1
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Klein RH, Knoepfler PS. Knockout tales: the versatile roles of histone H3.3 in development and disease. Epigenetics Chromatin 2023; 16:38. [PMID: 37814296 PMCID: PMC10563256 DOI: 10.1186/s13072-023-00512-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2023] [Accepted: 10/04/2023] [Indexed: 10/11/2023] Open
Abstract
Histone variant H3.3 plays novel roles in development as compared to canonical H3 proteins and is the most commonly mutated histone protein of any kind in human disease. Here we discuss how gene targeting studies of the two H3.3-coding genes H3f3a and H3f3b have provided important insights into H3.3 functions including in gametes as well as brain and lung development. Knockouts have also provided insights into the important roles of H3.3 in maintaining genomic stability and chromatin organization, processes that are also affected when H3.3 is mutated in human diseases such as pediatric tumors and neurodevelopmental syndromes. Overall, H3.3 is a unique histone linking development and disease via epigenomic machinery.
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Affiliation(s)
- Rachel H Klein
- Department of Cell Biology and Human Anatomy, University of California Davis, Davis, CA, 95616, USA
- Institute for Pediatric Regenerative Medicine, Shriners Hospital for Children Northern California, Sacramento, CA, 95817, USA
- Genome Center, University of California Davis, Davis, CA, 95616, USA
| | - Paul S Knoepfler
- Department of Cell Biology and Human Anatomy, University of California Davis, Davis, CA, 95616, USA.
- Institute for Pediatric Regenerative Medicine, Shriners Hospital for Children Northern California, Sacramento, CA, 95817, USA.
- Genome Center, University of California Davis, Davis, CA, 95616, USA.
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2
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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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3
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Aguilera P, López-Contreras AJ. ATRX, a guardian of chromatin. Trends Genet 2023; 39:505-519. [PMID: 36894374 DOI: 10.1016/j.tig.2023.02.009] [Citation(s) in RCA: 12] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2022] [Revised: 02/07/2023] [Accepted: 02/14/2023] [Indexed: 03/09/2023]
Abstract
ATRX (alpha-thalassemia mental retardation X-linked) is one of the most frequently mutated tumor suppressor genes in human cancers, especially in glioma, and recent findings indicate roles for ATRX in key molecular pathways, such as the regulation of chromatin state, gene expression, and DNA damage repair, placing ATRX as a central player in the maintenance of genome stability and function. This has led to new perspectives about the functional role of ATRX and its relationship with cancer. Here, we provide an overview of ATRX interactions and molecular functions and discuss the consequences of its impairment, including alternative lengthening of telomeres and therapeutic vulnerabilities that may be exploited in cancer cells.
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Affiliation(s)
- Paula Aguilera
- Centro Andaluz de Biología Molecular y Medicina Regenerativa (CABIMER), Consejo Superior de Investigaciones Científicas (CSIC), Universidad de Sevilla - Universidad Pablo de Olavide, Seville, Spain.
| | - Andrés J López-Contreras
- Centro Andaluz de Biología Molecular y Medicina Regenerativa (CABIMER), Consejo Superior de Investigaciones Científicas (CSIC), Universidad de Sevilla - Universidad Pablo de Olavide, Seville, Spain.
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4
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León NY, Harley VR. ATR-X syndrome: genetics, clinical spectrum, and management. Hum Genet 2021; 140:1625-1634. [PMID: 34524523 DOI: 10.1007/s00439-021-02361-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2021] [Accepted: 08/30/2021] [Indexed: 12/13/2022]
Abstract
ATR-X, an acronym for alpha thalassemia and mental retardation X-linked, syndrome is a congenital condition predominantly affecting males, characterized by mild to severe intellectual disability, facial, skeletal, urogenital, and hematopoietic anomalies. Less common are heart defects, eye anomalies, renal abnormalities, and gastrointestinal dysfunction. ATR-X syndrome is caused by germline variants in the ATRX gene. Until recently, the diagnosis of the ATR-X syndrome had been guided by the classical clinical manifestations and confirmed by molecular techniques. However, our new systematic analysis shows that the only clinical sign shared by all affected individuals is intellectual disability, with the other manifestations varying even within the same family. More than 190 different germline ATRX mutations in some 200 patients have been analyzed. With improved and more frequent analysis by molecular technologies, more subtle deletions and insertions have been detected recently. Moreover, emerging technologies reveal non-classic phenotypes of ATR-X syndrome as well as the description of a new clinical feature, the development of osteosarcoma which suggests an increased cancer risk in ATR-X syndrome. This review will focus on the different types of inherited ATRX mutations and their relation to clinical features in the ATR-X syndrome. We will provide an update of the frequency of clinical manifestations, the affected organs, and the genotype-phenotype correlations. Finally, we propose a shift in the diagnosis of ATR-X patients, from a clinical diagnosis to a molecular-based approach. This may assist clinicians in patient management, risk assessment and genetic counseling.
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Affiliation(s)
- Nayla Y León
- Sex Development Laboratory, Centre for Endocrinology and Metabolism, Hudson Institute of Medical Research, 27-31 Wright Street, Melbourne, VIC, 3168, Australia.,Department of Molecular and Translational Science, Monash University, Melbourne, VIC, Australia
| | - Vincent R Harley
- Sex Development Laboratory, Centre for Endocrinology and Metabolism, Hudson Institute of Medical Research, 27-31 Wright Street, Melbourne, VIC, 3168, Australia. .,Department of Molecular and Translational Science, Monash University, Melbourne, VIC, Australia.
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5
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Delbarre E, Janicki SM. Modulation of H3.3 chromatin assembly by PML: A way to regulate epigenetic inheritance. Bioessays 2021; 43:e2100038. [PMID: 34423467 DOI: 10.1002/bies.202100038] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2021] [Revised: 08/04/2021] [Accepted: 08/06/2021] [Indexed: 12/15/2022]
Abstract
Although the promyelocytic leukemia (PML) protein is renowned for regulating a wide range of cellular processes and as an essential component of PML nuclear bodies (PML-NBs), the mechanisms through which it exerts its broad physiological impact are far from fully elucidated. Here, we review recent studies supporting an emerging view that PML's pleiotropic effects derive, at least partially, from its role in regulating histone H3.3 chromatin assembly, a critical epigenetic mechanism. These studies suggest that PML maintains heterochromatin organization by restraining H3.3 incorporation. Examination of PML's contribution to H3.3 chromatin assembly in the context of the cell cycle and PML-NB assembly suggests that PML represses heterochromatic H3.3 deposition during S phase and that transcription and SUMOylation regulate PML's recruitment to heterochromatin. Elucidating PML' s contributions to H3.3-mediated epigenetic regulation will provide insight into PML's expansive influence on cellular physiology and open new avenues for studying oncogenesis linked to PML malfunction.
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Affiliation(s)
- Erwan Delbarre
- Faculty of Health Sciences, OsloMet-Oslo Metropolitan University, Oslo, Norway
| | - Susan M Janicki
- Drexel University Thomas R. Kline School of Law, Philadelphia, Pennsylvania, USA
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6
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Mutations inhibiting KDM4B drive ALT activation in ATRX-mutated glioblastomas. Nat Commun 2021; 12:2584. [PMID: 33972520 PMCID: PMC8110556 DOI: 10.1038/s41467-021-22543-z] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2020] [Accepted: 03/16/2021] [Indexed: 12/24/2022] Open
Abstract
Alternative Lengthening of Telomeres (ALT) is a telomere maintenance pathway utilised in 15% of cancers. ALT cancers are strongly associated with inactivating mutations in ATRX; yet loss of ATRX alone is insufficient to trigger ALT, suggesting that additional cooperating factors are involved. We identify H3.3G34R and IDH1/2 mutations as two such factors in ATRX-mutated glioblastomas. Both mutations are capable of inactivating histone demethylases, and we identify KDM4B as the key demethylase inactivated in ALT. Mouse embryonic stem cells inactivated for ATRX, TP53, TERT and KDM4B (KDM4B knockout or H3.3G34R) show characteristic features of ALT. Conversely, KDM4B over-expression in ALT cancer cells abrogates ALT-associated features. In this work, we demonstrate that inactivation of KDM4B, through H3.3G34R or IDH1/2 mutations, acts in tandem with ATRX mutations to promote ALT in glioblastomas. Alternative Lengthening of Telomeres (ALT) is a telomere maintenance pathway utilised in 15% of cancers that have been associated with mutations in ATRX. Here the authors reveal a functional role of histone demethylases KDM4B in regulating ALT activation.
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7
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Cabral JM, Cushman CH, Sodroski CN, Knipe DM. ATRX limits the accessibility of histone H3-occupied HSV genomes during lytic infection. PLoS Pathog 2021; 17:e1009567. [PMID: 33909709 PMCID: PMC8109836 DOI: 10.1371/journal.ppat.1009567] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2020] [Revised: 05/10/2021] [Accepted: 04/15/2021] [Indexed: 12/24/2022] Open
Abstract
Histones are rapidly loaded on the HSV genome upon entry into the nucleus of human fibroblasts, but the effects of histone loading on viral replication have not been fully defined. We showed recently that ATRX is dispensable for de novo deposition of H3 to HSV genomes after nuclear entry but restricted infection through maintenance of viral heterochromatin. To further investigate the roles that ATRX and other histone H3 chaperones play in restriction of HSV, we infected human fibroblasts that were systematically depleted of nuclear H3 chaperones. We found that the ATRX/DAXX complex is unique among nuclear H3 chaperones in its capacity to restrict ICP0-null HSV infection. Only depletion of ATRX significantly alleviated restriction of viral replication. Interestingly, no individual nuclear H3 chaperone was required for deposition of H3 onto input viral genomes, suggesting that during lytic infection, H3 deposition may occur through multiple pathways. ChIP-seq for total histone H3 in control and ATRX-KO cells infected with ICP0-null HSV showed that HSV DNA is loaded with high levels of histones across the entire viral genome. Despite high levels of H3, ATAC-seq analysis revealed that HSV DNA is highly accessible, especially in regions of high GC content, and is not organized largely into ordered nucleosomes during lytic infection. ATRX reduced accessibility of viral DNA to the activity of a TN5 transposase and enhanced accumulation of viral DNA fragment sizes associated with nucleosome-like structures. Together, these findings support a model in which ATRX restricts viral infection by altering the structure of histone H3-loaded viral chromatin that reduces viral DNA accessibility for transcription. High GC rich regions of the HSV genome, especially the S component inverted repeats of the HSV-1 genome, show increased accessibility, which may lead to increased ability to transcribe the IE genes encoded in these regions during initiation of infection.
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Affiliation(s)
- Joseph M. Cabral
- Department of Microbiology, Blavatnik Institute, Harvard Medical School, Boston, Massachusetts, United States of America
- Program in Virology, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Camille H. Cushman
- Program in Virology, Harvard Medical School, Boston, Massachusetts, United States of America
- Department of Medical Oncology, Dana-Farber Cancer Institute, Boston, Massachusetts, United States of America
| | - Catherine N. Sodroski
- Department of Microbiology, Blavatnik Institute, Harvard Medical School, Boston, Massachusetts, United States of America
- Program in Virology, Harvard Medical School, Boston, Massachusetts, United States of America
| | - David M. Knipe
- Department of Microbiology, Blavatnik Institute, Harvard Medical School, Boston, Massachusetts, United States of America
- Program in Virology, Harvard Medical School, Boston, Massachusetts, United States of America
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8
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Phillips RE, Soshnev AA, Allis CD. Epigenomic Reprogramming as a Driver of Malignant Glioma. Cancer Cell 2020; 38:647-660. [PMID: 32916125 PMCID: PMC8248764 DOI: 10.1016/j.ccell.2020.08.008] [Citation(s) in RCA: 60] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/18/2020] [Revised: 07/21/2020] [Accepted: 08/10/2020] [Indexed: 12/13/2022]
Abstract
Malignant gliomas are central nervous system tumors and remain among the most treatment-resistant cancers. Exome sequencing has revealed significant heterogeneity and important insights into the molecular pathogenesis of gliomas. Mutations in chromatin modifiers-proteins that shape the epigenomic landscape through remodeling and regulation of post-translational modifications on chromatin-are very frequent and often define specific glioma subtypes. This suggests that epigenomic reprogramming may be a fundamental driver of glioma. Here, we describe the key chromatin regulatory pathways disrupted in gliomas, delineating their physiological function and our current understanding of how their dysregulation may contribute to gliomagenesis.
