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Melnikova L, Golovnin A. Multiple Roles of dXNP and dADD1- Drosophila Orthologs of ATRX Chromatin Remodeler. Int J Mol Sci 2023; 24:16486. [PMID: 38003676 PMCID: PMC10671109 DOI: 10.3390/ijms242216486] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2023] [Revised: 11/11/2023] [Accepted: 11/16/2023] [Indexed: 11/26/2023] Open
Abstract
The Drosophila melanogaster dADD1 and dXNP proteins are orthologues of the ADD and SNF2 domains of the vertebrate ATRX (Alpha-Thalassemia with mental Retardation X-related) protein. ATRX plays a role in general molecular processes, such as regulating chromatin status and gene expression, while dADD1 and dXNP have similar functions in the Drosophila genome. Both ATRX and dADD1/dXNP interact with various protein partners and participate in various regulatory complexes. Disruption of ATRX expression in humans leads to the development of α-thalassemia and cancer, especially glioma. However, the mechanisms that allow ATRX to regulate various cellular processes are poorly understood. Studying the functioning of dADD1/dXNP in the Drosophila model may contribute to understanding the mechanisms underlying the multifunctional action of ATRX and its connection with various cellular processes. This review provides a brief overview of the currently available information in mammals and Drosophila regarding the roles of ATRX, dXNP, and dADD1. It discusses possible mechanisms of action of complexes involving these proteins.
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Affiliation(s)
- Larisa Melnikova
- Department of Drosophila Molecular Genetics, Institute of Gene Biology, Russian Academy of Sciences, 34/5 Vavilov St., 119334 Moscow, Russia
| | - Anton Golovnin
- Department of Drosophila Molecular Genetics, Institute of Gene Biology, Russian Academy of Sciences, 34/5 Vavilov St., 119334 Moscow, Russia
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2
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Carraro M, Hendriks IA, Hammond CM, Solis-Mezarino V, Völker-Albert M, Elsborg JD, Weisser MB, Spanos C, Montoya G, Rappsilber J, Imhof A, Nielsen ML, Groth A. DAXX adds a de novo H3.3K9me3 deposition pathway to the histone chaperone network. Mol Cell 2023; 83:1075-1092.e9. [PMID: 36868228 PMCID: PMC10114496 DOI: 10.1016/j.molcel.2023.02.009] [Citation(s) in RCA: 22] [Impact Index Per Article: 22.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2022] [Revised: 11/29/2022] [Accepted: 02/08/2023] [Indexed: 03/05/2023]
Abstract
A multitude of histone chaperones are required to support histones from their biosynthesis until DNA deposition. They cooperate through the formation of histone co-chaperone complexes, but the crosstalk between nucleosome assembly pathways remains enigmatic. Using exploratory interactomics, we define the interplay between human histone H3-H4 chaperones in the histone chaperone network. We identify previously uncharacterized histone-dependent complexes and predict the structure of the ASF1 and SPT2 co-chaperone complex, expanding the role of ASF1 in histone dynamics. We show that DAXX provides a unique functionality to the histone chaperone network, recruiting histone methyltransferases to promote H3K9me3 catalysis on new histone H3.3-H4 prior to deposition onto DNA. Hereby, DAXX provides a molecular mechanism for de novo H3K9me3 deposition and heterochromatin assembly. Collectively, our findings provide a framework for understanding how cells orchestrate histone supply and employ targeted deposition of modified histones to underpin specialized chromatin states.
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Affiliation(s)
- Massimo Carraro
- Novo Nordisk Foundation Center for Protein Research (CPR), Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark; Biotech Research and Innovation Centre (BRIC), Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Ivo A Hendriks
- Novo Nordisk Foundation Center for Protein Research (CPR), Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Colin M Hammond
- Novo Nordisk Foundation Center for Protein Research (CPR), Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark; Biotech Research and Innovation Centre (BRIC), Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.
