101
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ATRX ADD domain links an atypical histone methylation recognition mechanism to human mental-retardation syndrome. Nat Struct Mol Biol 2011; 18:769-76. [PMID: 21666679 PMCID: PMC3130887 DOI: 10.1038/nsmb.2062] [Citation(s) in RCA: 197] [Impact Index Per Article: 15.2] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2010] [Accepted: 03/18/2011] [Indexed: 12/12/2022]
Abstract
ATR-X (alpha thalassemia/mental retardation, X-linked) syndrome is a human congenital disorder that causes severe intellectual disabilities. Mutations in the ATRX gene, which encodes an ATP-dependent chromatin-remodeler, are responsible for the syndrome. Approximately 50% of the patient missense mutations are clustered in a cysteine-rich domain termed ADD (ATRX-DNMT3-DNMT3L, AD-DATRX), indicating its importance. However, the function of ADDATRX has remained elusive. Here we identify ADDATRX as a novel histone H3 binding module, whose binding is promoted by lysine 9 trimethylation (H3K9me3) but inhibited by H3K4me3. The co-crystal structures of ADDATRX bound to H31–15K9me3 peptide reveals an atypical composite H3K9me3-binding pocket, which is distinct from the conventional trimethyllysine-binding aromatic cage. Importantly, H3K9me3-pocket mutants and ATR-X syndrome mutants are defective in both H3K9me3 binding and localization at pericentromeric heterochromatin. Thus, we have discovered a unique histone recognition mechanism underlying the ATR-X etiology.
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102
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Mitson M, Kelley LA, Sternberg MJE, Higgs DR, Gibbons RJ. Functional significance of mutations in the Snf2 domain of ATRX. Hum Mol Genet 2011; 20:2603-10. [PMID: 21505078 DOI: 10.1093/hmg/ddr163] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
ATRX is a member of the Snf2 family of chromatin-remodelling proteins and is mutated in an X-linked mental retardation syndrome associated with alpha-thalassaemia (ATR-X syndrome). We have carried out an analysis of 21 disease-causing mutations within the Snf2 domain of ATRX by quantifying the expression of the ATRX protein and placing all missense mutations in their structural context by homology modelling. While demonstrating the importance of protein dosage to the development of ATR-X syndrome, we also identified three mutations which primarily affect function rather than protein structure. We show that all three of these mutant proteins are defective in translocating along DNA while one mutant, uniquely for a human disease-causing mutation, partially uncouples adenosine triphosphate (ATP) hydrolysis from DNA binding. Our results highlight important mechanistic aspects in the development of ATR-X syndrome and identify crucial functional residues within the Snf2 domain of ATRX. These findings are important for furthering our understanding of how ATP hydrolysis is harnessed as useful work in chromatin remodelling proteins and the wider family of nucleic acid translocating motors.
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Affiliation(s)
- Matthew Mitson
- MRC Molecular Haematology Unit, Weatherall Institute of Molecular Medicine, John Radcliffe Hospital, Headington, Oxford, UK
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103
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D'Aiuto L, Di Maio R, Mohan KN, Minervini C, Saporiti F, Soreca I, Greenamyre JT, Chaillet JR. Mouse ES cells overexpressing DNMT1 produce abnormal neurons with upregulated NMDA/NR1 subunit. Differentiation 2011; 82:9-17. [PMID: 21492995 DOI: 10.1016/j.diff.2011.03.003] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2010] [Revised: 03/23/2011] [Accepted: 03/24/2011] [Indexed: 10/18/2022]
Abstract
High levels of DNA methyltransferase 1 (DNMT1), hypermethylation, and downregulation of GAD(67) and reelin have been described in GABAergic interneurons of patients with schizophrenia (SZ) and bipolar (BP) disorders. However, overexpression of DNMT1 is lethal, making it difficult to assess the direct effect of high levels of DNMT1 on neuronal development in vivo. We therefore used Dnmt1(tet/tet) mouse ES cells that overexpress DNMT1 as an in vitro model to investigate the impact of high levels of DNMT1 on neuronal differentiation. Although there is down-regulation of DNMT1 during early stages of differentiation in wild type and Dnmt1(tet/tet) ES cell lines, neurons derived from Dnmt1(tet/tet) cells showed abnormal dendritic arborization and branching. The Dnmt1(tet/tet) neuronal cells also showed elevated levels of functional N-methyl d-aspartate receptor (NMDAR), a feature also reported in some neurological and neurodegenerative disorders. Considering the roles of reelin and GAD(67) in neuronal networking and excitatory/inhibitory balance, respectively, we studied methylation of these genes' promoters in Dnmt1(tet/tet) ES cells and neurons. Both reelin and GAD(67) promoters were not hypermethylated in the Dnmt1(tet/tet) ES cells and neurons, suggesting that overexpression of DNMT1 may not directly result in methylation-mediated repression of these two genes. Taken together, our results suggest that overexpression of DNMT1 in ES cells results in an epigenetic change prior to the onset of differentiation. This epigenetic change in turn results in abnormal neuronal differentiation and upregulation of functional NMDA receptor.
