1
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León NY, Le TNU, Garvie A, Wong LH, Bagheri-Fam S, Harley VR. Y chromosome damage underlies testicular abnormalities in ATR-X syndrome. iScience 2024; 27:109629. [PMID: 38616920 PMCID: PMC11015497 DOI: 10.1016/j.isci.2024.109629] [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: 11/23/2023] [Revised: 02/27/2024] [Accepted: 03/26/2024] [Indexed: 04/16/2024] Open
Abstract
ATR-X (alpha thalassemia, mental retardation, X-linked) syndrome features genital and testicular abnormalities including atypical genitalia and small testes with few seminiferous tubules. Our mouse model recapitulated the testicular defects when Atrx was deleted in Sertoli cells (ScAtrxKO) which displayed G2/M arrest and apoptosis. Here, we investigated the mechanisms underlying these defects. In control mice, Sertoli cells contain a single novel "GATA4 PML nuclear body (NB)" that contained the transcription factor GATA4, ATRX, DAXX, HP1α, and PH3 and co-localized with the Y chromosome short arm (Yp). ScAtrxKO mice contain single giant GATA4 PML-NBs with frequent DNA double-strand breaks (DSBs) in G2/M-arrested apoptotic Sertoli cells. HP1α and PH3 were absent from giant GATA4 PML-NBs indicating a failure in heterochromatin formation and chromosome condensation. Our data suggest that ATRX protects a Yp region from DNA damage, thereby preventing Sertoli cell death. We discuss Y chromosome damage/decondensation as a mechanism for testicular failure.
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Affiliation(s)
- Nayla Y. León
- Hudson Institute of Medical Research, Melbourne, VIC 3168, Australia
- Department of Molecular & Translational Science, Monash University, Melbourne, VIC 3168, Australia
| | - Thanh Nha Uyen Le
- Hudson Institute of Medical Research, Melbourne, VIC 3168, Australia
- Department of Molecular & Translational Science, Monash University, Melbourne, VIC 3168, Australia
| | - Andrew Garvie
- Department of Biochemistry and Molecular Biology, Biomedicine Discovery Institute, Monash University, Wellington Road, Clayton, VIC 3800, Australia
| | - Lee H. Wong
- Department of Biochemistry and Molecular Biology, Biomedicine Discovery Institute, Monash University, Wellington Road, Clayton, VIC 3800, Australia
| | - Stefan Bagheri-Fam
- Hudson Institute of Medical Research, Melbourne, VIC 3168, Australia
- Department of Molecular & Translational Science, Monash University, Melbourne, VIC 3168, Australia
| | - Vincent R. Harley
- Hudson Institute of Medical Research, Melbourne, VIC 3168, Australia
- Department of Molecular & Translational Science, Monash University, Melbourne, VIC 3168, Australia
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2
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Schmidt A, Zhang H, Schmitt S, Rausch C, Popp O, Chen J, Cmarko D, Butter F, Dittmar G, Lermyte F, Cardoso MC. The Proteomic Composition and Organization of Constitutive Heterochromatin in Mouse Tissues. Cells 2024; 13:139. [PMID: 38247831 PMCID: PMC10814525 DOI: 10.3390/cells13020139] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2023] [Revised: 12/13/2023] [Accepted: 01/09/2024] [Indexed: 01/23/2024] Open
Abstract
Pericentric heterochromatin (PCH) forms spatio-temporarily distinct compartments and affects chromosome organization and stability. Albeit some of its components are known, an elucidation of its proteome and how it differs between tissues in vivo is lacking. Here, we find that PCH compartments are dynamically organized in a tissue-specific manner, possibly reflecting compositional differences. As the mouse brain and liver exhibit very different PCH architecture, we isolated native PCH fractions from these tissues, analyzed their protein compositions using quantitative mass spectrometry, and compared them to identify common and tissue-specific PCH proteins. In addition to heterochromatin-enriched proteins, the PCH proteome includes RNA/transcription and membrane-related proteins, which showed lower abundance than PCH-enriched proteins. Thus, we applied a cut-off of PCH-unspecific candidates based on their abundance and validated PCH-enriched proteins. Amongst the hits, MeCP2 was classified into brain PCH-enriched proteins, while linker histone H1 was not. We found that H1 and MeCP2 compete to bind to PCH and regulate PCH organization in opposite ways. Altogether, our workflow of unbiased PCH isolation, quantitative mass spectrometry, and validation-based analysis allowed the identification of proteins that are common and tissue-specifically enriched at PCH. Further investigation of selected hits revealed their opposing role in heterochromatin higher-order architecture in vivo.
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Affiliation(s)
- Annika Schmidt
- Cell Biology and Epigenetics, Department of Biology, Technical University of Darmstadt, 64287 Darmstadt, Germany (S.S.)
| | - Hui Zhang
- Cell Biology and Epigenetics, Department of Biology, Technical University of Darmstadt, 64287 Darmstadt, Germany (S.S.)
| | - Stephanie Schmitt
- Cell Biology and Epigenetics, Department of Biology, Technical University of Darmstadt, 64287 Darmstadt, Germany (S.S.)
| | - Cathia Rausch
- Cell Biology and Epigenetics, Department of Biology, Technical University of Darmstadt, 64287 Darmstadt, Germany (S.S.)
| | - Oliver Popp
- Proteomics Platform, Max-Delbrueck-Center for Molecular Medicine in the Helmholtz Association, 13125 Berlin, Germany
| | - Jiaxuan Chen
- Institute of Molecular Biology (IMB), 55128 Mainz, Germany
| | - Dusan Cmarko
- Institute of Biology and Medical Genetics, First Faculty of Medicine, Charles University and General University Hospital in Prague, 128 00 Prague, Czech Republic
| | - Falk Butter
- Institute of Molecular Biology (IMB), 55128 Mainz, Germany
| | - Gunnar Dittmar
- Proteomics Platform, Max-Delbrueck-Center for Molecular Medicine in the Helmholtz Association, 13125 Berlin, Germany
| | - Frederik Lermyte
- Clemens-Schöpf Institute of Organic Chemistry and Biochemistry, Department of Chemistry, Technical University of Darmstadt, 64287 Darmstadt, Germany
| | - M. Cristina Cardoso
- Cell Biology and Epigenetics, Department of Biology, Technical University of Darmstadt, 64287 Darmstadt, Germany (S.S.)
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3
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van Gerven MR, Schild L, van Arkel J, Koopmans B, Broeils LA, Meijs LAM, van Oosterhout R, van Noesel MM, Koster J, van Hooff SR, Molenaar JJ, van den Boogaard ML. Two opposing gene expression patterns within ATRX aberrant neuroblastoma. PLoS One 2023; 18:e0289084. [PMID: 37540673 PMCID: PMC10403137 DOI: 10.1371/journal.pone.0289084] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2023] [Accepted: 07/02/2023] [Indexed: 08/06/2023] Open
Abstract
Neuroblastoma is the most common extracranial solid tumor in children. A subgroup of high-risk patients is characterized by aberrations in the chromatin remodeller ATRX that is encoded by 35 exons. In contrast to other pediatric cancer where ATRX point mutations are most frequent, multi-exon deletions (MEDs) are the most frequent type of ATRX aberrations in neuroblastoma. 75% of these MEDs are predicted to produce in-frame fusion proteins, suggesting a potential gain-of-function effect compared to nonsense mutations. For neuroblastoma there are only a few patient-derived ATRX aberrant models. Therefore, we created isogenic ATRX aberrant models using CRISPR-Cas9 in several neuroblastoma cell lines and one tumoroid and performed total RNA-sequencing on these and the patient-derived models. Gene set enrichment analysis (GSEA) showed decreased expression of genes related to both ribosome biogenesis and several metabolic processes in our isogenic ATRX exon 2-10 MED model systems, the patient-derived MED models and in tumor data containing two patients with an ATRX exon 2-10 MED. In sharp contrast, these same processes showed an increased expression in our isogenic ATRX knock-out and exon 2-13 MED models. Our validations confirmed a role of ATRX in the regulation of ribosome homeostasis. The two distinct molecular expression patterns within ATRX aberrant neuroblastomas that we identified imply that there might be a need for distinct treatment regimens.
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Affiliation(s)
- Michael R van Gerven
- Princess Máxima Center for Pediatric Oncology, Utrecht, Utrecht, The Netherlands
| | - Linda Schild
- Princess Máxima Center for Pediatric Oncology, Utrecht, Utrecht, The Netherlands
| | - Jennemiek van Arkel
- Princess Máxima Center for Pediatric Oncology, Utrecht, Utrecht, The Netherlands
| | - Bianca Koopmans
- Princess Máxima Center for Pediatric Oncology, Utrecht, Utrecht, The Netherlands
| | - Luuk A Broeils
- Princess Máxima Center for Pediatric Oncology, Utrecht, Utrecht, The Netherlands
| | - Loes A M Meijs
- Princess Máxima Center for Pediatric Oncology, Utrecht, Utrecht, The Netherlands
| | - Romy van Oosterhout
- Princess Máxima Center for Pediatric Oncology, Utrecht, Utrecht, The Netherlands
| | - Max M van Noesel
- Princess Máxima Center for Pediatric Oncology, Utrecht, Utrecht, The Netherlands
- Department of Cancer and Imaging, University Medical Center Utrecht, Utrecht, Utrecht, The Netherlands
| | - Jan Koster
- Department of Oncogenomics, University Medical Center Amsterdam, Amsterdam, North-Holland, The Netherlands
| | - Sander R van Hooff
- Princess Máxima Center for Pediatric Oncology, Utrecht, Utrecht, The Netherlands
| | - Jan J Molenaar
- Princess Máxima Center for Pediatric Oncology, Utrecht, Utrecht, The Netherlands
- Department of Pharmaceutical Sciences, Faculty of Science, Utrecht University, Utrecht, Utrecht, The Netherlands
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4
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Rose AM, Goncalves T, Cunniffe S, Geiller HEB, Kent T, Shepherd S, Ratnaweera M, O’Sullivan R, Gibbons R, Clynes D. Induction of the alternative lengthening of telomeres pathway by trapping of proteins on DNA. Nucleic Acids Res 2023; 51:6509-6527. [PMID: 36940725 PMCID: PMC10359465 DOI: 10.1093/nar/gkad150] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2022] [Revised: 02/06/2023] [Accepted: 02/21/2023] [Indexed: 03/23/2023] Open
Abstract
Telomere maintenance is a hallmark of malignant cells and allows cancers to divide indefinitely. In some cancers, this is achieved through the alternative lengthening of telomeres (ALT) pathway. Whilst loss of ATRX is a near universal feature of ALT-cancers, it is insufficient in isolation. As such, other cellular events must be necessary - but the exact nature of the secondary events has remained elusive. Here, we report that trapping of proteins (such as TOP1, TOP2A and PARP1) on DNA leads to ALT induction in cells lacking ATRX. We demonstrate that protein-trapping chemotherapeutic agents, such as etoposide, camptothecin and talazoparib, induce ALT markers specifically in ATRX-null cells. Further, we show that treatment with G4-stabilising drugs cause an increase in trapped TOP2A levels which leads to ALT induction in ATRX-null cells. This process is MUS81-endonuclease and break-induced replication dependent, suggesting that protein trapping leads to replication fork stalling, with these forks being aberrantly processed in the absence of ATRX. Finally, we show ALT-positive cells harbour a higher load of genome-wide trapped proteins, such as TOP1, and knockdown of TOP1 reduced ALT activity. Taken together, these findings suggest that protein trapping is a fundamental driving force behind ALT-biology in ATRX-deficient malignancies.
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Affiliation(s)
- Anna M Rose
- MRC Molecular Haematology Unit, Weatherall Institute of Molecular Medicine, University of Oxford, John Radcliffe Hospital, Oxford OX3 9DS, UK
- Department of Paediatrics, University of Oxford, John Radcliffe Hospital, Oxford OX3 9DS, UK
| | - Tomas Goncalves
- MRC Molecular Haematology Unit, Weatherall Institute of Molecular Medicine, University of Oxford, John Radcliffe Hospital, Oxford OX3 9DS, UK
| | - Siobhan Cunniffe
- Department of Oncology, University of Oxford, Oxford OX3 7DQ, UK
| | | | - Thomas Kent
- MRC Molecular Haematology Unit, Weatherall Institute of Molecular Medicine, University of Oxford, John Radcliffe Hospital, Oxford OX3 9DS, UK
| | - Sam Shepherd
- Department of Oncology, University of Oxford, Oxford OX3 7DQ, UK
| | | | - Roderick J O’Sullivan
- Department of Pharmacology and Chemical Biology, UPMC Hillman Cancer Center, University of Pittsburgh, Pittsburgh, PA, USA
| | - Richard J Gibbons
- MRC Molecular Haematology Unit, Weatherall Institute of Molecular Medicine, University of Oxford, John Radcliffe Hospital, Oxford OX3 9DS, UK
| | - David Clynes
- Department of Oncology, University of Oxford, Oxford OX3 7DQ, UK
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5
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Tillotson R, Yan K, Ruston J, DeYoung T, Córdova A, Turcotte-Cardin V, Yee Y, Taylor C, Visuvanathan S, Babbs C, Ivakine EA, Sled JG, Nieman BJ, Picketts DJ, Justice MJ. A new mouse model of ATR-X syndrome carrying a common patient mutation exhibits neurological and morphological defects. Hum Mol Genet 2023; 32:2485-2501. [PMID: 37171606 PMCID: PMC10360390 DOI: 10.1093/hmg/ddad075] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2023] [Revised: 03/18/2023] [Accepted: 05/05/2023] [Indexed: 05/13/2023] Open
Abstract
ATRX is a chromatin remodelling ATPase that is involved in transcriptional regulation, DNA damage repair and heterochromatin maintenance. It has been widely studied for its role in ALT-positive cancers, but its role in neurological function remains elusive. Hypomorphic mutations in the X-linked ATRX gene cause a rare form of intellectual disability combined with alpha-thalassemia called ATR-X syndrome in hemizygous males. Clinical features also include facial dysmorphism, microcephaly, short stature, musculoskeletal defects and genital abnormalities. As complete deletion of ATRX in mice results in early embryonic lethality, the field has largely relied on conditional knockout models to assess the role of ATRX in multiple tissues. Given that null alleles are not found in patients, a more patient-relevant model was needed. Here, we have produced and characterized the first patient mutation knock-in model of ATR-X syndrome, carrying the most common causative mutation, R246C. This is one of a cluster of missense mutations located in the chromatin-binding domain and disrupts its function. The knock-in mice recapitulate several aspects of the patient disorder, including craniofacial defects, microcephaly, reduced body size and impaired neurological function. They provide a powerful model for understanding the molecular mechanisms underlying ATR-X syndrome and testing potential therapeutic strategies.