| | | | | | - Jonas D Elsborg
- Novo Nordisk Foundation Center for Protein Research (CPR), Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Melanie B Weisser
- Novo Nordisk Foundation Center for Protein Research (CPR), Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Christos Spanos
- Wellcome Centre for Cell Biology, University of Edinburgh, Edinburgh, UK; Technische Universität Berlin, Chair of Bioanalytics, Berlin, Germany
| | - Guillermo Montoya
- Novo Nordisk Foundation Center for Protein Research (CPR), Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Juri Rappsilber
- Wellcome Centre for Cell Biology, University of Edinburgh, Edinburgh, UK; Technische Universität Berlin, Chair of Bioanalytics, Berlin, Germany
| | - Axel Imhof
- EpiQMAx GmbH, Planegg, Germany; Faculty of Medicine, Biomedical Center, Protein Analysis Unit, Ludwig-Maximilians-Universität München, Planegg-Martinsried, Germany
| | - Michael L Nielsen
- Novo Nordisk Foundation Center for Protein Research (CPR), Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.
| | - Anja Groth
- Novo Nordisk Foundation Center for Protein Research (CPR), Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark; Biotech Research and Innovation Centre (BRIC), Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.
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Thakar T, Dhoonmoon A, Straka J, Schleicher EM, Nicolae CM, Moldovan GL. Lagging strand gap suppression connects BRCA-mediated fork protection to nucleosome assembly through PCNA-dependent CAF-1 recycling. Nat Commun 2022; 13:5323. [PMID: 36085347 PMCID: PMC9463168 DOI: 10.1038/s41467-022-33028-y] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2022] [Accepted: 08/29/2022] [Indexed: 11/17/2022] Open
Abstract
The inability to protect stalled replication forks from nucleolytic degradation drives genome instability and underlies chemosensitivity in BRCA-deficient tumors. An emerging hallmark of BRCA-deficiency is the inability to suppress replication-associated single-stranded DNA (ssDNA) gaps. Here, we report that lagging strand ssDNA gaps interfere with the ASF1-CAF-1 nucleosome assembly pathway, and drive fork degradation in BRCA-deficient cells. We show that CAF-1 function at replication forks is lost in BRCA-deficient cells, due to defects in its recycling during replication stress. This CAF-1 recycling defect is caused by lagging strand gaps which preclude PCNA unloading, causing sequestration of PCNA-CAF-1 complexes on chromatin. Importantly, correcting PCNA unloading defects in BRCA-deficient cells restores CAF-1-dependent fork stability. We further show that the activation of a HIRA-dependent compensatory histone deposition pathway restores fork stability to BRCA-deficient cells. We thus define lagging strand gap suppression and nucleosome assembly as critical enablers of BRCA-mediated fork stability. Efficient DNA replication is crucial for genome stability. Here, Thakar et al. report that accumulation of lagging strand ssDNA gaps during replication interferes with nucleosome assembly and drives replication fork degradation in BRCA-deficient cells.
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Affiliation(s)
- Tanay Thakar
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University College of Medicine, Hershey, PA, 17033, USA
| | - Ashna Dhoonmoon
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University College of Medicine, Hershey, PA, 17033, USA
| | - Joshua Straka
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University College of Medicine, Hershey, PA, 17033, USA
| | - Emily M Schleicher
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University College of Medicine, Hershey, PA, 17033, USA
| | - Claudia M Nicolae
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University College of Medicine, Hershey, PA, 17033, USA
| | - George-Lucian Moldovan
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University College of Medicine, Hershey, PA, 17033, USA.
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Reduce, Retain, Recycle: Mechanisms for Promoting Histone Protein Degradation versus Stability and Retention. Mol Cell Biol 2021; 41:e0000721. [PMID: 33753462 DOI: 10.1128/mcb.00007-21] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
The eukaryotic genome is packaged into chromatin. The nucleosome, the basic unit of chromatin, is composed of DNA coiled around a histone octamer. Histones are among the longest-lived protein species in mammalian cells due to their thermodynamic stability and their associations with DNA and histone chaperones. Histone metabolism plays an integral role in homeostasis. While histones are largely stable, the degradation of histone proteins is necessary under specific conditions. Here, we review the physiological and cellular contexts that promote histone degradation. We describe specific known mechanisms that drive histone proteolysis. Finally, we discuss the importance of histone degradation and regulation of histone supply for organismal and cellular fitness.