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Affiliation(s)
- Leonardo D'Aiuto
- Department of Microbiology and Molecular Genetics, Magee-Womens Research Institute, University of Pittsburgh, 204 Craft Avenue, Pittsburgh, PA 15213, USA.
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104
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Bagheri-Fam S, Argentaro A, Svingen T, Combes AN, Sinclair AH, Koopman P, Harley VR. Defective survival of proliferating Sertoli cells and androgen receptor function in a mouse model of the ATR-X syndrome. Hum Mol Genet 2011; 20:2213-24. [PMID: 21427128 DOI: 10.1093/hmg/ddr109] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
X-linked ATR-X (alpha thalassemia, mental retardation, X-linked) syndrome in males is characterized by mental retardation, facial dysmorphism, alpha thalassemia and urogenital abnormalities, including small testes. It is unclear how mutations in the chromatin-remodeling protein ATRX cause these highly specific clinical features, since ATRX is widely expressed during organ development. To investigate the mechanisms underlying the testicular defects observed in ATR-X syndrome, we generated ScAtrxKO (Sertoli cell Atrx knockout) mice with Atrx specifically inactivated in the supporting cell lineage (Sertoli cells) of the mouse testis. ScAtrxKO mice developed small testes and discontinuous tubules, due to prolonged G2/M phase and apoptosis of proliferating Sertoli cells during fetal life. Apoptosis might be a consequence of the cell cycle defect. We also found that the onset of spermatogenesis was delayed in postnatal mice, with a range of spermatogenesis defects evident in adult ScAtrxKO mice. ATRX and the androgen receptor (AR) physically interact in the testis and in the Sertoli cell line TM4 and co-operatively activate the promoter of Rhox5, an important direct AR target. We also demonstrate that ATRX directly binds to the Rhox5 promoter in TM4 cells. Finally, gene expression of Rhox5 and of another AR-dependent gene, Spinlw1, was reduced in ScAtrxKO testes. These data suggest that ATRX can directly enhance the expression of androgen-dependent genes through physical interaction with AR. Recruitment of ATRX by DNA sequence-specific transcription factors could be a general mechanism by which ATRX achieves tissue-specific transcriptional regulation which could explain the highly specific clinical features of ATR-X syndrome when ATRX is mutated.
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Affiliation(s)
- Stefan Bagheri-Fam
- Molecular Genetics and Development Division, Prince Henry’s Institute of Medical Research, Clayton, VIC 3168, Australia
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105
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Dhayalan A, Tamas R, Bock I, Tattermusch A, Dimitrova E, Kudithipudi S, Ragozin S, Jeltsch A. The ATRX-ADD domain binds to H3 tail peptides and reads the combined methylation state of K4 and K9. Hum Mol Genet 2011; 20:2195-203. [PMID: 21421568 DOI: 10.1093/hmg/ddr107] [Citation(s) in RCA: 117] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
Mutations in the ATRX protein are associated with the alpha-thalassemia and mental retardation X-linked syndrome (ATR-X). Almost half of the disease-causing mutations occur in its ATRX-Dnmt3-Dnmt3L (ADD) domain. By employing peptide arrays, chromatin pull-down and peptide binding assays, we show specific binding of the ADD domain to H3 histone tail peptides containing H3K9me3. Peptide binding was disrupted by the presence of the H3K4me3 and H3K4me2 modification marks indicating that the ATRX-ADD domain has a combined readout of these two important marks (absence of H3K4me2 and H3K4me3 and presence of H3K9me3). Disease-causing mutations reduced ATRX-ADD binding to H3 tail peptides. ATRX variants, which fail in the H3K9me3 interaction, show a loss of heterochromatic localization in cells, which indicates the chromatin targeting function of the ADD domain of ATRX. Disruption of H3K9me3 binding may be a general pathogenicity pathway of ATRX mutations in the ADD domain which may explain the clustering of disease mutations in this part of the ATRX protein.