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Affiliation(s)
- Rebekah Tillotson
- Genetics and Genome Biology Program, The Hospital for Sick Children, The Peter Gilgan Centre for Research and Learning, Toronto, ON M5G 0A4, Canada
- MRC Molecular Haematology Unit, Weatherall Institute of Molecular Medicine, John Radcliffe Hospital/Headley Way, Oxford OX3 9DS, UK
| | - Keqin Yan
- Regenerative Medicine Program, Ottawa Hospital Research Institute, Ottawa, ON K1H 8L6, Canada
| | - Julie Ruston
- Genetics and Genome Biology Program, The Hospital for Sick Children, The Peter Gilgan Centre for Research and Learning, Toronto, ON M5G 0A4, Canada
| | - Taylor DeYoung
- Mouse Imaging Centre, The Hospital for Sick Children, Toronto, ON M5T 3H7, Canada
| | - Alex Córdova
- Regenerative Medicine Program, Ottawa Hospital Research Institute, Ottawa, ON K1H 8L6, Canada
| | - Valérie Turcotte-Cardin
- Regenerative Medicine Program, Ottawa Hospital Research Institute, Ottawa, ON K1H 8L6, Canada
- Cellular & Molecular Medicine, University of Ottawa, Ottawa, ON K1H 8M5, Canada
| | - Yohan Yee
- Mouse Imaging Centre, The Hospital for Sick Children, Toronto, ON M5T 3H7, Canada
- Department of Medical Biophysics, University of Toronto, Toronto, ON M5G 1L7, Canada
| | - Christine Taylor
- Genetics and Genome Biology Program, The Hospital for Sick Children, The Peter Gilgan Centre for Research and Learning, Toronto, ON M5G 0A4, Canada
| | - Shagana Visuvanathan
- Genetics and Genome Biology Program, The Hospital for Sick Children, The Peter Gilgan Centre for Research and Learning, Toronto, ON M5G 0A4, Canada
| | - Christian Babbs
- MRC Molecular Haematology Unit, Weatherall Institute of Molecular Medicine, John Radcliffe Hospital/Headley Way, Oxford OX3 9DS, UK
| | - Evgueni A Ivakine
- Genetics and Genome Biology Program, The Hospital for Sick Children, The Peter Gilgan Centre for Research and Learning, Toronto, ON M5G 0A4, Canada
- Department of Physiology, University of Toronto, Toronto, ON M5S 1A8, Canada
| | - John G Sled
- Mouse Imaging Centre, The Hospital for Sick Children, Toronto, ON M5T 3H7, Canada
- Department of Medical Biophysics, University of Toronto, Toronto, ON M5G 1L7, Canada
- Translational Medicine Program, The Hospital for Sick Children, The Peter Gilgan Centre for Research and Learning, Toronto, ON M5G 0A4, Canada
| | - Brian J Nieman
- Mouse Imaging Centre, The Hospital for Sick Children, Toronto, ON M5T 3H7, Canada
- Department of Medical Biophysics, University of Toronto, Toronto, ON M5G 1L7, Canada
- Translational Medicine Program, The Hospital for Sick Children, The Peter Gilgan Centre for Research and Learning, Toronto, ON M5G 0A4, Canada
- Ontario Institute for Cancer Research, Toronto, ON M5G 0A3, Canada
| | - David J Picketts
- Regenerative Medicine Program, Ottawa Hospital Research Institute, Ottawa, ON K1H 8L6, Canada
- Cellular & Molecular Medicine, University of Ottawa, Ottawa, ON K1H 8M5, Canada
| | - Monica J Justice
- Genetics and Genome Biology Program, The Hospital for Sick Children, The Peter Gilgan Centre for Research and Learning, Toronto, ON M5G 0A4, Canada
- Department of Molecular Genetics, University of Toronto, Toronto, ON M5S 1A1, Canada
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6
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Guthmann M, Qian C, Gialdini I, Nakatani T, Ettinger A, Schauer T, Kukhtevich I, Schneider R, Lamb DC, Burton A, Torres-Padilla ME. A change in biophysical properties accompanies heterochromatin formation in mouse embryos. Genes Dev 2023; 37:336-350. [PMID: 37072228 PMCID: PMC10153458 DOI: 10.1101/gad.350353.122] [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: 12/13/2022] [Accepted: 03/31/2023] [Indexed: 04/20/2023]
Abstract
The majority of our genome is composed of repeated DNA sequences that assemble into heterochromatin, a highly compacted structure that constrains their mutational potential. How heterochromatin forms during development and how its structure is maintained are not fully understood. Here, we show that mouse heterochromatin phase-separates after fertilization, during the earliest stages of mammalian embryogenesis. Using high-resolution quantitative imaging and molecular biology approaches, we show that pericentromeric heterochromatin displays properties consistent with a liquid-like state at the two-cell stage, which change at the four-cell stage, when chromocenters mature and heterochromatin becomes silent. Disrupting the condensates results in altered transcript levels of pericentromeric heterochromatin, suggesting a functional role for phase separation in heterochromatin function. Thus, our work shows that mouse heterochromatin forms membrane-less compartments with biophysical properties that change during development and provides new insights into the self-organization of chromatin domains during mammalian embryogenesis.
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Affiliation(s)
- Manuel Guthmann
- Institute of Epigenetics and Stem Cells (IES), Helmholtz Zentrum München, D-81377 München, Germany
| | - Chen Qian
- Department of Chemistry, Center for NanoScience (CeNS), Ludwig Maximilians-Universität München, 81377 München, Germany
| | - Irene Gialdini
- Department of Chemistry, Center for NanoScience (CeNS), Ludwig Maximilians-Universität München, 81377 München, Germany
| | - Tsunetoshi Nakatani
- Institute of Epigenetics and Stem Cells (IES), Helmholtz Zentrum München, D-81377 München, Germany
| | - Andreas Ettinger
- Institute of Epigenetics and Stem Cells (IES), Helmholtz Zentrum München, D-81377 München, Germany
| | - Tamas Schauer
- Institute of Epigenetics and Stem Cells (IES), Helmholtz Zentrum München, D-81377 München, Germany
| | - Igor Kukhtevich
- Institute of Functional Epigenetics (IFE), Helmholtz Zentrum München, D-85764 Neuherberg, Germany
| | - Robert Schneider
- Institute of Functional Epigenetics (IFE), Helmholtz Zentrum München, D-85764 Neuherberg, Germany
| | - Don C Lamb
- Department of Chemistry, Center for NanoScience (CeNS), Ludwig Maximilians-Universität München, 81377 München, Germany
| | - Adam Burton
- Institute of Epigenetics and Stem Cells (IES), Helmholtz Zentrum München, D-81377 München, Germany
| | - Maria-Elena Torres-Padilla
- Institute of Epigenetics and Stem Cells (IES), Helmholtz Zentrum München, D-81377 München, Germany;
- Faculty of Biology, Ludwig-Maximilians Universität, München, 82152 Planegg, Germany
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7
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Clatterbuck Soper SF, Meltzer PS. ATRX/DAXX: Guarding the Genome against the Hazards of ALT. Genes (Basel) 2023; 14:genes14040790. [PMID: 37107548 PMCID: PMC10137841 DOI: 10.3390/genes14040790] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2023] [Revised: 03/21/2023] [Accepted: 03/22/2023] [Indexed: 03/29/2023] Open
Abstract
Proliferating cells must enact a telomere maintenance mechanism to ensure genomic stability. In a subset of tumors, telomeres are maintained not by telomerase, but through a homologous recombination-based mechanism termed Alternative Lengthening of Telomeres or ALT. The ALT process is linked to mutations in the ATRX/DAXX/H3.3 histone chaperone complex. This complex is responsible for depositing non-replicative histone variant H3.3 at pericentric and telomeric heterochromatin but has also been found to have roles in ameliorating replication in repeat sequences and in promoting DNA repair. In this review, we will discuss ways in which ATRX/DAXX helps to protect the genome, and how loss of this complex allows ALT to take hold.
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8
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Stilp AC, Scherer M, König P, Fürstberger A, Kestler HA, Stamminger T. The chromatin remodeling protein ATRX positively regulates IRF3-dependent type I interferon production and interferon-induced gene expression. PLoS Pathog 2022; 18:e1010748. [PMID: 35939517 PMCID: PMC9387936 DOI: 10.1371/journal.ppat.1010748] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2022] [Revised: 08/18/2022] [Accepted: 07/15/2022] [Indexed: 11/22/2022] Open
Abstract
The chromatin remodeling protein alpha thalassemia/mental retardation syndrome X-linked (ATRX) is a component of promyelocytic leukemia nuclear bodies (PML-NBs) and thereby mediates intrinsic immunity against several viruses including human cytomegalovirus (HCMV). As a consequence, viruses have evolved different mechanisms to antagonize ATRX, such as displacement from PML-NBs or degradation. Here, we show that depletion of ATRX results in an overall impaired antiviral state by decreasing transcription and subsequent secretion of type I IFNs, which is followed by reduced expression of interferon-stimulated genes (ISGs). ATRX interacts with the transcription factor interferon regulatory factor 3 (IRF3) and associates with the IFN-β promoter to facilitate transcription. Furthermore, whole transcriptome sequencing revealed that ATRX is required for efficient IFN-induced expression of a distinct set of ISGs. Mechanistically, we found that ATRX positively modulates chromatin accessibility specifically upon IFN signaling, thereby affecting promoter regions with recognition motifs for AP-1 family transcription factors. In summary, our study uncovers a novel co-activating function of the chromatin remodeling factor ATRX in innate immunity that regulates chromatin accessibility and subsequent transcription of interferons and ISGs. Consequently, ATRX antagonization by viral proteins and ATRX mutations in tumors represent important strategies to broadly compromise both intrinsic and innate immune responses. ATRX is a member of a family of chromatin remodeling proteins required for deposition of the histone variant H3.3 at specific genomic regions. This is important to maintain silencing at these sites. Furthermore, ATRX represents a component of PML nuclear bodies (PML-NBs) which are considered as enigmatic nuclear protein accumulations exhibiting a tight link to cell-intrinsic restriction of viral infections. Previous studies demonstrated that many viruses target ATRX by either displacement or degradation. So far, it is believed that this serves to alleviate ATRX-instituted silencing of viral gene expression. Our results reveal a novel and unexpectedly broad function of ATRX as a co-activator of the innate immune response. We show that ATRX is required for both DNA and RNA sensing pathways to activate interferon (IFN) gene expression as well as for upregulation of a distinct set of interferon-stimulated genes. Assessment of chromatin accessibility detected that IFN acts as a switch to regulate the function of ATRX in heterochromatin remodeling. ATRX positively modulates chromatin accessibility specifically upon IFN signaling, thereby affecting promoter regions with recognition motifs for AP-1 family transcription factors. Loss of ATRX due to viral infection or due to tumor mutations may thus broadly compromise cellular innate immunity.
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Affiliation(s)
| | - Myriam Scherer
- Institute of Virology, Ulm University Medical Center, Ulm, Germany
| | - Patrick König
- Institute of Virology, Ulm University Medical Center, Ulm, Germany
| | - Axel Fürstberger
- Institute of Medical Systems Biology, Ulm University, Ulm, Germany
| | - Hans A. Kestler
- Institute of Medical Systems Biology, Ulm University, Ulm, Germany
| | - Thomas Stamminger
- Institute of Virology, Ulm University Medical Center, Ulm, Germany
- * E-mail:
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9
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Epigenetic genes and epilepsy - emerging mechanisms and clinical applications. Nat Rev Neurol 2022; 18:530-543. [PMID: 35859062 DOI: 10.1038/s41582-022-00693-y] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/16/2022] [Indexed: 12/21/2022]
Abstract
An increasing number of epilepsies are being attributed to variants in genes with epigenetic functions. The products of these genes include factors that regulate the structure and function of chromatin and the placing, reading and removal of epigenetic marks, as well as other epigenetic processes. In this Review, we provide an overview of the various epigenetic processes, structuring our discussion around five function-based categories: DNA methylation, histone modifications, histone-DNA crosstalk, non-coding RNAs and chromatin remodelling. We provide background information on each category, describing the general mechanism by which each process leads to altered gene expression. We also highlight key clinical and mechanistic aspects, providing examples of genes that strongly associate with epilepsy within each class. We consider the practical applications of these findings, including tissue-based and biofluid-based diagnostics and precision medicine-based treatments. We conclude that variants in epigenetic genes are increasingly found to be causally involved in the epilepsies, with implications for disease mechanisms, treatments and diagnostics.
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10
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The chromatin remodeller ATRX facilitates diverse nuclear processes, in a stochastic manner, in both heterochromatin and euchromatin. Nat Commun 2022; 13:3485. [PMID: 35710802 PMCID: PMC9203812 DOI: 10.1038/s41467-022-31194-7] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2021] [Accepted: 06/07/2022] [Indexed: 12/20/2022] Open
Abstract
The chromatin remodeller ATRX interacts with the histone chaperone DAXX to deposit the histone variant H3.3 at sites of nucleosome turnover. ATRX is known to bind repetitive, heterochromatic regions of the genome including telomeres, ribosomal DNA and pericentric repeats, many of which are putative G-quadruplex forming sequences (PQS). At these sites ATRX plays an ancillary role in a wide range of nuclear processes facilitating replication, chromatin modification and transcription. Here, using an improved protocol for chromatin immunoprecipitation, we show that ATRX also binds active regulatory elements in euchromatin. Mutations in ATRX lead to perturbation of gene expression associated with a reduction in chromatin accessibility, histone modification, transcription factor binding and deposition of H3.3 at the sequences to which it normally binds. In erythroid cells where downregulation of α-globin expression is a hallmark of ATR-X syndrome, perturbation of chromatin accessibility and gene expression occurs in only a subset of cells. The stochastic nature of this process suggests that ATRX acts as a general facilitator of cell specific transcriptional and epigenetic programmes, both in heterochromatin and euchromatin.
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11
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ATRX proximal protein associations boast roles beyond histone deposition. PLoS Genet 2021; 17:e1009909. [PMID: 34780483 PMCID: PMC8629390 DOI: 10.1371/journal.pgen.1009909] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2021] [Revised: 11/29/2021] [Accepted: 10/23/2021] [Indexed: 12/31/2022] Open
Abstract
The ATRX ATP-dependent chromatin remodelling/helicase protein associates with the DAXX histone chaperone to deposit histone H3.3 over repetitive DNA regions. Because ATRX-protein interactions impart functions, such as histone deposition, we used proximity-dependent biotinylation (BioID) to identify proximal associations for ATRX. The proteomic screen captured known interactors, such as DAXX, NBS1, and PML, but also identified a range of new associating proteins. To gauge the scope of their roles, we examined three novel ATRX-associating proteins that likely differed in function, and for which little data were available. We found CCDC71 to associate with ATRX, but also HP1 and NAP1, suggesting a role in chromatin maintenance. Contrastingly, FAM207A associated with proteins involved in ribosome biosynthesis and localized to the nucleolus. ATRX proximal associations with the SLF2 DNA damage response factor help inhibit telomere exchanges. We further screened for the proteomic changes at telomeres when ATRX, SLF2, or both proteins were deleted. The loss caused important changes in the abundance of chromatin remodelling, DNA replication, and DNA repair factors at telomeres. Interestingly, several of these have previously been implicated in alternative lengthening of telomeres. Altogether, this study expands the repertoire of ATRX-associating proteins and functions. ATRX is a protein that is needed to keep repetitive DNA regions organized. It does so in part by binding the DAXX histone chaperone to deposit histone proteins on DNA and assemble structures known as nucleosomes. While important, ATRX has additional functions that remain understudied. To better understand its various biological roles, we first identified the other proteins that are found in its proximity. ATRX-associating proteins were implicated in a range of functions, in addition to histone deposition. Our results suggest that ATRX-associating proteins likely help compact DNA after it is assembled into nucleosomes, and also promote its stability. We then examined the effect of ATRX on telomeres (repetitive DNA regions at the end of chromosomes). ATRX and at least one of its associating proteins suppressed spurious DNA exchanges at telomeres. To understand why, we then identified proteomic changes that occur at telomeres when ATRX was deleted. Loss of ATRX altered the enrichment of a surprising number of proteins at telomeres, including several DNA damage response and chromatin remodelling proteins.
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Forsyth RG, Krenács T, Athanasou N, Hogendoorn PCW. Cell Biology of Giant Cell Tumour of Bone: Crosstalk between m/wt Nucleosome H3.3, Telomeres and Osteoclastogenesis. Cancers (Basel) 2021; 13:5119. [PMID: 34680268 PMCID: PMC8534144 DOI: 10.3390/cancers13205119] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2021] [Revised: 10/06/2021] [Accepted: 10/08/2021] [Indexed: 12/14/2022] Open
Abstract
Giant cell tumour of bone (GCTB) is a rare and intriguing primary bone neoplasm. Worrisome clinical features are its local destructive behaviour, its high tendency to recur after surgical therapy and its ability to create so-called benign lung metastases (lung 'plugs'). GCTB displays a complex and difficult-to-understand cell biological behaviour because of its heterogenous morphology. Recently, a driver mutation in histone H3.3 was found. This mutation is highly conserved in GCTB but can also be detected in glioblastoma. Denosumab was recently introduced as an extra option of medical treatment next to traditional surgical and in rare cases, radiotherapy. Despite these new insights, many 'old' questions about the key features of GCTB remain unanswered, such as the presence of telomeric associations (TAs), the reactivation of hTERT, and its slight genomic instability. This review summarises the recent relevant literature of histone H3.3 in relation to the GCTB-specific G34W mutation and pays specific attention to the G34W mutation in relation to the development of TAs, genomic instability, and the characteristic morphology of GCTB. As pieces of an etiogenetic puzzle, this review tries fitting all these molecular features and the unique H3.3 G34W mutation together in GCTB.