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Genome assembly, sex-biased gene expression and dosage compensation in the damselfly Ischnura elegans. Genomics 2021; 113:1828-1837. [PMID: 33831439 DOI: 10.1016/j.ygeno.2021.04.003] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2020] [Revised: 02/27/2021] [Accepted: 04/04/2021] [Indexed: 12/14/2022]
Abstract
The evolution of sex chromosomes, and patterns of sex-biased gene expression and dosage compensation, are poorly known among early winged insects such as odonates. We assembled and annotated the genome of Ischnura elegans (blue-tailed damselfly), which, like other odonates, has a male-hemigametic sex-determining system (X0 males, XX females). By identifying X-linked genes in I. elegans and their orthologs in other insect genomes, we found homologies between the X chromosome in odonates and chromosomes of other orders, including the X chromosome in Coleoptera. Next, we showed balanced expression of X-linked genes between sexes in adult I. elegans, i.e. evidence of dosage compensation. Finally, among the genes in the sex-determining pathway only fruitless was found to be X-linked, while only doublesex showed sex-biased expression. This study reveals partly conserved sex chromosome synteny and independent evolution of dosage compensation among insect orders separated by several hundred million years of evolutionary history.
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Structural insights into histone chaperone Asf1 and its characterization from Plasmodium falciparum. Biochem J 2021; 478:1117-1136. [PMID: 33501928 DOI: 10.1042/bcj20200891] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2020] [Revised: 01/24/2021] [Accepted: 01/27/2021] [Indexed: 02/06/2023]
Abstract
Asf1 is a highly conserved histone chaperone that regulates tightly coupled nucleosome assembly/disassembly process. We observed that Plasmodium falciparum Asf1 (PfAsf1) is ubiquitously expressed in different stages of the life cycle of the parasite. To gain further insight into its biological activity, we solved the structure of N-terminal histone chaperone domain of PfAsf1 (1-159 amino acids) by X-ray crystallography to a resolution of 2.4 Å. The structure is composed of two beta-sheet to form a beta-sandwich, which resembles an immunoglobulin-like fold. The surface-charge distribution of PfAsf1 is distinct from yAsf1 and hAsf1 although the core-structure shows significant similarity. The crystal-structure indicated that PfAsf1 may exist in a dimeric-state which was further confirmed by solution cross-linking experiment. PfAsf1 was found to specifically interact with Plasmodium histone H3 and H4 and was able to deposit H3/H4 dimer onto DNA-template to form disomes, showing its characteristic histone chaperone activity. We mapped the critical residues of PfAsf1 involved in histone H3/H4 interaction and confirmed by site-directed mutagenesis. Further analysis indicates that histone interacting surface of Asf1 is highly conserved while the dimerization interface is variable. Our results identify the role of PfAsf1 as a mediator of chromatin assembly in Plasmodium falciparum, which is the causative agent of malignant malaria in humans.
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The histone replacement gene His4r is involved in heat stress induced chromatin rearrangement. Sci Rep 2021; 11:4878. [PMID: 33649489 PMCID: PMC7921661 DOI: 10.1038/s41598-021-84413-4] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2020] [Accepted: 02/16/2021] [Indexed: 01/31/2023] Open
Abstract
His4r is the only known variant of histone H4 in Drosophila. It is encoded by the His4r single-copy gene that is located outside of the histone gene cluster and expressed in a different pattern than H4, although the encoded polypeptides are identical. We generated a null mutant (His4rΔ42) which is homozygous viable and fertile without any apparent morphological defects. Heterozygous His4rΔ42 is a mild suppressor of position-effect variegation, suggesting that His4r has a role in the formation or maintenance of condensed chromatin. Under standard conditions loss of His4r has a modest effect on gene expression. Upon heat-stress the induction of the Heat shock protein (HSP) genes Hsp27 and Hsp68 is stronger in His4rΔ42 mutants with concordantly increased survival rate. Analysis of chromatin accessibility after heat shock at a Hsp27 regulatory region showed less condensed chromatin in the absence of His4r while there was no difference at the gene body. Interestingly, preconditioning before heat shock led to increased chromatin accessibility, HSP gene transcription and survival rate in control flies while it did not cause notable changes in His4rΔ42. Thus, our results suggest that His4r might play a role in fine tuning chromatin structure at inducible gene promoters upon environmental stress conditions.