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Affiliation(s)
- Arunkumar Dhayalan
- Biochemistry Laboratory, Jacobs University Bremen, Campus Ring 1, 28759 Bremen, Germany
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106
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Aberrant calcium/calmodulin-dependent protein kinase II (CaMKII) activity is associated with abnormal dendritic spine morphology in the ATRX mutant mouse brain. J Neurosci 2011; 31:346-58. [PMID: 21209221 DOI: 10.1523/jneurosci.4816-10.2011] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
In humans, mutations in the gene encoding ATRX, a chromatin remodeling protein of the sucrose-nonfermenting 2 family, cause several mental retardation disorders, including α-thalassemia X-linked mental retardation syndrome. We generated ATRX mutant mice lacking exon 2 (ATRX(ΔE2) mice), a mutation that mimics exon 2 mutations seen in human patients and associated with milder forms of retardation. ATRX(ΔE2) mice exhibited abnormal dendritic spine formation in the medial prefrontal cortex (mPFC). Consistent with other mouse models of mental retardation, ATRX(ΔE2) mice exhibited longer and thinner dendritic spines compared with wild-type mice without changes in spine number. Interestingly, aberrant increased calcium/calmodulin-dependent protein kinase II (CaMKII) activity was observed in the mPFC of ATRX(ΔE2) mice. Increased CaMKII autophosphorylation and activity were associated with increased phosphorylation of the Rac1-guanine nucleotide exchange factors (GEFs) T-cell lymphoma invasion and metastasis 1 (Tiam1) and kalirin-7, known substrates of CaMKII. We confirmed increased phosphorylation of p21-activated kinases (PAKs) in mPFC extracts. Furthermore, reduced protein expression and activity of protein phosphatase 1 (PP1) was evident in the mPFC of ATRX(ΔE2) mice. In cultured cortical neurons, PP1 inhibition by okadaic acid increased CaMKII-dependent Tiam1 and kalirin-7 phosphorylation. Together, our data strongly suggest that aberrant CaMKII activation likely mediates abnormal spine formation in the mPFC. Such morphological changes plus elevated Rac1-GEF/PAK signaling seen in ATRX(ΔE2) mice may contribute to mental retardation syndromes seen in human patients.
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107
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Jiao Y, Shi C, Edil BH, de Wilde RF, Klimstra DS, Maitra A, Schulick RD, Tang LH, Wolfgang CL, Choti MA, Velculescu VE, Diaz LA, Vogelstein B, Kinzler KW, Hruban RH, Papadopoulos N. DAXX/ATRX, MEN1, and mTOR pathway genes are frequently altered in pancreatic neuroendocrine tumors. Science 2011; 331:1199-203. [PMID: 21252315 DOI: 10.1126/science.1200609] [Citation(s) in RCA: 1245] [Impact Index Per Article: 95.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Pancreatic neuroendocrine tumors (PanNETs) are a rare but clinically important form of pancreatic neoplasia. To explore the genetic basis of PanNETs, we determined the exomic sequences of 10 nonfamilial PanNETs and then screened the most commonly mutated genes in 58 additional PanNETs. The most frequently mutated genes specify proteins implicated in chromatin remodeling: 44% of the tumors had somatic inactivating mutations in MEN1, which encodes menin, a component of a histone methyltransferase complex, and 43% had mutations in genes encoding either of the two subunits of a transcription/chromatin remodeling complex consisting of DAXX (death-domain-associated protein) and ATRX (α thalassemia/mental retardation syndrome X-linked). Clinically, mutations in the MEN1 and DAXX/ATRX genes were associated with better prognosis. We also found mutations in genes in the mTOR (mammalian target of rapamycin) pathway in 14% of the tumors, a finding that could potentially be used to stratify patients for treatment with mTOR inhibitors.
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Affiliation(s)
- Yuchen Jiao
- Ludwig Center for Cancer Genetics and Howard Hughes Medical Institutions, Johns Hopkins Kimmel Cancer Center, Baltimore, MD 21231, USA
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108
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Yun KW, Chae SA, Lee JJ, Yun SW, Yoo BH, Lim IS, Choi ES, Lee MK. The first case of X-linked Alpha-thalassemia/mental retardation (ATR-X) syndrome in Korea. J Korean Med Sci 2011; 26:146-9. [PMID: 21218045 PMCID: PMC3012841 DOI: 10.3346/jkms.2011.26.1.146] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/09/2010] [Accepted: 04/30/2010] [Indexed: 11/20/2022] Open
Abstract
Mutation of the ATRX gene leads to X-linked alpha-thalassemia/mental retardation (ATR-X) syndrome and several other X-linked mental retardation syndromes. We report the first case of ATR-X syndrome documented here in Korea. A 32-month-old boy came in with irritability and fever. He showed dysmorphic features, mental retardation and epilepsy, so ATR-X syndrome was considered. Hemoglobin H inclusions in red blood cells supported the diagnosis and genetic studies confirmed it. Mutation analysis for our patient showed a point mutation of thymine to cytosine on the 9th exon in the ATRX gene, indicating that Trp(C), the 220th amino acid, was replaced by Ser(R). Furthermore, we investigated the same mutation in family members, and his mother and two sisters were found to be carriers.