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Affiliation(s)
- Ramses G. Forsyth
- Department of Pathology, University Hospital Brussels (UZB), Laarbeeklaan 101, 1090 Brussels, Belgium;
- Labaratorium for Experimental Pathology (EXPA), Vrije Universiteit Brussel (VUB), Laarbeeklaan 103, 1090 Brussels, Belgium
| | - Tibor Krenács
- 1st Department of Pathology and Experimental Cancer Research, Semmelweis University, Üllöi ut 26, 1085 Budapest, Hungary;
| | - Nicholas Athanasou
- Department of Histopathology, Nuffield Orthopaedic Centre, University of Oxford, NDORMS, Oxford OX3 7HE, UK;
| | - Pancras C. W. Hogendoorn
- Department of Pathology, University Hospital Brussels (UZB), Laarbeeklaan 101, 1090 Brussels, Belgium;
- Labaratorium for Experimental Pathology (EXPA), Vrije Universiteit Brussel (VUB), Laarbeeklaan 103, 1090 Brussels, Belgium
- 1st Department of Pathology and Experimental Cancer Research, Semmelweis University, Üllöi ut 26, 1085 Budapest, Hungary;
- Department of Histopathology, Nuffield Orthopaedic Centre, University of Oxford, NDORMS, Oxford OX3 7HE, UK;
- Department of Pathology, Leiden University Medical Center (LUMC), Albinusdreef 2, 2300 RC Leiden, The Netherlands
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13
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Clapier CR. Sophisticated Conversations between Chromatin and Chromatin Remodelers, and Dissonances in Cancer. Int J Mol Sci 2021; 22:5578. [PMID: 34070411 PMCID: PMC8197500 DOI: 10.3390/ijms22115578] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2021] [Revised: 05/18/2021] [Accepted: 05/18/2021] [Indexed: 01/13/2023] Open
Abstract
The establishment and maintenance of genome packaging into chromatin contribute to define specific cellular identity and function. Dynamic regulation of chromatin organization and nucleosome positioning are critical to all DNA transactions-in particular, the regulation of gene expression-and involve the cooperative action of sequence-specific DNA-binding factors, histone modifying enzymes, and remodelers. Remodelers are molecular machines that generate various chromatin landscapes, adjust nucleosome positioning, and alter DNA accessibility by using ATP binding and hydrolysis to perform DNA translocation, which is highly regulated through sophisticated structural and functional conversations with nucleosomes. In this review, I first present the functional and structural diversity of remodelers, while emphasizing the basic mechanism of DNA translocation, the common regulatory aspects, and the hand-in-hand progressive increase in complexity of the regulatory conversations between remodelers and nucleosomes that accompanies the increase in challenges of remodeling processes. Next, I examine how, through nucleosome positioning, remodelers guide the regulation of gene expression. Finally, I explore various aspects of how alterations/mutations in remodelers introduce dissonance into the conversations between remodelers and nucleosomes, modify chromatin organization, and contribute to oncogenesis.
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Affiliation(s)
- Cedric R Clapier
- Department of Oncological Sciences & Howard Hughes Medical Institute, Huntsman Cancer Institute, University of Utah School of Medicine, 2000 Circle of Hope, Salt Lake City, UT 84112, USA
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14
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The Multiple Facets of ATRX Protein. Cancers (Basel) 2021; 13:cancers13092211. [PMID: 34062956 PMCID: PMC8124985 DOI: 10.3390/cancers13092211] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2021] [Revised: 04/30/2021] [Accepted: 05/02/2021] [Indexed: 12/21/2022] Open
Abstract
Simple Summary The gene encoding for the epigenetic regulator ATRX is gaining a prominent position among the most important oncosuppressive genes of the human genome. ATRX gene somatic mutations are found across a number of diverse cancer types, suggesting its relevance in tumor induction and progression. In the present review, the multiple activities of ATRX protein are described in the light of the most recent literature available highlighting its multifaceted role in the caretaking of the human genome. Abstract ATRX gene codifies for a protein member of the SWI-SNF family and was cloned for the first time over 25 years ago as the gene responsible for a rare developmental disorder characterized by α-thalassemia and intellectual disability called Alpha Thalassemia/mental Retardation syndrome X-linked (ATRX) syndrome. Since its discovery as a helicase involved in alpha-globin gene transcriptional regulation, our understanding of the multiple roles played by the ATRX protein increased continuously, leading to the recognition of this multifaceted protein as a central “caretaker” of the human genome involved in cancer suppression. In this review, we report recent advances in the comprehension of the ATRX manifold functions that encompass heterochromatin epigenetic regulation and maintenance, telomere function, replicative stress response, genome stability, and the suppression of endogenous transposable elements and exogenous viral genomes.
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Wu S, Zheng Y, Xu C, Fu J, Xiong F, Yang F. A Novel Mutation in ATRX Causes Alpha-Thalassemia X-Linked Intellectual Disability Syndrome in a Han Chinese Family. Front Pediatr 2021; 9:811812. [PMID: 35127601 PMCID: PMC8811470 DOI: 10.3389/fped.2021.811812] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/09/2021] [Accepted: 12/30/2021] [Indexed: 11/24/2022] Open
Abstract
OBJECTIVE To analyze genetic mutations in a Chinese pedigree affected with Alpha-thalassemia X-linked intellectual disability syndrome, providing a precise diagnosis and genetic counseling. METHODS Clinical data was collected. A novel alternative splicing variant detected by whole-exome sequencing was validated by Sanger sequencing. The functional effect of the mutation was predicted with Mutation Tasting. The analysis of 5' splice site score was estimated with MaxEntScan. Changes in amino acid sequencing were predicted with Mutalyzer. The tertiary structures of the wild type and mutation-carrying protein were predicted by I-TASSER. RNA was extracted from peripheral blood lymphocytes from the proband, his mother and a healthy control. Quantitative Real-Time PCR was used to detect mRNA expression. RESULTS The proband presented with severe intellectual disability, developmental delay, characteristic facies, seizures and cryptorchidism. A novel hemizygous duplication mutation in the ATRX gene in a splice site between exons 3 and 4, NM_000489: c.189+1dupG, was identified with WES in the proband. Sanger sequencing confirmed that the mutation was inherited from his mother, who carried a heterozygous mutation, while his father was not affected. Bioinformatics analysis indicated that the splicing region where the mutation was located is highly conserved and the variant was damaging, producing a truncated protein due to the premature translation of a stop codon. Sanger sequencing with the Quantitative Real-Time PCR product containing a G base inserted between bases 189 and 190. The level of mRNA expression showed that ATRX gene transcription decreased due to the mutation (P < 0.05). CONCLUSIONS A novel mutation in ATRX was found in this pedigree and was confirmed to be pathogenic through functional studies. Our research expanded the spectrum of ATRX gene mutations, providing a precise diagnosis and a basis for genetic counseling.
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Affiliation(s)
- Shaomin Wu
- Department of Fetal Medicine and Prenatal Diagnosis, Zhujiang Hospital, Southern Medical University, Guangzhou, China.,Prenatal Diagnosis Center, Affiliated Dongguan Hospital, Southern Medical University (Dongguan People's Hospital), Dongguan, China
| | - Yingchun Zheng
- Department of Medical Genetics, School of Basic Medical Sciences, Southern Medical University, Guangzhou, China
| | - Cailing Xu
- Department of Fetal Medicine and Prenatal Diagnosis, Zhujiang Hospital, Southern Medical University, Guangzhou, China
| | - Jiahui Fu
- Department of Fetal Medicine and Prenatal Diagnosis, Zhujiang Hospital, Southern Medical University, Guangzhou, China
| | - Fu Xiong
- Department of Fetal Medicine and Prenatal Diagnosis, Zhujiang Hospital, Southern Medical University, Guangzhou, China.,Department of Medical Genetics, School of Basic Medical Sciences, Southern Medical University, Guangzhou, China
| | - Fang Yang
- Department of Fetal Medicine and Prenatal Diagnosis, Zhujiang Hospital, Southern Medical University, Guangzhou, China
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16
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Altıner Ş, Raymond L. A Novel ATRX Mutation Presenting with Intellectual Disability and Severe Kyphoscoliosis. Fetal Pediatr Pathol 2020; 39:539-543. [PMID: 31608750 DOI: 10.1080/15513815.2019.1675833] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
Background: ATR-X syndrome is an X-linked clinical condition usually associated with profound intellectual disability, facial dysmorphism and alpha-thalassemia. The syndrome is clinically heterogeneous with a broad phenotypic spectrum. Although, alpha-thalassaemia is commonly present, it may not manifest in some patients.Case report: A novel missence mutation (NM_000489: ATRX; c.6130C > T; p.Leu2044Phe) was detected in the ATR-X gene in two male siblings with severe intellectual disability, dysmorphic facial appearance and skeletal anomalies. Severe kyphoscoliosis was the main finding. Hematologic findings, one of the well-known clinical entities, were not present.Conclusion: The missense mutation we have described in our patients has not been previously reported. This finding enriches mutation spectrum of ATRX (OMIM #300032) gene. This missense mutation, which is associated with ID and kyphoscoliosis and without alpha-thalassemia, contributes to genotype-phenotype correlation of the ATR-X spectrum. This case report provides further evidence that reverse genetics is a useful approach in diagnostic process of syndromic patients in adulthood.
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Affiliation(s)
- Şule Altıner
- Department of Medical Genetics, Trabzon Kanuni Training and Research Hospital, University of Health Sciences, Trabzon, Turkey
| | - Lucy Raymond
- Department of Medical Genetics, University of Cambridge, Cambridge, UK
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Liu J, Li C, Wang J, Xu D, Wang H, Wang T, Li L, Li H, Nan P, Zhang J, Wang Y, Huang C, Chen D, Zhang Y, Wen T, Zhan Q, Ma F, Qian H. Chromatin modifier MTA1 regulates mitotic transition and tumorigenesis by orchestrating mitotic mRNA processing. Nat Commun 2020; 11:4455. [PMID: 32901005 PMCID: PMC7479136 DOI: 10.1038/s41467-020-18259-1] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2019] [Accepted: 08/10/2020] [Indexed: 02/08/2023] Open
Abstract
Dysregulated alternative splicing (AS) driving carcinogenetic mitosis remains poorly understood. Here, we demonstrate that cancer metastasis-associated antigen 1 (MTA1), a well-known oncogenic chromatin modifier, broadly interacts and co-expresses with RBPs across cancers, contributing to cancerous mitosis-related AS. Using developed fCLIP-seq technology, we show that MTA1 binds abundant transcripts, preferentially at splicing-responsible motifs, influencing the abundance and AS pattern of target transcripts. MTA1 regulates the mRNA level and guides the AS of a series of mitosis regulators. MTA1 deletion abrogated the dynamic AS switches of variants for ATRX and MYBL2 at mitotic stage, which are relevant to mitosis-related tumorigenesis. MTA1 dysfunction causes defective mitotic arrest, leads to aberrant chromosome segregation, and results in chromosomal instability (CIN), eventually contributing to tumorigenesis. Currently, little is known about the RNA splicing during mitosis; here, we uncover that MTA1 binds transcripts and orchestrates dynamic splicing of mitosis regulators in tumorigenesis.
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Grants
- the National Natural Science Foundation of China, No.81502384
- the National Natural Science Foundation of China, No.81672459
- grant from ABLife, No.ABL2014-03005
- the CAMS Innovation Fund for Medical Sciences (CIFMS) No.2017-I2M-3-004 the National Natural Science Foundation of China, No.81874122
- the National Basic Research Program of China (973 Program) (No.2015CB553904), the CAMS Innovation Fund for Medical Sciences (CIFMS) (No.2016-I2M-1-001, 2019‐I2M‐1‐003), the National Natural Science Foundation of China (No. 81572842, 81872280), the Non-profit Central Research Institute Fund of Chinese Academy of Medical Sciences (2017PT31029), the Open Issue of State Key Laboratory of Molecular Oncology (No. SKL-KF-2017-16), the Independent Issue of State Key Laboratory of Molecular Oncology (No. SKL-2017-16)
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Affiliation(s)
- Jian Liu
- State Key Laboratory of Molecular Oncology, National Cancer Center/National Clinical Research Center for Cancer/Cancer Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, 100021, China
- Medical Research Center, Beijing Chao-Yang Hospital, Capital Medical University, Beijing, 100020, China
| | - Chunxiao Li
- State Key Laboratory of Molecular Oncology, National Cancer Center/National Clinical Research Center for Cancer/Cancer Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, 100021, China
- Department of Medical Oncology, National Cancer Center/National Clinical Research Center for Cancer/Cancer Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, 100021, China
| | - Jinsong Wang
- State Key Laboratory of Molecular Oncology, National Cancer Center/National Clinical Research Center for Cancer/Cancer Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, 100021, China
| | - Dongkui Xu
- VIP Department, National Cancer Center/National Clinical Research Center for Cancer/Cancer Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, 100021, China
| | - Haijuan Wang
- State Key Laboratory of Molecular Oncology, National Cancer Center/National Clinical Research Center for Cancer/Cancer Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, 100021, China
| | - Ting Wang
- State Key Laboratory of Molecular Oncology, National Cancer Center/National Clinical Research Center for Cancer/Cancer Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, 100021, China
| | - Lina Li
- Medical Research Center, Beijing Chao-Yang Hospital, Capital Medical University, Beijing, 100020, China
| | - Hui Li
- State Key Laboratory of Molecular Oncology, National Cancer Center/National Clinical Research Center for Cancer/Cancer Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, 100021, China
| | - Peng Nan
- State Key Laboratory of Molecular Oncology, National Cancer Center/National Clinical Research Center for Cancer/Cancer Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, 100021, China
| | - Jingyao Zhang
- State Key Laboratory of Molecular Oncology, National Cancer Center/National Clinical Research Center for Cancer/Cancer Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, 100021, China
| | - Yang Wang
- Institute of Cancer Stem Cell, Dalian Medical University, Dalian, 116044, China
| | - Changzhi Huang
- State Key Laboratory of Molecular Oncology, National Cancer Center/National Clinical Research Center for Cancer/Cancer Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, 100021, China
| | - Dong Chen
- Center for Genome Analysis, ABLife Inc, Wuhan, 430075, China
| | - Yi Zhang
- Center for Genome Analysis, ABLife Inc, Wuhan, 430075, China
| | - Tao Wen
- Medical Research Center, Beijing Chao-Yang Hospital, Capital Medical University, Beijing, 100020, China.
| | - Qimin Zhan
- State Key Laboratory of Molecular Oncology, National Cancer Center/National Clinical Research Center for Cancer/Cancer Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, 100021, China.
- Key laboratory of Carcinogenesis and Translational Research (Ministry of Education/Beijing), Laboratory of Molecular Oncology, Peking University Cancer Hospital & Institute, Beijing, 100142, China.
| | - Fei Ma
- Department of Medical Oncology, National Cancer Center/National Clinical Research Center for Cancer/Cancer Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, 100021, China.
| | - Haili Qian
- State Key Laboratory of Molecular Oncology, National Cancer Center/National Clinical Research Center for Cancer/Cancer Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, 100021, China.
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Timpano S, Picketts DJ. Neurodevelopmental Disorders Caused by Defective Chromatin Remodeling: Phenotypic Complexity Is Highlighted by a Review of ATRX Function. Front Genet 2020; 11:885. [PMID: 32849845 PMCID: PMC7432156 DOI: 10.3389/fgene.2020.00885] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2020] [Accepted: 07/20/2020] [Indexed: 12/15/2022] Open
Abstract
The ability to determine the genetic etiology of intellectual disability (ID) and neurodevelopmental disorders (NDD) has improved immensely over the last decade. One prevailing metric from these studies is the large percentage of genes encoding epigenetic regulators, including many members of the ATP-dependent chromatin remodeling enzyme family. Chromatin remodeling proteins can be subdivided into five classes that include SWI/SNF, ISWI, CHD, INO80, and ATRX. These proteins utilize the energy from ATP hydrolysis to alter nucleosome positioning and are implicated in many cellular processes. As such, defining their precise roles and contributions to brain development and disease pathogenesis has proven to be complex. In this review, we illustrate that complexity by reviewing the roles of ATRX on genome stability, replication, and transcriptional regulation and how these mechanisms provide key insight into the phenotype of ATR-X patients.