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Abstract
Nucleosome dynamics and properties are central to all forms of genomic activities. Among the core histones, H3 variants play a pivotal role in modulating nucleosome structure and function. Here, we focus on the impact of H3 variants on various facets of development. The deposition of the replicative H3 variant following DNA replication is essential for the transmission of the epigenomic information encoded in posttranscriptional modifications. Through this process, replicative H3 maintains cell fate while, in contrast, the replacement H3.3 variant opposes cell differentiation during early embryogenesis. In later steps of development, H3.3 and specialized H3 variants are emerging as new, important regulators of terminal cell differentiation, including neurons and gametes. The specific pathways that regulate the dynamics of the deposition of H3.3 are paramount during reprogramming events that drive zygotic activation and the initiation of a new cycle of development.
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Affiliation(s)
- Benjamin Loppin
- Laboratoire de Biologie et de Modélisation de la Cellule, CNRS UMR 5239, Ecole Normale Supérieure de Lyon, University of Lyon, F-69007 Lyon, France;
| | - Frédéric Berger
- Gregor Mendel Institute (GMI), Austrian Academy of Sciences, Vienna BioCenter (VBC), 1030 Vienna, Austria;
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Abstract
Histone variants regulate chromatin accessibility and gene transcription. Given their distinct properties and functions, histone varint substitutions allow for profound alteration of nucleosomal architecture and local chromatin landscape. Skeletal myogenesis driven by the key transcription factor MyoD is characterized by precise temporal regulation of myogenic genes. Timed substitution of variants within the nucleosomes provides a powerful means to ensure sequential expression of myogenic genes. Indeed, growing evidence has shown H3.3, H2A.Z, macroH2A, and H1b to be critical for skeletal myogenesis. However, the relative importance of various histone variants and their associated chaperones in myogenesis is not fully appreciated. In this review, we summarize the role that histone variants play in altering chromatin landscape to ensure proper muscle differentiation. The temporal regulation and cross talk between histones variants and their chaperones in conjunction with other forms of epigenetic regulation could be critical to understanding myogenesis and their involvement in myopathies.
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Affiliation(s)
- Nandini Karthik
- Department of Physiology, Yong Loo Lin School of Medicine, National University of Singapore , Singapore
| | - Reshma Taneja
- Department of Physiology, Yong Loo Lin School of Medicine, National University of Singapore , Singapore
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Xiao Q, Hu Y, Yang X, Tang J, Wang X, Xue X, Li M, Wang M, Zhao Y, Liu J, Wang H. Changes in Protein Phosphorylation during Salivary Gland Degeneration in Haemaphysalis longicornis. THE KOREAN JOURNAL OF PARASITOLOGY 2020; 58:161-171. [PMID: 32418385 PMCID: PMC7231830 DOI: 10.3347/kjp.2020.58.2.161] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/12/2019] [Accepted: 03/10/2020] [Indexed: 01/19/2023]
Abstract
The ticks feed large amount of blood from their hosts and transmit pathogens to the victims. The salivary gland plays an important role in the blood feeding. When the female ticks are near engorgement, the salivary gland gradually loses its functions and begins to rapidly degenerate. In this study, data-independent acquisition quantitative proteomics was used to study changes in the phosphorylation modification of proteins during salivary gland degeneration in Haemaphysalis longicornis. In this quantitative study, 400 phosphorylated proteins and 850 phosphorylation modification sites were identified. Trough RNA interference experiments, we found that among the proteins with changes in phosphorylation, apoptosis-promoting Hippo protein played a role in salivary gland degeneration.
