes, such as the bristle position or cuticle pigmentation, as read-outs of regulatory processes, the identification of mutated genes led to the discovery of major chromatin regulators. These are often conserved in distantly related organisms such as vertebrates or even plants. Many of them deposit, recognize, or erase post-translational modifications on histones (histone marks). Others are members of chromatin remodeling complexes that move, eject, or exchange nucleosomes. We review the role of D. melanogaster research in three epigenetic fields: Heterochromatin formation and maintenance, the repression of transposable elements by piRNAs, and the regulation of gene expression by the antagonistic Polycomb and Trithorax complexes. We then describe how genetic tools available in D. melanogaster allowed to examine the role of histone marks and show that some histone marks are dispensable for gene regulation, whereas others play essential roles. Next, we describe how D. melanogaster has been particularly important in defining chromatin types, higher-order chromatin structures, and their dynamic changes during development. Lastly, we discuss the role of epigenetics in a changing environment.
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Affiliation(s)
- Jean-Michel Gibert
- Centre National de la Recherche Scientifique (CNRS), Laboratoire de Biologie du Développement (LBD), Institut de Biologie Paris Seine (IBPS), Sorbonne Université, 75005 Paris, France
| | - Frédérique Peronnet
- Centre National de la Recherche Scientifique (CNRS), Laboratoire de Biologie du Développement (LBD), Institut de Biologie Paris Seine (IBPS), Sorbonne Université, 75005 Paris, France
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11
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The Sound of Silence: How Silenced Chromatin Orchestrates the Repair of Double-Strand Breaks. Genes (Basel) 2021; 12:genes12091415. [PMID: 34573397 PMCID: PMC8467445 DOI: 10.3390/genes12091415] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2021] [Revised: 09/07/2021] [Accepted: 09/13/2021] [Indexed: 12/29/2022] Open
Abstract
The eukaryotic nucleus is continuously being exposed to endogenous and exogenous sources that cause DNA breaks, whose faithful repair requires the activity of dedicated nuclear machineries. DNA is packaged into a variety of chromatin domains, each characterized by specific molecular properties that regulate gene expression and help maintain nuclear structure. These different chromatin environments each demand a tailored response to DNA damage. Silenced chromatin domains in particular present a major challenge to the cell’s DNA repair machinery due to their specific biophysical properties and distinct, often repetitive, DNA content. To this end, we here discuss the interplay between silenced chromatin domains and DNA damage repair, specifically double-strand breaks, and how these processes help maintain genome stability.
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12
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Kim YJ, Tamadon A, Kim YY, Kang BC, Ku SY. Epigenetic Regulation of Cardiomyocyte Differentiation from Embryonic and Induced Pluripotent Stem Cells. Int J Mol Sci 2021; 22:8599. [PMID: 34445302 PMCID: PMC8395249 DOI: 10.3390/ijms22168599] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2021] [Revised: 08/05/2021] [Accepted: 08/06/2021] [Indexed: 12/17/2022] Open
Abstract
With the intent to achieve the best modalities for myocardial cell therapy, different cell types are being evaluated as potent sources for differentiation into cardiomyocytes. Embryonic stem cells and induced pluripotent stem cells have great potential for future progress in the treatment of myocardial diseases. We reviewed aspects of epigenetic mechanisms that play a role in the differentiation of these cells into cardiomyocytes. Cardiomyocytes proliferate during fetal life, and after birth, they undergo permanent terminal differentiation. Upregulation of cardiac-specific genes in adults induces hypertrophy due to terminal differentiation. The repression or expression of these genes is controlled by chromatin structural and epigenetic changes. However, few studies have reviewed and analyzed the epigenetic aspects of the differentiation of embryonic stem cells and induced pluripotent stem cells into cardiac lineage cells. In this review, we focus on the current knowledge of epigenetic regulation of cardiomyocyte proliferation and differentiation from embryonic and induced pluripotent stem cells through histone modification and microRNAs, the maintenance of pluripotency, and its alteration during cardiac lineage differentiation.
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Affiliation(s)
- Yong-Jin Kim
- Department of Obstetrics and Gynecology, Korea University College of Medicine, Seoul 08308, Korea;
| | - Amin Tamadon
- Department of Marine Stem Cell and Tissue Engineering, Bushehr University of Medical Sciences, Bushehr 14174, Iran;
| | - Yoon-Young Kim
- Department of Obstetrics and Gynecology, Seoul National University College of Medicine, Seoul 03080, Korea;
- Biomedical Research Institute, Seoul National University Hospital, Seoul 03080, Korea;
- Institute of Reproductive Medicine and Population, Medical Research Center, Seoul National University, Seoul 03080, Korea
| | - Byeong-Cheol Kang
- Biomedical Research Institute, Seoul National University Hospital, Seoul 03080, Korea;
| | - Seung-Yup Ku
- Department of Obstetrics and Gynecology, Seoul National University College of Medicine, Seoul 03080, Korea;
- Institute of Reproductive Medicine and Population, Medical Research Center, Seoul National University, Seoul 03080, Korea
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13
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Casale AM, Cappucci U, Piacentini L. Unravelling HP1 functions: post-transcriptional regulation of stem cell fate. Chromosoma 2021; 130:103-111. [PMID: 34128099 PMCID: PMC8426308 DOI: 10.1007/s00412-021-00760-1] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2021] [Revised: 05/17/2021] [Accepted: 06/01/2021] [Indexed: 12/20/2022]
Abstract
Heterochromatin protein 1 (HP1) is a non-histone chromosomal protein first identified in Drosophila as a major component of constitutive heterochromatin, required for stable epigenetic gene silencing in many species including humans. Over the years, several studies have highlighted additional roles of HP1 in different cellular processes including telomere maintenance, DNA replication and repair, chromosome segregation and, surprisingly, positive regulation of gene expression. In this review, we briefly summarize past research and recent results supporting the unexpected and emerging role of HP1 in activating gene expression. In particular, we discuss the role of HP1 in post-transcriptional regulation of mRNA processing because it has proved decisive in the control of germline stem cells homeostasis in Drosophila and has certainly added a new dimension to our understanding on HP1 targeting and functions in epigenetic regulation of stem cell behaviour.
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Affiliation(s)
- Assunta Maria Casale
- Department of Biology and Biotechnology "C. Darwin", Sapienza University of Rome, Rome, Italy.
| | - Ugo Cappucci
- Department of Biology and Biotechnology "C. Darwin", Sapienza University of Rome, Rome, Italy
| | - Lucia Piacentini
- Department of Biology and Biotechnology "C. Darwin", Sapienza University of Rome, Rome, Italy.
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14
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Strom AR, Biggs RJ, Banigan EJ, Wang X, Chiu K, Herman C, Collado J, Yue F, Ritland Politz JC, Tait LJ, Scalzo D, Telling A, Groudine M, Brangwynne CP, Marko JF, Stephens AD. HP1α is a chromatin crosslinker that controls nuclear and mitotic chromosome mechanics. eLife 2021; 10:e63972. [PMID: 34106828 PMCID: PMC8233041 DOI: 10.7554/elife.63972] [Citation(s) in RCA: 61] [Impact Index Per Article: 20.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2020] [Accepted: 06/08/2021] [Indexed: 12/14/2022] Open
Abstract
Chromatin, which consists of DNA and associated proteins, contains genetic information and is a mechanical component of the nucleus. Heterochromatic histone methylation controls nucleus and chromosome stiffness, but the contribution of heterochromatin protein HP1α (CBX5) is unknown. We used a novel HP1α auxin-inducible degron human cell line to rapidly degrade HP1α. Degradation did not alter transcription, local chromatin compaction, or histone methylation, but did decrease chromatin stiffness. Single-nucleus micromanipulation reveals that HP1α is essential to chromatin-based mechanics and maintains nuclear morphology, separate from histone methylation. Further experiments with dimerization-deficient HP1αI165E indicate that chromatin crosslinking via HP1α dimerization is critical, while polymer simulations demonstrate the importance of chromatin-chromatin crosslinkers in mechanics. In mitotic chromosomes, HP1α similarly bolsters stiffness while aiding in mitotic alignment and faithful segregation. HP1α is therefore a critical chromatin-crosslinking protein that provides mechanical strength to chromosomes and the nucleus throughout the cell cycle and supports cellular functions.
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Affiliation(s)
- Amy R Strom
- Howard Hughes Medical Institute, Department of Chemical and Biological Engineering, Princeton UniversityPrincetonUnited States
| | - Ronald J Biggs
- Department of Molecular Biosciences, Northwestern UniversityEvanstonUnited States
| | - Edward J Banigan
- Institute for Medical Engineering and Science and Department of Physics, Massachusetts Institute of TechnologyCambridgeUnited States
| | - Xiaotao Wang
- Department of Biochemistry and Molecular Genetics, Feinberg School of Medicine, Northwestern UniversityChicagoUnited States
| | - Katherine Chiu
- Biology Department, University of Massachusetts AmherstAmherstUnited States
| | - Cameron Herman
- Department of Molecular Biosciences, Northwestern UniversityEvanstonUnited States
| | - Jimena Collado
- Department of Molecular Biosciences, Northwestern UniversityEvanstonUnited States
| | - Feng Yue
- Department of Biochemistry and Molecular Genetics, Feinberg School of Medicine, Northwestern UniversityChicagoUnited States
- Robert H. Lurie Comprehensive Cancer Center, Feinberg School of Medicine, Northwestern UniversityChicagoUnited States
| | | | - Leah J Tait
- The Fred Hutchinson Cancer Research CenterSeattleUnited States
| | - David Scalzo
- The Fred Hutchinson Cancer Research CenterSeattleUnited States
| | - Agnes Telling
- The Fred Hutchinson Cancer Research CenterSeattleUnited States
| | - Mark Groudine
- The Fred Hutchinson Cancer Research CenterSeattleUnited States
| | - Clifford P Brangwynne
- Howard Hughes Medical Institute, Department of Chemical and Biological Engineering, Princeton UniversityPrincetonUnited States
| | - John F Marko
- Department of Molecular Biosciences, Northwestern UniversityEvanstonUnited States
- Department of Physics and Astronomy, Northwestern UniversityEvanstonUnited States
| | - Andrew D Stephens
- Biology Department, University of Massachusetts AmherstAmherstUnited States
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15
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Carlier F, Li M, Maroc L, Debuchy R, Souaid C, Noordermeer D, Grognet P, Malagnac F. Loss of EZH2-like or SU(VAR)3-9-like proteins causes simultaneous perturbations in H3K27 and H3K9 tri-methylation and associated developmental defects in the fungus Podospora anserina. Epigenetics Chromatin 2021; 14:22. [PMID: 33962663 PMCID: PMC8105982 DOI: 10.1186/s13072-021-00395-7] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2020] [Accepted: 04/19/2021] [Indexed: 12/19/2022] Open
Abstract
BACKGROUND Selective gene silencing is key to development. It is generally accepted that H3K27me3-enriched heterochromatin maintains transcriptional repression established during early development and regulates cell fate. Conversely, H3K9me3-enriched heterochromatin prevents differentiation but constitutes protection against transposable elements. We exploited the fungus Podospora anserina, a valuable alternative to higher eukaryote models, to question the biological relevance and functional interplay of these two distinct heterochromatin conformations. RESULTS We established genome-wide patterns of H3K27me3 and H3K9me3 modifications, and found these marks mutually exclusive within gene-rich regions but not within repeats. We generated the corresponding histone methyltransferase null mutants and showed an interdependence of H3K9me3 and H3K27me3 marks. Indeed, removal of the PaKmt6 EZH2-like enzyme resulted not only in loss of H3K27me3 but also in significant H3K9me3 reduction. Similarly, removal of PaKmt1 SU(VAR)3-9-like enzyme caused loss of H3K9me3 and substantial decrease of H3K27me3. Removal of the H3K9me binding protein PaHP1 provided further support to the notion that each type of heterochromatin requires the presence of the other. We also established that P. anserina developmental programs require H3K27me3-mediated silencing, since loss of the PaKmt6 EZH2-like enzyme caused severe defects in most aspects of the life cycle including growth, differentiation processes and sexual reproduction, whereas loss of the PaKmt1 SU(VAR)3-9-like enzyme resulted only in marginal defects, similar to loss of PaHP1. CONCLUSIONS Our findings support a conserved function of the PRC2 complex in fungal development. However, we uncovered an intriguing evolutionary fluidity in the repressive histone deposition machinery, which challenges canonical definitions of constitutive and facultative heterochromatin.