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Affiliation(s)
- Richard E Phillips
- Department of Neurology and Brain Tumor Center, Memorial Sloan Kettering Cancer Center, New York, NY 10065, USA; Laboratory of Chromatin Biology and Epigenetics, The Rockefeller University, New York, NY 10065, USA.
| | - Alexey A Soshnev
- Laboratory of Chromatin Biology and Epigenetics, The Rockefeller University, New York, NY 10065, USA
| | - C David Allis
- Laboratory of Chromatin Biology and Epigenetics, The Rockefeller University, New York, NY 10065, USA.
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9
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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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10
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Abstract
Histone variants regulate chromatin accessibility and gene transcription. Given their distinct properties and functions, histone varint substitutions allow for profound alteration of nucleosomal architecture and local chromatin landscape. Skeletal myogenesis driven by the key transcription factor MyoD is characterized by precise temporal regulation of myogenic genes. Timed substitution of variants within the nucleosomes provides a powerful means to ensure sequential expression of myogenic genes. Indeed, growing evidence has shown H3.3, H2A.Z, macroH2A, and H1b to be critical for skeletal myogenesis. However, the relative importance of various histone variants and their associated chaperones in myogenesis is not fully appreciated. In this review, we summarize the role that histone variants play in altering chromatin landscape to ensure proper muscle differentiation. The temporal regulation and cross talk between histones variants and their chaperones in conjunction with other forms of epigenetic regulation could be critical to understanding myogenesis and their involvement in myopathies.
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Affiliation(s)
- Nandini Karthik
- Department of Physiology, Yong Loo Lin School of Medicine, National University of Singapore , Singapore
| | - Reshma Taneja
- Department of Physiology, Yong Loo Lin School of Medicine, National University of Singapore , Singapore
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11
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Zeineldin M, Federico S, Chen X, Fan Y, Xu B, Stewart E, Zhou X, Jeon J, Griffiths L, Nguyen R, Norrie J, Easton J, Mulder H, Yergeau D, Liu Y, Wu J, Van Ryn C, Naranjo A, Hogarty MD, Kamiński MM, Valentine M, Pruett-Miller SM, Pappo A, Zhang J, Clay MR, Bahrami A, Vogel P, Lee S, Shelat A, Sarthy JF, Meers MP, George RE, Mardis ER, Wilson RK, Henikoff S, Downing JR, Dyer MA. MYCN amplification and ATRX mutations are incompatible in neuroblastoma. Nat Commun 2020; 11:913. [PMID: 32060267 PMCID: PMC7021759 DOI: 10.1038/s41467-020-14682-6] [Citation(s) in RCA: 55] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2019] [Accepted: 01/23/2020] [Indexed: 12/31/2022] Open
Abstract
Aggressive cancers often have activating mutations in growth-controlling oncogenes and inactivating mutations in tumor-suppressor genes. In neuroblastoma, amplification of the MYCN oncogene and inactivation of the ATRX tumor-suppressor gene correlate with high-risk disease and poor prognosis. Here we show that ATRX mutations and MYCN amplification are mutually exclusive across all ages and stages in neuroblastoma. Using human cell lines and mouse models, we found that elevated MYCN expression and ATRX mutations are incompatible. Elevated MYCN levels promote metabolic reprogramming, mitochondrial dysfunction, reactive-oxygen species generation, and DNA-replicative stress. The combination of replicative stress caused by defects in the ATRX-histone chaperone complex, and that induced by MYCN-mediated metabolic reprogramming, leads to synthetic lethality. Therefore, ATRX and MYCN represent an unusual example, where inactivation of a tumor-suppressor gene and activation of an oncogene are incompatible. This synthetic lethality may eventually be exploited to improve outcomes for patients with high-risk neuroblastoma.
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Affiliation(s)
- Maged Zeineldin
- Department of Developmental Neurobiology, St. Jude Children's Research Hospital, Memphis, TN, 38105, USA
| | - Sara Federico
- Department of Oncology, St. Jude Children's Research Hospital, Memphis, TN, 38105, USA
| | - Xiang Chen
- Department of Computational Biology, St. Jude Children's Research Hospital, Memphis, TN, 38105, USA
- St. Jude Children's Research Hospital-Washington University Pediatric Cancer Genome Project, St. Louis, MO, USA
| | - Yiping Fan
- Department of Computational Biology, St. Jude Children's Research Hospital, Memphis, TN, 38105, USA
| | - Beisi Xu
- Department of Computational Biology, St. Jude Children's Research Hospital, Memphis, TN, 38105, USA
| | - Elizabeth Stewart
- Department of Oncology, St. Jude Children's Research Hospital, Memphis, TN, 38105, USA
| | - Xin Zhou
- Department of Computational Biology, St. Jude Children's Research Hospital, Memphis, TN, 38105, USA
| | - Jongrye Jeon
- Department of Developmental Neurobiology, St. Jude Children's Research Hospital, Memphis, TN, 38105, USA
| | - Lyra Griffiths
- Department of Developmental Neurobiology, St. Jude Children's Research Hospital, Memphis, TN, 38105, USA
| | - Rosa Nguyen
- Department of Developmental Neurobiology, St. Jude Children's Research Hospital, Memphis, TN, 38105, USA
| | - Jackie Norrie
- Department of Developmental Neurobiology, St. Jude Children's Research Hospital, Memphis, TN, 38105, USA
| | - John Easton
- Department of Computational Biology, St. Jude Children's Research Hospital, Memphis, TN, 38105, USA
| | - Heather Mulder
- Department of Computational Biology, St. Jude Children's Research Hospital, Memphis, TN, 38105, USA
| | - Donald Yergeau
- Department of Computational Biology, St. Jude Children's Research Hospital, Memphis, TN, 38105, USA
| | - Yanling Liu
- Department of Computational Biology, St. Jude Children's Research Hospital, Memphis, TN, 38105, USA
| | - Jianrong Wu
- Department of Biostatistics, St. Jude Children's Research Hospital, Memphis, TN, 38105, USA
| | - Collin Van Ryn
- Children's Oncology Group Statistics and Data Center, Department of Biostatistics, University of Florida, Gainesville, FlL, 32607, USA
| | - Arlene Naranjo
- Children's Oncology Group Statistics and Data Center, Department of Biostatistics, University of Florida, Gainesville, FlL, 32607, USA
| | - Michael D Hogarty
- Division of Oncology, Children's Hospital of Philadelphia, Philadelphia, PA, 19104, USA
| | - Marcin M Kamiński
- Department of Immunology, St. Jude Children's Research Hospital, Memphis, TN, 38105, USA
| | - Marc Valentine
- Cytogenetics Shared Resource, St. Jude Children's Research Hospital, Memphis, TN, 38105, USA
| | - Shondra M Pruett-Miller
- Center for Advanced Genome Engineering, St. Jude Children's Research Hospital, Memphis, TN, 38105, USA
| | - Alberto Pappo
- Department of Oncology, St. Jude Children's Research Hospital, Memphis, TN, 38105, USA
| | - Jinghui Zhang
- Department of Computational Biology, St. Jude Children's Research Hospital, Memphis, TN, 38105, USA
| | - Michael R Clay
- Department of Pathology, St. Jude Children's Research Hospital, Memphis, TN, 38105, USA
| | - Armita Bahrami
- Department of Pathology, St. Jude Children's Research Hospital, Memphis, TN, 38105, USA
| | - Peter Vogel
- Department of Pathology, St. Jude Children's Research Hospital, Memphis, TN, 38105, USA
| | - Seungjae Lee
- Department of Pathology, St. Jude Children's Research Hospital, Memphis, TN, 38105, USA
| | - Anang Shelat
- Department of Chemical Biology and Therapeutics St. Jude Children's Research Hospital, Memphis, TN, 38105, USA
| | - Jay F Sarthy
- Basic Science Division, Fred Hutchinson Cancer Research Center, Seattle, WA, 98109, USA
| | - Michael P Meers
- Basic Science Division, Fred Hutchinson Cancer Research Center, Seattle, WA, 98109, USA
| | - Rani E George
- Department of Hematology/Oncology, Dana Farber Cancer Institute, Boston, MA, 02215, USA
| | - Elaine R Mardis
- The Institute for Genomic Medicine, Nationwide Children's Hospital, Columbus, OH, 43205, USA
| | - Richard K Wilson
- The Institute for Genomic Medicine, Nationwide Children's Hospital, Columbus, OH, 43205, USA
| | - Steven Henikoff
- Basic Science Division, Fred Hutchinson Cancer Research Center, Seattle, WA, 98109, USA
- Howard Hughes Medical Institute, Chevy Chase, MD, 20815, USA
| | - James R Downing
- Department of Pathology, St. Jude Children's Research Hospital, Memphis, TN, 38105, USA
| | - Michael A Dyer
- Department of Developmental Neurobiology, St. Jude Children's Research Hospital, Memphis, TN, 38105, USA.
- St. Jude Children's Research Hospital-Washington University Pediatric Cancer Genome Project, St. Louis, MO, USA.
- Howard Hughes Medical Institute, Chevy Chase, MD, 20815, USA.
- Department of Ophthalmology, University of Tennessee Health Science Center, Memphis, TN, 38163, USA.
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12
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Lovejoy CA, Takai K, Huh MS, Picketts DJ, de Lange T. ATRX affects the repair of telomeric DSBs by promoting cohesion and a DAXX-dependent activity. PLoS Biol 2020; 18:e3000594. [PMID: 31895940 PMCID: PMC6959610 DOI: 10.1371/journal.pbio.3000594] [Citation(s) in RCA: 39] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2019] [Revised: 01/14/2020] [Accepted: 12/19/2019] [Indexed: 12/20/2022] Open
Abstract
Alpha thalassemia/mental retardation syndrome X-linked chromatin remodeler (ATRX), a DAXX (death domain-associated protein) interacting protein, is often lost in cells using the alternative lengthening of telomeres (ALT) pathway, but it is not known how ATRX loss leads to ALT. We report that ATRX deletion from mouse cells altered the repair of telomeric double-strand breaks (DSBs) and induced ALT-like phenotypes, including ALT-associated promyelocytic leukemia (PML) bodies (APBs), telomere sister chromatid exchanges (T-SCEs), and extrachromosomal telomeric signals (ECTSs). Mechanistically, we show that ATRX affects telomeric DSB repair by promoting cohesion of sister telomeres and that loss of ATRX in ALT cells results in diminished telomere cohesion. In addition, we document a role for DAXX in the repair of telomeric DSBs. Removal of telomeric cohesion in combination with DAXX deficiency recapitulates all telomeric DSB repair phenotypes associated with ATRX loss. The data reveal that ATRX has an effect on telomeric DSB repair and that this role involves both telomere cohesion and a DAXX-dependent pathway.
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Affiliation(s)
- Courtney A. Lovejoy
- Laboratory for Cell Biology and Genetics, The Rockefeller University, New York, New York, United States of America
| | - Kaori Takai
- Laboratory for Cell Biology and Genetics, The Rockefeller University, New York, New York, United States of America
| | - Michael S. Huh
- Regenerative Medicine Program, Ottawa Hospital Research Institute, Ottawa, Ontario, Canada
| | - David J. Picketts
- Regenerative Medicine Program, Ottawa Hospital Research Institute, Ottawa, Ontario, Canada
- Department of Biochemistry, Microbiology and Immunology, University of Ottawa, Ottawa, Ontario, Canada
- Department of Cellular and Molecular Medicine, University of Ottawa, Ottawa, Ontario, Canada
| | - Titia de Lange
- Laboratory for Cell Biology and Genetics, The Rockefeller University, New York, New York, United States of America
- * E-mail:
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13
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Alvarez-Saavedra M, Yan K, De Repentigny Y, Hashem LE, Chaudary N, Sarwar S, Yang D, Ioshikhes I, Kothary R, Hirayama T, Yagi T, Picketts DJ. Snf2h Drives Chromatin Remodeling to Prime Upper Layer Cortical Neuron Development. Front Mol Neurosci 2019; 12:243. [PMID: 31680852 PMCID: PMC6811508 DOI: 10.3389/fnmol.2019.00243] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2019] [Accepted: 09/20/2019] [Indexed: 01/23/2023] Open
Abstract
Alterations in the homeostasis of either cortical progenitor pool, namely the apically located radial glial (RG) cells or the basal intermediate progenitors (IPCs) can severely impair cortical neuron production. Such changes are reflected by microcephaly and are often associated with cognitive defects. Genes encoding epigenetic regulators are a frequent cause of intellectual disability and many have been shown to regulate progenitor cell growth, including our inactivation of the Smarca1 gene encoding Snf2l, which is one of two ISWI mammalian orthologs. Loss of the Snf2l protein resulted in dysregulation of Foxg1 and IPC proliferation leading to macrocephaly. Here we show that inactivation of the closely related Smarca5 gene encoding the Snf2h chromatin remodeler is necessary for embryonic IPC expansion and subsequent specification of callosal projection neurons. Telencephalon-specific Smarca5 cKO embryos have impaired cell cycle kinetics and increased cell death, resulting in fewer Tbr2+ and FoxG1+ IPCs by mid-neurogenesis. These deficits give rise to adult mice with a dramatic reduction in Satb2+ upper layer neurons, and partial agenesis of the corpus callosum. Mice survive into adulthood but molecularly display reduced expression of the clustered protocadherin genes that may further contribute to altered dendritic arborization and a hyperactive behavioral phenotype. Our studies provide novel insight into the developmental function of Snf2h-dependent chromatin remodeling processes during brain development.