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Affiliation(s)
- Sara Timpano
- Regenerative Medicine Program, Ottawa Hospital Research Institute, Ottawa, ON, Canada
| | - David J. Picketts
- Regenerative Medicine Program, Ottawa Hospital Research Institute, Ottawa, ON, Canada
- Department of Biochemistry, Microbiology, and Immunology, University of Ottawa, Ottawa, ON, Canada
- Department of Cellular and Molecular Medicine, University of Ottawa, Ottawa, ON, Canada
- Department of Medicine, University of Ottawa, Ottawa, ON, Canada
- University of Ottawa Brain and Mind Research Institute, Ottawa, ON, Canada
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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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20
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Bunina D, Abazova N, Diaz N, Noh KM, Krijgsveld J, Zaugg JB. Genomic Rewiring of SOX2 Chromatin Interaction Network during Differentiation of ESCs to Postmitotic Neurons. Cell Syst 2020; 10:480-494.e8. [PMID: 32553182 PMCID: PMC7322528 DOI: 10.1016/j.cels.2020.05.003] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2019] [Revised: 03/19/2020] [Accepted: 05/15/2020] [Indexed: 02/08/2023]
Abstract
Cellular differentiation requires dramatic changes in chromatin organization, transcriptional regulation, and protein production. To understand the regulatory connections between these processes, we generated proteomic, transcriptomic, and chromatin accessibility data during differentiation of mouse embryonic stem cells (ESCs) into postmitotic neurons and found extensive associations between different molecular layers within and across differentiation time points. We observed that SOX2, as a regulator of pluripotency and neuronal genes, redistributes from pluripotency enhancers to neuronal promoters during differentiation, likely driven by changes in its protein interaction network. We identified ATRX as a major SOX2 partner in neurons, whose co-localization correlated with an increase in active enhancer marks and increased expression of nearby genes, which we experimentally confirmed for three loci. Collectively, our data provide key insights into the regulatory transformation of SOX2 during neuronal differentiation, and we highlight the significance of multi-omic approaches in understanding gene regulation in complex systems. Complex interplay of RNA, protein, and chromatin during neuronal differentiation Multi-omic profiling reveals divergent roles of SOX2 in stem cells and neurons SOX2 on-chromatin interaction network changes from pluripotent to neuronal factors ATRX interacts with SOX2 in neurons and co-binds highly expressed neuronal genes
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Affiliation(s)
- Daria Bunina
- Structural and Computational Biology Unit, European Molecular Biology Laboratory, EMBL, Meyerhofstrasse 1 Heidelberg 69117, Germany; Genome Biology Unit, European Molecular Biology Laboratory, EMBL, Meyerhofstrasse 1 Heidelberg 69117, Germany
| | - Nade Abazova
- Genome Biology Unit, European Molecular Biology Laboratory, EMBL, Meyerhofstrasse 1 Heidelberg 69117, Germany; Proteomics of Stem Cells and Cancer, German Cancer Research Center (DKFZ), Heidelberg 69120, Germany; Collaboration for joint PhD degree between the European Molecular Biology Laboratory and Heidelberg University, Faculty of Biosciences, Heidelberg, Germany
| | - Nichole Diaz
- Genome Biology Unit, European Molecular Biology Laboratory, EMBL, Meyerhofstrasse 1 Heidelberg 69117, Germany
| | - Kyung-Min Noh
- Genome Biology Unit, European Molecular Biology Laboratory, EMBL, Meyerhofstrasse 1 Heidelberg 69117, Germany.
| | - Jeroen Krijgsveld
- Proteomics of Stem Cells and Cancer, German Cancer Research Center (DKFZ), Heidelberg 69120, Germany; Heidelberg University, Medical Faculty Heidelberg University, Faculty of Biosciences, Heidelberg, Germany.
| | - Judith B Zaugg
- Structural and Computational Biology Unit, European Molecular Biology Laboratory, EMBL, Meyerhofstrasse 1 Heidelberg 69117, Germany.
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21
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O'Shea LC, Fair T, Hensey C. X-linked α-thalassemia with mental retardation is downstream of protein kinase A in the meiotic cell cycle signaling cascade in Xenopus oocytes and is dynamically regulated in response to DNA damage†. Biol Reprod 2020; 100:1238-1249. [PMID: 30649195 DOI: 10.1093/biolre/ioz001] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2018] [Revised: 10/19/2018] [Accepted: 01/08/2019] [Indexed: 12/19/2022] Open
Abstract
X-linked α-thalassemia with mental retardation (ATRX) is a chromatin remodeling protein that belongs to the SWItch/sucrose non-fermentable (SWI2/SNF2) family of helicase/ATPases. During meiosis, ATRX is necessary for heterochromatin formation and maintenance of chromosome stability in order to ensure proper assembly of the metaphase II spindle. Previously, we established ATRX as a novel progesterone regulated protein during bovine meiotic maturation, in addition to being dynamically regulated in response to DNA damage in oocytes. In the present study, we utilize the Xenopus laevis model system to further elucidate the signaling pathways regulating ATRX expression within the oocyte. Here, we present an analysis of endogenous ATRX protein expression during oogenesis, oocyte meiotic maturation, and early embryonic development. ATRX expression is dynamically regulated as evidenced by loss of the protein in metaphase II of meiosis. The downstream activation of meiosis via protein kinase A inhibition resulted in a similar decrease in ATRX protein expression. We demonstrate that the ATRX protein is detected in ubiquitin immuno-precipitates from germinal vesicle oocyte extracts and experimentally demonstrate that proteosomal degradation is responsible for the decreased expression of ATRX during meiosis. ATRX expression is significantly increased in response to gamma-irradiation induced DNA damage in oocytes and embryos. This increased expression is independent of p53 protein expression in apoptotic embryos, as determined by the expression of active caspase-3. Thus, regulation of ATRX protein expression impacts on G2-M progression and ultimately has consequences for cell survival.
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Affiliation(s)
| | - Trudee Fair
- UCD School of Agriculture and Food Science, Dublin, Ireland
| | - Carmel Hensey
- UCD School of Bimolecular and Biomedical Science, University College Dublin, Dublin, Ireland
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22
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Epigenetic Factors That Control Pericentric Heterochromatin Organization in Mammals. Genes (Basel) 2020; 11:genes11060595. [PMID: 32481609 PMCID: PMC7349813 DOI: 10.3390/genes11060595] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2020] [Revised: 05/17/2020] [Accepted: 05/25/2020] [Indexed: 12/11/2022] Open
Abstract
Pericentric heterochromatin (PCH) is a particular form of constitutive heterochromatin that is localized to both sides of centromeres and that forms silent compartments enriched in repressive marks. These genomic regions contain species-specific repetitive satellite DNA that differs in terms of nucleotide sequences and repeat lengths. In spite of this sequence diversity, PCH is involved in many biological phenomena that are conserved among species, including centromere function, the preservation of genome integrity, the suppression of spurious recombination during meiosis, and the organization of genomic silent compartments in the nucleus. PCH organization and maintenance of its repressive state is tightly regulated by a plethora of factors, including enzymes (e.g., DNA methyltransferases, histone deacetylases, and histone methyltransferases), DNA and histone methylation binding factors (e.g., MECP2 and HP1), chromatin remodeling proteins (e.g., ATRX and DAXX), and non-coding RNAs. This evidence helps us to understand how PCH organization is crucial for genome integrity. It then follows that alterations to the molecular signature of PCH might contribute to the onset of many genetic pathologies and to cancer progression. Here, we describe the most recent updates on the molecular mechanisms known to underlie PCH organization and function.
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Disruption of ATRX-RNA interactions uncovers roles in ATRX localization and PRC2 function. Nat Commun 2020; 11:2219. [PMID: 32376827 PMCID: PMC7203109 DOI: 10.1038/s41467-020-15902-9] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2019] [Accepted: 03/27/2020] [Indexed: 01/01/2023] Open
Abstract
Heterochromatin in the eukaryotic genome is rigorously controlled by the concerted action of protein factors and RNAs. Here, we investigate the RNA binding function of ATRX, a chromatin remodeler with roles in silencing of repetitive regions of the genome and in recruitment of the polycomb repressive complex 2 (PRC2). We identify ATRX RNA binding regions (RBRs) and discover that the major ATRX RBR lies within the N-terminal region of the protein, distinct from its PHD and helicase domains. Deletion of this ATRX RBR (ATRXΔRBR) compromises ATRX interactions with RNAs in vitro and in vivo and alters its chromatin binding properties. Genome-wide studies reveal that loss of RNA interactions results in a redistribution of ATRX on chromatin. Finally, our studies identify a role for ATRX-RNA interactions in regulating PRC2 localization to a subset of polycomb target genes. ATRX is an RNA binding protein that mediates targeting of polycomb repressive complex 2 (PRC2) to genomic sites. Here the authors identify the RNA binding region and show that the RNA binding is required for ATRX localization and for its recruitment of PRC2 to a subset of polycomb targets.
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24
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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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25
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Two Novel Variants in the ATRX Gene Associated with Variable Phenotypes. Case Rep Genet 2019; 2019:2687595. [PMID: 31781420 PMCID: PMC6875291 DOI: 10.1155/2019/2687595] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2019] [Revised: 09/17/2019] [Accepted: 10/04/2019] [Indexed: 11/18/2022] Open
Abstract
The X-linked alpha-thalassemia mental retardation (ATR-X) syndrome is a rare genetic condition caused by mutations in the X‐encoded gene ATRX. Here we describe two unrelated patients of Sri Lankan origin with novel missense variants in the ATRX gene: c.839C>T|p.Cys280Tyr and c.5369C>T|p.Ala1790Val. These two novel variants were associated with variable phenotypes which clinically resembled X-linked mental retardation-hypotonic facies syndrome and Smith-Fineman-Myers syndrome respectively. These cases expand the clinical spectrum of ATR-X syndrome and open new opportunities for the molecular diagnosis of ATRX mutations in male patients with severe global developmental delay and intellectual disabilities.
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Gugustea R, Tamming RJ, Martin-Kenny N, Bérubé NG, Leung LS. Inactivation of ATRX in forebrain excitatory neurons affects hippocampal synaptic plasticity. Hippocampus 2019; 30:565-581. [PMID: 31713968 DOI: 10.1002/hipo.23174] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2019] [Revised: 10/23/2019] [Accepted: 10/28/2019] [Indexed: 12/26/2022]
Abstract
α-Thalassemia X-linked intellectual disability (ATR-X) syndrome is a neurodevelopmental disorder caused by mutations in the ATRX gene that encodes a SNF2-type chromatin-remodeling protein. The ATRX protein regulates chromatin structure and gene expression in the developing mouse brain and early inactivation leads to DNA replication stress, extensive cell death, and microcephaly. However, the outcome of Atrx loss of function postnatally in neurons is less well understood. We recently reported that conditional inactivation of Atrx in postnatal forebrain excitatory neurons (ATRX-cKO) causes deficits in long-term hippocampus-dependent spatial memory. Thus, we hypothesized that ATRX-cKO mice will display impaired hippocampal synaptic transmission and plasticity. In the present study, evoked field potentials and current source density analysis were recorded from a multichannel electrode in male, urethane-anesthetized mice. Three major excitatory synapses, the Schaffer collaterals to basal dendrites and proximal apical dendrites, and the temporoammonic path to distal apical dendrites on hippocampal CA1 pyramidal cells were assessed by their baseline synaptic transmission, including paired-pulse facilitation (PPF) at 50-ms interpulse interval, and by their long-term potentiation (LTP) induced by theta-frequency burst stimulation. Baseline single-pulse excitatory response at each synapse did not differ between ATRX-cKO and control mice, but baseline PPF was reduced at the CA1 basal dendritic synapse in ATRX-cKO mice. While basal dendritic LTP of the first-pulse excitatory response was not affected in ATRX-cKO mice, proximal and distal apical dendritic LTP were marginally and significantly reduced, respectively. These results suggest that ATRX is required in excitatory neurons of the forebrain to achieve normal hippocampal LTP and PPF at the CA1 apical and basal dendritic synapses, respectively. Such alterations in hippocampal synaptic transmission and plasticity could explain the long-term spatial memory deficits in ATRX-cKO mice and provide insight into the physiological mechanisms underlying intellectual disability in ATR-X syndrome patients.
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Affiliation(s)
- Radu Gugustea
- Graduate Program in Neuroscience, Western University, London, Ontario, Canada
| | - Renee J Tamming
- Department of Biochemistry, Western University, London, Ontario, Canada.,Department of Paediatrics, Western University, London, Ontario, Canada.,Division of Genetics and Development, Children's Health Research Institute, London, Ontario, Canada
| | - Nicole Martin-Kenny
- Department of Paediatrics, Western University, London, Ontario, Canada.,Division of Genetics and Development, Children's Health Research Institute, London, Ontario, Canada.,Department of Anatomy and Cell Biology, Western University, London, Ontario, Canada
| | - Nathalie G Bérubé
- Graduate Program in Neuroscience, Western University, London, Ontario, Canada.,Department of Paediatrics, Western University, London, Ontario, Canada.,Division of Genetics and Development, Children's Health Research Institute, London, Ontario, Canada.,Department of Anatomy and Cell Biology, Western University, London, Ontario, Canada.,Department of Oncology, Schulich School of Medicine and Dentistry, Western University, London, Ontario, Canada
| | - L Stan Leung
- Graduate Program in Neuroscience, Western University, London, Ontario, Canada.,Department of Physiology and Pharmacology, Western University, London, Ontario, Canada
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27
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Marano D, Fioriniello S, Fiorillo F, Gibbons RJ, D'Esposito M, Della Ragione F. ATRX Contributes to MeCP2-Mediated Pericentric Heterochromatin Organization during Neural Differentiation. Int J Mol Sci 2019; 20:E5371. [PMID: 31671722 PMCID: PMC6862095 DOI: 10.3390/ijms20215371] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2019] [Accepted: 10/24/2019] [Indexed: 11/16/2022] Open
Abstract
Methyl-CpG binding protein 2 (MeCP2) is a multi-function factor involved in locus-specific transcriptional modulation and the regulation of genome architecture, e.g., pericentric heterochromatin (PCH) organization. MECP2 mutations are responsible for Rett syndrome (RTT), a devastating postnatal neurodevelopmental disorder, the pathogenetic mechanisms of which are still unknown. MeCP2, together with Alpha-thalassemia/mental retardation syndrome X-linked protein (ATRX), accumulates at chromocenters, which are repressive PCH domains. As with MECP2, mutations in ATRX cause ATR-X syndrome which is associated with severe intellectual disability. We exploited two murine embryonic stem cell lines, in which the expression of MeCP2 or ATRX is abolished. Through immunostaining, chromatin immunoprecipitation and western blot, we show that MeCP2 and ATRX are reciprocally dependent both for their expression and targeting to chromocenters. Moreover, ATRX plays a role in the accumulation of members of the heterochromatin protein 1 (HP1) family at PCH and, as MeCP2, modulates their expression. Furthermore, ATRX and HP1 targeting to chromocenters depends on an RNA component. 3D-DNA fluorescence in situ hybridization (FISH) highlighted, for the first time, a contribution of ATRX in MeCP2-mediated chromocenter clustering during neural differentiation. Overall, we provide a detailed dissection of the functional interplay between MeCP2 and ATRX in higher-order PCH organization in neurons. Our findings suggest molecular defects common to RTT and ATR-X syndrome, including an alteration in PCH.
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Affiliation(s)
- Domenico Marano
- Institute of Genetics and Biophysics 'A. Buzzati-Traverso', National Research Council (CNR), 80131 Naples, Italy.
| | - Salvatore Fioriniello
- Institute of Genetics and Biophysics 'A. Buzzati-Traverso', National Research Council (CNR), 80131 Naples, Italy.
| | - Francesca Fiorillo
- Institute of Genetics and Biophysics 'A. Buzzati-Traverso', National Research Council (CNR), 80131 Naples, Italy.
| | - Richard J Gibbons
- MRC Molecular Haematology Unit, MRC Weatherall Institute of Molecular Medicine, University of Oxford, Oxford OX3 9DS, UK.
| | - Maurizio D'Esposito
- Institute of Genetics and Biophysics 'A. Buzzati-Traverso', National Research Council (CNR), 80131 Naples, Italy.
| | - Floriana Della Ragione
- Institute of Genetics and Biophysics 'A. Buzzati-Traverso', National Research Council (CNR), 80131 Naples, Italy.