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Affiliation(s)
- F Carlier
- Institute for Integrative Biology of the Cell (I2BC), Université Paris-Saclay, CEA, CNRS, 91198, Gif-sur-Yvette, France
- Group Fungal Epigenomics, Department of Mycology, Institut Pasteur, Paris, France
| | - M Li
- Institute for Integrative Biology of the Cell (I2BC), Université Paris-Saclay, CEA, CNRS, 91198, Gif-sur-Yvette, France
| | - L Maroc
- Génétique Quantitative et Évolution-Le Moulon, INRA-Université Paris-Saclay-CNRS-AgroParisTech, Batiment 400, UFR Des Sciences, 91405, Orsay CEDEX, France
| | - R Debuchy
- Institute for Integrative Biology of the Cell (I2BC), Université Paris-Saclay, CEA, CNRS, 91198, Gif-sur-Yvette, France
| | - C Souaid
- Institute for Integrative Biology of the Cell (I2BC), Université Paris-Saclay, CEA, CNRS, 91198, Gif-sur-Yvette, France
- Inserm, Theories and Approaches of Genomic Complexity (TAGC), UMR1090, Aix-Marseille University, 13288, Marseille, France
| | - D Noordermeer
- Institute for Integrative Biology of the Cell (I2BC), Université Paris-Saclay, CEA, CNRS, 91198, Gif-sur-Yvette, France
| | - P Grognet
- Institute for Integrative Biology of the Cell (I2BC), Université Paris-Saclay, CEA, CNRS, 91198, Gif-sur-Yvette, France.
| | - F Malagnac
- Institute for Integrative Biology of the Cell (I2BC), Université Paris-Saclay, CEA, CNRS, 91198, Gif-sur-Yvette, France.
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16
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Zenk F, Zhan Y, Kos P, Löser E, Atinbayeva N, Schächtle M, Tiana G, Giorgetti L, Iovino N. HP1 drives de novo 3D genome reorganization in early Drosophila embryos. Nature 2021; 593:289-293. [PMID: 33854237 PMCID: PMC8116211 DOI: 10.1038/s41586-021-03460-z] [Citation(s) in RCA: 67] [Impact Index Per Article: 22.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2019] [Accepted: 03/16/2021] [Indexed: 12/03/2022]
Abstract
Fundamental features of 3D genome organization are established de novo in the early embryo, including clustering of pericentromeric regions, the folding of chromosome arms and the segregation of chromosomes into active (A-) and inactive (B-) compartments. However, the molecular mechanisms that drive de novo organization remain unknown1,2. Here, by combining chromosome conformation capture (Hi-C), chromatin immunoprecipitation with high-throughput sequencing (ChIP–seq), 3D DNA fluorescence in situ hybridization (3D DNA FISH) and polymer simulations, we show that heterochromatin protein 1a (HP1a) is essential for de novo 3D genome organization during Drosophila early development. The binding of HP1a at pericentromeric heterochromatin is required to establish clustering of pericentromeric regions. Moreover, HP1a binding within chromosome arms is responsible for overall chromosome folding and has an important role in the formation of B-compartment regions. However, depletion of HP1a does not affect the A-compartment, which suggests that a different molecular mechanism segregates active chromosome regions. Our work identifies HP1a as an epigenetic regulator that is involved in establishing the global structure of the genome in the early embryo. The heterochromatin protein HP1 has an essential role in establishing several features of the 3D nuclear organization of the genome during early embryonic development in Drosophila.
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Affiliation(s)
- Fides Zenk
- Max Planck Institute of Immunobiology and Epigenetics, Freiburg im Breisgau, Germany.,Albert-Ludwigs-Universität Freiburg, Freiburg im Breisgau, Germany
| | - Yinxiu Zhan
- Friedrich Miescher Institute for Biomedical Research, Basel, Switzerland.,University of Basel, Basel, Switzerland
| | - Pavel Kos
- Friedrich Miescher Institute for Biomedical Research, Basel, Switzerland
| | - Eva Löser
- Max Planck Institute of Immunobiology and Epigenetics, Freiburg im Breisgau, Germany
| | - Nazerke Atinbayeva
- Max Planck Institute of Immunobiology and Epigenetics, Freiburg im Breisgau, Germany.,Albert-Ludwigs-Universität Freiburg, Freiburg im Breisgau, Germany.,CIBSS - Centre for Integrative Biological Signalling Studies, University of Freiburg, Freiburg im Breisgau, Germany
| | - Melanie Schächtle
- Max Planck Institute of Immunobiology and Epigenetics, Freiburg im Breisgau, Germany
| | - Guido Tiana
- Università degli Studi di Milano and INFN, Milan, Italy
| | - Luca Giorgetti
- Friedrich Miescher Institute for Biomedical Research, Basel, Switzerland.
| | - Nicola Iovino
- Max Planck Institute of Immunobiology and Epigenetics, Freiburg im Breisgau, Germany.
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17
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Zhao Z, Fan R, Xu W, Kou Y, Wang Y, Ma X, Du Z. Single-cell dynamics of chromatin activity during cell lineage differentiation in Caenorhabditis elegans embryos. Mol Syst Biol 2021; 17:e10075. [PMID: 33900055 PMCID: PMC8073016 DOI: 10.15252/msb.202010075] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2020] [Revised: 03/22/2021] [Accepted: 03/23/2021] [Indexed: 11/09/2022] Open
Abstract
Elucidating the chromatin dynamics that orchestrate embryogenesis is a fundamental question in developmental biology. Here, we exploit position effects on expression as an indicator of chromatin activity and infer the chromatin activity landscape in every lineaged cell during Caenorhabditis elegans early embryogenesis. Systems-level analyses reveal that chromatin activity distinguishes cellular states and correlates with fate patterning in the early embryos. As cell lineage unfolds, chromatin activity diversifies in a lineage-dependent manner, with switch-like changes accompanying anterior-posterior fate asymmetry and characteristic landscapes being established in different cell lineages. Upon tissue differentiation, cellular chromatin from distinct lineages converges according to tissue types but retains stable memories of lineage history, contributing to intra-tissue cell heterogeneity. However, the chromatin landscapes of cells organized in a left-right symmetric pattern are predetermined to be analogous in early progenitors so as to pre-set equivalent states. Finally, genome-wide analysis identifies many regions exhibiting concordant chromatin activity changes that mediate the co-regulation of functionally related genes during differentiation. Collectively, our study reveals the developmental and genomic dynamics of chromatin activity at the single-cell level.
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Affiliation(s)
- Zhiguang Zhao
- State Key Laboratory of Molecular Developmental BiologyInstitute of Genetics and Developmental BiologyChinese Academy of SciencesBeijingChina
- University of Chinese Academy of SciencesBeijingChina
| | - Rong Fan
- State Key Laboratory of Molecular Developmental BiologyInstitute of Genetics and Developmental BiologyChinese Academy of SciencesBeijingChina
- University of Chinese Academy of SciencesBeijingChina
| | - Weina Xu
- State Key Laboratory of Molecular Developmental BiologyInstitute of Genetics and Developmental BiologyChinese Academy of SciencesBeijingChina
- University of Chinese Academy of SciencesBeijingChina
| | - Yahui Kou
- State Key Laboratory of Molecular Developmental BiologyInstitute of Genetics and Developmental BiologyChinese Academy of SciencesBeijingChina
- University of Chinese Academy of SciencesBeijingChina
| | - Yangyang Wang
- State Key Laboratory of Molecular Developmental BiologyInstitute of Genetics and Developmental BiologyChinese Academy of SciencesBeijingChina
| | - Xuehua Ma
- State Key Laboratory of Molecular Developmental BiologyInstitute of Genetics and Developmental BiologyChinese Academy of SciencesBeijingChina
| | - Zhuo Du
- State Key Laboratory of Molecular Developmental BiologyInstitute of Genetics and Developmental BiologyChinese Academy of SciencesBeijingChina
- University of Chinese Academy of SciencesBeijingChina
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18
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Zhang C, Cheng Q, Wang H, Gao H, Fang X, Chen X, Zhao M, Wei W, Song B, Liu S, Wu J, Zhang S, Xu P. GmBTB/POZ promotes the ubiquitination and degradation of LHP1 to regulate the response of soybean to Phytophthora sojae. Commun Biol 2021; 4:372. [PMID: 33742112 PMCID: PMC7979691 DOI: 10.1038/s42003-021-01907-7] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2019] [Accepted: 02/24/2021] [Indexed: 01/07/2023] Open
Abstract
Phytophthora sojae is a pathogen that causes stem and root rot in soybean (Glycine max [L.] Merr.). We previously demonstrated that GmBTB/POZ, a BTB/POZ domain-containing nuclear protein, enhances resistance to P. sojae in soybean, via a process that depends on salicylic acid (SA). Here, we demonstrate that GmBTB/POZ associates directly with soybean LIKE HETEROCHROMATIN PROTEIN1 (GmLHP1) in vitro and in vivo and promotes its ubiquitination and degradation. Both overexpression and RNA interference analysis of transgenic lines demonstrate that GmLHP1 negatively regulates the response of soybean to P. sojae by reducing SA levels and repressing GmPR1 expression. The WRKY transcription factor gene, GmWRKY40, a SA-induced gene in the SA signaling pathway, is targeted by GmLHP1, which represses its expression via at least two mechanisms (directly binding to its promoter and impairing SA accumulation). Furthermore, the nuclear localization of GmLHP1 is required for the GmLHP1-mediated negative regulation of immunity, SA levels and the suppression of GmWRKY40 expression. Finally, GmBTB/POZ releases GmLHP1-regulated GmWRKY40 suppression and increases resistance to P. sojae in GmLHP1-OE hairy roots. These findings uncover a regulatory mechanism by which GmBTB/POZ-GmLHP1 modulates resistance to P. sojae in soybean, likely by regulating the expression of downstream target gene GmWRKY40.
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Affiliation(s)
- Chuanzhong Zhang
- Soybean Research Institute, Northeast Agricultural University, Key Laboratory of Soybean Biology of Chinese Education Ministry, Harbin, China
- Key Laboratory of Soybean Molecular Design Breeding, Northeast Institute of Geography and Agroecology, Chinese Academy of Sciences, Harbin, China
| | - Qun Cheng
- Soybean Research Institute, Northeast Agricultural University, Key Laboratory of Soybean Biology of Chinese Education Ministry, Harbin, China
| | - Huiyu Wang
- Soybean Research Institute, Northeast Agricultural University, Key Laboratory of Soybean Biology of Chinese Education Ministry, Harbin, China
| | - Hong Gao
- Soybean Research Institute, Northeast Agricultural University, Key Laboratory of Soybean Biology of Chinese Education Ministry, Harbin, China
| | - Xin Fang
- Soybean Research Institute, Northeast Agricultural University, Key Laboratory of Soybean Biology of Chinese Education Ministry, Harbin, China
| | - Xi Chen
- Soybean Research Institute, Northeast Agricultural University, Key Laboratory of Soybean Biology of Chinese Education Ministry, Harbin, China
| | - Ming Zhao
- Soybean Research Institute, Northeast Agricultural University, Key Laboratory of Soybean Biology of Chinese Education Ministry, Harbin, China
| | - Wanling Wei
- Soybean Research Institute, Northeast Agricultural University, Key Laboratory of Soybean Biology of Chinese Education Ministry, Harbin, China
| | - Bo Song
- Soybean Research Institute, Northeast Agricultural University, Key Laboratory of Soybean Biology of Chinese Education Ministry, Harbin, China
| | - Shanshan Liu
- Soybean Research Institute, Northeast Agricultural University, Key Laboratory of Soybean Biology of Chinese Education Ministry, Harbin, China
| | - Junjiang Wu
- Soybean Research Institute of Heilongjiang Academy of Agricultural Sciences, Key Laboratory of Soybean Cultivation of Ministry of Agriculture, Harbin, China
| | - Shuzhen Zhang
- Soybean Research Institute, Northeast Agricultural University, Key Laboratory of Soybean Biology of Chinese Education Ministry, Harbin, China.
| | - Pengfei Xu
- Soybean Research Institute, Northeast Agricultural University, Key Laboratory of Soybean Biology of Chinese Education Ministry, Harbin, China.