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Affiliation(s)
- Matías Alvarez-Saavedra
- Regenerative Medicine Program, Ottawa Hospital Research Institute, Ottawa, ON, Canada.,Department of Cellular and Molecular Medicine, University of Ottawa, Ottawa, ON, Canada.,Departamento de Biología Celular y Molecular, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Keqin Yan
- Regenerative Medicine Program, Ottawa Hospital Research Institute, Ottawa, ON, Canada
| | - Yves De Repentigny
- Regenerative Medicine Program, Ottawa Hospital Research Institute, Ottawa, ON, Canada
| | - Lukas E Hashem
- Regenerative Medicine Program, Ottawa Hospital Research Institute, Ottawa, ON, Canada
| | - Nidhi Chaudary
- Regenerative Medicine Program, Ottawa Hospital Research Institute, Ottawa, ON, Canada
| | - Shihab Sarwar
- Regenerative Medicine Program, Ottawa Hospital Research Institute, Ottawa, ON, Canada
| | - Doo Yang
- Departments of Biochemistry, Microbiology and Immunology, University of Ottawa, Ottawa, ON, Canada.,Ottawa Institute of Systems Biology, University of Ottawa, Ottawa, ON, Canada
| | - Ilya Ioshikhes
- Departments of Biochemistry, Microbiology and Immunology, University of Ottawa, Ottawa, ON, Canada.,Ottawa Institute of Systems Biology, University of Ottawa, Ottawa, ON, Canada
| | - Rashmi Kothary
- Regenerative Medicine Program, Ottawa Hospital Research Institute, Ottawa, ON, Canada.,Department of Cellular and Molecular Medicine, University of Ottawa, Ottawa, ON, Canada.,Departments of Biochemistry, Microbiology and Immunology, University of Ottawa, Ottawa, ON, Canada
| | - Teruyoshi Hirayama
- KOKORO-Biology Group, Integrated Biology Laboratories, Graduate School of Frontier Biosciences, Osaka University, Suita, Japan.,Department of Anatomy and Developmental Neurobiology, Tokushima University Graduate School of Medical Sciences, Tokushima, Japan
| | - Takeshi Yagi
- KOKORO-Biology Group, Integrated Biology Laboratories, Graduate School of Frontier Biosciences, Osaka University, Suita, Japan
| | - David J Picketts
- Regenerative Medicine Program, Ottawa Hospital Research Institute, Ottawa, ON, Canada.,Department of Cellular and Molecular Medicine, University of Ottawa, Ottawa, ON, Canada.,Departments of Biochemistry, Microbiology and Immunology, University of Ottawa, Ottawa, ON, Canada
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14
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Bryan TM. Mechanisms of DNA Replication and Repair: Insights from the Study of G-Quadruplexes. Molecules 2019; 24:E3439. [PMID: 31546714 PMCID: PMC6804030 DOI: 10.3390/molecules24193439] [Citation(s) in RCA: 55] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2019] [Revised: 09/18/2019] [Accepted: 09/18/2019] [Indexed: 12/13/2022] Open
Abstract
G-quadruplexes are four-stranded guanine-rich structures that have been demonstrated to occur across the genome in humans and other organisms. They provide regulatory functions during transcription, translation and immunoglobulin gene rearrangement, but there is also a large amount of evidence that they can present a potent barrier to the DNA replication machinery. This mini-review will summarize recent advances in understanding the many strategies nature has evolved to overcome G-quadruplex-mediated replication blockage, including removal of the structure by helicases or nucleases, or circumventing the deleterious effects on the genome through homologous recombination, alternative end-joining or synthesis re-priming. Paradoxically, G-quadruplexes have also recently been demonstrated to provide a positive role in stimulating the initiation of DNA replication. These recent studies have not only illuminated the many roles and consequences of G-quadruplexes, but have also provided fundamental insights into the general mechanisms of DNA replication and its links with genetic and epigenetic stability.
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Affiliation(s)
- Tracy M Bryan
- Children's Medical Research Institute, University of Sydney, Westmead, NSW 2145, Australia.
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15
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Young KG, Yan K, Picketts DJ. C3aR signaling and gliosis in response to neurodevelopmental damage in the cerebellum. J Neuroinflammation 2019; 16:135. [PMID: 31272467 PMCID: PMC6610970 DOI: 10.1186/s12974-019-1530-4] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2019] [Accepted: 06/24/2019] [Indexed: 12/12/2022] Open
Abstract
BACKGROUND Conditional ablation of the Smarca5 gene in mice severely impairs the postnatal growth of the cerebellum and causes an ataxic phenotype. Comparative gene expression studies indicated that complement-related proteins were upregulated in the cerebellum of Smarca5 mutant mice. Complement proteins play critical roles within innate immune signaling pathways and, in the brain, are produced by glial cells under both normal and pathological conditions. The C3 complement protein-derived signaling peptide, C3a, has been implicated in contributing to both tissue damage and repair in conditions such as multiple sclerosis and stroke. Here, we investigated whether C3a receptor (C3aR) signaling promoted damage or repair in the developing cerebellum of Smarca5 mutant mice. METHODS Brain and cerebellum lysates from single Smarca5 conditional knockout (Smarca5 cKO) mice, C3aR1 KO mice, or double mutant mice were used for qRT-PCR and immunoblotting to assess the contribution of C3aR to the Smarca5 cKO brain pathology. Immunohistochemistry was used to characterize alterations to astroglia and phagocyte cells in the developing cerebellum of each of the genotypes. RESULTS C3aR signaling was observed to limit gliosis and promote granule neuron survival during postnatal cerebellar development. In Smarca5 cKO mice, disorganized astroglia with increased GFAP expression develops concurrently with cerebellar granule neuron loss and phagocyte invasion over the first 10 days following birth. Potential ligand precursors of C3aR-VGF and C3-were found to have upregulated expression and/or altered processing during this time. Phagocytes (microglia and macrophages) in both the control and Smarca5 mutant mice were the only cells observed to express C3aR. Loss of C3aR in the Smarca5 cKO cerebellum resulted in increased numbers of apoptotic cells and early phagocyte invasion into the external granule cell layer, as well as an exacerbated disorganization of the Bergmann glia. The loss of C3aR expression also attenuated an increase in the expression of the efferocytosis-related protein, MerTK, whose transcript was upregulated ~ 2.5-fold in the Smarca5 mutant cerebellum at P10. CONCLUSIONS This data indicates that C3aR can play an important role in limiting astrogliosis and regulating phagocyte phenotypes following developmental cell loss in the brain.
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Affiliation(s)
- Kevin G Young
- Regenerative Medicine Program, Ottawa Hospital Research Institute, Ottawa, ON, K1H 8L6, Canada.,Present address: Therapeutic Products Directorate, Health Canada, 1600 Scott St, Ottawa, ON, K1A 0K9, Canada
| | - Keqin Yan
- Regenerative Medicine Program, Ottawa Hospital Research Institute, Ottawa, ON, K1H 8L6, 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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16
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Shastrula PK, Sierra I, Deng Z, Keeney F, Hayden JE, Lieberman PM, Janicki SM. PML is recruited to heterochromatin during S phase and represses DAXX-mediated histone H3.3 chromatin assembly. J Cell Sci 2019; 132:jcs.220970. [PMID: 30796101 DOI: 10.1242/jcs.220970] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2018] [Accepted: 02/09/2019] [Indexed: 12/18/2022] Open
Abstract
The incorporation of the histone H3 variant, H3.3, into chromatin by the H3.3-specific chaperone DAXX and the ATP-dependent chromatin remodeling factor ATRX is a critical mechanism for silencing repetitive DNA. DAXX and ATRX are also components of promyelocytic nuclear bodies (PML-NBs), which have been identified as sites of H3.3 chromatin assembly. Here, we use a transgene array that can be visualized in single living cells to investigate the mechanisms that recruit PML-NB proteins (i.e. PML, DAXX, ATRX, and SUMO-1, SUMO-2 and SUMO-3) to heterochromatin and their functions in H3.3 chromatin assembly. We show that DAXX and PML are recruited to the array through distinct SUMOylation-dependent mechanisms. Additionally, PML is recruited during S phase and its depletion increases H3.3 deposition. Since this effect is abrogated when PML and DAXX are co-depleted, it is likely that PML represses DAXX-mediated H3.3 chromatin assembly. Taken together, these results suggest that, at heterochromatin, PML-NBs coordinate H3.3 chromatin assembly with DNA replication, which has important implications for understanding how transcriptional silencing is established and maintained.
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Affiliation(s)
- Prashanth Krishna Shastrula
- The Wistar Institute, 3601 Spruce Street, Philadelphia, PA 19104, USA.,University of the Sciences in Philadelphia, Department of Biological Sciences, 600 South 43rd Street, Philadelphia, PA 19104, USA
| | - Isabel Sierra
- The Wistar Institute, 3601 Spruce Street, Philadelphia, PA 19104, USA
| | - Zhong Deng
- The Wistar Institute, 3601 Spruce Street, Philadelphia, PA 19104, USA
| | - Frederick Keeney
- The Wistar Institute, 3601 Spruce Street, Philadelphia, PA 19104, USA
| | - James E Hayden
- The Wistar Institute, 3601 Spruce Street, Philadelphia, PA 19104, USA
| | - Paul M Lieberman
- The Wistar Institute, 3601 Spruce Street, Philadelphia, PA 19104, USA
| | - Susan M Janicki
- The Wistar Institute, 3601 Spruce Street, Philadelphia, PA 19104, USA
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17
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Kim J, Sun C, Tran AD, Chin PJ, Ruiz PD, Wang K, Gibbons RJ, Gamble MJ, Liu Y, Oberdoerffer P. The macroH2A1.2 histone variant links ATRX loss to alternative telomere lengthening. Nat Struct Mol Biol 2019; 26:213-219. [PMID: 30833786 PMCID: PMC6537592 DOI: 10.1038/s41594-019-0192-3] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2018] [Accepted: 01/23/2019] [Indexed: 01/22/2023]
Abstract
The growth of telomerase-deficient cancers depends on the alternative lengthening of telomeres (ALT), a homology-directed telomere-maintenance pathway. ALT telomeres exhibit a unique chromatin environment and generally lack the nucleosome remodeler ATRX, pointing to an epigenetic basis for ALT. Recently, we identified a protective role for the ATRX-interacting macroH2A1.2 histone variant during homologous recombination and replication stress (RS). Consistent with an inherent susceptibility to RS, we show that human ALT telomeres are highly enriched for macroH2A1.2. However, in contrast to ATRX-proficient cells, ALT telomeres transiently lose macroH2A1.2 during acute RS to facilitate DNA double-strand break (DSB) formation, a process that is almost completely prevented by ectopic ATRX expression. Telomeric macroH2A1.2 is re-deposited in a DNA damage response (DDR)-dependent manner to promote homologous recombination-associated ALT pathways. Our findings thus identify the dynamic exchange of macroH2A1.2 on chromatin as an epigenetic link among ATRX loss, RS-induced DDR initiation and telomere maintenance via homologous recombination.