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Affiliation(s)
- Qi Xiao
- Hebei Key Laboratory of Animal Physiology, Biochemistry and Molecular Biology, College of Life Sciences, Hebei Normal University, Shijiazhuang, Hebei 050024, PR China
| | - Yuhong Hu
- Instrumental Analysis Center, Hebei Normal University, Shijiazhuang, Hebei 050024, PR China
| | - Xiaohong Yang
- Department of Pathogenic Biology, College of Basic Medicine, Hebei Medical University, Shijiazhuang, Hebei 050017, PR China.,State Key Laboratory of Veterinary Etiological Biology, Lanzhou Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Lanzhou, Gansu 730046, PR China
| | - Jianna Tang
- Hebei Key Laboratory of Animal Physiology, Biochemistry and Molecular Biology, College of Life Sciences, Hebei Normal University, Shijiazhuang, Hebei 050024, PR China
| | - Xiaoshuang Wang
- Hebei Key Laboratory of Animal Physiology, Biochemistry and Molecular Biology, College of Life Sciences, Hebei Normal University, Shijiazhuang, Hebei 050024, PR China
| | - Xiaomin Xue
- Hebei Key Laboratory of Animal Physiology, Biochemistry and Molecular Biology, College of Life Sciences, Hebei Normal University, Shijiazhuang, Hebei 050024, PR China
| | - Mengxue Li
- Hebei Key Laboratory of Animal Physiology, Biochemistry and Molecular Biology, College of Life Sciences, Hebei Normal University, Shijiazhuang, Hebei 050024, PR China
| | - Minjing Wang
- Hebei Key Laboratory of Animal Physiology, Biochemistry and Molecular Biology, College of Life Sciences, Hebei Normal University, Shijiazhuang, Hebei 050024, PR China
| | - Yinan Zhao
- Hebei Key Laboratory of Animal Physiology, Biochemistry and Molecular Biology, College of Life Sciences, Hebei Normal University, Shijiazhuang, Hebei 050024, PR China
| | - Jingze Liu
- Hebei Key Laboratory of Animal Physiology, Biochemistry and Molecular Biology, College of Life Sciences, Hebei Normal University, Shijiazhuang, Hebei 050024, PR China
| | - Hui Wang
- Hebei Key Laboratory of Animal Physiology, Biochemistry and Molecular Biology, College of Life Sciences, Hebei Normal University, Shijiazhuang, Hebei 050024, PR China
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Meyer-Nava S, Torres A, Zurita M, Valadez-Graham V. Molecular effects of dADD1 misexpression in chromatin organization and transcription. BMC Mol Cell Biol 2020; 21:17. [PMID: 32293240 PMCID: PMC7092677 DOI: 10.1186/s12860-020-00257-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2019] [Accepted: 03/04/2020] [Indexed: 12/14/2022] Open
Abstract
Background dADD1 and dXNP proteins are the orthologs in Drosophila melanogaster of the ADD and SNF2 domains, respectively, of the ATRX vertebrate’s chromatin remodeler, they suppress position effect variegation phenotypes and participate in heterochromatin maintenance. Results We performed a search in human cancer databases and found that ATRX protein levels were elevated in more than 4.4% of the samples analyzed. Using the Drosophila model, we addressed the effects of over and under-expression of dADD1 proteins in polytene cells. Elevated levels of dADD1 in fly tissues caused different phenotypes, such as chromocenter disruption and loss of banding pattern at the chromosome arms. Analyses of the heterochromatin maintenance protein HP1a, the dXNP ATPase and the histone post-translational modification H3K9me3 revealed changes in their chromatin localization accompanied by mild transcriptional defects of genes embedded in heterochromatic regions. Furthermore, the expression of heterochromatin embedded genes in null dadd1 organisms is lower than in the wild-type conditions. Conclusion These data indicate that dADD1 overexpression induces chromatin changes, probably affecting the stoichiometry of HP1a containing complexes that lead to transcriptional and architectural changes. Our results place dADD1 proteins as important players in the maintenance of chromatin architecture and heterochromatic gene expression.