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19
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Keenen MM, Brown D, Brennan LD, Renger R, Khoo H, Carlson CR, Huang B, Grill SW, Narlikar GJ, Redding S. HP1 proteins compact DNA into mechanically and positionally stable phase separated domains. eLife 2021; 10:e64563. [PMID: 33661100 PMCID: PMC7932698 DOI: 10.7554/elife.64563] [Citation(s) in RCA: 103] [Impact Index Per Article: 34.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2020] [Accepted: 02/22/2021] [Indexed: 12/11/2022] Open
Abstract
In mammals, HP1-mediated heterochromatin forms positionally and mechanically stable genomic domains even though the component HP1 paralogs, HP1α, HP1β, and HP1γ, display rapid on-off dynamics. Here, we investigate whether phase-separation by HP1 proteins can explain these biological observations. Using bulk and single-molecule methods, we show that, within phase-separated HP1α-DNA condensates, HP1α acts as a dynamic liquid, while compacted DNA molecules are constrained in local territories. These condensates are resistant to large forces yet can be readily dissolved by HP1β. Finally, we find that differences in each HP1 paralog's DNA compaction and phase-separation properties arise from their respective disordered regions. Our findings suggest a generalizable model for genome organization in which a pool of weakly bound proteins collectively capitalize on the polymer properties of DNA to produce self-organizing domains that are simultaneously resistant to large forces at the mesoscale and susceptible to competition at the molecular scale.
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Affiliation(s)
- Madeline M Keenen
- Department of Biochemistry and Biophysics, University of California, San FranciscoSan FranciscoUnited States
- Tetrad Graduate Program, University of California, San FranciscoSan FranciscoUnited States
| | - David Brown
- Department of Pharmaceutical Chemistry, University of California, San FranciscoSan FranciscoUnited States
| | - Lucy D Brennan
- Department of Biochemistry and Biophysics, University of California, San FranciscoSan FranciscoUnited States
| | - Roman Renger
- Max Planck Institute of Molecular Cell Biology and GeneticsDresdenGermany
- German Center for Neurodegenerative Diseases (DZNE)BonnGermany
| | - Harrison Khoo
- Department of Mechanical Engineering, Johns Hopkins UniversityBaltimoreUnited States
| | - Christopher R Carlson
- Tetrad Graduate Program, University of California, San FranciscoSan FranciscoUnited States
- Department of Physiology, University of California, San FranciscoSan FranciscoUnited States
| | - Bo Huang
- Department of Biochemistry and Biophysics, University of California, San FranciscoSan FranciscoUnited States
- Department of Pharmaceutical Chemistry, University of California, San FranciscoSan FranciscoUnited States
- Chan Zuckerberg BiohubSan FranciscoUnited States
| | - Stephan W Grill
- Max Planck Institute of Molecular Cell Biology and GeneticsDresdenGermany
- Cluster of Excellence Physics of Life, Technische Universität DresdenDresdenGermany
| | - Geeta J Narlikar
- Department of Biochemistry and Biophysics, University of California, San FranciscoSan FranciscoUnited States
| | - Sy Redding
- Department of Biochemistry and Biophysics, University of California, San FranciscoSan FranciscoUnited States
- Marine Biological LaboratoryWoods HoleUnited States
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20
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Vidaurre V, Chen X. Epigenetic regulation of drosophila germline stem cell maintenance and differentiation. Dev Biol 2021; 473:105-118. [PMID: 33610541 DOI: 10.1016/j.ydbio.2021.02.003] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2020] [Revised: 01/26/2021] [Accepted: 02/06/2021] [Indexed: 12/13/2022]
Abstract
Gametogenesis is one of the most extreme cellular differentiation processes that takes place in Drosophila male and female germlines. This process begins at the germline stem cell, which undergoes asymmetric cell division (ACD) to produce a self-renewed daughter that preserves its stemness and a differentiating daughter cell that undergoes epigenetic and genomic changes to eventually produce haploid gametes. Research in molecular genetics and cellular biology are beginning to take advantage of the continually advancing genomic tools to understand: (1) how germ cells are able to maintain their identity throughout the adult reproductive lifetime, and (2) undergo differentiation in a balanced manner. In this review, we focus on the epigenetic mechanisms that address these two questions through their regulation of germline-soma communication to ensure germline stem cell identity and activity.
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Affiliation(s)
- Velinda Vidaurre
- Department of Biology, The Johns Hopkins University, 3400 North Charles Street, Baltimore, Baltimore, MD, 21218, USA
| | - Xin Chen
- Department of Biology, The Johns Hopkins University, 3400 North Charles Street, Baltimore, Baltimore, MD, 21218, USA.
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21
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Bui HTN, Passecker A, Brancucci NMB, Voss TS. Investigation of Heterochromatin Protein 1 Function in the Malaria Parasite Plasmodium falciparum Using a Conditional Domain Deletion and Swapping Approach. mSphere 2021; 6:e01220-20. [PMID: 33536327 PMCID: PMC7860992 DOI: 10.1128/msphere.01220-20] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2020] [Accepted: 01/15/2021] [Indexed: 12/12/2022] Open
Abstract
The human malaria parasite Plasmodium falciparum encodes a single ortholog of heterochromatin protein 1 (PfHP1) that plays a crucial role in the epigenetic regulation of various survival-related processes. PfHP1 is essential for parasite proliferation and the heritable silencing of genes linked to antigenic variation, host cell invasion, and sexual conversion. Here, we employed CRISPR/Cas9-mediated genome editing combined with the DiCre/loxP system to investigate how the PfHP1 chromodomain (CD), hinge domain, and chromoshadow domain (CSD) contribute to overall PfHP1 function. We show that the 76 C-terminal residues are responsible for targeting PfHP1 to the nucleus. Furthermore, we reveal that each of the three functional domains of PfHP1 are required for heterochromatin formation, gene silencing, and mitotic parasite proliferation. Finally, we discovered that the hinge domain and CSD of HP1 are functionally conserved between P. falciparum and P. berghei, a related malaria parasite infecting rodents. In summary, our study provides new insights into PfHP1 function and offers a tool for further studies on epigenetic regulation and life cycle decision in malaria parasites.IMPORTANCE Malaria is caused by unicellular Plasmodium species parasites that repeatedly invade and replicate inside red blood cells. Some blood-stage parasites exit the cell cycle and differentiate into gametocytes that are essential for malaria transmission via the mosquito vector. Epigenetic control mechanisms allow the parasites to alter the expression of surface antigens and to balance the switch between parasite multiplication and gametocyte production. These processes are crucial to establish chronic infection and optimize parasite transmission. Here, we performed a mutational analysis of heterochromatin protein 1 (HP1) in P. falciparum We demonstrate that all three domains of this protein are indispensable for the proper function of HP1 in parasite multiplication, heterochromatin formation, and gene silencing. Moreover, expression of chimeric proteins revealed the functional conservation of HP1 proteins between different Plasmodium species. These results provide new insight into the function and evolution of HP1 as an essential epigenetic regulator of parasite survival.
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Affiliation(s)
- Hai T N Bui
- Department of Medical Parasitology and Infection Biology, Swiss Tropical and Public Health Institute, Basel, Switzerland
- University of Basel, Basel, Switzerland
| | - Armin Passecker
- Department of Medical Parasitology and Infection Biology, Swiss Tropical and Public Health Institute, Basel, Switzerland
- University of Basel, Basel, Switzerland
| | - Nicolas M B Brancucci
- Department of Medical Parasitology and Infection Biology, Swiss Tropical and Public Health Institute, Basel, Switzerland
- University of Basel, Basel, Switzerland
| | - Till S Voss
- Department of Medical Parasitology and Infection Biology, Swiss Tropical and Public Health Institute, Basel, Switzerland
- University of Basel, Basel, Switzerland
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22
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Zaidan NZ, Sridharan R. HP1γ regulates H3K36 methylation and pluripotency in embryonic stem cells. Nucleic Acids Res 2020; 48:12660-12674. [PMID: 33237287 PMCID: PMC7736818 DOI: 10.1093/nar/gkaa1091] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2020] [Revised: 10/12/2020] [Accepted: 10/27/2020] [Indexed: 01/01/2023] Open
Abstract
The heterochromatin protein 1 (HP1) family members are canonical effectors and propagators of gene repression mediated by histone H3 lysine 9 (H3K9) methylation. HP1γ exhibits an increased interaction with active transcription elongation-associated factors in embryonic stem cells (ESCs) compared to somatic cells. However, whether this association has a functional consequence remains elusive. Here we find that genic HP1γ colocalizes and enhances enrichment of transcription elongation-associated H3K36me3 rather than H3K9me3. Unexpectedly, sustained H3K36me3 deposition is dependent on HP1γ. HP1γ-deleted ESCs display reduced H3K36me3 enrichment, concomitant with decreased expression at shared genes which function to maintain cellular homeostasis. Both the H3K9me3-binding chromodomain and histone binding ability of HP1γ are dispensable for maintaining H3K36me3 levels. Instead, the chromoshadow together with the hinge domain of HP1γ that confer protein and nucleic acid-binding ability are sufficient because they retain the ability to interact with NSD1, an H3K36 methyltransferase. HP1γ-deleted ESCs have a slower self-renewal rate and an impaired ability to differentiate towards cardiac mesoderm. Our findings reveal a requirement for HP1γ in faithful establishment of transcription elongation in ESCs, which regulates pluripotency.
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Affiliation(s)
- Nur Zafirah Zaidan
- Wisconsin Institute for Discovery, University of Wisconsin-Madison, Madison, WI 53715, USA.,Genetics Training Program, University of Wisconsin-Madison, Madison, WI 53715, USA
| | - Rupa Sridharan
- Wisconsin Institute for Discovery, University of Wisconsin-Madison, Madison, WI 53715, USA.,Department of Cell and Regenerative Biology, University of Wisconsin-Madison, Madison, WI 53715, USA
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23
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Himeda CL, Jones TI, Jones PL. Targeted epigenetic repression by CRISPR/dSaCas9 suppresses pathogenic DUX4-fl expression in FSHD. MOLECULAR THERAPY-METHODS & CLINICAL DEVELOPMENT 2020; 20:298-311. [PMID: 33511244 PMCID: PMC7806950 DOI: 10.1016/j.omtm.2020.12.001] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/01/2020] [Accepted: 12/02/2020] [Indexed: 02/07/2023]
Abstract
Facioscapulohumeral muscular dystrophy (FSHD) is caused by incomplete silencing of the disease locus, leading to pathogenic misexpression of DUX4 in skeletal muscle. Previously, we showed that CRISPR inhibition could successfully target and repress DUX4 in FSHD myocytes. However, an effective therapy will require both efficient delivery of therapeutic components to skeletal muscles and long-term repression of the disease locus. Thus, we re-engineered our platform to allow in vivo delivery of more potent epigenetic repressors. We designed an FSHD-optimized regulatory cassette to drive skeletal muscle-specific expression of dCas9 from Staphylococcus aureus fused to HP1α, HP1γ, the MeCP2 transcriptional repression domain, or the SUV39H1 SET domain. Targeting each regulator to the DUX4 promoter/exon 1 increased chromatin repression at the locus, specifically suppressing DUX4 and its target genes in FSHD myocytes and in a mouse model of the disease. Importantly, minimizing the regulatory cassette and using the smaller Cas9 ortholog allowed our therapeutic cassettes to be effectively packaged into adeno-associated virus (AAV) vectors for in vivo delivery. By engineering a muscle-specific epigenetic CRISPR platform compatible with AAV vectors for gene therapy, we have laid the groundwork for clinical use of dCas9-based chromatin effectors in skeletal muscle disorders.