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Affiliation(s)
- Jeongkyu Kim
- Laboratory of Receptor Biology and Gene Expression, National Cancer Institute, NIH, Bethesda, MD, USA
| | - Chongkui Sun
- Laboratory of Molecular Gerontology, National Institute on Aging, NIH, Baltimore, MD, USA
| | - Andy D Tran
- Laboratory of Receptor Biology and Gene Expression, National Cancer Institute, NIH, Bethesda, MD, USA
| | - Pei-Ju Chin
- Laboratory of Molecular Gerontology, National Institute on Aging, NIH, Baltimore, MD, USA
- Tissue Microbiology Laboratory, Food and Drug Administration, Silver Spring, MD, USA
| | - Penelope D Ruiz
- Department of Molecular Pharmacology, Albert Einstein College of Medicine, New York, NY, USA
| | - Kun Wang
- Laboratory of Molecular Gerontology, National Institute on Aging, NIH, Baltimore, MD, USA
| | - Richard J Gibbons
- Medical Research Council, Molecular Hematology Unit, Weatherall Institute of Molecular Medicine, University of Oxford, John Radcliff Hospital, Oxford, UK
| | - Matthew J Gamble
- Department of Molecular Pharmacology, Albert Einstein College of Medicine, New York, NY, USA
- Department of Cell Biology, Albert Einstein College of Medicine, New York, NY, USA
| | - Yie Liu
- Laboratory of Molecular Gerontology, National Institute on Aging, NIH, Baltimore, MD, USA.
| | - Philipp Oberdoerffer
- Laboratory of Receptor Biology and Gene Expression, National Cancer Institute, NIH, Bethesda, MD, USA.
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18
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Wasylishen AR, Estrella JS, Pant V, Chau GP, Lozano G. Daxx Functions Are p53-Independent In Vivo. Mol Cancer Res 2018; 16:1523-1529. [PMID: 29903771 PMCID: PMC6233723 DOI: 10.1158/1541-7786.mcr-18-0281] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2018] [Revised: 05/02/2018] [Accepted: 05/31/2018] [Indexed: 02/03/2023]
Abstract
Mutations in the death domain-associated protein (DAXX) have been recently identified in a substantial proportion of human pancreatic neuroendocrine tumors (PanNETs). Remarkably, however, little is known about the physiologic role(s) of DAXX despite in vitro studies suggesting potential functions. Most prominently, and supported by tumor sequencing data, DAXX functions in concert with alpha thalassemia/mental retardation X-linked (ATRX) as a histone chaperone complex for the H3.3 variant. Studies have also identified potential roles in apoptosis, transcription, and negative regulation of the p53 tumor suppressor pathway. Herein, a mouse modeling approach was used to specifically address the latter and no significant genetic interaction between Daxx and the p53 pathway was determined. The embryonic lethal phenotype of Daxx loss is not p53-dependent. In addition, Daxx heterozygosity does not sensitize mice to a sublethal dose of ionizing radiation or alter the survival or tumor phenotype of Mdm2 transgenic mice. However, the data support a tumor suppressor role for DAXX as low-dose ionizing radiation produced a higher proportion of carcinomas in Daxx heterozygous mice than wild-type controls.Implications: While DAXX has important in vivo functions, they are independent of an inhibitory role on the p53 tumor suppressor pathway. Mol Cancer Res; 16(10); 1523-9. ©2018 AACR.
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Affiliation(s)
- Amanda R. Wasylishen
- Department of Genetics, The University of Texas MD Anderson Cancer Center, Houston, TX, United States of America
| | - Jeannelyn S. Estrella
- Department of Pathology, The University of Texas MD Anderson Cancer Center, Houston, TX, United States of America
| | - Vinod Pant
- Department of Genetics, The University of Texas MD Anderson Cancer Center, Houston, TX, United States of America
| | - Gilda P. Chau
- Department of Genetics, The University of Texas MD Anderson Cancer Center, Houston, TX, United States of America
| | - Guillermina Lozano
- Department of Genetics, The University of Texas MD Anderson Cancer Center, Houston, TX, United States of America,Corresponding author: Guillermina Lozano, The University of Texas MD Anderson Cancer Center, Department of Genetics, 1515 Holcombe Blvd, Unit 1010, Houston, TX 77030, , Phone: 713-834-6386, Fax: 713-834-6380
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19
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Haase S, Garcia-Fabiani MB, Carney S, Altshuler D, Núñez FJ, Méndez FM, Núñez F, Lowenstein PR, Castro MG. Mutant ATRX: uncovering a new therapeutic target for glioma. Expert Opin Ther Targets 2018; 22:599-613. [PMID: 29889582 PMCID: PMC6044414 DOI: 10.1080/14728222.2018.1487953] [Citation(s) in RCA: 90] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2018] [Accepted: 06/08/2018] [Indexed: 12/29/2022]
Abstract
INTRODUCTION ATRX is a chromatin remodeling protein whose main function is the deposition of the histone variant H3.3. ATRX mutations are widely distributed in glioma, and correlate with alternative lengthening of telomeres (ALT) development, but they also affect other cellular functions related to epigenetic regulation. Areas covered: We discuss the main molecular characteristics of ATRX, from its various functions in normal development to the effects of its loss in ATRX syndrome patients and animal models. We focus on the salient consequences of ATRX mutations in cancer, from a clinical to a molecular point of view, focusing on both adult and pediatric glioma. Finally, we will discuss the therapeutic opportunities future research perspectives. Expert opinion: ATRX is a major component of various essential cellular pathways, exceeding its functions as a histone chaperone (e.g. DNA replication and repair, chromatin higher-order structure regulation, gene transcriptional regulation, etc.). However, it is unclear how the loss of these functions in ATRX-null cancer cells affects cancer development and progression. We anticipate new treatments and clinical approaches will emerge for glioma and other cancer types as mechanistic and molecular studies on ATRX are only just beginning to reveal the many critical functions of this protein in cancer.
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Affiliation(s)
- Santiago Haase
- a Department of Neurosurgery , The University of Michigan School of Medicine , Ann Arbor , MI , USA
- b Department of Cell & Developmental Biology , The University of Michigan School of Medicine , Ann Arbor , MI , USA
| | - María Belén Garcia-Fabiani
- a Department of Neurosurgery , The University of Michigan School of Medicine , Ann Arbor , MI , USA
- b Department of Cell & Developmental Biology , The University of Michigan School of Medicine , Ann Arbor , MI , USA
| | - Stephen Carney
- a Department of Neurosurgery , The University of Michigan School of Medicine , Ann Arbor , MI , USA
- b Department of Cell & Developmental Biology , The University of Michigan School of Medicine , Ann Arbor , MI , USA
| | - David Altshuler
- a Department of Neurosurgery , The University of Michigan School of Medicine , Ann Arbor , MI , USA
- b Department of Cell & Developmental Biology , The University of Michigan School of Medicine , Ann Arbor , MI , USA
| | - Felipe J Núñez
- a Department of Neurosurgery , The University of Michigan School of Medicine , Ann Arbor , MI , USA
- b Department of Cell & Developmental Biology , The University of Michigan School of Medicine , Ann Arbor , MI , USA
| | - Flor M Méndez
- a Department of Neurosurgery , The University of Michigan School of Medicine , Ann Arbor , MI , USA
- b Department of Cell & Developmental Biology , The University of Michigan School of Medicine , Ann Arbor , MI , USA
| | - Fernando Núñez
- a Department of Neurosurgery , The University of Michigan School of Medicine , Ann Arbor , MI , USA
- b Department of Cell & Developmental Biology , The University of Michigan School of Medicine , Ann Arbor , MI , USA
| | - Pedro R Lowenstein
- a Department of Neurosurgery , The University of Michigan School of Medicine , Ann Arbor , MI , USA
- b Department of Cell & Developmental Biology , The University of Michigan School of Medicine , Ann Arbor , MI , USA
| | - Maria G Castro
- a Department of Neurosurgery , The University of Michigan School of Medicine , Ann Arbor , MI , USA
- b Department of Cell & Developmental Biology , The University of Michigan School of Medicine , Ann Arbor , MI , USA
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20
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Truch J, Telenius J, Higgs DR, Gibbons RJ. How to Tackle Challenging ChIP-Seq, with Long-Range Cross-Linking, Using ATRX as an Example. Methods Mol Biol 2018; 1832:105-130. [PMID: 30073524 DOI: 10.1007/978-1-4939-8663-7_6] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Chromatin immunoprecipitation coupled with high-throughput, next-generation DNA sequencing (ChIP-seq) has enabled researchers to establish the genome-wide patterns of chromatin modifications and binding of chromatin-associated proteins. Well-established protocols produce robust ChIP-seq data for many proteins by sequencing the DNA obtained following immunoprecipitation of fragmented chromatin using a wide range of specific antibodies. In general, the quality of these data mainly depends on the specificity and avidity of the antibody used. However, even using optimal antibodies, ChIP-seq can become more challenging when the protein associates with chromatin via protein-protein interactions rather than directly binding DNA. An example of such a protein is the alpha-thalassaemia mental retardation X-linked (ATRX) protein; a chromatin remodeler that associates with the histone chaperone DAXX, in the deposition of the replication-independent histone variant H3.3 and plays an important role in maintaining chromatin integrity. Inherited mutations of ATRX cause syndromal mental retardation (ATR-X Syndrome) whereas acquired mutations are associated with myelodysplasia, acute myeloid leukemia (ATMDS syndrome), and a range of solid tumors. Therefore, high quality ChIP-seq data have been needed to analyze the genome-wide distribution of ATRX, to advance our understanding of its normal role and to comprehend how mutations contribute to human disease. Here, we describe an optimized ChIP-seq protocol for ATRX which can also be used to produce high quality data sets for other challenging proteins which are indirectly associated with DNA and complement the ChIP-seq toolkit for genome-wide analyses of histone chaperon complexes and associated chromatin remodelers. Although not a focus of this chapter, we will also provide some insight for the analysis of the large dataset generated by ChIP-seq. Even though this protocol has been fully optimized for ATRX, it should also provide guidance for efficient ChIP-seq analysis, using the appropriate antibodies, for other proteins interacting indirectly with DNA.
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Affiliation(s)
- Julia Truch
- Medical Research Council (MRC) Molecular Haematology Unit, Weatherall Institute of Molecular Medicine, University of Oxford, Oxford, OX3 9DS, UK
| | - Jelena Telenius
- Medical Research Council (MRC) Molecular Haematology Unit, Weatherall Institute of Molecular Medicine, University of Oxford, Oxford, OX3 9DS, UK
| | - Douglas R Higgs
- Medical Research Council (MRC) Molecular Haematology Unit, Weatherall Institute of Molecular Medicine, University of Oxford, Oxford, OX3 9DS, UK
| | - Richard J Gibbons
- Medical Research Council (MRC) Molecular Haematology Unit, Weatherall Institute of Molecular Medicine, University of Oxford, Oxford, OX3 9DS, UK.
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21
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Pompili L, Leonetti C, Biroccio A, Salvati E. Diagnosis and treatment of ALT tumors: is Trabectedin a new therapeutic option? JOURNAL OF EXPERIMENTAL & CLINICAL CANCER RESEARCH : CR 2017; 36:189. [PMID: 29273061 PMCID: PMC5741932 DOI: 10.1186/s13046-017-0657-3] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/24/2017] [Accepted: 12/01/2017] [Indexed: 12/22/2022]
Abstract
Telomeres are specialized nucleoprotein structures responsible for protecting chromosome ends in order to prevent the loss of genomic information. Telomere maintenance is required for achieving immortality by neoplastic cells. While most cancer cells rely on telomerase re-activation for linear chromosome maintenance and sustained proliferation, a significant population of cancers (10-15%) employs telomerase-independent strategies, collectively referred to as Alternative Lengthening of Telomeres (ALT). ALT mechanisms involve different types of homology-directed telomere recombination and synthesis. These processes are facilitated by loss of the ATRX or DAXX chromatin-remodeling factors and by abnormalities of the telomere nucleoprotein architecture. Although the functional consequences of telomerase and ALT up-regulation are similar in that they both prevent overall telomere shortening in tumors, these telomere maintenance mechanisms (TMMs) differ in several aspects which may account for their differential prognostic significance and response to therapy in various tumor types. Therefore, reliable methods for detecting telomerase activity and ALT are likely to become an important pre-requisite for the use of treatments targeting one or other of these mechanisms. However, the question whether ALT presence can confer sensitivity to rationally designed anti-cancer therapies is still open. Here we review the latest discoveries in terms of mechanisms of ALT activation and maintenance in human tumors, methods for ALT identification in cell lines and human tissues and biomarkers validation. Then, original results on sensitivity to rational based pre-clinical and clinical anti-tumor drugs in ALT vs hTERT positive cells will be presented.