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Affiliation(s)
- Silvia Meyer-Nava
- Instituto de Biotecnología. Universidad Nacional Autónoma de México, Campus Morelos, Av. Universidad 2001, C.P, 62210, Cuernavaca, Morelos, Mexico
| | - Amada Torres
- Instituto de Biotecnología. Universidad Nacional Autónoma de México, Campus Morelos, Av. Universidad 2001, C.P, 62210, Cuernavaca, Morelos, Mexico
| | - Mario Zurita
- Instituto de Biotecnología. Universidad Nacional Autónoma de México, Campus Morelos, Av. Universidad 2001, C.P, 62210, Cuernavaca, Morelos, Mexico
| | - Viviana Valadez-Graham
- Instituto de Biotecnología. Universidad Nacional Autónoma de México, Campus Morelos, Av. Universidad 2001, C.P, 62210, Cuernavaca, Morelos, Mexico.
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Wei SC, Tsai CH, Hsu WT, Chao YC. Baculovirus IE2 Interacts with Viral DNA through Daxx To Generate an Organized Nuclear Body Structure for Gene Activation in Vero Cells. J Virol 2019; 93:e00149-19. [PMID: 30728268 PMCID: PMC6450129 DOI: 10.1128/jvi.00149-19] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2019] [Accepted: 01/31/2019] [Indexed: 12/14/2022] Open
Abstract
Upon virus infection of a cell, the uncoated DNA is usually blocked by the host intrinsic immune system inside the nucleus. Although it is crucial for the virus to counteract the host intrinsic immune system and access its genome, little is known about how viruses can knock down host restriction and identify their blocked genomes for later viral gene activation and replication. We found that upon baculovirus transduction into Vero E6 cells, the invading viral DNA is trapped by the cellular death domain-associated protein (Daxx) and histone H3.3 in the nucleus, resulting in gene inactivation. IE2, a baculovirus transactivator, targets host Daxx through IE2 SUMO-interacting motifs (SIMs) to indirectly access viral DNA and forms unique nuclear body structures, which we term clathrate cage-like apparatus (CCLAs), at the early transduction stage. At the later transduction stage, CCLAs gradually enlarge, and IE2 continues to closely interact with viral DNA but no longer associates with Daxx. The association with Daxx is essential for IE2 CCLA formation, and the enlarged CCLAs are capable of transactivating viral but not chromosomal DNA of Vero E6 cells. Our study reveals that baculovirus IE2 counteracts the cellular intrinsic immune system by specifically targeting Daxx and H3.3 to associate with viral DNA indirectly and efficiently. IE2 then utilizes this association with viral DNA to establish a unique CCLA cellular nanomachinery, which is visible under light microscopy as an enclosed environment for proper viral gene expression.IMPORTANCE The major breakthrough of this work is that viral protein IE2 localizes and transactivates its own viral DNA through a most unlikely route, i.e., host proteins Daxx and H3.3, which are designed to efficiently restrict viral DNA from expression. By interacting with these host intrinsic immune factors, IE2 can thus target the viral DNA and then form a unique spherical nuclear body, which we name the CCLA, to enclose the viral DNA and necessary factors to assist in high-level transactivation. Our study represents one of the most complete investigations of nuclear body formation. In addition, so far only RNA or protein molecules have been reported as potential nucleators for initiating nuclear body formation; our study may represent the first example showing that DNA can be a nucleator for a new class of nuclear body formation.