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28
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Cabral JM, Oh HS, Knipe DM. ATRX promotes maintenance of herpes simplex virus heterochromatin during chromatin stress. eLife 2018; 7:40228. [PMID: 30465651 PMCID: PMC6307862 DOI: 10.7554/elife.40228] [Citation(s) in RCA: 44] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2018] [Accepted: 11/20/2018] [Indexed: 12/17/2022] Open
Abstract
The mechanisms by which mammalian cells recognize and epigenetically restrict viral DNA are not well defined. We used herpes simplex virus with bioorthogonally labeled genomes to detect host factors recruited to viral DNA shortly after its nuclear entry and found that the cellular IFI16, PML, and ATRX proteins colocalized with viral DNA by 15 min post infection. HSV-1 infection of ATRX-depleted fibroblasts resulted in elevated viral mRNA and accelerated viral DNA accumulation. Despite the early association of ATRX with vDNA, we found that initial viral heterochromatin formation is ATRX-independent. However, viral heterochromatin stability required ATRX from 4 to 8 hr post infection. Inhibition of transcription blocked viral chromatin loss in ATRX-knockout cells; thus, ATRX is uniquely required for heterochromatin maintenance during chromatin stress. These results argue that the initial formation and the subsequent maintenance of viral heterochromatin are separable mechanisms, a concept that likely extrapolates to host cell chromatin and viral latency. Cells carefully package their DNA, tightly wrapping the long, stringy molecule around spool-like groups of proteins called histones. However, the genes that are draped around histones are effectively silenced, because they are ‘hidden’ from the molecular actors that read the genetic information to create proteins. A cell can control which of its genes are active by using proteins to move histones on or off specific portions of DNA. For example, a protein known as ATRX associates with a partner to load histones onto precise DNA regions and switch them off. Wrapping DNA around histones can also be a defense mechanism against viruses, which are tiny cellular parasites that hijack the molecular machinery of a cell to create more of themselves. For instance, the herpes simplex virus, which causes cold sores and genital herpes, injects its DNA into a cell where it is used as a template to create new viral particles. By packaging the DNA of the virus around histones, the cell ensures that this foreign genetic information cannot be used to make more invaders. However, the details of this process remain unknown. In particular, it is still unclear what happens immediately after the virus penetrates the nucleus, the compartment that shelters the DNA of the cell. Here, Cabral et al. explored this question by dissecting the role of ATRX in silencing the genetic information of the herpes simplex virus. The viral DNA was labeled while inside the virus itself, and then tracked using microscopy imaging techniques as it made its way into the cell and inside the nucleus. This revealed that, almost immediately after the viral DNA had entered the nucleus, ATRX came in contact with the foreign molecule. One possibility was that ATRX would be responsible for loading certain forms of histones onto the viral DNA. However, after Cabral et al. deleted ATRX from the cell, histones were still present on the genetic information of the virus, but this association was less stable. This indicated that ATRX was only required to keep histones latched onto the viral DNA, but not to load the proteins in the first place. Overall, these results show that using histones to silence viral DNA in done in several steps: first, the foreign genetic material needs to be recognized, then histones have to be attached, and finally molecular actors should be recruited to keep histones onto the DNA. Knowing how cells ward off the herpes simplex virus could help us find ways to ‘boost’ this defense mechanism. Armed with this knowledge, we could also begin to understand why certain people are more likely to be infected by this virus.
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Affiliation(s)
- Joseph M Cabral
- Department of Microbiology, Blavatnik Institute, Harvard Medical School, Boston, United States.,Program in Virology, Harvard Medical School, Boston, United States
| | - Hyung Suk Oh
- Department of Microbiology, Blavatnik Institute, Harvard Medical School, Boston, United States
| | - David M Knipe
- Department of Microbiology, Blavatnik Institute, Harvard Medical School, Boston, United States.,Program in Virology, Harvard Medical School, Boston, United States
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29
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Wang H, Jiang D, Axelsson E, Lorković ZJ, Montgomery S, Holec S, Pieters BJGE, Al Temimi AHK, Mecinović J, Berger F. LHP1 Interacts with ATRX through Plant-Specific Domains at Specific Loci Targeted by PRC2. MOLECULAR PLANT 2018; 11:1038-1052. [PMID: 29793052 DOI: 10.1016/j.molp.2018.05.004] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/26/2017] [Revised: 04/10/2018] [Accepted: 05/11/2018] [Indexed: 06/08/2023]
Abstract
Heterochromatin Protein 1 (HP1) is a major regulator of chromatin structure and function. In animals, the network of proteins interacting with HP1 is mainly associated with constitutive heterochromatin marked by H3K9me3. HP1 physically interacts with the putative ortholog of the SNF2 chromatin remodeler ATRX, which controls deposition of histone variant H3.3 in mammals. In this study, we show that the Arabidopsis thaliana ortholog of ATRX participates in H3.3 deposition and possesses specific conserved domains in plants. We found that plant Like HP1 (LHP1) protein interacts with ATRX through domains that evolved specifically in land plant ancestors. Loss of ATRX function in Arabidopsis affects the expression of a limited subset of genes controlled by PRC2 (POLYCOMB REPRESSIVE COMPLEX 2), including the flowering time regulator FLC. The function of ATRX in regulation of flowering time requires novel LHP1-interacting domain and ATPase activity of the ATRX SNF2 helicase domain. Taken together, these results suggest that distinct evolutionary pathways led to the interaction between ATRX and HP1 in mammals and its counterpart LHP1 in plants, resulting in distinct modes of transcriptional regulation.
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Affiliation(s)
- Haifeng Wang
- Gregor Mendel Institute (GMI), Austrian Academy of Sciences, Vienna Biocenter (VBC), Dr. Bohr-Gasse 3, 1030 Vienna, Austria; Temasek Lifesciences Laboratory, 1 Research Link, National University of Singapore, 117604 Singapore, Singapore; Department of Biological Sciences, National University of Singapore, 14 Science Drive 4, 117543 Singapore, Singapore
| | - Danhua Jiang
- Gregor Mendel Institute (GMI), Austrian Academy of Sciences, Vienna Biocenter (VBC), Dr. Bohr-Gasse 3, 1030 Vienna, Austria; Temasek Lifesciences Laboratory, 1 Research Link, National University of Singapore, 117604 Singapore, Singapore
| | - Elin Axelsson
- Gregor Mendel Institute (GMI), Austrian Academy of Sciences, Vienna Biocenter (VBC), Dr. Bohr-Gasse 3, 1030 Vienna, Austria
| | - Zdravko J Lorković
- Gregor Mendel Institute (GMI), Austrian Academy of Sciences, Vienna Biocenter (VBC), Dr. Bohr-Gasse 3, 1030 Vienna, Austria
| | - Sean Montgomery
- Gregor Mendel Institute (GMI), Austrian Academy of Sciences, Vienna Biocenter (VBC), Dr. Bohr-Gasse 3, 1030 Vienna, Austria
| | - Sarah Holec
- Temasek Lifesciences Laboratory, 1 Research Link, National University of Singapore, 117604 Singapore, Singapore
| | - Bas J G E Pieters
- Institute for Molecules and Materials, Radboud University, Heyendaalseweg 135, 6525 AJ Nijmegen, the Netherlands
| | - Abbas H K Al Temimi
- Institute for Molecules and Materials, Radboud University, Heyendaalseweg 135, 6525 AJ Nijmegen, the Netherlands
| | - Jasmin Mecinović
- Institute for Molecules and Materials, Radboud University, Heyendaalseweg 135, 6525 AJ Nijmegen, the Netherlands
| | - Frédéric Berger
- Gregor Mendel Institute (GMI), Austrian Academy of Sciences, Vienna Biocenter (VBC), Dr. Bohr-Gasse 3, 1030 Vienna, Austria; Temasek Lifesciences Laboratory, 1 Research Link, National University of Singapore, 117604 Singapore, Singapore; Department of Biological Sciences, National University of Singapore, 14 Science Drive 4, 117543 Singapore, Singapore.
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30
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Rowland ME, Jiang Y, Beier F, Bérubé NG. Inactivation of hepatic ATRX in Atrx Foxg1cre mice prevents reversal of aging-like phenotypes by thyroxine. Aging (Albany NY) 2018; 10:1223-1238. [PMID: 29883366 PMCID: PMC6046231 DOI: 10.18632/aging.101462] [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: 01/24/2018] [Accepted: 05/30/2018] [Indexed: 11/25/2022]
Abstract
ATRX is an ATP-dependent chromatin remodeler required for the maintenance of genomic integrity. We previously reported that conditional Atrx ablation in the mouse embryonic forebrain and anterior pituitary using the Foxg1cre driver causes reduced health and lifespan. In these mice, premature aging-like phenotypes were accompanied by low circulating levels of insulin-like growth factor 1 (IGF-1) and thyroxine (T4), hormones that maintain stem cell pools and normal metabolic profiles, respectively. Based on emerging evidence that T4 stimulates expression of IGF-1 in pre-pubertal mice, we tested whether T4 supplementation in Atrx Foxg1cre mice could restore IGF-1 levels and ameliorate premature aging-like phenotypes. Despite restoration of normal serum T4 levels, we did not observe improvements in circulating IGF-1. In the liver, thyroid hormone target genes were differentially affected upon T4 treatment, with Igf1 and several other thyroid hormone responsive genes failing to recover normal expression levels. These findings hinted at Cre-mediated Atrx inactivation in the liver of Atrx Foxg1cre mice, which we confirmed. We conclude that the phenotypes observed in the Atrx Foxg1cre mice can be explained in part by a role of ATRX in the liver to promote T4-mediated Igf1 expression, thus explaining the inefficacy of T4 therapy observed in this study.
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Affiliation(s)
- Megan E Rowland
- Departments of Paediatrics and Biochemistry, Schulich School of Medicine and Dentistry, Western University, London, ON, Canada.,Children's Health Research Institute, London, ON, Canada
| | - Yan Jiang
- Departments of Paediatrics and Biochemistry, Schulich School of Medicine and Dentistry, Western University, London, ON, Canada.,Children's Health Research Institute, London, ON, Canada
| | - Frank Beier
- Children's Health Research Institute, London, ON, Canada.,Department of Physiology and Pharmacology, Schulich School of Medicine and Dentistry, Western University, London, ON, Canada.,Western Bone and Joint Institute, Western University, London, ON, Canada
| | - Nathalie G Bérubé
- Departments of Paediatrics and Biochemistry, Schulich School of Medicine and Dentistry, Western University, London, ON, Canada.,Children's Health Research Institute, London, ON, Canada
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Morozov VM, Giovinazzi S, Ishov AM. CENP-B protects centromere chromatin integrity by facilitating histone deposition via the H3.3-specific chaperone Daxx. Epigenetics Chromatin 2017; 10:63. [PMID: 29273057 PMCID: PMC5741900 DOI: 10.1186/s13072-017-0164-y] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2017] [Accepted: 11/24/2017] [Indexed: 12/27/2022] Open
Abstract
Background The main chromatin unit, the nucleosome, can be modulated by the incorporation of histone variants that, in combination with posttranslational histones modifications, determine epigenetics properties of chromatin. Understanding the mechanism that creates a histone variants landscape at different genomic elements is expected to elevate our comprehension of chromatin assembly and function. The Daxx chaperone deposits transcription-associated histone H3.3 at centromeres, but mechanism of centromere-specific Daxx targeting remains unclear. Results In this study, we identified an unexpected function of the constitutive centromeric protein CENP-B that serves as a “beacon” for H3.3 incorporation. CENP-B depletion reduces Daxx association and H3.3 incorporation at centromeres. Daxx/CENP-B interaction and Daxx centromeric association are SUMO dependent and requires SIMs of Daxx. Depletion of SUMO-2, but not SUMO-1, decreases Daxx/CENP-B interaction and reduces centromeric accumulation of Daxx and H3.3, demonstrating distinct functions of SUMO paralogs in H3.3 chaperoning. Finally, disruption of CENP-B/Daxx-dependent H3.3 pathway deregulates heterochromatin marks H3K9me3, ATRX and HP1α at centromeres and elevates chromosome instability. Conclusion The demonstrated roles of CENP-B and SUMO-2 in H3.3 loading reveal a novel mechanism controlling chromatin maintenance and genome stability. Given that CENP-B is the only centromere protein that binds centromere-specific DNA elements, our study provides a new link between centromere DNA and unique epigenetic landscape of centromere chromatin. Electronic supplementary material The online version of this article (10.1186/s13072-017-0164-y) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Viacheslav M Morozov
- Department of Anatomy and Cell Biology, University of Florida College of Medicine, and University of Florida Cancer Center, 2033 Mowry Road, Room 358, Gainesville, FL, 32610, USA
| | - Serena Giovinazzi
- Department of Anatomy and Cell Biology, University of Florida College of Medicine, and University of Florida Cancer Center, 2033 Mowry Road, Room 358, Gainesville, FL, 32610, USA.,Division of Food Safety, Florida Department of Agriculture and Consumer Services, Tallahassee, FL, USA
| | - Alexander M Ishov
- Department of Anatomy and Cell Biology, University of Florida College of Medicine, and University of Florida Cancer Center, 2033 Mowry Road, Room 358, Gainesville, FL, 32610, USA.
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Bano D, Piazzesi A, Salomoni P, Nicotera P. The histone variant H3.3 claims its place in the crowded scene of epigenetics. Aging (Albany NY) 2017; 9:602-614. [PMID: 28284043 PMCID: PMC5391221 DOI: 10.18632/aging.101194] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2016] [Accepted: 02/26/2017] [Indexed: 12/16/2022]
Abstract
Histones are evolutionarily conserved DNA-binding proteins. As scaffolding molecules, they significantly regulate the DNA packaging into the nucleus of all eukaryotic cells. As docking units, they influence the recruitment of the transcriptional machinery, thus establishing unique gene expression patterns that ultimately promote different biological outcomes. While canonical histones H3.1 and H3.2 are synthetized and loaded during DNA replication, the histone variant H3.3 is expressed and deposited into the chromatin throughout the cell cycle. Recent findings indicate that H3.3 replaces the majority of canonical H3 in non-dividing cells, reaching almost saturation levels in a time-dependent manner. Consequently, H3.3 incorporation and turnover represent an additional layer in the regulation of the chromatin landscape during aging. In this respect, work from our group and others suggest that H3.3 plays an important function in age-related processes throughout evolution. Here, we summarize the current knowledge on H3.3 biology and discuss the implications of its aberrant dynamics in the establishment of cellular states that may lead to human pathology. Critically, we review the importance of H3.3 turnover as part of epigenetic events that influence senescence and age-related processes. We conclude with the emerging evidence that H3.3 is required for proper neuronal function and brain plasticity.
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Affiliation(s)
- Daniele Bano
- German Center for Neurodegenerative Diseases (DZNE), 53127 Bonn, Germany
| | - Antonia Piazzesi
- German Center for Neurodegenerative Diseases (DZNE), 53127 Bonn, Germany
| | - Paolo Salomoni
- German Center for Neurodegenerative Diseases (DZNE), 53127 Bonn, Germany
| | - Pierluigi Nicotera
- German Center for Neurodegenerative Diseases (DZNE), 53127 Bonn, Germany
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Nandakumar P, Mansouri A, Das S. The Role of ATRX in Glioma Biology. Front Oncol 2017; 7:236. [PMID: 29034211 PMCID: PMC5626857 DOI: 10.3389/fonc.2017.00236] [Citation(s) in RCA: 54] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2017] [Accepted: 09/14/2017] [Indexed: 02/03/2023] Open
Abstract
The current World Health Organization classification of CNS tumors has made a tremendous leap from past editions by incorporating molecular criteria in addition to the pre-existing histological parameters. The revised version has had a particular impact on the classification of diffuse low-grade gliomas and their high-grade variants. The ATRX status is one of the critical markers that define the molecular classification of gliomas. In this review, we will first provide an overview of the role of ATRX in regular cell biology. Furthermore, the role of ATRX in tumorigenesis, specifically gliomas, is comprehensively elucidated. The possible correlation of ATRX status with other genetic/epigenetic modifications is also presented. We conclude by discussing some of the challenges associated with incorporating ATRX status assessment into routine clinical practice while also exploring opportunities for future diagnostics/therapeutics in gliomas based on ATRX status.