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Affiliation(s)
- Luca Pompili
- UOSD SAFU, Regina Elena National Cancer Institute, Rome, Italy.,University of Tuscia, Viterbo, Italy
| | - Carlo Leonetti
- UOSD SAFU, Regina Elena National Cancer Institute, Rome, Italy
| | - Annamaria Biroccio
- Oncogenomic and Epigenetic Unit, Regina Elena National Cancer Institute, Via Elio Chianesi, 53 -, 00144, Rome, Italy
| | - Erica Salvati
- Oncogenomic and Epigenetic Unit, Regina Elena National Cancer Institute, Via Elio Chianesi, 53 -, 00144, Rome, Italy.
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22
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Huh MS, Young KG, Yan K, Price-O’Dea T, Picketts DJ. Recovery from impaired muscle growth arises from prolonged postnatal accretion of myonuclei in Atrx mutant mice. PLoS One 2017; 12:e0186989. [PMID: 29095838 PMCID: PMC5667798 DOI: 10.1371/journal.pone.0186989] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2017] [Accepted: 10/11/2017] [Indexed: 01/13/2023] Open
Abstract
Reduced muscle mass due to pathological development can occur through several mechanisms, including the loss or reduced proliferation of muscle stem cells. Muscle-specific ablation of the α-thalassemia mental retardation syndrome mutant protein, Atrx, in transgenic mice results in animals with a severely reduced muscle mass at three weeks of age; yet this muscle mass reduction resolves by adult age. Here, we explore the cellular mechanism underlying this effect. Analysis of Atrx mutant mice included testing for grip strength and rotorod performance. Muscle fiber length, fiber volume and numbers of myofiber-associated nuclei were determined from individual EDL or soleus myofibers isolated at three, five, or eight weeks. Myofibers from three week old Atrx mutant mice are smaller with fewer myofiber-associated nuclei and reduced volume compared to control animals, despite similar fiber numbers. Nonetheless, the grip strength of Atrx mutant mice was comparable to control mice when adjusted for body weight. Myofiber volume remained smaller at five weeks, becoming comparable to controls by 8 weeks of age. Concomitantly, increased numbers of myofiber-associated nuclei and Ki67+ myoblasts indicated that the recovery of muscle mass likely arises from the prolonged accretion of new myonuclei. This suggests that under disease conditions the muscle satellite stem cell niche can remain in a prolonged active state, allowing for the addition of a minimum number of myonuclei required to achieve a normal muscle size.
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Affiliation(s)
- Michael S. Huh
- Regenerative Medicine Program, Ottawa Hospital Research Institute, 501 Smyth Road, Ottawa, ON Canada
| | - Kevin G. Young
- Regenerative Medicine Program, Ottawa Hospital Research Institute, 501 Smyth Road, Ottawa, ON Canada
| | - Keqin Yan
- Regenerative Medicine Program, Ottawa Hospital Research Institute, 501 Smyth Road, Ottawa, ON Canada
| | - Tina Price-O’Dea
- Regenerative Medicine Program, Ottawa Hospital Research Institute, 501 Smyth Road, Ottawa, ON Canada
| | - David J. Picketts
- Regenerative Medicine Program, Ottawa Hospital Research Institute, 501 Smyth Road, Ottawa, ON Canada
- Department of Biochemistry, Microbiology & Immunology, University of Ottawa, Ottawa, ON Canada
- Department of Cellular and Molecular Medicine, University of Ottawa, Ottawa, ON Canada
- * E-mail:
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23
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Kovatcheva M, Liao W, Klein ME, Robine N, Geiger H, Crago AM, Dickson MA, Tap WD, Singer S, Koff A. ATRX is a regulator of therapy induced senescence in human cells. Nat Commun 2017; 8:386. [PMID: 28855512 PMCID: PMC5577318 DOI: 10.1038/s41467-017-00540-5] [Citation(s) in RCA: 54] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2016] [Accepted: 07/07/2017] [Indexed: 01/24/2023] Open
Abstract
Senescence is a state of stable cell cycle exit with important implications for development and disease. Here, we demonstrate that the chromatin remodeling enzyme ATRX is required for therapy-induced senescence. ATRX accumulates in nuclear foci and is required for therapy-induced senescence in multiple types of transformed cells exposed to either DNA damaging agents or CDK4 inhibitors. Mobilization into foci depends on the ability of ATRX to interact with H3K9me3 histone and HP1. Foci form soon after cells exit the cell cycle, before other hallmarks of senescence appear. Eliminating ATRX in senescent cells destabilizes the senescence-associated heterochromatic foci. Additionally, ATRX binds to and suppresses expression from the HRAS locus; repression of HRAS is sufficient to promote the transition of quiescent cells into senescence and preventing repression blocks progression into senescence. Thus ATRX is a critical regulator of therapy-induced senescence and acts in multiple ways to drive cells into this state. Therapy induced senescence (TIS) is a growth suppressive program activated by cytostatic agents in some cancer cells. Here the authors show that the chromatin remodeling enzyme ATRX is a regulator of TIS and drives cells into this state via multiple mechanisms.
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Affiliation(s)
- Marta Kovatcheva
- The Louis V. Gerstner Graduate School of Biomedical Sciences, Sloan Kettering Institute, Memorial Sloan Kettering Cancer Center, New York, 10065, USA.,Program in Molecular Biology, Memorial Sloan Kettering Cancer Center, New York, 10065, USA
| | - Will Liao
- The New York Genome Center, New York, 10013, USA
| | - Mary E Klein
- The Louis V. Gerstner Graduate School of Biomedical Sciences, Sloan Kettering Institute, Memorial Sloan Kettering Cancer Center, New York, 10065, USA.,Program in Molecular Biology, Memorial Sloan Kettering Cancer Center, New York, 10065, USA
| | | | | | - Aimee M Crago
- Program in Molecular Biology, Memorial Sloan Kettering Cancer Center, New York, 10065, USA.,Department of Surgery, Memorial Sloan Kettering Cancer Center, New York, 10065, USA
| | - Mark A Dickson
- Department of Medicine, Weill College of Medicine, Cornell University, New York, 10065, USA.,Department of Medicine, Memorial Sloan Kettering Cancer Center, New York, 10065, USA
| | - William D Tap
- Department of Medicine, Weill College of Medicine, Cornell University, New York, 10065, USA.,Department of Medicine, Memorial Sloan Kettering Cancer Center, New York, 10065, USA
| | - Samuel Singer
- Department of Surgery, Memorial Sloan Kettering Cancer Center, New York, 10065, USA
| | - Andrew Koff
- The Louis V. Gerstner Graduate School of Biomedical Sciences, Sloan Kettering Institute, Memorial Sloan Kettering Cancer Center, New York, 10065, USA. .,Program in Molecular Biology, Memorial Sloan Kettering Cancer Center, New York, 10065, USA.
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24
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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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25
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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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26
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Salsman J, Rapkin LM, Margam NN, Duncan R, Bazett-Jones DP, Dellaire G. Myogenic differentiation triggers PML nuclear body loss and DAXX relocalization to chromocentres. Cell Death Dis 2017; 8:e2724. [PMID: 28358373 PMCID: PMC5386546 DOI: 10.1038/cddis.2017.151] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2016] [Revised: 03/05/2017] [Accepted: 03/07/2017] [Indexed: 12/12/2022]
Abstract
The promyelocytic leukemia protein (PML) is expressed in most normal human tissues and forms nuclear bodies (NBs) that have roles in gene regulation and cellular processes such as DNA repair, cell cycle control, and cell fate decisions. Using murine C2C12 myoblasts, we demonstrate that activation of skeletal muscle differentiation results in loss of PML and PML NBs prior to myotube fusion. Myotube formation was associated with marked chromatin reorganization and the relocalization of DAXX from PML NBs to chromocentres. MyoD expression was sufficient to cause PML NB loss, and silencing of PML induced DAXX relocalization. Fusion of C2C12 cells using the reptilian reovirus p14 fusogenic protein failed to disrupt PML NBs yet still promoted DAXX redistribution and loss; whereas ectopic expression of PML in differentiated cells only partially restored PML NB formation and DAXX localization at NBs. Finally, we determined that the C-terminal SUMO-interacting motif of DAXX is required for its colocalization with ATRX in heterochromatin domains during myotube formation. These data support a model in which activation of myogenic differentiation results in PML NB loss, chromatin reorganization and DAXX relocalization, and provides a paradigm for understanding the consequence of PML loss in other cellular contexts, such as during cancer development and progression.
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Affiliation(s)
- Jayme Salsman
- Department of Pathology, Dalhousie University, Halifax, NS, Canada, B3H 4R2
| | - Lindsy M Rapkin
- Genetics & Genome Biology Program, The Hospital for Sick Children, Toronto, ON, Canada, M5G 1X8
| | - Nandini N Margam
- Department of Microbiology & Immunology, Dalhousie University, Halifax, NS, Canada, B3H 4R2
| | - Roy Duncan
- Department of Microbiology & Immunology, Dalhousie University, Halifax, NS, Canada, B3H 4R2
| | - David P Bazett-Jones
- Genetics & Genome Biology Program, The Hospital for Sick Children, Toronto, ON, Canada, M5G 1X8
| | - Graham Dellaire
- Department of Pathology, Dalhousie University, Halifax, NS, Canada, B3H 4R2.,Department of Biochemistry & Molecular Biology, Dalhousie University, Halifax, NS, Canada, B3H 4R2
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27
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Marinoni I, Wiederkeher A, Wiedmer T, Pantasis S, Di Domenico A, Frank R, Vassella E, Schmitt A, Perren A. Hypo-methylation mediates chromosomal instability in pancreatic NET. Endocr Relat Cancer 2017; 24:137-146. [PMID: 28115389 DOI: 10.1530/erc-16-0554] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/23/2016] [Accepted: 01/23/2017] [Indexed: 12/22/2022]
Abstract
DAXX and or ATRX loss occur in 40% of pancreatic neuroendocrine tumors (PanNETs). PanNETs negative for DAXX or ATRX show an increased risk of relapse. The tumor-associated pathways activated upon DAXX or ATRX loss and how this event may induce chromosomal instability (CIN) and alternative lengthening telomeres (ALT) are still unknown. Both DAXX and ATRX are involved in DNA methylation regulation. DNA methylation of heterochromatin and of non-coding sequences is extremely important for the maintenance of genomic stability. We analyzed the association of DAXX and/or ATRX loss and CIN with global DNA methylation in human PanNET samples and the effect of DAXX knock-down on methylation and cell proliferation. We assessed LINE1 as well as global DNA methylation in 167 PanNETs, and we found that DAXX and or ATRX-negative tumors and tumors with CIN were hypomethylated. DAXX knock-down in PanNET cell lines blocked cells in G1/G0 phase and seemed to increase CIN in QGP-1 cells. However, no direct changes in DNA methylation were observed after DAXX knock-down in vitro In conclusion, our data indicate that epigenetic changes are crucial steps in the progression of PanNETs loss and suggest that DNA methylation is the mechanism via which CIN is induced, allowing clonal expansion and selection.