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Affiliation(s)
- Sung-Chan Wei
- Graduate Institute of Life Sciences, National Defense Medical Center, Taipei, Taiwan, Republic of China
- Institute of Molecular Biology, Academia Sinica, Taipei, Taiwan, Republic of China
| | - Chih-Hsuan Tsai
- Institute of Molecular Biology, Academia Sinica, Taipei, Taiwan, Republic of China
- Molecular and Cell Biology, Taiwan International Graduate Program, National Defense Medical Center and Academia Sinica, Taipei, Taiwan, Republic of China
| | - Wei-Ting Hsu
- Graduate Institute of Life Sciences, National Defense Medical Center, Taipei, Taiwan, Republic of China
- Institute of Molecular Biology, Academia Sinica, Taipei, Taiwan, Republic of China
| | - Yu-Chan Chao
- Graduate Institute of Life Sciences, National Defense Medical Center, Taipei, Taiwan, Republic of China
- Institute of Molecular Biology, Academia Sinica, Taipei, Taiwan, Republic of China
- Molecular and Cell Biology, Taiwan International Graduate Program, National Defense Medical Center and Academia Sinica, Taipei, Taiwan, Republic of China
- Department of Plant Pathology and Microbiology, College of Bioresources and Agriculture, National Taiwan University, Taipei, Taiwan, Republic of China
- Department of Life Sciences, College of Life Sciences, National Chung Hsing University, Taichung, Taiwan, Republic of China
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Horard B, Sapey-Triomphe L, Bonnefoy E, Loppin B. ASF1 is required to load histones on the HIRA complex in preparation of paternal chromatin assembly at fertilization. Epigenetics Chromatin 2018; 11:19. [PMID: 29751847 PMCID: PMC5946387 DOI: 10.1186/s13072-018-0189-x] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2018] [Accepted: 04/24/2018] [Indexed: 12/15/2022] Open
Abstract
Background Anti-Silencing Factor 1 (ASF1) is a conserved H3–H4 histone chaperone involved in both Replication-Coupled and Replication-Independent (RI) nucleosome assembly pathways. At DNA replication forks, ASF1 plays an important role in regulating the supply of H3.1/2 and H4 to the CAF-1 chromatin assembly complex. ASF1 also provides H3.3–H4 dimers to HIRA and DAXX chaperones for RI nucleosome assembly. The early Drosophila embryo is an attractive system to study chromatin assembly in a developmental context. The formation of a diploid zygote begins with the unique, genome-wide RI assembly of paternal chromatin following sperm protamine eviction. Then, within the same cytoplasm, syncytial embryonic nuclei undergo a series of rapid, synchronous S and M phases to form the blastoderm embryo. Here, we have investigated the implication of ASF1 in these two distinct assembly processes. Results We show that depletion of the maternal pool of ASF1 with a specific shRNA induces a fully penetrant, maternal effect embryo lethal phenotype. Unexpectedly, despite the depletion of ASF1 protein to undetectable levels, we show that asf1 knocked-down (KD) embryos can develop to various stages, thus demonstrating that ASF1 is not absolutely required for the amplification of cleavage nuclei. Remarkably, we found that ASF1 is required for the formation of the male pronucleus, although ASF1 protein does not reside in the decondensing sperm nucleus. In asf1 KD embryos, HIRA localizes to the male nucleus but is only capable of limited and insufficient chromatin assembly. Finally, we show that the conserved HIRA B domain, which is involved in ASF1-HIRA interaction, is dispensable for female fertility. Conclusions We conclude that ASF1 is critically required to load H3.3–H4 dimers on the HIRA complex prior to histone deposition on paternal DNA. This separation of tasks could optimize the rapid assembly of paternal chromatin within the gigantic volume of the egg cell. In contrast, ASF1 is surprisingly dispensable for the amplification of cleavage nuclei, although chromatin integrity is likely compromised in KD embryos. Electronic supplementary material The online version of this article (10.1186/s13072-018-0189-x) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Béatrice Horard
- Laboratoire de Biométrie et Biologie Evolutive - CNRS - UMR5558, Université Claude Bernard Lyon I, 16, rue R. Dubois - Bât. G. Mendel, 69622, Villeurbanne Cedex, France.
| | - Laure Sapey-Triomphe
- Laboratoire de Biométrie et Biologie Evolutive - CNRS - UMR5558, Université Claude Bernard Lyon I, 16, rue R. Dubois - Bât. G. Mendel, 69622, Villeurbanne Cedex, France
| | - Emilie Bonnefoy
- Laboratoire de Biométrie et Biologie Evolutive - CNRS - UMR5558, Université Claude Bernard Lyon I, 16, rue R. Dubois - Bât. G. Mendel, 69622, Villeurbanne Cedex, France
| | - Benjamin Loppin
- Laboratoire de Biométrie et Biologie Evolutive - CNRS - UMR5558, Université Claude Bernard Lyon I, 16, rue R. Dubois - Bât. G. Mendel, 69622, Villeurbanne Cedex, France.
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