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Affiliation(s)
- Charis L. Himeda
- Department of Pharmacology, University of Nevada, Reno School of Medicine, Reno, NV 89557, USA
| | - Takako I. Jones
- Department of Pharmacology, University of Nevada, Reno School of Medicine, Reno, NV 89557, USA
| | - Peter L. Jones
- Department of Pharmacology, University of Nevada, Reno School of Medicine, Reno, NV 89557, USA
- Corresponding author Peter L. Jones, Department of Pharmacology, Center for Molecular Medicine/MS-0318, University of Nevada, Reno School of Medicine, 1664 N. Virginia St., Reno, NV 89557, USA.
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Phillips RE, Soshnev AA, Allis CD. Epigenomic Reprogramming as a Driver of Malignant Glioma. Cancer Cell 2020; 38:647-660. [PMID: 32916125 PMCID: PMC8248764 DOI: 10.1016/j.ccell.2020.08.008] [Citation(s) in RCA: 62] [Impact Index Per Article: 15.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/18/2020] [Revised: 07/21/2020] [Accepted: 08/10/2020] [Indexed: 12/13/2022]
Abstract
Malignant gliomas are central nervous system tumors and remain among the most treatment-resistant cancers. Exome sequencing has revealed significant heterogeneity and important insights into the molecular pathogenesis of gliomas. Mutations in chromatin modifiers-proteins that shape the epigenomic landscape through remodeling and regulation of post-translational modifications on chromatin-are very frequent and often define specific glioma subtypes. This suggests that epigenomic reprogramming may be a fundamental driver of glioma. Here, we describe the key chromatin regulatory pathways disrupted in gliomas, delineating their physiological function and our current understanding of how their dysregulation may contribute to gliomagenesis.
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Affiliation(s)
- Richard E Phillips
- Department of Neurology and Brain Tumor Center, Memorial Sloan Kettering Cancer Center, New York, NY 10065, USA; Laboratory of Chromatin Biology and Epigenetics, The Rockefeller University, New York, NY 10065, USA.
| | - Alexey A Soshnev
- Laboratory of Chromatin Biology and Epigenetics, The Rockefeller University, New York, NY 10065, USA
| | - C David Allis
- Laboratory of Chromatin Biology and Epigenetics, The Rockefeller University, New York, NY 10065, USA.
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25
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From 1957 to Nowadays: A Brief History of Epigenetics. Int J Mol Sci 2020; 21:ijms21207571. [PMID: 33066397 PMCID: PMC7588895 DOI: 10.3390/ijms21207571] [Citation(s) in RCA: 68] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2020] [Revised: 10/07/2020] [Accepted: 10/13/2020] [Indexed: 01/01/2023] Open
Abstract
Due to the spectacular number of studies focusing on epigenetics in the last few decades, and particularly for the last few years, the availability of a chronology of epigenetics appears essential. Indeed, our review places epigenetic events and the identification of the main epigenetic writers, readers and erasers on a historic scale. This review helps to understand the increasing knowledge in molecular and cellular biology, the development of new biochemical techniques and advances in epigenetics and, more importantly, the roles played by epigenetics in many physiological and pathological situations.
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26
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Meyer-Nava S, Nieto-Caballero VE, Zurita M, Valadez-Graham V. Insights into HP1a-Chromatin Interactions. Cells 2020; 9:E1866. [PMID: 32784937 PMCID: PMC7465937 DOI: 10.3390/cells9081866] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2020] [Revised: 07/18/2020] [Accepted: 07/21/2020] [Indexed: 12/17/2022] Open
Abstract
Understanding the packaging of DNA into chromatin has become a crucial aspect in the study of gene regulatory mechanisms. Heterochromatin establishment and maintenance dynamics have emerged as some of the main features involved in genome stability, cellular development, and diseases. The most extensively studied heterochromatin protein is HP1a. This protein has two main domains, namely the chromoshadow and the chromodomain, separated by a hinge region. Over the years, several works have taken on the task of identifying HP1a partners using different strategies. In this review, we focus on describing these interactions and the possible complexes and subcomplexes associated with this critical protein. Characterization of these complexes will help us to clearly understand the implications of the interactions of HP1a in heterochromatin maintenance, heterochromatin dynamics, and heterochromatin's direct relationship to gene regulation and chromatin organization.
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Affiliation(s)
| | | | | | - Viviana Valadez-Graham
- Instituto de Biotecnología, Departamento de Genética del Desarrollo y Fisiología Molecular, Universidad Nacional Autónoma de México, Cuernavaca Morelos 62210, Mexico; (S.M.-N.); (V.E.N.-C.); (M.Z.)
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27
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Palladino J, Chavan A, Sposato A, Mason TD, Mellone BG. Targeted De Novo Centromere Formation in Drosophila Reveals Plasticity and Maintenance Potential of CENP-A Chromatin. Dev Cell 2020; 52:379-394.e7. [PMID: 32049040 DOI: 10.1016/j.devcel.2020.01.005] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2019] [Revised: 10/17/2019] [Accepted: 01/06/2020] [Indexed: 11/25/2022]
Abstract
Centromeres are essential for accurate chromosome segregation and are marked by centromere protein A (CENP-A) nucleosomes. Mis-targeted CENP-A chromatin has been shown to seed centromeres at non-centromeric DNA. However, the requirements for such de novo centromere formation and transmission in vivo remain unknown. Here, we employ Drosophila melanogaster and the LacI/lacO system to investigate the ability of targeted de novo centromeres to assemble and be inherited through development. De novo centromeres form efficiently at six distinct genomic locations, which include actively transcribed chromatin and heterochromatin, and cause widespread chromosomal instability. During tethering, de novo centromeres sometimes prevail, causing the loss of the endogenous centromere via DNA breaks and HP1-dependent epigenetic inactivation. Transient induction of de novo centromeres and chromosome healing in early embryogenesis show that, once established, these centromeres can be maintained through development. Our results underpin the ability of CENP-A chromatin to establish and sustain mitotic centromere function in Drosophila.
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Affiliation(s)
- Jason Palladino
- Department of Molecular and Cell Biology, University of Connecticut, Storrs, CT 06269, USA
| | - Ankita Chavan
- Department of Molecular and Cell Biology, University of Connecticut, Storrs, CT 06269, USA
| | - Anthony Sposato
- Department of Molecular and Cell Biology, University of Connecticut, Storrs, CT 06269, USA
| | - Timothy D Mason
- Department of Molecular and Cell Biology, University of Connecticut, Storrs, CT 06269, USA
| | - Barbara G Mellone
- Department of Molecular and Cell Biology, University of Connecticut, Storrs, CT 06269, USA; Institute for Systems Genomics, University of Connecticut, Storrs, CT 06269, USA.
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28
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Kochanova NY, Schauer T, Mathias GP, Lukacs A, Schmidt A, Flatley A, Schepers A, Thomae AW, Imhof A. A multi-layered structure of the interphase chromocenter revealed by proximity-based biotinylation. Nucleic Acids Res 2020; 48:4161-4178. [PMID: 32182352 PMCID: PMC7192626 DOI: 10.1093/nar/gkaa145] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2019] [Revised: 02/18/2020] [Accepted: 02/25/2020] [Indexed: 12/26/2022] Open
Abstract
During interphase centromeres often coalesce into a small number of chromocenters, which can be visualized as distinct, DAPI dense nuclear domains. Intact chromocenters play a major role in maintaining genome stability as they stabilize the transcriptionally silent state of repetitive DNA while ensuring centromere function. Despite its biological importance, relatively little is known about the molecular composition of the chromocenter or the processes that mediate chromocenter formation and maintenance. To provide a deeper molecular insight into the composition of the chromocenter and to demonstrate the usefulness of proximity-based biotinylation as a tool to investigate those questions, we performed super resolution microscopy and proximity-based biotinylation experiments of three distinct proteins associated with the chromocenter in Drosophila. Our work revealed an intricate internal architecture of the chromocenter suggesting a complex multilayered structure of this intranuclear domain.
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Affiliation(s)
- Natalia Y Kochanova
- Biomedical Center, Chromatin Proteomics Group, Department of Molecular Biology, Faculty of Medicine, Ludwig-Maximilians-Universität München, Großhaderner Strasse 9, 82152 Planegg-Martinsried, Germany
| | - Tamas Schauer
- Biomedical Center, Bioinformatics Core Facility, Ludwig-Maximilians-Universität München, Großhaderner Strasse 9, 82152 Planegg-Martinsried, Germany
| | - Grusha Primal Mathias
- Biomedical Center, Core Facility Bioimaging, Ludwig-Maximilians-Universität München, Großhaderner Strasse 9, 82152 Planegg-Martinsried, Germany
| | - Andrea Lukacs
- Biomedical Center, Chromatin Proteomics Group, Department of Molecular Biology, Faculty of Medicine, Ludwig-Maximilians-Universität München, Großhaderner Strasse 9, 82152 Planegg-Martinsried, Germany
| | - Andreas Schmidt
- Biomedical Center, Protein Analysis Unit, Faculty of Medicine, Ludwig-Maximilians-Universität München, Großhaderner Strasse 9, 82152 Planegg-Martinsried, Germany
| | - Andrew Flatley
- Helmholtz Zentrum München, Deutsches Forschungszentrum für Gesundheit und Umwelt (GmbH), Institute for Diabetes and Obesity, Monoclonal Antibody Core Facility and Research Group Ingolstädter Landstr. 1, 85764 Neuherberg, Germany
| | - Aloys Schepers
- Helmholtz Zentrum München, Deutsches Forschungszentrum für Gesundheit und Umwelt (GmbH), Institute for Diabetes and Obesity, Monoclonal Antibody Core Facility and Research Group Ingolstädter Landstr. 1, 85764 Neuherberg, Germany
| | - Andreas W Thomae
- Biomedical Center, Core Facility Bioimaging, Ludwig-Maximilians-Universität München, Großhaderner Strasse 9, 82152 Planegg-Martinsried, Germany
| | - Axel Imhof
- Biomedical Center, Chromatin Proteomics Group, Department of Molecular Biology, Faculty of Medicine, Ludwig-Maximilians-Universität München, Großhaderner Strasse 9, 82152 Planegg-Martinsried, Germany
- Biomedical Center, Protein Analysis Unit, Faculty of Medicine, Ludwig-Maximilians-Universität München, Großhaderner Strasse 9, 82152 Planegg-Martinsried, Germany
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29
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Kumar A, Kono H. Heterochromatin protein 1 (HP1): interactions with itself and chromatin components. Biophys Rev 2020; 12:387-400. [PMID: 32144738 PMCID: PMC7242596 DOI: 10.1007/s12551-020-00663-y] [Citation(s) in RCA: 36] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2020] [Accepted: 02/23/2020] [Indexed: 12/12/2022] Open
Abstract
Isoforms of heterochromatin protein 1 (HP1) have been known to perform a multitude of functions ranging from gene silencing, gene activation to cell cycle regulation, and cell differentiation. This functional diversity arises from the dissimilarities coded in protein sequence which confers different biophysical and biochemical properties to individual structural elements of HP1 and thereby different behavior and interaction patterns. Hence, an understanding of various interactions of the structural elements of HP1 will be of utmost importance to better elucidate chromatin dynamics in its presence. In this review, we have gathered available information about interactions of HP1 both within and with itself as well as with chromatin elements. Also, the possible implications of these interactions are discussed.