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Affiliation(s)
- I Marinoni
- Institute of PathologyUniversity of Bern, Bern, Switzerland
| | - A Wiederkeher
- Institute of PathologyUniversity of Bern, Bern, Switzerland
| | - T Wiedmer
- Institute of PathologyUniversity of Bern, Bern, Switzerland
- GCB Graduate School BernBern, Switzerland
| | - S Pantasis
- Institute of PathologyUniversity of Bern, Bern, Switzerland
| | - A Di Domenico
- Institute of PathologyUniversity of Bern, Bern, Switzerland
- GCB Graduate School BernBern, Switzerland
| | - R Frank
- Institute of PathologyUniversity of Bern, Bern, Switzerland
| | - E Vassella
- Institute of PathologyUniversity of Bern, Bern, Switzerland
| | - A Schmitt
- Institute of PathologyUniversity of Bern, Bern, Switzerland
| | - A Perren
- Institute of PathologyUniversity of Bern, Bern, Switzerland
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28
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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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29
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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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30
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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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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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Loss of ATRX, associated with DNA methylation pattern of chromosome end, impacted biological behaviors of astrocytic tumors. Oncotarget 2016; 6:18105-15. [PMID: 25971279 PMCID: PMC4627238 DOI: 10.18632/oncotarget.3906] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2014] [Accepted: 04/24/2015] [Indexed: 12/31/2022] Open
Abstract
Loss of ATRX leads to epigenetic alterations, including abnormal levels of DNA methylation at repetitive elements such as telomeres in murine cells. We conducted an extensive DNA methylation and mRNA expression profile study on a cohort of 82 patients with astrocytic tumors to study whether ATRX expression was associated with DNA methylation level in astrocytic tumors and in which cellular functions it participated. We observed that astrocytic tumors with lower ATRX expression harbored higher DNA methylation level at chromatin end and astrocytic tumors with ATRX-low had distinct gene expression profile and DNA methylation profile compared with ATRX-high tumors. Then, we uncovered that several ATRX associated biological functions in the DNA methylation and mRNA expression profile (GEP), including apoptotic process, DNA-dependent positive regulation of transcription, chromatin modification, and observed that ATRX expression was companied by MGMT methylation and expression. We also found that loss of ATRX caused by siRNA induced apoptotic cells increasing, reduced tumor cell proliferation and repressed the cell migration in glioma cells. Our results showed ATRX-related regulatory functions of the combined profiles from DNA methylation and mRNA expression in astrocytic tumors, and delineated that loss of ATRX impacted biological behaviors of astrocytic tumor cells, providing important resources for future dissection of ATRX role in glioma.
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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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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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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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36
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Abdouh M, Hanna R, El Hajjar J, Flamier A, Bernier G. The Polycomb Repressive Complex 1 Protein BMI1 Is Required for Constitutive Heterochromatin Formation and Silencing in Mammalian Somatic Cells. J Biol Chem 2015; 291:182-97. [PMID: 26468281 DOI: 10.1074/jbc.m115.662403] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2015] [Indexed: 01/08/2023] Open
Abstract
The polycomb repressive complex 1 (PRC1), containing the core BMI1 and RING1A/B proteins, mono-ubiquitinylates histone H2A (H2A(ub)) and is associated with silenced developmental genes at facultative heterochromatin. It is, however, assumed that the PRC1 is excluded from constitutive heterochromatin in somatic cells based on work performed on mouse embryonic stem cells and oocytes. We show here that BMI1 is required for constitutive heterochromatin formation and silencing in human and mouse somatic cells. BMI1 was highly enriched at intergenic and pericentric heterochromatin, co-immunoprecipitated with the architectural heterochromatin proteins HP1, DEK1, and ATRx, and was required for their localization. In contrast, BRCA1 localization was BMI1-independent and partially redundant with that of BMI1 for H2A(ub) deposition, constitutive heterochromatin formation, and silencing. These observations suggest a dynamic and developmentally regulated model of PRC1 occupancy at constitutive heterochromatin, and where BMI1 function in somatic cells is to stabilize the repetitive genome.
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Affiliation(s)
- Mohamed Abdouh
- From the Department of Neurosciences, University of Montreal, and The Stem Cell and Developmental Biology Laboratory, Hôpital Maisonneuve-Rosemont, 5415 Boul. l'Assomption, Montreal H1T 2M4, Canada
| | - Roy Hanna
- From the Department of Neurosciences, University of Montreal, and The Stem Cell and Developmental Biology Laboratory, Hôpital Maisonneuve-Rosemont, 5415 Boul. l'Assomption, Montreal H1T 2M4, Canada
| | - Jida El Hajjar
- From the Department of Neurosciences, University of Montreal, and The Stem Cell and Developmental Biology Laboratory, Hôpital Maisonneuve-Rosemont, 5415 Boul. l'Assomption, Montreal H1T 2M4, Canada
| | - Anthony Flamier
- From the Department of Neurosciences, University of Montreal, and The Stem Cell and Developmental Biology Laboratory, Hôpital Maisonneuve-Rosemont, 5415 Boul. l'Assomption, Montreal H1T 2M4, Canada
| | - Gilbert Bernier
- From the Department of Neurosciences, University of Montreal, and The Stem Cell and Developmental Biology Laboratory, Hôpital Maisonneuve-Rosemont, 5415 Boul. l'Assomption, Montreal H1T 2M4, Canada
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37
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Clynes D, Jelinska C, Xella B, Ayyub H, Scott C, Mitson M, Taylor S, Higgs DR, Gibbons RJ. Suppression of the alternative lengthening of telomere pathway by the chromatin remodelling factor ATRX. Nat Commun 2015; 6:7538. [PMID: 26143912 PMCID: PMC4501375 DOI: 10.1038/ncomms8538] [Citation(s) in RCA: 201] [Impact Index Per Article: 22.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2015] [Accepted: 05/19/2015] [Indexed: 02/08/2023] Open
Abstract
Fifteen per cent of cancers maintain telomere length independently of telomerase by the homologous recombination (HR)-associated alternative lengthening of telomeres (ALT) pathway. A unifying feature of these tumours are mutations in ATRX. Here we show that expression of ectopic ATRX triggers a suppression of the pathway and telomere shortening. Importantly ATRX-mediated ALT suppression is dependent on the histone chaperone DAXX. Re-expression of ATRX is associated with a reduction in replication fork stalling, a known trigger for HR and loss of MRN from telomeres. A G-quadruplex stabilizer partially reverses the effect of ATRX, inferring ATRX may normally facilitate replication through these sequences that, if they persist, promote ALT. We propose that defective telomere chromatinization through loss of ATRX promotes the persistence of aberrant DNA secondary structures, which in turn present a barrier to DNA replication, leading to replication fork stalling, collapse, HR and subsequent recombination-mediated telomere synthesis in ALT cancers. ATRX, a chromatin remodelling factor, is mutated in cancers that maintain telomere length by alternative lengthening of telomeres (ALT). Here, the authors show that ectopic expression of ATRX triggers telomere shortening, ALT suppression and reduced replication fork stalling.
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Affiliation(s)
- David Clynes
- MRC Molecular Haematology Unit, Weatherall Institute of Molecular Medicine, University of Oxford, John Radcliffe Hospital, Oxford OX3 9DS, UK
| | - Clare Jelinska
- MRC Molecular Haematology Unit, Weatherall Institute of Molecular Medicine, University of Oxford, John Radcliffe Hospital, Oxford OX3 9DS, UK
| | - Barbara Xella
- MRC Molecular Haematology Unit, Weatherall Institute of Molecular Medicine, University of Oxford, John Radcliffe Hospital, Oxford OX3 9DS, UK
| | - Helena Ayyub
- MRC Molecular Haematology Unit, Weatherall Institute of Molecular Medicine, University of Oxford, John Radcliffe Hospital, Oxford OX3 9DS, UK
| | - Caroline Scott
- MRC Molecular Haematology Unit, Weatherall Institute of Molecular Medicine, University of Oxford, John Radcliffe Hospital, Oxford OX3 9DS, UK
| | - Matthew Mitson
- MRC Molecular Haematology Unit, Weatherall Institute of Molecular Medicine, University of Oxford, John Radcliffe Hospital, Oxford OX3 9DS, UK
| | - Stephen Taylor
- Computational Biology Research Group, Weatherall Institute of Molecular Medicine, University of Oxford, John Radcliffe Hospital, Oxford OX3 9DS, UK
| | - Douglas R Higgs
- MRC Molecular Haematology Unit, Weatherall Institute of Molecular Medicine, University of Oxford, John Radcliffe Hospital, Oxford OX3 9DS, UK
| | - Richard J Gibbons
- MRC Molecular Haematology Unit, Weatherall Institute of Molecular Medicine, University of Oxford, John Radcliffe Hospital, Oxford OX3 9DS, UK
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38
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Point mutations in an epigenetic factor lead to multiple types of bone tumors: role of H3.3 histone variant in bone development and disease. BONEKEY REPORTS 2015; 4:715. [PMID: 26157578 DOI: 10.1038/bonekey.2015.84] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/15/2015] [Accepted: 04/24/2015] [Indexed: 12/27/2022]
Abstract
Coordinated post-translational modifications (PTMs) of nucleosomal histones emerge as a key mechanism of gene regulation by defining chromatin configuration. Patterns of histone modifications vary in different cells and constitute core elements of cell-specific epigenomes. Recently, in addition to canonical histone proteins produced during the S phase of cell cycle, several non-canonical histone variants have been identified and shown to express in a DNA replication-independent manner. These histone variants generate diversity in nucleosomal structures and add further complexity to mechanisms of epigenetic regulation. Cell-specific functions of histone variants remain to be determined. Several recent studies reported an association between some point mutations in the non-canonical histone H3.3 and particular types of brain and bone tumors. This suggests a possibility of differential physiological effects of histone variants in different cells and tissues, including bone. In this review, we outline the roles of histone variants and their PTMs in the epigenetic regulation of chromatin structure and discuss possible mechanisms of biological effects of the non-canonical histone mutations found in bone tumors on tumorigenesis in differentiating bone stem cells.
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39
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Chang FTM, Chan FL, R McGhie JD, Udugama M, Mayne L, Collas P, Mann JR, Wong LH. CHK1-driven histone H3.3 serine 31 phosphorylation is important for chromatin maintenance and cell survival in human ALT cancer cells. Nucleic Acids Res 2015; 43:2603-14. [PMID: 25690891 PMCID: PMC4357709 DOI: 10.1093/nar/gkv104] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Human ALT cancers show high mutation rates in ATRX and DAXX. Although it is well known that the absence of ATRX/DAXX disrupts H3.3 deposition at heterochromatin, its impact on H3.3 deposition and post-translational modification in the global genome remains unclear. Here, we explore the dynamics of phosphorylated H3.3 serine 31 (H3.3S31ph) in human ALT cancer cells. While H3.3S31ph is found only at pericentric satellite DNA repeats during mitosis in most somatic human cells, a high level of H3.3S31ph is detected on the entire chromosome in ALT cells, attributable to an elevated CHK1 activity in these cells. Drug inhibition of CHK1 activity during mitosis and expression of mutant H3.3S31A in these ALT cells result in a decrease in H3.3S31ph levels accompanied with increased levels of phosphorylated H2AX serine 139 on chromosome arms and at the telomeres. Furthermore, the inhibition of CHK1 activity in these cells also reduces cell viability. Our findings suggest a novel role of CHK1 as an H3.3S31 kinase, and that CHK1-mediated H3.3S31ph plays an important role in the maintenance of chromatin integrity and cell survival in ALT cancer cells.
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Affiliation(s)
- Fiona T M Chang
- Department of Biochemistry and Molecular Biology, Monash University, Clayton, Victoria 3800, Australia
| | - F Lyn Chan
- Department of Biochemistry and Molecular Biology, Monash University, Clayton, Victoria 3800, Australia
| | - James D R McGhie
- Department of Biochemistry and Molecular Biology, Monash University, Clayton, Victoria 3800, Australia
| | - Maheshi Udugama
- Department of Biochemistry and Molecular Biology, Monash University, Clayton, Victoria 3800, Australia
| | - Lynne Mayne
- Department of Biochemistry and Molecular Biology, Monash University, Clayton, Victoria 3800, Australia
| | - Philippe Collas
- Institute of Basic Medical Sciences, and Norwegian Center for Stem Cell Research, Faculty of Medicine, University of Oslo, Oslo 0317, Norway
| | - Jeffrey R Mann
- Stem Cell Epigenetics Laboratory, Murdoch Childrens Research Institute, Flemington Road, Parkville, Victoria 3052, Australia
| | - Lee H Wong
- Department of Biochemistry and Molecular Biology, Monash University, Clayton, Victoria 3800, Australia
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40
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Kernohan KD, Vernimmen D, Gloor GB, Bérubé NG. Analysis of neonatal brain lacking ATRX or MeCP2 reveals changes in nucleosome density, CTCF binding and chromatin looping. Nucleic Acids Res 2014; 42:8356-68. [PMID: 24990380 PMCID: PMC4117782 DOI: 10.1093/nar/gku564] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
ATRX and MeCP2 belong to an expanding group of chromatin-associated proteins implicated in human neurodevelopmental disorders, although their gene-regulatory activities are not fully resolved. Loss of ATRX prevents full repression of an imprinted gene network in the postnatal brain and in this study we address the mechanistic aspects of this regulation. We show that ATRX binds many imprinted domains individually but that transient co-localization between imprinted domains in the nuclei of neurons does not require ATRX. We demonstrate that MeCP2 is required for ATRX recruitment and that deficiency of either ATRX or MeCP2 causes decreased frequency of long-range chromatin interactions associated with altered nucleosome density at CTCF-binding sites and reduced CTCF occupancy. These findings indicate that MeCP2 and ATRX regulate gene expression at a subset of imprinted domains by maintaining a nucleosome configuration conducive to CTCF binding and to the maintenance of higher order chromatin structure.