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Affiliation(s)
- Ki Wook Yun
- Department of Pediatrics, Chung-Ang University College of Medicine, Seoul, Korea
| | - Soo Ahn Chae
- Department of Pediatrics, Chung-Ang University College of Medicine, Seoul, Korea
| | - Jung Ju Lee
- Department of Pediatrics, Chung-Ang University College of Medicine, Seoul, Korea
| | - Sin Weon Yun
- Department of Pediatrics, Chung-Ang University College of Medicine, Seoul, Korea
| | - Byoung Hoon Yoo
- Department of Pediatrics, Chung-Ang University College of Medicine, Seoul, Korea
| | - In Seok Lim
- Department of Pediatrics, Chung-Ang University College of Medicine, Seoul, Korea
| | - Eung Sang Choi
- Department of Pediatrics, Chung-Ang University College of Medicine, Seoul, Korea
| | - Mi-Kyung Lee
- Department of Laboratory Medicine, Chung-Ang University College of Medicine, Seoul, Korea
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109
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ATR-X syndrome protein targets tandem repeats and influences allele-specific expression in a size-dependent manner. Cell 2010; 143:367-78. [PMID: 21029860 DOI: 10.1016/j.cell.2010.09.023] [Citation(s) in RCA: 309] [Impact Index Per Article: 22.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2010] [Revised: 08/03/2010] [Accepted: 09/13/2010] [Indexed: 11/22/2022]
Abstract
ATRX is an X-linked gene of the SWI/SNF family, mutations in which cause syndromal mental retardation and downregulation of α-globin expression. Here we show that ATRX binds to tandem repeat (TR) sequences in both telomeres and euchromatin. Genes associated with these TRs can be dysregulated when ATRX is mutated, and the change in expression is determined by the size of the TR, producing skewed allelic expression. This reveals the characteristics of the affected genes, explains the variable phenotypes seen with identical ATRX mutations, and illustrates a new mechanism underlying variable penetrance. Many of the TRs are G rich and predicted to form non-B DNA structures (including G-quadruplex) in vivo. We show that ATRX binds G-quadruplex structures in vitro, suggesting a mechanism by which ATRX may play a role in various nuclear processes and how this is perturbed when ATRX is mutated.
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110
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Chao MM, Todd MA, Kontny U, Neas K, Sullivan MJ, Hunter AG, Picketts DJ, Kratz CP. T-cell acute lymphoblastic leukemia in association with Börjeson-Forssman-Lehmann syndrome due to a mutation in PHF6. Pediatr Blood Cancer 2010; 55:722-4. [PMID: 20806366 PMCID: PMC2933084 DOI: 10.1002/pbc.22574] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Börjeson-Forssman-Lehmann syndrome (BFLS) is a rare X-linked mental retardation syndrome that is caused by germline mutations in PHF6. We describe a 9-year-old male with BFLS, who developed T-cell acute lymphoblastic leukemia (T-ALL). The PHF6 gene is located on the X chromosome and encodes a protein with two PHD-type zinc finger domains and four nuclear localization sequences. Previously, overexpression of Phf6 was observed in murine T-cell lymphomas. Our observation indicates that BFLS may represent a cancer predisposition syndrome and that mutations of PHF6 contribute to T-ALL.