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Affiliation(s)
- Amarjeet Kumar
- Molecular Modelling and Simulation (MMS) Group, Institute for Quantum Life Science (iQLS), National Institutes for Quantum and Radiological Science and Technology (QST), Kizugawa, Kyoto, 619-0215, Japan
| | - Hidetoshi Kono
- Molecular Modelling and Simulation (MMS) Group, Institute for Quantum Life Science (iQLS), National Institutes for Quantum and Radiological Science and Technology (QST), Kizugawa, Kyoto, 619-0215, Japan.
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30
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Pericentromeric heterochromatin is hierarchically organized and spatially contacts H3K9me2 islands in euchromatin. PLoS Genet 2020; 16:e1008673. [PMID: 32203508 PMCID: PMC7147806 DOI: 10.1371/journal.pgen.1008673] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2019] [Revised: 04/10/2020] [Accepted: 02/14/2020] [Indexed: 01/02/2023] Open
Abstract
Membraneless pericentromeric heterochromatin (PCH) domains play vital roles in chromosome dynamics and genome stability. However, our current understanding of 3D genome organization does not include PCH domains because of technical challenges associated with repetitive sequences enriched in PCH genomic regions. We investigated the 3D architecture of Drosophila melanogaster PCH domains and their spatial associations with the euchromatic genome by developing a novel analysis method that incorporates genome-wide Hi-C reads originating from PCH DNA. Combined with cytogenetic analysis, we reveal a hierarchical organization of the PCH domains into distinct “territories.” Strikingly, H3K9me2-enriched regions embedded in the euchromatic genome show prevalent 3D interactions with the PCH domain. These spatial contacts require H3K9me2 enrichment, are likely mediated by liquid-liquid phase separation, and may influence organismal fitness. Our findings have important implications for how PCH architecture influences the function and evolution of both repetitive heterochromatin and the gene-rich euchromatin. The three dimensional (3D) organization of genomes in cell nuclei can influence a wide variety of genome functions. However, most of our understanding of this critical architecture has been limited to the gene-rich euchromatin, and largely ignores the gene-poor and repeat-rich pericentromeric heterochromatin, or PCH. PCH comprises a large part of most eukaryotic genomes, forms 3D membraneless PCH domains in nuclei, and plays a vital role in chromosome dynamics and genome stability. In this study, we developed a new method that overcomes the technical challenges imposed by the highly repetitive PCH DNA, and generated a comprehensive picture of its 3D organization. Combined with image analyses, we reveal a hierarchical organization of the PCH domains. Surprisingly, we showed that distant euchromatic regions enriched for repressive epigenetic marks also dynamically interact with the main PCH domains. These 3D interactions are likely mediated by liquid-liquid phase separation (similar to how oil and vinegar separate in salad dressing) and the resulting liquid-like fusion events, and can influence the fitness of individuals. Our discoveries have strong implications for how seemingly “junk” DNA could impact functions in the gene-rich euchromatin.
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31
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Mathison A, Milech De Assuncao T, Dsouza NR, Williams M, Zimmermann MT, Urrutia R, Lomberk G. Discovery, expression, cellular localization, and molecular properties of a novel, alternative spliced HP1γ isoform, lacking the chromoshadow domain. PLoS One 2020; 15:e0217452. [PMID: 32027651 PMCID: PMC7004349 DOI: 10.1371/journal.pone.0217452] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2019] [Accepted: 01/16/2020] [Indexed: 12/13/2022] Open
Abstract
By reading the H3K9Me3 mark through their N-terminal chromodomain (CD), HP1 proteins play a significant role in cancer-associated processes, including cell proliferation, differentiation, chromosomal stability, and DNA repair. Here, we used a combination of bioinformatics-based methodologies, as well as experimentally-derived datasets, that reveal the existence of a novel short HP1γ (CBX3) isoform, named here sHP1γ, generated by alternative splicing of the CBX3 locus. The sHP1γ mRNA encodes a protein composed of 101 residues and lacks the C-terminal chromoshadow domain (CSD) that is required for dimerization and heterodimerization in the previously described 183 a. a HP1γ protein. Fold recognition, order-to-disorder calculations, threading, homology-based molecular modeling, docking, and molecular dynamic simulations show that the sHP1γ is comprised of a CD flanked by intrinsically disordered regions (IDRs) with an IDR-CD-IDR domain organization and likely retains the ability to bind to the H3K9Me3. Both qPCR analyses and mRNA-seq data derived from large-scale studies confirmed that sHP1γ mRNA is expressed in the majority of human tissues at approximately constant ratios with the chromoshadow domain containing isoform. However, sHP1γ mRNA levels appear to be dysregulated in different cancer types. Thus, our data supports the notion that, due to the existence of functionally different isoforms, the regulation of HP1γ-mediated functions is more complex than previously anticipated.
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Affiliation(s)
- Angela Mathison
- Genomics and Precision Medicine Center (GSPMC), Medical College of Wisconsin, Milwaukee, Wisconsin, United States of America
- Division of Research, Department of Surgery, Medical College of Wisconsin, WI Center, Medical College of Wisconsin, Milwaukee, Wisconsin, United States of America
| | - Thiago Milech De Assuncao
- Genomics and Precision Medicine Center (GSPMC), Medical College of Wisconsin, Milwaukee, Wisconsin, United States of America
- Division of Research, Department of Surgery, Medical College of Wisconsin, WI Center, Medical College of Wisconsin, Milwaukee, Wisconsin, United States of America
| | - Nikita R. Dsouza
- Bioinformatics Research and Development Laboratory, and Precision Medicine Simulation Unit, Genomics and Precision Medicine Center (GSPMC), Medical College of Wisconsin, Milwaukee, Wisconsin, United States of America
| | - Monique Williams
- Department of Surgery, Duke University Medical Center, Durham, North Carolina, United States of America
| | - Michael T. Zimmermann
- Bioinformatics Research and Development Laboratory, and Precision Medicine Simulation Unit, Genomics and Precision Medicine Center (GSPMC), Medical College of Wisconsin, Milwaukee, Wisconsin, United States of America
- Clinical and Translational Sciences Institute, Medical College of Wisconsin, Milwaukee, Wisconsin, United States of America
| | - Raul Urrutia
- Genomics and Precision Medicine Center (GSPMC), Medical College of Wisconsin, Milwaukee, Wisconsin, United States of America
- Division of Research, Department of Surgery, Medical College of Wisconsin, WI Center, Medical College of Wisconsin, Milwaukee, Wisconsin, United States of America
- Department of Biochemistry, Medical College of Wisconsin, Milwaukee, Wisconsin, United States of America
| | - Gwen Lomberk
- Genomics and Precision Medicine Center (GSPMC), Medical College of Wisconsin, Milwaukee, Wisconsin, United States of America
- Division of Research, Department of Surgery, Medical College of Wisconsin, WI Center, Medical College of Wisconsin, Milwaukee, Wisconsin, United States of America
- Department of Pharmacology and Toxicology, Medical College of Wisconsin, Milwaukee, Wisconsin, United States of America
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32
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The mouse HP1 proteins are essential for preventing liver tumorigenesis. Oncogene 2020; 39:2676-2691. [PMID: 32020053 DOI: 10.1038/s41388-020-1177-8] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2019] [Revised: 01/06/2020] [Accepted: 01/21/2020] [Indexed: 12/16/2022]
Abstract
Chromatin organization is essential for appropriate interpretation of the genetic information. Here, we demonstrated that the chromatin-associated proteins HP1 are dispensable for hepatocytes survival but are essential within hepatocytes to prevent liver tumor development in mice with HP1β being pivotal in these functions. Yet, we found that the loss of HP1 per se is not sufficient to induce cell transformation but renders cells more resistant to specific stress such as the expression of oncogenes and thus in fine, more prone to cell transformation. Molecular characterization of HP1-Triple KO premalignant livers and BMEL cells revealed that HP1 are essential for the maintenance of heterochromatin organization and for the regulation of specific genes with most of them having well characterized functions in liver functions and homeostasis. We further showed that some specific retrotransposons get reactivated upon loss of HP1, correlating with overexpression of genes in their neighborhood. Interestingly, we found that, although HP1-dependent genes are characterized by enrichment H3K9me3, this mark does not require HP1 for its maintenance and is not sufficient to maintain gene repression in absence of HP1. Finally, we demonstrated that the loss of TRIM28 association with HP1 recapitulated several phenotypes induced by the loss of HP1 including the reactivation of some retrotransposons and the increased incidence of liver cancer development. Altogether, our findings indicate that HP1 proteins act as guardians of liver homeostasis to prevent tumor development by modulating multiple chromatin-associated events within both the heterochromatic and euchromatic compartments, partly through regulation of the corepressor TRIM28 activity.
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33
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Benner L, Castro EA, Whitworth C, Venken KJT, Yang H, Fang J, Oliver B, Cook KR, Lerit DA. Drosophila Heterochromatin Stabilization Requires the Zinc-Finger Protein Small Ovary. Genetics 2019; 213:877-895. [PMID: 31558581 PMCID: PMC6827387 DOI: 10.1534/genetics.119.302590] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2019] [Accepted: 09/21/2019] [Indexed: 02/04/2023] Open
Abstract
Heterochromatin-mediated repression is essential for controlling the expression of transposons and for coordinated cell type-specific gene regulation. The small ovary (sov) locus was identified in a screen for female-sterile mutations in Drosophila melanogaster, and mutants show dramatic ovarian morphogenesis defects. We show that the null sov phenotype is lethal and map the locus to the uncharacterized gene CG14438, which encodes a nuclear zinc-finger protein that colocalizes with the essential Heterochromatin Protein 1 (HP1a). We demonstrate Sov functions to repress inappropriate gene expression in the ovary, silence transposons, and suppress position-effect variegation in the eye, suggesting a central role in heterochromatin stabilization.
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Affiliation(s)
- Leif Benner
- Section of Developmental Genomics, Laboratory of Cellular and Developmental Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892
- Department of Biology, Johns Hopkins University, Baltimore, Maryland 21218
| | - Elias A Castro
- Department of Cell Biology, Emory University School of Medicine, Atlanta, Georgia 30322
| | - Cale Whitworth
- Section of Developmental Genomics, Laboratory of Cellular and Developmental Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892
- Department of Biology, Indiana University, Bloomington, Indiana 47405
| | - Koen J T Venken
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology
- McNair Medical Institute at the Robert and Janice McNair Foundation
- Dan L. Duncan Cancer Center, Center for Drug Discovery
- Department of Pharmacology and Chemical Biology, Baylor College of Medicine, Houston, Texas 77030
| | - Haiwang Yang
- Section of Developmental Genomics, Laboratory of Cellular and Developmental Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892
| | - Junnan Fang
- Department of Cell Biology, Emory University School of Medicine, Atlanta, Georgia 30322
| | - Brian Oliver
- Section of Developmental Genomics, Laboratory of Cellular and Developmental Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892
| | - Kevin R Cook
- Department of Biology, Indiana University, Bloomington, Indiana 47405
| | - Dorothy A Lerit
- Department of Cell Biology, Emory University School of Medicine, Atlanta, Georgia 30322
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Romero-Bueno R, de la Cruz Ruiz P, Artal-Sanz M, Askjaer P, Dobrzynska A. Nuclear Organization in Stress and Aging. Cells 2019; 8:cells8070664. [PMID: 31266244 PMCID: PMC6678840 DOI: 10.3390/cells8070664] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2019] [Revised: 06/23/2019] [Accepted: 06/25/2019] [Indexed: 12/18/2022] Open
Abstract
The eukaryotic nucleus controls most cellular processes. It is isolated from the cytoplasm by the nuclear envelope, which plays a prominent role in the structural organization of the cell, including nucleocytoplasmic communication, chromatin positioning, and gene expression. Alterations in nuclear composition and function are eminently pronounced upon stress and during premature and physiological aging. These alterations are often accompanied by epigenetic changes in histone modifications. We review, here, the role of nuclear envelope proteins and histone modifiers in the 3-dimensional organization of the genome and the implications for gene expression. In particular, we focus on the nuclear lamins and the chromatin-associated protein BAF, which are linked to Hutchinson–Gilford and Nestor–Guillermo progeria syndromes, respectively. We also discuss alterations in nuclear organization and the epigenetic landscapes during normal aging and various stress conditions, ranging from yeast to humans.