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Affiliation(s)
- Kristin D Kernohan
- Department of Biochemistry, University of Western Ontario, London N6C 2V5, Canada Children's Health Research Institute, London, Canada
| | - Douglas Vernimmen
- Medical Research Council (MRC) Molecular Haematology Unit, Weatherall Institute of Molecular Medicine, University of Oxford, John Radcliffe Hospital, Oxford, UK
| | - Gregory B Gloor
- Department of Biochemistry, University of Western Ontario, London N6C 2V5, Canada
| | - Nathalie G Bérubé
- Department of Biochemistry, University of Western Ontario, London N6C 2V5, Canada Children's Health Research Institute, London, Canada Department of Paediatrics, University of Western Ontario, London N6C 2V5, Canada
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41
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Alvarez-Saavedra M, De Repentigny Y, Lagali PS, Raghu Ram EVS, Yan K, Hashem E, Ivanochko D, Huh MS, Yang D, Mears AJ, Todd MAM, Corcoran CP, Bassett EA, Tokarew NJA, Kokavec J, Majumder R, Ioshikhes I, Wallace VA, Kothary R, Meshorer E, Stopka T, Skoultchi AI, Picketts DJ. Snf2h-mediated chromatin organization and histone H1 dynamics govern cerebellar morphogenesis and neural maturation. Nat Commun 2014; 5:4181. [PMID: 24946904 PMCID: PMC4083431 DOI: 10.1038/ncomms5181] [Citation(s) in RCA: 60] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2014] [Accepted: 05/15/2014] [Indexed: 12/28/2022] Open
Abstract
Chromatin compaction mediates progenitor to post-mitotic cell transitions and modulates gene expression programs, yet the mechanisms are poorly defined. Snf2h and Snf2l are ATP-dependent chromatin remodelling proteins that assemble, reposition and space nucleosomes, and are robustly expressed in the brain. Here we show that mice conditionally inactivated for Snf2h in neural progenitors have reduced levels of histone H1 and H2A variants that compromise chromatin fluidity and transcriptional programs within the developing cerebellum. Disorganized chromatin limits Purkinje and granule neuron progenitor expansion, resulting in abnormal post-natal foliation, while deregulated transcriptional programs contribute to altered neural maturation, motor dysfunction and death. However, mice survive to young adulthood, in part from Snf2l compensation that restores Engrailed-1 expression. Similarly, Purkinje-specific Snf2h ablation affects chromatin ultrastructure and dendritic arborization, but alters cognitive skills rather than motor control. Our studies reveal that Snf2h controls chromatin organization and histone H1 dynamics for the establishment of gene expression programs underlying cerebellar morphogenesis and neural maturation.
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Affiliation(s)
- Matías Alvarez-Saavedra
- 1] Regenerative Medicine Program, Ottawa Hospital Research Institute, Ottawa, Ontario, Canada K1H 8L6 [2] Department of Cellular and Molecular Medicine, University of Ottawa, Ottawa, Ontario, Canada K1H 8M5
| | - Yves De Repentigny
- Regenerative Medicine Program, Ottawa Hospital Research Institute, Ottawa, Ontario, Canada K1H 8L6
| | - Pamela S Lagali
- Regenerative Medicine Program, Ottawa Hospital Research Institute, Ottawa, Ontario, Canada K1H 8L6
| | - Edupuganti V S Raghu Ram
- Department of Genetics, The Alexander Silberman Institute of Life Sciences, The Hebrew University of Jerusalem, Jerusalem 91904, Israel
| | - Keqin Yan
- Regenerative Medicine Program, Ottawa Hospital Research Institute, Ottawa, Ontario, Canada K1H 8L6
| | - Emile Hashem
- 1] Regenerative Medicine Program, Ottawa Hospital Research Institute, Ottawa, Ontario, Canada K1H 8L6 [2] Department of Cellular and Molecular Medicine, University of Ottawa, Ottawa, Ontario, Canada K1H 8M5
| | - Danton Ivanochko
- 1] Regenerative Medicine Program, Ottawa Hospital Research Institute, Ottawa, Ontario, Canada K1H 8L6 [2] Department of Biochemistry, Microbiology and Immunology, University of Ottawa, Ottawa, Ontario, Canada K1H 8M5
| | - Michael S Huh
- Regenerative Medicine Program, Ottawa Hospital Research Institute, Ottawa, Ontario, Canada K1H 8L6
| | - Doo Yang
- 1] Department of Biochemistry, Microbiology and Immunology, University of Ottawa, Ottawa, Ontario, Canada K1H 8M5 [2] Institute of Systems Biology, University of Ottawa, Ottawa, Ontario, Canada K1H 8M5
| | - Alan J Mears
- Vision Program, Ottawa Hospital Research Institute, Ottawa, Ontario, Canada K1H 8L6
| | - Matthew A M Todd
- 1] Regenerative Medicine Program, Ottawa Hospital Research Institute, Ottawa, Ontario, Canada K1H 8L6 [2] Department of Biochemistry, Microbiology and Immunology, University of Ottawa, Ottawa, Ontario, Canada K1H 8M5
| | - Chelsea P Corcoran
- Regenerative Medicine Program, Ottawa Hospital Research Institute, Ottawa, Ontario, Canada K1H 8L6
| | - Erin A Bassett
- Department of Biochemistry, Microbiology and Immunology, University of Ottawa, Ottawa, Ontario, Canada K1H 8M5
| | - Nicholas J A Tokarew
- Department of Biochemistry, Microbiology and Immunology, University of Ottawa, Ottawa, Ontario, Canada K1H 8M5
| | - Juraj Kokavec
- Institute of Pathologic Physiology, First Faculty of Medicine, Charles University in Prague, Prague 12853, Czech Republic
| | - Romit Majumder
- Department of Cell Biology, Albert Einstein College of Medicine, Bronx, New York 10461, USA
| | - Ilya Ioshikhes
- 1] Department of Biochemistry, Microbiology and Immunology, University of Ottawa, Ottawa, Ontario, Canada K1H 8M5 [2] Institute of Systems Biology, University of Ottawa, Ottawa, Ontario, Canada K1H 8M5
| | - Valerie A Wallace
- 1] Department of Biochemistry, Microbiology and Immunology, University of Ottawa, Ottawa, Ontario, Canada K1H 8M5 [2] Vision Program, Ottawa Hospital Research Institute, Ottawa, Ontario, Canada K1H 8L6
| | - Rashmi Kothary
- 1] Regenerative Medicine Program, Ottawa Hospital Research Institute, Ottawa, Ontario, Canada K1H 8L6 [2] Department of Cellular and Molecular Medicine, University of Ottawa, Ottawa, Ontario, Canada K1H 8M5
| | - Eran Meshorer
- Department of Genetics, The Alexander Silberman Institute of Life Sciences, The Hebrew University of Jerusalem, Jerusalem 91904, Israel
| | - Tomas Stopka
- Institute of Pathologic Physiology, First Faculty of Medicine, Charles University in Prague, Prague 12853, Czech Republic
| | - Arthur I Skoultchi
- Department of Cell Biology, Albert Einstein College of Medicine, Bronx, New York 10461, USA
| | - David J Picketts
- 1] Regenerative Medicine Program, Ottawa Hospital Research Institute, Ottawa, Ontario, Canada K1H 8L6 [2] Department of Cellular and Molecular Medicine, University of Ottawa, Ottawa, Ontario, Canada K1H 8M5 [3] Department of Biochemistry, Microbiology and Immunology, University of Ottawa, Ottawa, Ontario, Canada K1H 8M5
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42
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Meeker A, Heaphy C. Gastroenteropancreatic endocrine tumors. Mol Cell Endocrinol 2014; 386:101-20. [PMID: 23906538 DOI: 10.1016/j.mce.2013.07.015] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/15/2013] [Revised: 07/19/2013] [Accepted: 07/22/2013] [Indexed: 02/06/2023]
Abstract
Gastroenteropancreatic endocrine tumors (GEP-NETs) are relatively uncommon; comprising approximately 0.5% of all human cancers. Although they often exhibit relatively indolent clinical courses, GEP-NETs have the potential for lethal progression. Due to their scarcity and various technical challenges, GEP-NETs have been understudied. As a consequence, we have few diagnostic, prognostic and predictive biomarkers for these tumors. Early detection and surgical removal is currently the only reliable curative treatment for GEP-NET patients; many of whom, unfortunately, present with advanced disease. Here, we review the genetics and epigenetics of GEP-NETs. The last few years have witnessed unprecedented technological advances in these fields, and their application to GEP-NETS has already led to important new information on the molecular abnormalities underlying them. As outlined here, we expect that "omics" studies will provide us with new diagnostic and prognostic biomarkers, inform the development of improved pre-clinical models, and identify novel therapeutic targets for GEP-NET patients.
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Affiliation(s)
- Alan Meeker
- The Johns Hopkins University School of Medicine, Department of Pathology, Bond Street Research Annex Bldg., Room B300, 411 North Caroline Street, Baltimore, MD 21231, United States.
| | - Christopher Heaphy
- The Johns Hopkins University School of Medicine, Department of Pathology, Bond Street Research Annex Bldg., Room B300, 411 North Caroline Street, Baltimore, MD 21231, United States
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Clynes D, Jelinska C, Xella B, Ayyub H, Taylor S, Mitson M, Bachrati CZ, Higgs DR, Gibbons RJ. ATRX dysfunction induces replication defects in primary mouse cells. PLoS One 2014; 9:e92915. [PMID: 24651726 PMCID: PMC3961441 DOI: 10.1371/journal.pone.0092915] [Citation(s) in RCA: 72] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2014] [Accepted: 02/27/2014] [Indexed: 01/09/2023] Open
Abstract
The chromatin remodeling protein ATRX, which targets tandem repetitive DNA, has been shown to be required for expression of the alpha globin genes, for proliferation of a variety of cellular progenitors, for chromosome congression and for the maintenance of telomeres. Mutations in ATRX have recently been identified in tumours which maintain their telomeres by a telomerase independent pathway involving homologous recombination thought to be triggered by DNA damage. It is as yet unknown whether there is a central underlying mechanism associated with ATRX dysfunction which can explain the numerous cellular phenomena observed. There is, however, growing evidence for its role in the replication of various repetitive DNA templates which are thought to have a propensity to form secondary structures. Using a mouse knockout model we demonstrate that ATRX plays a direct role in facilitating DNA replication. Ablation of ATRX alone, although leading to a DNA damage response at telomeres, is not sufficient to trigger the alternative lengthening of telomere pathway in mouse embryonic stem cells.