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Affiliation(s)
- Pravanya Nandakumar
- Division of Neurosurgery, St. Michael's Hospital, University of Toronto, Toronto, ON, Canada
| | - Alireza Mansouri
- Center for Cancer Research, Neuro-Oncology Branch, National Cancer Institute, National Institutes of Health, Bethesda, MD, United States.,Division of Neuro-Oncology, Johns Hopkins University, Baltimore, MD, United States
| | - Sunit Das
- Division of Neurosurgery, St. Michael's Hospital, University of Toronto, Toronto, ON, Canada.,The Arthur and Sonia Labatt Brain Tumour Centre, Hospital for Sick Kids, University of Toronto, Toronto, ON, Canada
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34
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Duc C, Benoit M, Détourné G, Simon L, Poulet A, Jung M, Veluchamy A, Latrasse D, Le Goff S, Cotterell S, Tatout C, Benhamed M, Probst AV. Arabidopsis ATRX Modulates H3.3 Occupancy and Fine-Tunes Gene Expression. THE PLANT CELL 2017; 29:1773-1793. [PMID: 28684426 PMCID: PMC5559740 DOI: 10.1105/tpc.16.00877] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/28/2016] [Revised: 05/24/2017] [Accepted: 06/28/2017] [Indexed: 05/23/2023]
Abstract
Histones are essential components of the nucleosome, the major chromatin subunit that structures linear DNA molecules and regulates access of other proteins to DNA. Specific histone chaperone complexes control the correct deposition of canonical histones and their variants to modulate nucleosome structure and stability. In this study, we characterize the Arabidopsis thaliana Alpha Thalassemia-mental Retardation X-linked (ATRX) ortholog and show that ATRX is involved in histone H3 deposition. Arabidopsis ATRX mutant alleles are viable, but show developmental defects and reduced fertility. Their combination with mutants of the histone H3.3 chaperone HIRA (Histone Regulator A) results in impaired plant survival, suggesting that HIRA and ATRX function in complementary histone deposition pathways. Indeed, ATRX loss of function alters cellular histone H3.3 pools and in consequence modulates the H3.1/H3.3 balance in the cell. H3.3 levels are affected especially at genes characterized by elevated H3.3 occupancy, including the 45S ribosomal DNA (45S rDNA) loci, where loss of ATRX results in altered expression of specific 45S rDNA sequence variants. At the genome-wide scale, our data indicate that ATRX modifies gene expression concomitantly to H3.3 deposition at a set of genes characterized both by elevated H3.3 occupancy and high expression. Together, our results show that ATRX is involved in H3.3 deposition and emphasize the role of histone chaperones in adjusting genome expression.
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Affiliation(s)
- Céline Duc
- GReD, Université Clermont Auvergne, CNRS, INSERM, 63001 Clermont-Ferrand, France
| | - Matthias Benoit
- GReD, Université Clermont Auvergne, CNRS, INSERM, 63001 Clermont-Ferrand, France
- The Sainsbury Laboratory, University of Cambridge, Cambridge CB2 1LR, United Kingdom
| | - Gwénaëlle Détourné
- GReD, Université Clermont Auvergne, CNRS, INSERM, 63001 Clermont-Ferrand, France
- Department of Biological and Medical Sciences, Oxford Brookes University, Oxford OX3 0BP, United Kingdom
| | - Lauriane Simon
- GReD, Université Clermont Auvergne, CNRS, INSERM, 63001 Clermont-Ferrand, France
| | - Axel Poulet
- GReD, Université Clermont Auvergne, CNRS, INSERM, 63001 Clermont-Ferrand, France
- Department of Biological and Medical Sciences, Oxford Brookes University, Oxford OX3 0BP, United Kingdom
| | - Matthieu Jung
- Department of Functional Genomics and Cancer, Institut de Génétique et de Biologie Moléculaire et Cellulaire, CNRS/INSERM/ULP, 67404 Illkirch, France
| | - Alaguraj Veluchamy
- Institute of Plant Sciences Paris Saclay IPS2, CNRS, INRA, Université Paris-Sud, Université Evry, Université Paris-Saclay, 91405 Orsay, France
- Division of Biological and Environmental Sciences and Engineering, King Abdullah University of Science and Technology, Thuwal, 23955-6900, Kingdom of Saudi Arabia
| | - David Latrasse
- Institute of Plant Sciences Paris Saclay IPS2, CNRS, INRA, Université Paris-Sud, Université Evry, Université Paris-Saclay, 91405 Orsay, France
| | - Samuel Le Goff
- GReD, Université Clermont Auvergne, CNRS, INSERM, 63001 Clermont-Ferrand, France
| | - Sylviane Cotterell
- GReD, Université Clermont Auvergne, CNRS, INSERM, 63001 Clermont-Ferrand, France
| | - Christophe Tatout
- GReD, Université Clermont Auvergne, CNRS, INSERM, 63001 Clermont-Ferrand, France
| | - Moussa Benhamed
- Institute of Plant Sciences Paris Saclay IPS2, CNRS, INRA, Université Paris-Sud, Université Evry, Université Paris-Saclay, 91405 Orsay, France
- Division of Biological and Environmental Sciences and Engineering, King Abdullah University of Science and Technology, Thuwal, 23955-6900, Kingdom of Saudi Arabia
| | - Aline V Probst
- GReD, Université Clermont Auvergne, CNRS, INSERM, 63001 Clermont-Ferrand, France
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35
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Mangan H, Gailín MÓ, McStay B. Integrating the genomic architecture of human nucleolar organizer regions with the biophysical properties of nucleoli. FEBS J 2017; 284:3977-3985. [PMID: 28500793 DOI: 10.1111/febs.14108] [Citation(s) in RCA: 63] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2017] [Revised: 04/21/2017] [Accepted: 05/10/2017] [Indexed: 11/30/2022]
Abstract
Nucleoli are the sites of ribosome biogenesis and the largest membraneless subnuclear structures. They are intimately linked with growth and proliferation control and function as sensors of cellular stress. Nucleoli form around arrays of ribosomal gene (rDNA) repeats also called nucleolar organizer regions (NORs). In humans, NORs are located on the short arms of all five human acrocentric chromosomes. Multiple NORs contribute to the formation of large heterochromatin-surrounded nucleoli observed in most human cells. Here we will review recent findings about their genomic architecture. The dynamic nature of nucleoli began to be appreciated with the advent of photodynamic experiments using fluorescent protein fusions. We review more recent data on nucleoli in Xenopus germinal vesicles (GVs) which has revealed a liquid droplet-like behavior that facilitates nucleolar fusion. Further analysis in both XenopusGVs and Drosophila embryos indicates that the internal organization of nucleoli is generated by a combination of liquid-liquid phase separation and active processes involving rDNA. We will attempt to integrate these recent findings with the genomic architecture of human NORs to advance our understanding of how nucleoli form and respond to stress in human cells.
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Affiliation(s)
- Hazel Mangan
- Centre for Chromosome Biology, School of Natural Sciences, National University of Ireland Galway, Ireland
| | - Michael Ó Gailín
- Centre for Chromosome Biology, School of Natural Sciences, National University of Ireland Galway, Ireland
| | - Brian McStay
- Centre for Chromosome Biology, School of Natural Sciences, National University of Ireland Galway, Ireland
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Nguyen DT, Voon HPJ, Xella B, Scott C, Clynes D, Babbs C, Ayyub H, Kerry J, Sharpe JA, Sloane-Stanley JA, Butler S, Fisher CA, Gray NE, Jenuwein T, Higgs DR, Gibbons RJ. The chromatin remodelling factor ATRX suppresses R-loops in transcribed telomeric repeats. EMBO Rep 2017; 18:914-928. [PMID: 28487353 DOI: 10.15252/embr.201643078] [Citation(s) in RCA: 89] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2016] [Revised: 03/21/2017] [Accepted: 03/27/2017] [Indexed: 02/04/2023] Open
Abstract
ATRX is a chromatin remodelling factor found at a wide range of tandemly repeated sequences including telomeres (TTAGGG)n ATRX mutations are found in nearly all tumours that maintain their telomeres via the alternative lengthening of telomere (ALT) pathway, and ATRX is known to suppress this pathway. Here, we show that recruitment of ATRX to telomeric repeats depends on repeat number, orientation and, critically, on repeat transcription. Importantly, the transcribed telomeric repeats form RNA-DNA hybrids (R-loops) whose abundance correlates with the recruitment of ATRX Here, we show loss of ATRX is also associated with increased R-loop formation. Our data suggest that the presence of ATRX at telomeres may have a central role in suppressing deleterious DNA secondary structures that form at transcribed telomeric repeats, and this may account for the increased DNA damage, stalling of replication and homology-directed repair previously observed upon loss of ATRX function.
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Affiliation(s)
- Diu Tt Nguyen
- MRC Molecular Haematology Unit, Weatherall Institute of Molecular Medicine, John Radcliffe Hospital, University of Oxford, Oxford, UK
| | - Hsiao Phin J Voon
- MRC Molecular Haematology Unit, Weatherall Institute of Molecular Medicine, John Radcliffe Hospital, University of Oxford, Oxford, UK.,Department of Biochemistry and Molecular Biology, The Biomedicine Discovery Institute, Monash University, Clayton, Vic., Australia
| | - Barbara Xella
- MRC Molecular Haematology Unit, Weatherall Institute of Molecular Medicine, John Radcliffe Hospital, University of Oxford, Oxford, UK
| | - Caroline Scott
- MRC Molecular Haematology Unit, Weatherall Institute of Molecular Medicine, John Radcliffe Hospital, University of Oxford, Oxford, UK
| | - David Clynes
- MRC Molecular Haematology Unit, Weatherall Institute of Molecular Medicine, John Radcliffe Hospital, University of Oxford, Oxford, UK
| | - Christian Babbs
- MRC Molecular Haematology Unit, Weatherall Institute of Molecular Medicine, John Radcliffe Hospital, University of Oxford, Oxford, UK
| | - Helena Ayyub
- MRC Molecular Haematology Unit, Weatherall Institute of Molecular Medicine, John Radcliffe Hospital, University of Oxford, Oxford, UK
| | - Jon Kerry
- MRC Molecular Haematology Unit, Weatherall Institute of Molecular Medicine, John Radcliffe Hospital, University of Oxford, Oxford, UK
| | - Jacqueline A Sharpe
- MRC Molecular Haematology Unit, Weatherall Institute of Molecular Medicine, John Radcliffe Hospital, University of Oxford, Oxford, UK
| | - Jackie A Sloane-Stanley
- MRC Molecular Haematology Unit, Weatherall Institute of Molecular Medicine, John Radcliffe Hospital, University of Oxford, Oxford, UK
| | - Sue Butler
- MRC Molecular Haematology Unit, Weatherall Institute of Molecular Medicine, John Radcliffe Hospital, University of Oxford, Oxford, UK
| | - Chris A Fisher
- MRC Molecular Haematology Unit, Weatherall Institute of Molecular Medicine, John Radcliffe Hospital, University of Oxford, Oxford, UK
| | - Nicki E Gray
- Computational Biology Research Group, Weatherall Institute of Molecular Medicine, John Radcliffe Hospital, University of Oxford, Oxford, UK
| | - Thomas Jenuwein
- Department of Epigenetics, Max Planck Institute of Immunobiology and Epigenetics, Freiburg, Germany
| | - Douglas R Higgs
- MRC Molecular Haematology Unit, Weatherall Institute of Molecular Medicine, John Radcliffe Hospital, University of Oxford, Oxford, UK
| | - Richard J Gibbons
- MRC Molecular Haematology Unit, Weatherall Institute of Molecular Medicine, John Radcliffe Hospital, University of Oxford, Oxford, UK
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Magaraki A, van der Heijden G, Sleddens-Linkels E, Magarakis L, van Cappellen WA, Peters AHFM, Gribnau J, Baarends WM, Eijpe M. Silencing markers are retained on pericentric heterochromatin during murine primordial germ cell development. Epigenetics Chromatin 2017; 10:11. [PMID: 28293300 PMCID: PMC5346203 DOI: 10.1186/s13072-017-0119-3] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2016] [Accepted: 03/02/2017] [Indexed: 12/14/2022] Open
Abstract
Background In the nuclei of most mammalian cells, pericentric heterochromatin is characterized by DNA methylation, histone modifications such as H3K9me3 and H4K20me3, and specific binding proteins like heterochromatin-binding protein 1 isoforms (HP1 isoforms). Maintenance of this specialized chromatin structure is of great importance for genome integrity and for the controlled repression of the repetitive elements within the pericentric DNA sequence. Here we have studied histone modifications at pericentric heterochromatin during primordial germ cell (PGC) development using different fixation conditions and fluorescent immunohistochemical and immunocytochemical protocols. Results We observed that pericentric heterochromatin marks, such as H3K9me3, H4K20me3, and HP1 isoforms, were retained on pericentric heterochromatin throughout PGC development. However, the observed immunostaining patterns varied, depending on the fixation method, explaining previous findings of a general loss of pericentric heterochromatic features in PGCs. Also, in contrast to the general clustering of multiple pericentric regions and associated centromeres in DAPI-dense regions in somatic cells, the pericentric regions of PGCs were more frequently organized as individual entities. We also observed a transient enrichment of the chromatin remodeler ATRX in pericentric regions in embryonic day 11.5 (E11.5) PGCs. At this stage, a similar and low level of major satellite repeat RNA transcription was detected in both PGCs and somatic cells. Conclusions These results indicate that in pericentric heterochromatin of mouse PGCs, only minor reductions in levels of some chromatin-associated proteins occur, in association with a transient increase in ATRX, between E11.5 and E13.5. These pericentric heterochromatin regions more frequently contain only a single centromere in PGCs compared to the surrounding soma, indicating a difference in overall organization, but there is no de-repression of major satellite transcription. Electronic supplementary material The online version of this article (doi:10.1186/s13072-017-0119-3) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Aristea Magaraki
- Department of Developmental Biology, Erasmus MC, University Medical Center, Rotterdam, The Netherlands
| | - Godfried van der Heijden
- Division of Reproductive Medicine, Department of Obstetrics and Gynecology, Erasmus MC, Rotterdam, The Netherlands
| | - Esther Sleddens-Linkels
- Department of Developmental Biology, Erasmus MC, University Medical Center, Rotterdam, The Netherlands
| | - Leonidas Magarakis
- Division of Reproductive Medicine, Department of Obstetrics and Gynecology, Central Hospital of Karlstad, Karlstad, Värmland Sweden
| | | | - Antoine H F M Peters
- Friedrich Miescher Institute for Biomedical Research (FMI), Basel, Switzerland.,Faculty of Sciences, University of Basel, Basel, Switzerland
| | - Joost Gribnau
- Department of Developmental Biology, Erasmus MC, University Medical Center, Rotterdam, The Netherlands
| | - Willy M Baarends
- Department of Developmental Biology, Erasmus MC, University Medical Center, Rotterdam, The Netherlands
| | - Maureen Eijpe
- Department of Developmental Biology, Erasmus MC, University Medical Center, Rotterdam, The Netherlands
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38
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Dyer MA, Qadeer ZA, Valle-Garcia D, Bernstein E. ATRX and DAXX: Mechanisms and Mutations. Cold Spring Harb Perspect Med 2017; 7:cshperspect.a026567. [PMID: 28062559 DOI: 10.1101/cshperspect.a026567] [Citation(s) in RCA: 129] [Impact Index Per Article: 18.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Recent genome sequencing efforts in a variety of cancers have revealed mutations and/or structural alterations in ATRX and DAXX, which together encode a complex that deposits histone variant H3.3 into repetitive heterochromatin. These regions include retrotransposons, pericentric heterochromatin, and telomeres, the latter of which show deregulation in ATRX/DAXX-mutant tumors. Interestingly, ATRX and DAXX mutations are often found in pediatric tumors, suggesting a particular developmental context in which these mutations drive disease. Here we review the functions of ATRX and DAXX in chromatin regulation as well as their potential contributions to tumorigenesis. We place emphasis on the chromatin remodeler ATRX, which is mutated in the developmental disorder for which it is named, α-thalassemia, mental retardation, X-linked syndrome, and at high frequency in a number of adult and pediatric tumors.