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Affiliation(s)
- Raquel Romero-Bueno
- Andalusian Center for Developmental Biology (CABD), Consejo Superior de Investigaciones Científicas/Junta de Andalucia/Universidad Pablo de Olavide, 41013 Seville, Spain
| | - Patricia de la Cruz Ruiz
- Andalusian Center for Developmental Biology (CABD), Consejo Superior de Investigaciones Científicas/Junta de Andalucia/Universidad Pablo de Olavide, 41013 Seville, Spain
| | - Marta Artal-Sanz
- Andalusian Center for Developmental Biology (CABD), Consejo Superior de Investigaciones Científicas/Junta de Andalucia/Universidad Pablo de Olavide, 41013 Seville, Spain
| | - Peter Askjaer
- Andalusian Center for Developmental Biology (CABD), Consejo Superior de Investigaciones Científicas/Junta de Andalucia/Universidad Pablo de Olavide, 41013 Seville, Spain.
| | - Agnieszka Dobrzynska
- Andalusian Center for Developmental Biology (CABD), Consejo Superior de Investigaciones Científicas/Junta de Andalucia/Universidad Pablo de Olavide, 41013 Seville, Spain.
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35
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Chromatin Compaction by Small RNAs and the Nuclear RNAi Machinery in C. elegans. Sci Rep 2019; 9:9030. [PMID: 31227740 PMCID: PMC6588724 DOI: 10.1038/s41598-019-45052-y] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2018] [Accepted: 05/28/2019] [Indexed: 11/25/2022] Open
Abstract
DNA is organized and compacted into higher-order structures in order to fit within nuclei and to facilitate gene regulation. Mechanisms by which higher order chromatin structures are established and maintained are poorly understood. In C. elegans, nuclear-localized small RNAs engage the nuclear RNAi machinery to regulate gene expression and direct the post-translational modification of histone proteins. Here we confirm a recent report suggesting that nuclear small RNAs initiate or maintain chromatin compaction states in C. elegans germ cells. Additionally, we show that experimentally provided small RNAs are sufficient to direct chromatin compaction and that this compaction requires the small RNA-binding Argonaute NRDE-3, the pre-mRNA associated factor NRDE-2, and the HP1-like protein HPL-2. Our results show that small RNAs, acting via the nuclear RNAi machinery and an HP1-like protein, are capable of driving chromatin compaction in C. elegans.
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36
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Williams MM, Mathison AJ, Christensen T, Greipp PT, Knutson DL, Klee EW, Zimmermann MT, Iovanna J, Lomberk GA, Urrutia RA. Aurora kinase B-phosphorylated HP1α functions in chromosomal instability. Cell Cycle 2019; 18:1407-1421. [PMID: 31130069 PMCID: PMC6592258 DOI: 10.1080/15384101.2019.1618126] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2019] [Revised: 04/17/2019] [Accepted: 05/08/2019] [Indexed: 01/25/2023] Open
Abstract
Heterochromatin Protein 1 α (HP1α) associates with members of the chromosome passenger complex (CPC) during mitosis, at centromeres where it is required for full Aurora Kinase B (AURKB) activity. Conversely, recent reports have identified AURKB as the major kinase responsible for phosphorylation of HP1α at Serine 92 (S92) during mitosis. Thus, the current study was designed to better understand the functional role of this posttranslationally modified form of HP1α. We find that S92-phosphorylated HP1α is generated in cells at early prophase, localizes to centromeres, and associates with regulators of chromosome stability, such as Inner Centromere Protein, INCENP. In mouse embryonic fibroblasts, HP1α knockout alone or reconstituted with a non-phosphorylatable (S92A) HP1α mutant results in mitotic chromosomal instability characterized by the formation of anaphase/telophase chromatin bridges and micronuclei. These effects are rescued by exogenous expression of wild type HP1α or a phosphomimetic (S92D) variant. Thus, the results from the current study extend our knowledge of the role of HP1α in chromosomal stability during mitosis.
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Affiliation(s)
- Monique M. Williams
- Departments of Biochemistry and Biostatistics, Mayo Clinic, Rochester, MN, USA
| | - Angela J. Mathison
- Genomics and Precision Medicine Center (GSPMC), Medical College of Wisconsin, Milwaukee, WI, USA
- Division of Research, Department of Surgery, Medical College of Wisconsin, Milwaukee, WI, USA
| | - Trent Christensen
- Departments of Biochemistry and Biostatistics, Mayo Clinic, Rochester, MN, USA
| | - Patricia T. Greipp
- Medical Genome Facility, Cytogenetics Core Laboratory, Rochester, MN, USA
| | - Darlene L. Knutson
- Medical Genome Facility, Cytogenetics Core Laboratory, Rochester, MN, USA
| | - Eric W. Klee
- Departments of Biochemistry and Biostatistics, Mayo Clinic, Rochester, MN, USA
| | - Michael T. Zimmermann
- Bioinformatics Research and Development Laboratory, Genomics Sciences and Precision Medicine Center, Medical College of Wisconsin, Milwaukee, WI, USA
- Clinical and Translational Sciences Institute, Medical College of Wisconsin, Milwaukee, WI, USA
| | - Juan Iovanna
- Centre de Recherche en Cancérologie de Marseille (CRCM), INSERM U1068, CNRS UMR 7258, Aix-Marseille Université and Institut Paoli-Calmettes, Parc Scientifique et Technologique de Luminy, Marseille, France
| | - Gwen A. Lomberk
- Genomics and Precision Medicine Center (GSPMC), Medical College of Wisconsin, Milwaukee, WI, USA
- Division of Research, Department of Surgery, Medical College of Wisconsin, Milwaukee, WI, USA
- Department of Pharmacology and Toxicology, Medical College of Wisconsin, Milwaukee, WI, USA
| | - Raul A. Urrutia
- Genomics and Precision Medicine Center (GSPMC), Medical College of Wisconsin, Milwaukee, WI, USA
- Division of Research, Department of Surgery, Medical College of Wisconsin, Milwaukee, WI, USA
- Department of Biochemistry, Medical College of Wisconsin, Milwaukee, WI, USA
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Helleu Q, Levine MT. Recurrent Amplification of the Heterochromatin Protein 1 (HP1) Gene Family across Diptera. Mol Biol Evol 2019; 35:2375-2389. [PMID: 29924345 PMCID: PMC6188558 DOI: 10.1093/molbev/msy128] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
The heterochromatic genome compartment mediates strictly conserved cellular processes such as chromosome segregation, telomere integrity, and genome stability. Paradoxically, heterochromatic DNA sequence is wildly unconserved. Recent reports that many hybrid incompatibility genes encode heterochromatin proteins, together with the observation that interspecies hybrids suffer aberrant heterochromatin-dependent processes, suggest that heterochromatic DNA packaging requires species-specific innovations. Testing this model of coevolution between fast-evolving heterochromatic DNA and its packaging proteins begins with defining the latter. Here we describe many such candidates encoded by the Heterochromatin Protein 1 (HP1) gene family across Diptera, an insect Order that encompasses dramatic episodes of heterochromatic sequence turnover. Using BLAST, synteny analysis, and phylogenetic tree building across 64 Diptera genomes, we discovered a staggering 121 HP1 duplication events. In contrast, we observed virtually no gene duplication in gene families that share a common “chromodomain” with HP1s, including Polycomb and Su(var)3-9. The remarkably high number of Dipteran HP1 paralogs arises from distant clades undergoing convergent HP1 family amplifications. These independently derived, young HP1s span diverse ages, domain structures, and rates of molecular evolution, including episodes of positive selection. Moreover, independently derived HP1s exhibit convergent expression evolution. While ancient HP1 parent genes are transcribed ubiquitously, young HP1 paralogs are transcribed primarily in male germline tissue, a pattern typical of young genes. Pervasive gene youth, rapid evolution, and germline specialization implicate heterochromatin-encoded selfish elements driving recurrent HP1 gene family expansions. The 121 young genes offer valuable experimental traction for elucidating the germline processes shaped by Diptera’s many dramatic episodes of heterochromatin turnover.
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Affiliation(s)
- Quentin Helleu
- Department of Biology, Epigenetics Institute, University of Pennsylvania, Philadelphia, PA
| | - Mia T Levine
- Department of Biology, Epigenetics Institute, University of Pennsylvania, Philadelphia, PA
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38
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Sidorenko DS, Sidorenko IA, Zykova TY, Goncharov FP, Larsson J, Zhimulev IF. Molecular and genetic organization of bands and interbands in the dot chromosome of Drosophila melanogaster. Chromosoma 2019; 128:97-117. [PMID: 31041520 PMCID: PMC6536484 DOI: 10.1007/s00412-019-00703-x] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2018] [Revised: 01/09/2019] [Accepted: 04/02/2019] [Indexed: 12/24/2022]
Abstract
The fourth chromosome smallest in the genome of Drosophila melanogaster differs from other chromosomes in many ways. It has high repeat density in conditions of a large number of active genes. Gray bands represent a significant part of this polytene chromosome. Specific proteins including HP1a, POF, and dSETDB1 establish the epigenetic state of this unique chromatin domain. In order to compare maps of localization of genes, bands, and chromatin types of the fourth chromosome, we performed FISH analysis of 38 probes chosen according to the model of four chromatin types. It allowed clarifying the dot chromosome cytological map consisting of 16 loose gray bands, 11 dense black bands, and 26 interbands. We described the relation between chromatin states and bands. Open aquamarine chromatin mostly corresponds to interbands and it contains 5'UTRs of housekeeping genes. Their coding parts are embedded in gray bands substantially composed of lazurite chromatin of intermediate compaction. Polygenic black bands contain most of dense ruby chromatin, and also some malachite and lazurite. Having an accurate map of the fourth chromosome bands and its correspondence to physical map, we found that DNase I hypersensitivity sites, ORC2 protein, and P-elements are mainly located in open aquamarine chromatin, while element 1360, characteristic of the fourth chromosome, occupies band chromatin types. POF and HP1a proteins providing special organization of this chromosome are mostly located in aquamarine and lazurite chromatin. In general, band organization of the fourth chromosome shares the features of the whole Drosophila genome.
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Affiliation(s)
- Darya S Sidorenko
- Institute of Molecular and Cellular Biology of the Siberian Branch of the Russian Academy of Sciences, Lavrentiev Ave. 8/2, Novosibirsk, Russia, 630090
| | - Ivan A Sidorenko
- Institute of Cytology and Genetics of the Siberian Branch of the Russian Academy of Sciences, Novosibirsk, Russia
| | - Tatyana Yu Zykova
- Institute of Molecular and Cellular Biology of the Siberian Branch of the Russian Academy of Sciences, Lavrentiev Ave. 8/2, Novosibirsk, Russia, 630090
| | - Fedor P Goncharov
- Institute of Molecular and Cellular Biology of the Siberian Branch of the Russian Academy of Sciences, Lavrentiev Ave. 8/2, Novosibirsk, Russia, 630090
| | - Jan Larsson
- Department of Molecular Biology, Umeå University, Umeå, Sweden
| | - Igor F Zhimulev
- Institute of Molecular and Cellular Biology of the Siberian Branch of the Russian Academy of Sciences, Lavrentiev Ave. 8/2, Novosibirsk, Russia, 630090. .,Laboratory of structural, functional and comparative genomics of the Novosibirsk State University, Novosibirsk, Russia.