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Affiliation(s)
- David Clynes
- MRC Molecular Haematology Unit, Weatherall Institute of Molecular Medicine, University of Oxford, John Radcliffe Hospital, Oxford, United Kingdom
| | - Clare Jelinska
- MRC Molecular Haematology Unit, Weatherall Institute of Molecular Medicine, University of Oxford, John Radcliffe Hospital, Oxford, United Kingdom
| | - Barbara Xella
- MRC Molecular Haematology Unit, Weatherall Institute of Molecular Medicine, University of Oxford, John Radcliffe Hospital, Oxford, United Kingdom
| | - Helena Ayyub
- MRC Molecular Haematology Unit, Weatherall Institute of Molecular Medicine, University of Oxford, John Radcliffe Hospital, Oxford, United Kingdom
| | - Stephen Taylor
- Computational Biology Research Group, Weatherall Institute of Molecular Medicine, University of Oxford, John Radcliffe Hospital, Oxford, United Kingdom
| | - Matthew Mitson
- MRC Molecular Haematology Unit, Weatherall Institute of Molecular Medicine, University of Oxford, John Radcliffe Hospital, Oxford, United Kingdom
| | - Csanád Z Bachrati
- School of Life Sciences, University of Lincoln, Brayford Pool, Lincoln, United Kingdom
| | - Douglas R Higgs
- MRC Molecular Haematology Unit, Weatherall Institute of Molecular Medicine, University of Oxford, John Radcliffe Hospital, Oxford, United Kingdom
| | - Richard J Gibbons
- MRC Molecular Haematology Unit, Weatherall Institute of Molecular Medicine, University of Oxford, John Radcliffe Hospital, Oxford, United Kingdom
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Marinoni I, Kurrer AS, Vassella E, Dettmer M, Rudolph T, Banz V, Hunger F, Pasquinelli S, Speel EJ, Perren A. Loss of DAXX and ATRX are associated with chromosome instability and reduced survival of patients with pancreatic neuroendocrine tumors. Gastroenterology 2014; 146:453-60.e5. [PMID: 24148618 DOI: 10.1053/j.gastro.2013.10.020] [Citation(s) in RCA: 291] [Impact Index Per Article: 29.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/13/2013] [Revised: 09/09/2013] [Accepted: 10/16/2013] [Indexed: 02/07/2023]
Abstract
BACKGROUND & AIMS Sporadic pancreatic neuroendocrine tumors (pNETs) are rare and genetically heterogeneous. Chromosome instability (CIN) has been detected in pNETs from patients with poor outcomes, but no specific genetic factors have been associated with CIN. Mutations in death domain-associated protein gene (DAXX) or ATR-X gene (ATRX) (which both encode proteins involved in chromatin remodeling) have been detected in 40% of pNETs, in association with activation of alternative lengthening of telomeres. We investigated whether loss of DAXX or ATRX, and consequent alternative lengthening of telomeres, are related to CIN in pNETs. We also assessed whether loss of DAXX or ATRX is associated with specific phenotypes of pNETs. METHODS We collected well-differentiated primary pNET samples from 142 patients at the University Hospital Zurich and from 101 patients at the University Hospital Bern (both located in Switzerland). Clinical follow-up data were obtained for 149 patients from general practitioners and tumor registries. The tumors were reclassified into 3 groups according to the 2010 World Health Organization classification. Samples were analyzed by immunohistochemistry and telomeric fluorescence in situ hybridization. We correlated loss of DAXX, or ATRX, expression, and activation of alternative lengthening of telomeres with data from comparative genomic hybridization array studies, as well as with clinical and pathological features of the tumors and relapse and survival data. RESULTS Loss of DAXX or ATRX protein and alternative lengthening of telomeres were associated with CIN in pNETs. Furthermore, loss of DAXX or ATRX correlated with tumor stage and metastasis, reduced time of relapse-free survival, and decreased time of tumor-associated survival. CONCLUSIONS Loss of DAXX or ATRX is associated with CIN in pNETs and shorter survival times of patients. These results support the hypothesis that DAXX- and ATRX-negative tumors are a more aggressive subtype of pNET, and could lead to identification of strategies to target CIN in pancreatic tumors.
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Affiliation(s)
- Ilaria Marinoni
- Institute of Pathology, University of Bern, Bern, Switzerland
| | | | - Erik Vassella
- Institute of Pathology, University of Bern, Bern, Switzerland
| | | | - Thomas Rudolph
- Institute of Pathology, University of Bern, Bern, Switzerland
| | - Vanessa Banz
- Department of Visceral Surgery and Medicine, Inselspital, University Hospital Bern, Bern, Switzerland
| | - Fabio Hunger
- Institute of Pathology, University of Bern, Bern, Switzerland
| | | | - Ernst-Jan Speel
- Department of Molecular Cell Biology, Institute of Pathology University Medical Center, Maastricht, Holland
| | - Aurel Perren
- Institute of Pathology, University of Bern, Bern, Switzerland.
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45
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Loss of ATRX does not confer susceptibility to osteoarthritis. PLoS One 2013; 8:e85526. [PMID: 24386478 PMCID: PMC3875582 DOI: 10.1371/journal.pone.0085526] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2013] [Accepted: 11/27/2013] [Indexed: 11/19/2022] Open
Abstract
The chromatin remodelling protein ATRX is associated with the rare genetic disorder ATR-X syndrome. This syndrome includes developmental delay, cognitive impairment, and a variety of skeletal deformities. ATRX plays a role in several basic chromatin-mediated cellular events including DNA replication, telomere stability, gene transcription, and chromosome congression and cohesion during cell division. We have used a loss-of-function approach to directly investigate the role of Atrx in the adult skeleton in three different models of selective Atrx loss. We specifically targeted deletion of Atrx to the forelimb mesenchyme, to cartilage and to bone-forming osteoblasts. We previously demonstrated that loss of ATRX in forelimb mesenchyme causes brachydactyly while deletion in chondrocytes had minimal effects during development. We now show that targeted deletion of Atrx in osteoblasts causes minor dwarfism but does not recapitulate most of the skeletal phenotypes seen in ATR-X syndrome patients. In adult mice from all three models, we find that joints lacking Atrx are not more susceptible to osteoarthritis, as determined by OARSI scoring and immunohistochemistry. These results indicate that while ATRX plays limited roles during early stages of skeletal development, deficiency of the protein in adult tissues does not confer susceptibility to osteoarthritis.
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46
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Fontebasso AM, Liu XY, Sturm D, Jabado N. Chromatin remodeling defects in pediatric and young adult glioblastoma: a tale of a variant histone 3 tail. Brain Pathol 2013; 23:210-6. [PMID: 23432647 DOI: 10.1111/bpa.12023] [Citation(s) in RCA: 64] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2012] [Accepted: 12/29/2012] [Indexed: 12/26/2022] Open
Abstract
Primary brain tumors occur in 8 out of 100 000 people and are the leading cause of cancer-related death in children. Among brain tumors, high-grade astrocytomas (HGAs) including glioblastoma multiforme (GBM) are aggressive and are lethal human cancers. Despite decades of concerted therapeutic efforts, HGAs remain essentially incurable in adults and children. Recent discoveries have revolutionized our understanding of these tumors in children and young adults. Recurrent somatic driver mutations in the tail of histone 3 variant 3 (H3.3), leading to amino acid substitutions at key residues, namely lysine (K) 27 (K27M) and glycine 34 (G34R/G34V), were identified as a new molecular mechanism in pediatric GBM. These mutations represent the pediatric counterpart of the recurrent mutations in isocitrate dehydrogenases (IDH) identified in young adult gliomas and provide a much-needed new pathway that can be targeted for therapeutic development. This review will provide an overview of the potential role of these mutations in altering chromatin structure and affecting specific molecular pathways ultimately leading to gliomagenesis. The distinct changes in chromatin structure and the specific downstream events induced by each mutation need characterizing independently if progress is to be made in tackling this devastating cancer.
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Affiliation(s)
- Adam M Fontebasso
- Division of Experimental Medicine, McGill University and McGill University Health Centre, Montreal, QC, Canada
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Clynes D, Higgs DR, Gibbons RJ. The chromatin remodeller ATRX: a repeat offender in human disease. Trends Biochem Sci 2013; 38:461-6. [PMID: 23916100 DOI: 10.1016/j.tibs.2013.06.011] [Citation(s) in RCA: 90] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2013] [Revised: 06/19/2013] [Accepted: 06/25/2013] [Indexed: 01/21/2023]
Abstract
The regulation of chromatin structure is of paramount importance for a variety of fundamental nuclear processes, including gene expression, DNA repair, replication, and recombination. The ATP-dependent chromatin-remodelling factor ATRX (α thalassaemia/mental retardation X-linked) has emerged as a key player in each of these processes. Exciting recent developments suggest that ATRX plays a variety of key roles at tandem repeat sequences within the genome, including the deposition of a histone variant, prevention of replication fork stalling, and the suppression of a homologous recombination-based pathway of telomere maintenance. Here, we provide a mechanistic overview of the role of ATRX in each of these processes, and propose how they may be connected to give rise to seemingly disparate human diseases.
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Affiliation(s)
- David Clynes
- MRC Molecular Haematology Unit, Weatherall Institute of Molecular Medicine, University of Oxford, John Radcliffe Hospital, Oxford OX3 9DS, UK
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Solomon LA, Russell BA, Watson LA, Beier F, Bérubé NG. Targeted loss of the ATR-X syndrome protein in the limb mesenchyme of mice causes brachydactyly. Hum Mol Genet 2013; 22:5015-25. [PMID: 23892236 DOI: 10.1093/hmg/ddt351] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
ATR-X syndrome is a rare genetic disorder caused by mutations in the ATRX gene. Affected individuals are cognitively impaired and display a variety of developmental abnormalities, including skeletal deformities. To investigate the function of ATRX during skeletal development, we selectively deleted the gene in the developing forelimb mesenchyme of mice. The absence of ATRX in the limb mesenchyme resulted in shorter digits, or brachydactyly, a defect also observed in a subset of ATR-X patients. This phenotype persisted until adulthood, causing reduced grip strength and altered gait in mutant mice. Examination of the embryonic ATRX-null forelimbs revealed a significant increase in apoptotic cell death, which could explain the reduced digit length. In addition, staining for the DNA damage markers γ-histone 2A family member X (γ-H2AX) and 53BP1 demonstrated a significant increase in the number of cells with DNA damage in the embryonic ATRX-null forepaw. Strikingly, only one large bright DNA damage event was observed per nucleus in proliferating cells. These large γ-H2AX foci were located in close proximity to the nuclear lamina and remained largely unresolved after cell differentiation. In addition, ATRX-depleted forelimb mesenchymal cells did not exhibit hypersensitivity to DNA fork-stalling compounds, suggesting that the nature as well as the response to DNA damage incurred by loss of ATRX in the developing limb fundamentally differs from other tissues. Our data suggest that DNA damage-induced apoptosis is a novel cellular mechanism underlying brachydactyly that might be relevant to additional skeletal syndromes.
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Leung JWC, Ghosal G, Wang W, Shen X, Wang J, Li L, Chen J. Alpha thalassemia/mental retardation syndrome X-linked gene product ATRX is required for proper replication restart and cellular resistance to replication stress. J Biol Chem 2013; 288:6342-50. [PMID: 23329831 PMCID: PMC3585069 DOI: 10.1074/jbc.m112.411603] [Citation(s) in RCA: 71] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2012] [Revised: 01/16/2013] [Indexed: 02/05/2023] Open
Abstract
Alpha thalassemia/mental retardation syndrome X-linked (ATRX) is a member of the SWI/SNF protein family of DNA-dependent ATPases. It functions as a chromatin remodeler and is classified as an SNF2-like helicase. Here, we showed somatic knock-out of ATRX displayed perturbed S-phase progression as well as hypersensitivity to replication stress. ATRX is recruited to sites of DNA damage, required for efficient checkpoint activation and faithful replication restart. In addition, we identified ATRX as a binding partner of MRE11-RAD50-NBS1 (MRN) complex. Together, these results suggest a non-canonical function of ATRX in guarding genomic stability.
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Affiliation(s)
- Justin Wai-Chung Leung
- From the Department of Experimental Radiation Oncology, The University of Texas M.D. Anderson Cancer Center, Houston, Texas 77030
| | - Gargi Ghosal
- From the Department of Experimental Radiation Oncology, The University of Texas M.D. Anderson Cancer Center, Houston, Texas 77030
| | - Wenqi Wang
- From the Department of Experimental Radiation Oncology, The University of Texas M.D. Anderson Cancer Center, Houston, Texas 77030
| | - Xi Shen
- From the Department of Experimental Radiation Oncology, The University of Texas M.D. Anderson Cancer Center, Houston, Texas 77030
| | - Jiadong Wang
- From the Department of Experimental Radiation Oncology, The University of Texas M.D. Anderson Cancer Center, Houston, Texas 77030
| | - Lei Li
- From the Department of Experimental Radiation Oncology, The University of Texas M.D. Anderson Cancer Center, Houston, Texas 77030
| | - Junjie Chen
- From the Department of Experimental Radiation Oncology, The University of Texas M.D. Anderson Cancer Center, Houston, Texas 77030
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50
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ATRX and the replication of structured DNA. Curr Opin Genet Dev 2013; 23:289-94. [PMID: 23453691 DOI: 10.1016/j.gde.2013.01.005] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2012] [Accepted: 01/17/2013] [Indexed: 11/24/2022]
Abstract
Understanding the underlying molecular basis for disease can often be a prolonged and tortuous process with many false leads and blind alleys. Relating the cause of ATR-X syndrome to the function of the protein ATRX is a case in point. In this review we attempt to bring together the diverse biological phenomena associated with ATRX dysfunction with what has recently been discovered concerning the chromatin remodelling activity of this protein. This potentially casts light on how defective DNA replication/histone replacement can impact on transcription, telomere maintenance and also possibly chromosome segregation.
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