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Affiliation(s)
- Michael A Dyer
- Department of Developmental Neurobiology, St. Jude Children's Research Hospital, Memphis, Tennessee 38105
| | - Zulekha A Qadeer
- Departments of Oncological Sciences and Dermatology, Icahn School of Medicine at Mount Sinai, New York, New York 10029.,Graduate School of Biomedical Sciences, Icahn School of Medicine at Mount Sinai, New York, New York 10029
| | - David Valle-Garcia
- Departments of Oncological Sciences and Dermatology, Icahn School of Medicine at Mount Sinai, New York, New York 10029
| | - Emily Bernstein
- Departments of Oncological Sciences and Dermatology, Icahn School of Medicine at Mount Sinai, New York, New York 10029.,Graduate School of Biomedical Sciences, Icahn School of Medicine at Mount Sinai, New York, New York 10029
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39
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Talbert PB, Henikoff S. Histone variants on the move: substrates for chromatin dynamics. Nat Rev Mol Cell Biol 2016; 18:115-126. [PMID: 27924075 DOI: 10.1038/nrm.2016.148] [Citation(s) in RCA: 208] [Impact Index Per Article: 26.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Most histones are assembled into nucleosomes behind the replication fork to package newly synthesized DNA. By contrast, histone variants, which are encoded by separate genes, are typically incorporated throughout the cell cycle. Histone variants can profoundly change chromatin properties, which in turn affect DNA replication and repair, transcription, and chromosome packaging and segregation. Recent advances in the study of histone replacement have elucidated the dynamic processes by which particular histone variants become substrates of histone chaperones, ATP-dependent chromatin remodellers and histone-modifying enzymes. Here, we review histone variant dynamics and the effects of replacing DNA synthesis-coupled histones with their replication-independent variants on the chromatin landscape.
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Affiliation(s)
- Paul B Talbert
- Howard Hughes Medical Institute, Fred Hutchinson Cancer Research Center, 1100 Fairview Avenue North, Seattle, Washington 98109-1024, USA
| | - Steven Henikoff
- Howard Hughes Medical Institute, Fred Hutchinson Cancer Research Center, 1100 Fairview Avenue North, Seattle, Washington 98109-1024, USA
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40
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Fernández-Boo S, Villalba A, Cao A. Protein expression profiling in haemocytes and plasma of the Manila clam Ruditapes philippinarum in response to infection with Perkinsus olseni. JOURNAL OF FISH DISEASES 2016; 39:1369-1385. [PMID: 27233620 DOI: 10.1111/jfd.12470] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/07/2015] [Revised: 01/18/2016] [Accepted: 01/19/2016] [Indexed: 06/05/2023]
Abstract
The protein expression profiling in clam haemocytes and plasma in response to Perkinsus olseni was addressed. Adult Manila clams from a P. olseni-free bed were experimentally challenged with parasite zoospores to analyse immune response. In another experiment, the effects of longer term infection were assessed in adult clams collected from a P. olseni-affected bed, by comparing moderate to very heavily infected clams with non-infected ones. Haemocyte and plasma proteins were separated by two-dimensional electrophoresis; spot patterns were qualitatively compared between treatments within each experiment and the spots indicating differential protein expression associated with P. olseni challenge or with field infection were processed for protein identification. Fifteen clam proteins (four in haemocytes and eleven in plasma) of which expression was markedly affected by P. olseni were identified. Some of the identified proteins have a well-known role in clam immune response against the parasite, such as lysozyme and lectins. Rho GTPase-activating protein 6 could be a marker of resistance against P. olseni, which should be further studied.
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Affiliation(s)
- S Fernández-Boo
- Centro de Investigacións Mariñas, Consellería do Mar da Xunta de Galicia, Vilanova de Arousa, Spain
| | - A Villalba
- Centro de Investigacións Mariñas, Consellería do Mar da Xunta de Galicia, Vilanova de Arousa, Spain.
- Department of Life Sciences, University of Alcalá de Henares, Alcalá de Henares, Spain.
| | - A Cao
- Centro de Investigacións Mariñas, Consellería do Mar da Xunta de Galicia, Vilanova de Arousa, Spain
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41
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Lagali PS, Medina CF, Zhao BYH, Yan K, Baker AN, Coupland SG, Tsilfidis C, Wallace VA, Picketts DJ. Retinal interneuron survival requires non-cell-autonomous Atrx activity. Hum Mol Genet 2016; 25:4787-4803. [PMID: 28173139 DOI: 10.1093/hmg/ddw306] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2016] [Revised: 08/25/2016] [Accepted: 08/30/2016] [Indexed: 01/13/2023] Open
Abstract
ATRX is a chromatin remodeling protein that is mutated in several intellectual disability disorders including alpha-thalassemia/mental retardation, X-linked (ATR-X) syndrome. We previously reported the prevalence of ophthalmological defects in ATR-X syndrome patients, and accordingly we find morphological and functional visual abnormalities in a mouse model harboring a mutation occurring in ATR-X patients. The visual system abnormalities observed in these mice parallels the Atrx-null retinal phenotype characterized by interneuron defects and selective loss of amacrine and horizontal cells. The mechanisms that underlie selective neuronal vulnerability and neurodegeneration in the central nervous system upon Atrx mutation or deletion are unknown. To interrogate the cellular specificity of Atrx for its retinal neuroprotective functions, we employed a combination of temporal and lineage-restricted conditional ablation strategies to generate five different conditional knockout mouse models, and subsequently identified a non-cell-autonomous requirement for Atrx in bipolar cells for inhibitory interneuron survival in the retina. Atrx-deficient retinal bipolar cells exhibit functional, structural and molecular alterations consistent with impairments in neuronal activity and connectivity. Gene expression changes in the Atrx-null retina indicate defective synaptic structure and neuronal circuitry, suggest excitotoxic mechanisms of neurodegeneration, and demonstrate that common targets of ATRX in the forebrain and retina may contribute to similar neuropathological processes underlying cognitive impairment and visual dysfunction in ATR-X syndrome.
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Affiliation(s)
- Pamela S Lagali
- Regenerative Medicine Program, Ottawa Hospital Research Institute, Ottawa, ON K1H 8L6, Canada
| | - Chantal F Medina
- Regenerative Medicine Program, Ottawa Hospital Research Institute, Ottawa, ON K1H 8L6, Canada
| | - Brandon Y H Zhao
- Regenerative Medicine Program, Ottawa Hospital Research Institute, Ottawa, ON K1H 8L6, Canada
| | - Keqin Yan
- Regenerative Medicine Program, Ottawa Hospital Research Institute, Ottawa, ON K1H 8L6, Canada
| | - Adam N Baker
- Regenerative Medicine Program, Ottawa Hospital Research Institute, Ottawa, ON K1H 8L6, Canada
| | - Stuart G Coupland
- Regenerative Medicine Program, Ottawa Hospital Research Institute, Ottawa, ON K1H 8L6, Canada.,Department of Ophthalmology, University of Ottawa, Ottawa, ON K1H 8M5, Canada,,Department of Cellular and Molecular Medicine, University of Ottawa, Ottawa, ON K1H 8M5, Canada
| | - Catherine Tsilfidis
- Regenerative Medicine Program, Ottawa Hospital Research Institute, Ottawa, ON K1H 8L6, Canada.,Department of Ophthalmology, University of Ottawa, Ottawa, ON K1H 8M5, Canada,,Department of Cellular and Molecular Medicine, University of Ottawa, Ottawa, ON K1H 8M5, Canada
| | - Valerie A Wallace
- Vision Research Division, Krembil Research Institute, Toronto, Ontario, Canada M5T 2S8,,Department of Ophthalmology and Vision Sciences, University of Toronto, Toronto, ON M5T 3A9, Canada
| | - David J Picketts
- Regenerative Medicine Program, Ottawa Hospital Research Institute, Ottawa, ON K1H 8L6, Canada.,Department of Cellular and Molecular Medicine, University of Ottawa, Ottawa, ON K1H 8M5, Canada,,Department of Biochemistry, Microbiology, and Immunology, University of Ottawa, Ottawa, ON K1H 8M5, Canada
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42
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Amorim JP, Santos G, Vinagre J, Soares P. The Role of ATRX in the Alternative Lengthening of Telomeres (ALT) Phenotype. Genes (Basel) 2016; 7:E66. [PMID: 27657132 PMCID: PMC5042396 DOI: 10.3390/genes7090066] [Citation(s) in RCA: 63] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2016] [Revised: 09/07/2016] [Accepted: 09/12/2016] [Indexed: 12/15/2022] Open
Abstract
Telomeres are responsible for protecting chromosome ends in order to prevent the loss of coding DNA. Their maintenance is required for achieving immortality by neoplastic cells and can occur by upregulation of the telomerase enzyme or through a homologous recombination-associated process, the alternative lengthening of telomeres (ALT). The precise mechanisms that govern the activation of ALT or telomerase in tumor cells are not fully understood, although cellular origin may favor one of the other mechanisms that have been found thus far in mutual exclusivity. Specific mutational events influence ALT activation and maintenance: a unifying frequent feature of tumors that acquire this phenotype are the recurrent mutations of the Alpha Thalassemia/Mental Retardation Syndrome X-Linked (ATRX) or Death-Domain Associated Protein (DAXX) genes. This review summarizes the established criteria about this phenotype: its prevalence, theoretical molecular mechanisms and relation with ATRX, DAXX and other proteins (directly or indirectly interacting and resulting in the ALT phenotype).
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Affiliation(s)
- João P Amorim
- Instituto de Investigação e Inovação em Saúde (i3S), Universidade do Porto, Porto 4200-135, Portugal.
- Instituto de Patologia e Imunologia Molecular da Universidade do Porto (Ipatimup), Porto 4200-135, Portugal.
- Instituto de Ciências Biomédicas Abel Salazar da Universidade do Porto, Porto 4050-313, Portugal.
| | - Gustavo Santos
- Instituto de Investigação e Inovação em Saúde (i3S), Universidade do Porto, Porto 4200-135, Portugal.
- Instituto de Patologia e Imunologia Molecular da Universidade do Porto (Ipatimup), Porto 4200-135, Portugal.
- Instituto de Ciências Biomédicas Abel Salazar da Universidade do Porto, Porto 4050-313, Portugal.
| | - João Vinagre
- Instituto de Investigação e Inovação em Saúde (i3S), Universidade do Porto, Porto 4200-135, Portugal.
- Instituto de Patologia e Imunologia Molecular da Universidade do Porto (Ipatimup), Porto 4200-135, Portugal.
- Instituto de Ciências Biomédicas Abel Salazar da Universidade do Porto, Porto 4050-313, Portugal.
| | - Paula Soares
- Instituto de Investigação e Inovação em Saúde (i3S), Universidade do Porto, Porto 4200-135, Portugal.
- Instituto de Patologia e Imunologia Molecular da Universidade do Porto (Ipatimup), Porto 4200-135, Portugal.
- Instituto de Ciências Biomédicas Abel Salazar da Universidade do Porto, Porto 4050-313, Portugal.
- Departamento de Patologia e Oncologia, Faculdade de Medicina da Universidade do Porto, Porto 4200-139, Portugal.
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43
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He Q, Kim H, Huang R, Lu W, Tang M, Shi F, Yang D, Zhang X, Huang J, Liu D, Songyang Z. The Daxx/Atrx Complex Protects Tandem Repetitive Elements during DNA Hypomethylation by Promoting H3K9 Trimethylation. Cell Stem Cell 2016; 17:273-86. [PMID: 26340527 DOI: 10.1016/j.stem.2015.07.022] [Citation(s) in RCA: 101] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2014] [Revised: 06/14/2015] [Accepted: 07/28/2015] [Indexed: 01/02/2023]
Abstract
In mammals, DNA methylation is essential for protecting repetitive sequences from aberrant transcription and recombination. In some developmental contexts (e.g., preimplantation embryos) DNA is hypomethylated but repetitive elements are not dysregulated, suggesting that alternative protection mechanisms exist. Here we explore the processes involved by investigating the role of the chromatin factors Daxx and Atrx. Using genome-wide binding and transcriptome analysis, we found that Daxx and Atrx have distinct chromatin-binding profiles and are co-enriched at tandem repetitive elements in wild-type mouse ESCs. Global DNA hypomethylation further promoted recruitment of the Daxx/Atrx complex to tandem repeat sequences, including retrotransposons and telomeres. Knockdown of Daxx/Atrx in cells with hypomethylated genomes exacerbated aberrant transcriptional de-repression of repeat elements and telomere dysfunction. Mechanistically, Daxx/Atrx-mediated repression seems to involve Suv39h recruitment and H3K9 trimethylation. Our data therefore suggest that Daxx and Atrx safeguard the genome by silencing repetitive elements when DNA methylation levels are low.
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Affiliation(s)
- Quanyuan He
- Key Laboratory of Gene Engineering of the Ministry of Education, SYSU-BCM Joint Center for Biomedical Sciences and Institute of Healthy Aging Research, School of Life Sciences, Sun Yat-sen University, Guangzhou, 510275, China; Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030, USA
| | - Hyeung Kim
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030, USA
| | - Rui Huang
- Key Laboratory of Gene Engineering of the Ministry of Education, SYSU-BCM Joint Center for Biomedical Sciences and Institute of Healthy Aging Research, School of Life Sciences, Sun Yat-sen University, Guangzhou, 510275, China
| | - Weisi Lu
- Key Laboratory of Gene Engineering of the Ministry of Education, SYSU-BCM Joint Center for Biomedical Sciences and Institute of Healthy Aging Research, School of Life Sciences, Sun Yat-sen University, Guangzhou, 510275, China
| | - Mengfan Tang
- Key Laboratory of Gene Engineering of the Ministry of Education, SYSU-BCM Joint Center for Biomedical Sciences and Institute of Healthy Aging Research, School of Life Sciences, Sun Yat-sen University, Guangzhou, 510275, China
| | - Fengtao Shi
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030, USA
| | - Dong Yang
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030, USA
| | - Xiya Zhang
- Key Laboratory of Gene Engineering of the Ministry of Education, SYSU-BCM Joint Center for Biomedical Sciences and Institute of Healthy Aging Research, School of Life Sciences, Sun Yat-sen University, Guangzhou, 510275, China
| | - Junjiu Huang
- Key Laboratory of Gene Engineering of the Ministry of Education, SYSU-BCM Joint Center for Biomedical Sciences and Institute of Healthy Aging Research, School of Life Sciences, Sun Yat-sen University, Guangzhou, 510275, China; Key Laboratory of Reproductive Medicine of Guangdong Province, School of Life Sciences and the First Affiliated Hospital, Sun Yat-sen University, Guangzhou, 510275, China
| | - Dan Liu
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030, USA
| | - Zhou Songyang
- Key Laboratory of Gene Engineering of the Ministry of Education, SYSU-BCM Joint Center for Biomedical Sciences and Institute of Healthy Aging Research, School of Life Sciences, Sun Yat-sen University, Guangzhou, 510275, China; Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030, USA; Key Laboratory of Reproductive Medicine of Guangdong Province, School of Life Sciences and the First Affiliated Hospital, Sun Yat-sen University, Guangzhou, 510275, China.