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39
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Carlson J, Swisse T, Smith C, Deng H. Regulation of position effect variegation at pericentric heterochromatin by Drosophila Keap1-Nrf2 xenobiotic response factors. Genesis 2019; 57:e23290. [PMID: 30888733 DOI: 10.1002/dvg.23290] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2019] [Revised: 02/27/2019] [Accepted: 02/28/2019] [Indexed: 12/30/2022]
Abstract
The Keap1-Nrf2 signaling pathway plays a central role in the regulation of transcriptional responses to oxidative species and xenobiotic stimuli. The complete range of molecular mechanisms and biological functions of Keap1 and Nrf2 remain to be fully elucidated. To determine the potential roles of Keap1 and Nrf2 in chromatin architecture, we examined the effects of their Drosophila homologs (dKeap1 and CncC) on position effect variegation (PEV), which is a transcriptional reporter for heterochromatin formation and spreading. Loss of function mutations in cncC, dKeap1, and cncC/dKeap1 double mutants all suppressed the variegation of wm4 and SbV PEV alleles, indicating that reduction of CncC or dKeap1 causes a decrease of heterochromatic silencing at pericentric region. Depletion of CncC or dKeap1 in embryos reduced the level of the H3K9me2 heterochromatin marker, but had no effect on the transcription of the genes encoding Su(var)3-9 and HP1. These results support a potential role of dKeap1 and CncC in the establishment and/or maintenance of pericentric heterochromatin. Our study provides preliminary evidence for a novel epigenetic function of Keap1-Nrf2 oxidative/xenobiotic response factors in chromatin remodeling.
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Affiliation(s)
- Jennifer Carlson
- Department of Biology, University of Minnesota Duluth, Duluth, Minnesota
| | - Thane Swisse
- Department of Biology, University of Minnesota Duluth, Duluth, Minnesota
| | - Charles Smith
- Department of Biology, University of Minnesota Duluth, Duluth, Minnesota
| | - Huai Deng
- Department of Biology, University of Minnesota Duluth, Duluth, Minnesota
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40
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Heterochromatin protein 1 (HP1) is intrinsically required for post-transcriptional regulation of Drosophila Germline Stem Cell (GSC) maintenance. Sci Rep 2019; 9:4372. [PMID: 30867469 PMCID: PMC6416348 DOI: 10.1038/s41598-019-40152-1] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2018] [Accepted: 02/07/2019] [Indexed: 01/05/2023] Open
Abstract
A very important open question in stem cells regulation is how the fine balance between GSCs self-renewal and differentiation is orchestrated at the molecular level. In the past several years much progress has been made in understanding the molecular mechanisms underlying intrinsic and extrinsic controls of GSC regulation but the complex gene regulatory networks that regulate stem cell behavior are only partially understood. HP1 is a dynamic epigenetic determinant mainly involved in heterochromatin formation, epigenetic gene silencing and telomere maintenance. Furthermore, recent studies have revealed the importance of HP1 in DNA repair, sister chromatid cohesion and, surprisingly, in positive regulation of gene expression. Here, we show that HP1 plays a crucial role in the control of GSC homeostasis in Drosophila. Our findings demonstrate that HP1 is required intrinsically to promote GSC self-renewal and progeny differentiation by directly stabilizing the transcripts of key genes involved in GSCs maintenance.
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41
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The Drosophila Dot Chromosome: Where Genes Flourish Amidst Repeats. Genetics 2019; 210:757-772. [PMID: 30401762 PMCID: PMC6218221 DOI: 10.1534/genetics.118.301146] [Citation(s) in RCA: 34] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2018] [Accepted: 08/17/2018] [Indexed: 11/18/2022] Open
Abstract
The F element of the Drosophila karyotype (the fourth chromosome in Drosophila melanogaster) is often referred to as the "dot chromosome" because of its appearance in a metaphase chromosome spread. This chromosome is distinct from other Drosophila autosomes in possessing both a high level of repetitious sequences (in particular, remnants of transposable elements) and a gene density similar to that found in the other chromosome arms, ∼80 genes distributed throughout its 1.3-Mb "long arm." The dot chromosome is notorious for its lack of recombination and is often neglected as a consequence. This and other features suggest that the F element is packaged as heterochromatin throughout. F element genes have distinct characteristics (e.g, low codon bias, and larger size due both to larger introns and an increased number of exons), but exhibit expression levels comparable to genes found in euchromatin. Mapping experiments show the presence of appropriate chromatin modifications for the formation of DNaseI hypersensitive sites and transcript initiation at the 5' ends of active genes, but, in most cases, high levels of heterochromatin proteins are observed over the body of these genes. These various features raise many interesting questions about the relationships of chromatin structures with gene and chromosome function. The apparent evolution of the F element as an autosome from an ancestral sex chromosome also raises intriguing questions. The findings argue that the F element is a unique chromosome that occupies its own space in the nucleus. Further study of the F element should provide new insights into chromosome structure and function.
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42
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The Role of Maternal HP1a in Early Drosophila Embryogenesis via Regulation of Maternal Transcript Production. Genetics 2018; 211:201-217. [PMID: 30442760 DOI: 10.1534/genetics.118.301704] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2018] [Accepted: 11/07/2018] [Indexed: 11/18/2022] Open
Abstract
Heterochromatin protein 1a (HP1a) is a highly conserved and versatile epigenetic factor that can both silence and activate transcription. However, the function of HP1a in development has been underinvestigated. Here, we report the role of maternal HP1a in producing maternal transcripts that drive early Drosophila embryogenesis. Maternal HP1a upregulates genes involved in translation, mRNA splicing, and cell division, but downregulates genes involved in neurogenesis, organogenesis, and germline development, which all occur later in development. Our study reveals the earliest contribution of HP1a during oogenesis in regulating the production of maternal transcripts that drive early Drosophila embryogenesis.
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43
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HP1 cooperates with CAF-1 to compact heterochromatic transgene repeats in mammalian cells. Sci Rep 2018; 8:14141. [PMID: 30237539 PMCID: PMC6147918 DOI: 10.1038/s41598-018-32381-7] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2017] [Accepted: 09/04/2018] [Indexed: 11/19/2022] Open
Abstract
The nuclear organization of tightly condensed heterochromatin plays important roles in regulating gene transcription and genome integrity. Heterochromatic domains are usually present at chromosomal regions containing a large array of repeated DNA sequences. We previously showed that integration of a 1,000-copy tandem array of an inducible reporter gene into the genome of mammalian cells induces the formation of a highly compact heterochromatic domain enriched in heterochromatin protein 1 (HP1). It remains to be determined how these DNA repeats are packaged into a heterochromatic form and are silenced. Here, we show that HP1-mediated transgene condensation and silencing require the interaction with PxVxL motif-containing proteins. The chromatin assembly factor 1 (CAF-1) complex concentrates at the transgenic locus through the interaction of its PxVxL motif-containing p150 subunit with HP1. Knockdown of p150 relieves HP1-mediated transgene compaction and repression. When targeted to the transgenic locus, p150 mutants defective in binding HP1 cause transgene decondensation and activation. Taken together, these results suggest that HP1 cooperates with CAF-1 to compact transgene repeats. This study provides important insight into how heterochromatin is maintained at chromosomal regions with abundant DNA repeats.
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44
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Oyama K, El-Nachef D, Fang C, Kajimoto H, Brown JP, Singh PB, MacLellan WR. Deletion of HP1γ in cardiac myocytes affects H4K20me3 levels but does not impact cardiac growth. Epigenetics Chromatin 2018; 11:18. [PMID: 29665845 PMCID: PMC5905015 DOI: 10.1186/s13072-018-0187-z] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2018] [Accepted: 04/01/2018] [Indexed: 01/16/2023] Open
Abstract
BACKGROUND Heterochromatin, which is formed when tri-methyl lysine 9 of histone H3 (H3K9me3) is bound by heterochromatin 1 proteins (HP1s), plays an important role in differentiation and senescence by silencing cell cycle genes. Cardiac myocytes (CMs) accumulate heterochromatin during differentiation and demethylation of H3K9me3 inhibits cell cycle gene silencing and cell cycle exit in CMs; however, it is unclear if this process is mediated by HP1s. In this study, we created a conditional CM-specific HP1 gamma (HP1γ) knockout (KO) mouse model and tested whether HP1γ is required for cell cycle gene silencing and cardiac growth. RESULTS HP1γ KO mice were generated by crossing HP1γ floxed mice (fl) with mice expressing Cre recombinase driven by the Nkx2.5 (cardiac progenitor gene) promoter (Cre). We confirmed that deletion of critical exons of HP1γ led to undetectable levels of HP1γ protein in HP1γ KO (Cre;fl/fl) CMs. Analysis of cardiac size and function by echo revealed no significant differences between HP1γ KO and control (WT, Cre, fl/fl) mice. No significant difference in expression of cell cycle genes or cardiac-specific genes was observed. Global transcriptome analysis demonstrated a very moderate effect of HP1γ deletion on global gene expression, with only 51 genes differentially expressed in HP1γ KO CMs. We found that HP1β protein, but not HP1α, was significantly upregulated and that subnuclear localization of HP1β to perinuclear heterochromatin was increased in HP1γ KO CMs. Although HP1γ KO had no effect on H3K9me3 levels, we found a significant reduction in another major heterochromatin mark, tri-methylated lysine 20 of histone H4 (H4K20me3). CONCLUSIONS These data indicate that HP1γ is dispensable for cell cycle exit and normal cardiac growth but has a significant role in maintaining H4K20me3 and regulating a limited number of genes in CMs.
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Affiliation(s)
- Kyohei Oyama
- Division of Cardiology, Department of Medicine, Center for Cardiovascular Biology and Institute for Stem Cell and Regenerative Medicine, University of Washington, 1959 NE Pacific St, Box 356422, Seattle, WA, 98195-6422, USA
| | - Danny El-Nachef
- Division of Cardiology, Department of Medicine, Center for Cardiovascular Biology and Institute for Stem Cell and Regenerative Medicine, University of Washington, 1959 NE Pacific St, Box 356422, Seattle, WA, 98195-6422, USA
| | - Chen Fang
- Division of Cardiology, Department of Medicine, Center for Cardiovascular Biology and Institute for Stem Cell and Regenerative Medicine, University of Washington, 1959 NE Pacific St, Box 356422, Seattle, WA, 98195-6422, USA
| | - Hidemi Kajimoto
- Division of Cardiology, Department of Medicine, Center for Cardiovascular Biology and Institute for Stem Cell and Regenerative Medicine, University of Washington, 1959 NE Pacific St, Box 356422, Seattle, WA, 98195-6422, USA
| | - Jeremy P Brown
- Fächerverbund Anatomie, Institut für Zell-und Neurobiologie, Charite-Universitätsmedizin, 10117, Berlin, Germany
| | - Prim B Singh
- Fächerverbund Anatomie, Institut für Zell-und Neurobiologie, Charite-Universitätsmedizin, 10117, Berlin, Germany.,Department of Biomedical Sciences, Nazarbayev University School of Medicine, Astana, Kazakhstan, 010000.,Department of Natural Sciences, Laboratory of epigenetics, Novosibirsk State University, Pirogova str. 1, Novosibirsk, 630090, Russian Federation
| | - W Robb MacLellan
- Division of Cardiology, Department of Medicine, Center for Cardiovascular Biology and Institute for Stem Cell and Regenerative Medicine, University of Washington, 1959 NE Pacific St, Box 356422, Seattle, WA, 98195-6422, USA.
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45
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Cheng W, Tian L, Wang B, Qi Y, Huang W, Li H, Chen YJ. Downregulation of HP1α suppresses proliferation of cholangiocarcinoma by restoring SFRP1 expression. Oncotarget 2018; 7:48107-48119. [PMID: 27385214 PMCID: PMC5217004 DOI: 10.18632/oncotarget.10371] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2016] [Accepted: 06/12/2016] [Indexed: 12/29/2022] Open
Abstract
Heterochromatin protein 1α (HP1α) is a gene that mediates chromatin conformation, gene silencing and cancer progression. However, little is known regarding the impact of HP1α in the pathogenesis of cholangiocarcinoma (CCA). In the present study, we demonstrate that HP1α is significantly upregulated in CCA tissues and cell lines, while downregulation of HP1α leads to suppression of cell proliferation. Then we find that downregulation of HP1α can decrease H3K9me3 enrichment and DNA methylation rate of secreted frizzled-related protein 1 (SFRP1) promoter, resulting in restoring the expression of SFRP1. Moreover, restoration of SFRP1 expression can suppress CCA cells proliferation. These results provide a mechanistic understanding of the role of HP1α in the pathogenesis of CCA and may offer a novel therapeutic target in this disease.
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Affiliation(s)
- Wenlong Cheng
- Department of Biliary-Pancreatic Surgery, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei Province, China
| | - Li Tian
- Department of Wuhan Medical Care Center for Women and Children, Wuhan, Hubei Province, China
| | - Bing Wang
- Department of Biliary-Pancreatic Surgery, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei Province, China
| | - Yongqiang Qi
- Department of Biliary-Pancreatic Surgery, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei Province, China
| | - Wenhua Huang
- Department of Biliary-Pancreatic Surgery, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei Province, China
| | - Hongbo Li
- Department of Hepatobiliary Surgery, The First Affiliated Hospital of Bengbu Medical College, Bengbu, Anhui Province, China
| | - Yong-Jun Chen
- Department of Biliary-Pancreatic Surgery, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei Province, China
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46
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Gorab E, Pearson PL. Thiazole Orange as an Alternative to Antibody Binding for Detecting Triple-helical DNA in Heterochromatin of Drosophila and Rhynchosciara. J Histochem Cytochem 2017; 66:143-154. [PMID: 29268630 PMCID: PMC5833176 DOI: 10.1369/0022155417745496] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The standard method for detecting triple-stranded DNA over the last 1.5 decades has been immune detection using antibodies raised against non-canonical nucleic acid structures. Many fluorescent dyes bind differentially to nucleic acids and often exhibit distinctive staining patterns along metaphase chromosomes dependent upon features, including binding to the major and minor DNA grooves, level of chromatin compaction, nucleotide specificity, and level of dye stacking. Relatively recently, the fluorochrome Thiazole Orange (TO) was shown to preferentially bind to triplex DNA in gels. Here, we demonstrate that TO also detects triplex DNA in salivary gland chromosomes of Drosophila melanogaster and Rhynchosciara americana identical in location and specificity to observations using antibodies. This finding may enable triple-stranded DNA investigations to be carried out on a much broader and reproducible scale than hitherto possible using antibodies, where a frequently encountered problem is the difference in detection specificity and sensitivity between one antibody and another.
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Affiliation(s)
- Eduardo Gorab
- Department of Genetics and Evolutionary Biology, Institute of Biosciences, University of São Paulo, São Paulo, Brazil
| | - Peter Lees Pearson
- Department of Genetics and Evolutionary Biology, Institute of Biosciences, University of São Paulo, São Paulo, Brazil
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47
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Duronio RJ, O'Farrell PH, Sluder G, Su TT. Sophisticated lessons from simple organisms: appreciating the value of curiosity-driven research. Dis Model Mech 2017; 10:1381-1389. [PMID: 29259023 PMCID: PMC5769611 DOI: 10.1242/dmm.031203] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
For hundreds of years, biologists have studied accessible organisms such as garden peas, sea urchins collected at low tide, newt eggs, and flies circling rotten fruit. These organisms help us to understand the world around us, attracting and inspiring each new generation of biologists with the promise of mystery and discovery. Time and time again, what we learn from such simple organisms has emphasized our common biological origins by proving to be applicable to more complex organisms, including humans. Yet, biologists are increasingly being tasked with developing applications from the known, rather than being allowed to follow a path to discovery of the as yet unknown. Here, we provide examples of important lessons learned from research using selected non-vertebrate organisms. We argue that, for the purpose of understanding human disease, simple organisms cannot and should not be replaced solely by human cell-based culture systems. Rather, these organisms serve as powerful discovery tools for new knowledge that could subsequently be tested for conservation in human cell-based culture systems. In this way, curiosity-driven biological research in simple organisms has and will continue to pay huge dividends in both the short and long run for improving the human condition.
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Affiliation(s)
- Robert J Duronio
- Departments of Biology and Genetics, Integrative Program for Biological and Genome Sciences, and Lineberger Comprehensive Cancer Center, UNC Chapel Hill, NC 27599-3280, USA
| | - Patrick H O'Farrell
- Department of Biochemistry and Biophysics, University of California, San Francisco, CA 94158-2517, USA
| | - Greenfield Sluder
- Department of Radiology, University of Massachusetts Medical School, Worcester, MA 01655, USA
| | - Tin Tin Su
- Department of Molecular Cellular and Developmental Biology, University of Colorado, Boulder, CO 80309-0347, USA
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48
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Vo N, Anh Suong DN, Yoshino N, Yoshida H, Cotterill S, Yamaguchi M. Novel roles of HP1a and Mcm10 in DNA replication, genome maintenance and photoreceptor cell differentiation. Nucleic Acids Res 2017; 45:1233-1254. [PMID: 28180289 PMCID: PMC5388399 DOI: 10.1093/nar/gkw1174] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2016] [Revised: 11/04/2016] [Accepted: 11/13/2016] [Indexed: 01/21/2023] Open
Abstract
Both Mcm10 and HP1a are known to be required for DNA replication. However, underlying mechanism is not clarified yet especially for HP1. Knockdown of both HP1a and Mcm10 genes inhibited the progression of S phase in Drosophila eye imaginal discs. Proximity Ligation Assay (PLA) demonstrated that HP1a is in close proximity to DNA replication proteins including Mcm10, RFC140 and DNA polymerase ε 255 kDa subunit in S-phase. This was further confirmed by co-immunoprecipitation assay. The PLA signals between Mcm10 and HP1a are specifically observed in the mitotic cycling cells, but not in the endocycling cells. Interestingly, many cells in the posterior regions of eye imaginal discs carrying a double knockdown of Mcm10 and HP1a induced ectopic DNA synthesis and DNA damage without much of ectopic apoptosis. Therefore, the G1-S checkpoint may be affected by knockdown of both proteins. This event was also the case with other HP family proteins such as HP4 and HP6. In addition, both Mcm10 and HP1a are required for differentiation of photoreceptor cells R1, R6 and R7. Further analyses on several developmental genes involved in the photoreceptor cell differentiation suggest that a role of both proteins is mediated by regulation of the lozenge gene.
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Affiliation(s)
- Nicole Vo
- Department of Applied Biology, Kyoto Institute of Technology, Kyoto, Japan.,The Center for Advanced Insect Research, Kyoto Institute of Technology, Kyoto, Japan
| | - Dang Ngoc Anh Suong
- Department of Applied Biology, Kyoto Institute of Technology, Kyoto, Japan.,The Center for Advanced Insect Research, Kyoto Institute of Technology, Kyoto, Japan
| | - Natsuki Yoshino
- Department of Applied Biology, Kyoto Institute of Technology, Kyoto, Japan.,The Center for Advanced Insect Research, Kyoto Institute of Technology, Kyoto, Japan
| | - Hideki Yoshida
- Department of Applied Biology, Kyoto Institute of Technology, Kyoto, Japan.,The Center for Advanced Insect Research, Kyoto Institute of Technology, Kyoto, Japan
| | - Sue Cotterill
- Department of Basic Medical Sciences, St Georges, University of London, London, UK
| | - Masamitsu Yamaguchi
- Department of Applied Biology, Kyoto Institute of Technology, Kyoto, Japan.,The Center for Advanced Insect Research, Kyoto Institute of Technology, Kyoto, Japan
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49
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The Drosophila DAXX-Like Protein (DLP) Cooperates with ASF1 for H3.3 Deposition and Heterochromatin Formation. Mol Cell Biol 2017; 37:MCB.00597-16. [PMID: 28320872 DOI: 10.1128/mcb.00597-16] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2016] [Accepted: 03/09/2017] [Indexed: 01/22/2023] Open
Abstract
Histone variants are nonallelic isoforms of canonical histones, and they are deposited, in contrast to canonical histones, in a replication-independent (RI) manner. RI deposition of H3.3, a histone variant from the H3.3 family, is mediated in mammals by distinct pathways involving either the histone regulator A (HIRA) complex or the death-associated protein (DAXX)/α-thalassemia X-linked mental retardation protein (ATRX) complex. Here, we investigated the function of the Drosophila DAXX-like protein (DLP) by using both fly genetic approaches and protein biochemistry. DLP specifically interacts with H3.3 and shows a prominent localization on the base of the X chromosome, where it appears to act in concert with XNP, the Drosophila homolog of ATRX, in heterochromatin assembly and maintenance. The functional association between DLP and XNP is further supported by a series of experiments that illustrate genetic interactions and the DLP-XNP-dependent localization of specific chromosomal proteins. In addition, DLP both participates in the RI deposition of H3.3 and associates with anti-silencing factor 1 (ASF1). We suggest, in agreement with a recently proposed model, that DLP and ASF1 are part of a predeposition complex, which is recruited by XNP and is necessary to prevent DNA exposure in the nucleus.
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McMurchy AN, Stempor P, Gaarenstroom T, Wysolmerski B, Dong Y, Aussianikava D, Appert A, Huang N, Kolasinska-Zwierz P, Sapetschnig A, Miska EA, Ahringer J. A team of heterochromatin factors collaborates with small RNA pathways to combat repetitive elements and germline stress. eLife 2017; 6:e21666. [PMID: 28294943 PMCID: PMC5395297 DOI: 10.7554/elife.21666] [Citation(s) in RCA: 64] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2016] [Accepted: 03/10/2017] [Indexed: 12/26/2022] Open
Abstract
Repetitive sequences derived from transposons make up a large fraction of eukaryotic genomes and must be silenced to protect genome integrity. Repetitive elements are often found in heterochromatin; however, the roles and interactions of heterochromatin proteins in repeat regulation are poorly understood. Here we show that a diverse set of C. elegans heterochromatin proteins act together with the piRNA and nuclear RNAi pathways to silence repetitive elements and prevent genotoxic stress in the germ line. Mutants in genes encoding HPL-2/HP1, LIN-13, LIN-61, LET-418/Mi-2, and H3K9me2 histone methyltransferase MET-2/SETDB1 also show functionally redundant sterility, increased germline apoptosis, DNA repair defects, and interactions with small RNA pathways. Remarkably, fertility of heterochromatin mutants could be partially restored by inhibiting cep-1/p53, endogenous meiotic double strand breaks, or the expression of MIRAGE1 DNA transposons. Functional redundancy among factors and pathways underlies the importance of safeguarding the genome through multiple means.
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Affiliation(s)
- Alicia N McMurchy
- The Gurdon Institute and Department of Genetics, University of Cambridge, Cambridge, United Kingdom
| | - Przemyslaw Stempor
- The Gurdon Institute and Department of Genetics, University of Cambridge, Cambridge, United Kingdom
| | - Tessa Gaarenstroom
- The Gurdon Institute and Department of Genetics, University of Cambridge, Cambridge, United Kingdom
| | - Brian Wysolmerski
- The Gurdon Institute and Department of Genetics, University of Cambridge, Cambridge, United Kingdom
| | - Yan Dong
- The Gurdon Institute and Department of Genetics, University of Cambridge, Cambridge, United Kingdom
| | - Darya Aussianikava
- The Gurdon Institute and Department of Genetics, University of Cambridge, Cambridge, United Kingdom
| | - Alex Appert
- The Gurdon Institute and Department of Genetics, University of Cambridge, Cambridge, United Kingdom
| | - Ni Huang
- The Gurdon Institute and Department of Genetics, University of Cambridge, Cambridge, United Kingdom
| | | | - Alexandra Sapetschnig
- The Gurdon Institute and Department of Genetics, University of Cambridge, Cambridge, United Kingdom
| | - Eric A Miska
- The Gurdon Institute and Department of Genetics, University of Cambridge, Cambridge, United Kingdom
| | - Julie Ahringer
- The Gurdon Institute and Department of Genetics, University of Cambridge, Cambridge, United Kingdom
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