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Valle-García D, Qadeer ZA, McHugh DS, Ghiraldini FG, Chowdhury AH, Hasson D, Dyer MA, Recillas-Targa F, Bernstein E. ATRX binds to atypical chromatin domains at the 3' exons of zinc finger genes to preserve H3K9me3 enrichment. Epigenetics 2016; 11:398-414. [PMID: 27029610 PMCID: PMC4939920 DOI: 10.1080/15592294.2016.1169351] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2015] [Revised: 03/14/2016] [Accepted: 03/17/2016] [Indexed: 12/20/2022] Open
Abstract
ATRX is a SWI/SNF chromatin remodeler proposed to govern genomic stability through the regulation of repetitive sequences, such as rDNA, retrotransposons, and pericentromeric and telomeric repeats. However, few direct ATRX target genes have been identified and high-throughput genomic approaches are currently lacking for ATRX. Here we present a comprehensive ChIP-sequencing study of ATRX in multiple human cell lines, in which we identify the 3' exons of zinc finger genes (ZNFs) as a new class of ATRX targets. These 3' exonic regions encode the zinc finger motifs, which can range from 1-40 copies per ZNF gene and share large stretches of sequence similarity. These regions often contain an atypical chromatin signature: they are transcriptionally active, contain high levels of H3K36me3, and are paradoxically enriched in H3K9me3. We find that these ZNF 3' exons are co-occupied by SETDB1, TRIM28, and ZNF274, which form a complex with ATRX. CRISPR/Cas9-mediated loss-of-function studies demonstrate (i) a reduction of H3K9me3 at the ZNF 3' exons in the absence of ATRX and ZNF274 and, (ii) H3K9me3 levels at atypical chromatin regions are particularly sensitive to ATRX loss compared to other H3K9me3-occupied regions. As a consequence of ATRX or ZNF274 depletion, cells with reduced levels of H3K9me3 show increased levels of DNA damage, suggesting that ATRX binds to the 3' exons of ZNFs to maintain their genomic stability through preservation of H3K9me3.
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Affiliation(s)
- David Valle-García
- a Departments of Oncological Sciences and Dermatology , Icahn School of Medicine at Mount Sinai , New York , NY , USA
- b Instituto de Fisiología Celular, Departamento de Genética Molecular, Universidad Nacional Autónoma de México , Ciudad de México , México
| | - Zulekha A Qadeer
- a Departments of Oncological Sciences and Dermatology , Icahn School of Medicine at Mount Sinai , New York , NY , USA
- c Graduate School of Biomedical Sciences, Icahn School of Medicine at Mount Sinai , New York , NY , USA
| | - Domhnall S McHugh
- a Departments of Oncological Sciences and Dermatology , Icahn School of Medicine at Mount Sinai , New York , NY , USA
| | - Flávia G Ghiraldini
- a Departments of Oncological Sciences and Dermatology , Icahn School of Medicine at Mount Sinai , New York , NY , USA
| | - Asif H Chowdhury
- a Departments of Oncological Sciences and Dermatology , Icahn School of Medicine at Mount Sinai , New York , NY , USA
| | - Dan Hasson
- a Departments of Oncological Sciences and Dermatology , Icahn School of Medicine at Mount Sinai , New York , NY , USA
| | - Michael A Dyer
- d Department of Developmental Neurobiology , St Jude Children's Research Hospital , Memphis , Tennessee , USA
| | - Félix Recillas-Targa
- b Instituto de Fisiología Celular, Departamento de Genética Molecular, Universidad Nacional Autónoma de México , Ciudad de México , México
| | - Emily Bernstein
- a Departments of Oncological Sciences and Dermatology , Icahn School of Medicine at Mount Sinai , New York , NY , USA
- c Graduate School of Biomedical Sciences, Icahn School of Medicine at Mount Sinai , New York , NY , USA
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45
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Huh MS, Ivanochko D, Hashem LE, Curtin M, Delorme M, Goodall E, Yan K, Picketts DJ. Stalled replication forks within heterochromatin require ATRX for protection. Cell Death Dis 2016; 7:e2220. [PMID: 27171262 PMCID: PMC4917659 DOI: 10.1038/cddis.2016.121] [Citation(s) in RCA: 56] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2016] [Revised: 04/04/2016] [Accepted: 04/08/2016] [Indexed: 01/04/2023]
Abstract
Expansive growth of neural progenitor cells (NPCs) is a prerequisite to the temporal waves of neuronal differentiation that generate the six-layered neocortex, while also placing a heavy burden on proteins that regulate chromatin packaging and genome integrity. This problem is further reflected by the growing number of developmental disorders caused by mutations in chromatin regulators. ATRX gene mutations cause a severe intellectual disability disorder (α-thalassemia mental retardation X-linked (ATRX) syndrome; OMIM no. 301040), characterized by microcephaly, urogenital abnormalities and α-thalassemia. Although the ATRX protein is required for the maintenance of repetitive DNA within heterochromatin, how this translates to disease pathogenesis remain poorly understood and was a focus of this study. We demonstrate that Atrx(FoxG1Cre) forebrain-specific conditional knockout mice display poly(ADP-ribose) polymerase-1 (Parp-1) hyperactivation during neurogenesis and generate fewer late-born Cux1- and Brn2-positive neurons that accounts for the reduced cortical size. Moreover, DNA damage, induced Parp-1 and Atm activation is elevated in progenitor cells and contributes to their increased level of cell death. ATRX-null HeLa cells are similarly sensitive to hydroxyurea-induced replication stress, accumulate DNA damage and proliferate poorly. Impaired BRCA1-RAD51 colocalization and PARP-1 hyperactivation indicated that stalled replication forks are not efficiently protected. DNA fiber assays confirmed that MRE11 degradation of stalled replication forks was rampant in the absence of ATRX or DAXX. Indeed, fork degradation in ATRX-null cells could be attenuated by treatment with the MRE11 inhibitor mirin, or exacerbated by inhibiting PARP-1 activity. Taken together, these results suggest that ATRX is required to limit replication stress during cellular proliferation, whereas upregulation of PARP-1 activity functions as a compensatory mechanism to protect stalled forks, limiting genomic damage, and facilitating late-born neuron production.
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Affiliation(s)
- M S Huh
- Regenerative Medicine Program, Ottawa Hospital Research Institute, Ottawa, ON K1H 8L6, Canada
| | - D Ivanochko
- Regenerative Medicine Program, Ottawa Hospital Research Institute, Ottawa, ON K1H 8L6, Canada.,Department of Biochemistry, Microbiology, and Immunology, Faculty of Medicine, University of Ottawa, Ottawa, ON K1H 8M5, Canada
| | - L E Hashem
- Regenerative Medicine Program, Ottawa Hospital Research Institute, Ottawa, ON K1H 8L6, Canada.,Department of Cellular and Molecular Medicine, Faculty of Medicine, University of Ottawa, Ottawa, ON K1H 8M5, Canada
| | - M Curtin
- Regenerative Medicine Program, Ottawa Hospital Research Institute, Ottawa, ON K1H 8L6, Canada.,Department of Biochemistry, Microbiology, and Immunology, Faculty of Medicine, University of Ottawa, Ottawa, ON K1H 8M5, Canada
| | - M Delorme
- Regenerative Medicine Program, Ottawa Hospital Research Institute, Ottawa, ON K1H 8L6, Canada.,Department of Biochemistry, Microbiology, and Immunology, Faculty of Medicine, University of Ottawa, Ottawa, ON K1H 8M5, Canada
| | - E Goodall
- Regenerative Medicine Program, Ottawa Hospital Research Institute, Ottawa, ON K1H 8L6, Canada.,Department of Biochemistry, Microbiology, and Immunology, Faculty of Medicine, University of Ottawa, Ottawa, ON K1H 8M5, Canada
| | - K Yan
- Regenerative Medicine Program, Ottawa Hospital Research Institute, Ottawa, ON K1H 8L6, Canada
| | - D J Picketts
- Regenerative Medicine Program, Ottawa Hospital Research Institute, Ottawa, ON K1H 8L6, Canada.,Department of Biochemistry, Microbiology, and Immunology, Faculty of Medicine, University of Ottawa, Ottawa, ON K1H 8M5, Canada.,Department of Cellular and Molecular Medicine, Faculty of Medicine, University of Ottawa, Ottawa, ON K1H 8M5, Canada
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46
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Mirabella AC, Foster BM, Bartke T. Chromatin deregulation in disease. Chromosoma 2016; 125:75-93. [PMID: 26188466 PMCID: PMC4761009 DOI: 10.1007/s00412-015-0530-0] [Citation(s) in RCA: 77] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2015] [Revised: 06/30/2015] [Accepted: 07/02/2015] [Indexed: 12/21/2022]
Abstract
The regulation of chromatin by epigenetic mechanisms plays a central role in gene expression and is essential for development and maintenance of cell identity and function. Aberrant chromatin regulation is observed in many diseases where it leads to defects in epigenetic gene regulation resulting in pathological gene expression programmes. These defects are caused by inherited or acquired mutations in genes encoding enzymes that deposit or remove DNA and histone modifications and that shape chromatin architecture. Chromatin deregulation often results in neurodevelopmental disorders and intellectual disabilities, frequently linked to physical and developmental abnormalities, but can also cause neurodegenerative diseases, immunodeficiency, or muscle wasting syndromes. Epigenetic diseases can either be of monogenic origin or manifest themselves as complex multifactorial diseases such as in congenital heart disease, autism spectrum disorders, or cancer in which mutations in chromatin regulators are contributing factors. The environment directly influences the epigenome and can induce changes that cause or predispose to diseases through risk factors such as stress, malnutrition or exposure to harmful chemicals. The plasticity of chromatin regulation makes targeting the enzymatic machinery an attractive strategy for therapeutic intervention and an increasing number of small molecule inhibitors against a variety of epigenetic regulators are in clinical use or under development. In this review, we will give an overview of the molecular lesions that underlie epigenetic diseases, and we will discuss the impact of the environment and prospects for epigenetic therapies.
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Affiliation(s)
- Anne C Mirabella
- Chromatin Biochemistry Group, MRC Clinical Sciences Centre, Imperial College London, Du Cane Road, London, W12 0NN, UK
| | - Benjamin M Foster
- Chromatin Biochemistry Group, MRC Clinical Sciences Centre, Imperial College London, Du Cane Road, London, W12 0NN, UK
| | - Till Bartke
- Chromatin Biochemistry Group, MRC Clinical Sciences Centre, Imperial College London, Du Cane Road, London, W12 0NN, UK.
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47
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Abstract
Genetic causes for human disorders are being discovered at an unprecedented pace. A growing subclass of disease-causing mutations involves changes in the epigenome or in the abundance and activity of proteins that regulate chromatin structure. This article focuses on research that has uncovered human diseases that stem from such epigenetic deregulation. Disease may be caused by direct changes in epigenetic marks, such as DNA methylation, commonly found to affect imprinted gene regulation. Also described are disease-causing genetic mutations in epigenetic modifiers that either affect chromatin in trans or have a cis effect in altering chromatin configuration.
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Affiliation(s)
- Huda Y Zoghbi
- Howard Hughes Medical Institute, Baylor College of Medicine, and Jan and Dan Duncan Neurological Research Institute at Texas Children's Hospital, Houston, Texas 77030 Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas 77030
| | - Arthur L Beaudet
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas 77030
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48
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Abstract
ATRX was identified over 20 years ago as the gene responsible for a rare developmental disorder characterized by α-thalassemia and intellectual disability. Similarities to the sucrose nonfermentable SNF2 type chromatin remodelers initially suggested a role in transcriptional regulation. However, over the last years, our knowledge of the epigenetic activities of ATRX has expanded steadily. Recent exciting discoveries have propelled ATRX into the limelight of chromatin and telomere biology, development and cancer research. This review summarizes recent breakthroughs in understanding ATRX function in heterochromatin structure, genome stability and its frequent dysregulation in a variety of cancers.
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Affiliation(s)
- L Ashley Watson
- Departments of Paediatrics, Biochemistry & Oncology, University of Western Ontario, Victoria Research Laboratories, 800 Commissioners Road East, London, Canada.,Children's Health Research Institute, London, Canada.,Lawson Health Research Institute, London, Canada
| | - Hannah Goldberg
- Departments of Paediatrics, Biochemistry & Oncology, University of Western Ontario, Victoria Research Laboratories, 800 Commissioners Road East, London, Canada.,Children's Health Research Institute, London, Canada.,Lawson Health Research Institute, London, Canada
| | - Nathalie G Bérubé
- Departments of Paediatrics, Biochemistry & Oncology, University of Western Ontario, Victoria Research Laboratories, 800 Commissioners Road East, London, Canada.,Children's Health Research Institute, London, Canada.,Lawson Health Research Institute, London, Canada
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49
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Kunowska N, Rotival M, Yu L, Choudhary J, Dillon N. Identification of protein complexes that bind to histone H3 combinatorial modifications using super-SILAC and weighted correlation network analysis. Nucleic Acids Res 2015; 43:1418-32. [PMID: 25605797 PMCID: PMC4330348 DOI: 10.1093/nar/gku1350] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/02/2022] Open
Abstract
The large number of chemical modifications that are found on the histone proteins of eukaryotic cells form multiple complex combinations, which can act as recognition signals for reader proteins. We have used peptide capture in conjunction with super-SILAC quantification to carry out an unbiased high-throughput analysis of the composition of protein complexes that bind to histone H3K9/S10 and H3K27/S28 methyl-phospho modifications. The accurate quantification allowed us to perform Weighted correlation network analysis (WGCNA) to obtain a systems-level view of the histone H3 histone tail interactome. The analysis reveals the underlying modularity of the histone reader network with members of nuclear complexes exhibiting very similar binding signatures, which suggests that many proteins bind to histones as part of pre-organized complexes. Our results identify a novel complex that binds to the double H3K9me3/S10ph modification, which includes Atrx, Daxx and members of the FACT complex. The super-SILAC approach allows comparison of binding to multiple peptides with different combinations of modifications and the resolution of the WGCNA analysis is enhanced by maximizing the number of combinations that are compared. This makes it a useful approach for assessing the effects of changes in histone modification combinations on the composition and function of bound complexes.
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Affiliation(s)
- Natalia Kunowska
- Gene Regulation and Chromatin Group, MRC Clinical Sciences Centre, Imperial College, Hammersmith Hospital Campus, Du Cane Road, London W12 0NN, UK
| | - Maxime Rotival
- Integrative Genomics and Medicine Group, MRC Clinical Sciences Centre, Imperial College, Hammersmith Hospital Campus, Du Cane Road, London W12 0NN, UK
| | - Lu Yu
- Proteomic Mass Spectrometry, Wellcome Trust Sanger Institute, Cambridge, CB10 1SA, UK
| | - Jyoti Choudhary
- Proteomic Mass Spectrometry, Wellcome Trust Sanger Institute, Cambridge, CB10 1SA, UK
| | - Niall Dillon
- Gene Regulation and Chromatin Group, MRC Clinical Sciences Centre, Imperial College, Hammersmith Hospital Campus, Du Cane Road, London W12 0NN, UK
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50
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Saksouk N, Simboeck E, Déjardin J. Constitutive heterochromatin formation and transcription in mammals. Epigenetics Chromatin 2015; 8:3. [PMID: 25788984 PMCID: PMC4363358 DOI: 10.1186/1756-8935-8-3] [Citation(s) in RCA: 341] [Impact Index Per Article: 37.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2014] [Accepted: 12/16/2014] [Indexed: 12/17/2022] Open
Abstract
Constitutive heterochromatin, mainly formed at the gene-poor regions of pericentromeres, is believed to ensure a condensed and transcriptionally inert chromatin conformation. Pericentromeres consist of repetitive tandem satellite repeats and are crucial chromosomal elements that are responsible for accurate chromosome segregation in mitosis. The repeat sequences are not conserved and can greatly vary between different organisms, suggesting that pericentromeric functions might be controlled epigenetically. In this review, we will discuss how constitutive heterochromatin is formed and maintained at pericentromeres in order to ensure their integrity. We will describe the biogenesis and the function of main epigenetic pathways that are involved and how they are interconnected. Interestingly, recent findings suggest that alternative pathways could substitute for well-established pathways when disrupted, suggesting that constitutive heterochromatin harbors much more plasticity than previously assumed. In addition, despite of the heterochromatic nature of pericentromeres, there is increasing evidence for active and regulated transcription at these loci, in a multitude of organisms and under various biological contexts. Thus, in the second part of this review, we will address this relatively new aspect and discuss putative functions of pericentromeric expression.
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Affiliation(s)
- Nehmé Saksouk
- INSERM AVENIR Team, Institute of Human Genetics, CNRS UPR 1142, Montpellier, France
| | - Elisabeth Simboeck
- INSERM AVENIR Team, Institute of Human Genetics, CNRS UPR 1142, Montpellier, France
| | - Jérôme Déjardin
- INSERM AVENIR Team, Institute of Human Genetics, CNRS UPR 1142, Montpellier, France
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