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Affiliation(s)
- Mwe Mwe Chao
- Division of Pediatric Hematology-Oncology, Children’s National Medical Center, Washington, DC, USA
| | - Matthew A. Todd
- Ottawa Health Research Institute, University of Ottawa, Ottawa, Ontario, Canada
| | - Udo Kontny
- Division of Pediatric Hematology/Oncology, Department of Pediatrics and Adolescent Medicine, University of Freiburg, Freiburg, Germany
| | - Katherine Neas
- Central and Southern Regional Genetics Service, Capital and Coast District Health Board, Wellington, New Zealand
| | - Michael J. Sullivan
- Department of Paediatrics, Children's Cancer Research Group, Children's Haematology Oncology Centre, Christchurch School of Medicine, University of Otago, Christchurch, New Zealand
| | - Alasdair G. Hunter
- Department of Genetics, Children's Hospital of Eastern Ontario, Ottawa, Ontario, Canada
| | - David J. Picketts
- Ottawa Health Research Institute, University of Ottawa, Ottawa, Ontario, Canada
| | - Christian P. Kratz
- Clinical Genetics Branch, Division of Cancer Epidemiology and Genetics, National Cancer Institute, National Institutes of Health, Rockville, MD, USA
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111
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Higgs DR, Gibbons RJ. The molecular basis of α-thalassemia: a model for understanding human molecular genetics. Hematol Oncol Clin North Am 2010; 24:1033-54. [PMID: 21075279 DOI: 10.1016/j.hoc.2010.08.005] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Down-regulation of α-globin synthesis causes α-thalassemia with underproduction of fetal (HbF, α(2)γ(2)) and adult (HbA, α(2)β(2)) hemoglobin. This article focuses on the human α-globin cluster, which has been characterized in great depth over the past 30 years. In particular the authors describe how the α genes are normally switched on during erythropoiesis and switched off as hematopoietic stem cells commit to nonerythroid lineages. In addition, the principles by which α-globin expression may be perturbed by natural mutations that cause α-thalassemia are reviewed.
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Affiliation(s)
- Douglas R Higgs
- John Radcliffe Hospital, MRC Molecular Haematology Unit, Weatherall Institute of Molecular Medicine, University of Oxford, Headington, Oxford, UK.
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112
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Pavone P, Taibi R, Lionetti E, Incorpora G, Fisher CA. First case of dizygous twins with X-linked alpha-thalassemia/mental retardation syndrome showing wide clinical variability. Pediatr Int 2010; 52:e72-5. [PMID: 20500465 DOI: 10.1111/j.1442-200x.2010.03048.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Piero Pavone
- Department of Pediatrics, University of Catania, Viale Andrea Doria 6, 95125 Catania, Italy.
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113
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Distinct factors control histone variant H3.3 localization at specific genomic regions. Cell 2010; 140:678-91. [PMID: 20211137 DOI: 10.1016/j.cell.2010.01.003] [Citation(s) in RCA: 972] [Impact Index Per Article: 69.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2009] [Revised: 11/23/2009] [Accepted: 12/31/2009] [Indexed: 12/17/2022]
Abstract
The incorporation of histone H3 variants has been implicated in the epigenetic memory of cellular state. Using genome editing with zinc-finger nucleases to tag endogenous H3.3, we report genome-wide profiles of H3 variants in mammalian embryonic stem cells and neuronal precursor cells. Genome-wide patterns of H3.3 are dependent on amino acid sequence and change with cellular differentiation at developmentally regulated loci. The H3.3 chaperone Hira is required for H3.3 enrichment at active and repressed genes. Strikingly, Hira is not essential for localization of H3.3 at telomeres and many transcription factor binding sites. Immunoaffinity purification and mass spectrometry reveal that the proteins Atrx and Daxx associate with H3.3 in a Hira-independent manner. Atrx is required for Hira-independent localization of H3.3 at telomeres and for the repression of telomeric RNA. Our data demonstrate that multiple and distinct factors are responsible for H3.3 localization at specific genomic locations in mammalian cells.
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114
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Nogami T, Beppu H, Tokoro T, Moriguchi S, Shioda N, Fukunaga K, Ohtsuka T, Ishii Y, Sasahara M, Shimada Y, Nishijo H, Li E, Kitajima I. Reduced expression of the ATRX gene, a chromatin-remodeling factor, causes hippocampal dysfunction in mice. Hippocampus 2010; 21:678-87. [PMID: 20865721 DOI: 10.1002/hipo.20782] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/04/2010] [Indexed: 11/09/2022]
Abstract
Mutations of the ATRX gene, which encodes an ATP-dependent chromatin-remodeling factor, were identified in patients with α-thalassemia X-linked mental retardation (ATR-X) syndrome. There is a milder variant of ATR-X syndrome caused by mutations in the Exon 2 of the gene. To examine the impact of the Exon 2 mutation on neuronal development, we generated ATRX mutant (ATRX(ΔE2)) mice. Truncated ATRX protein was produced from the ATRX(ΔE2) mutant allele with reduced expression level. The ATRX(ΔE2) mice survived and reproduced normally. There was no significant difference in Morris water maze test between wild-type and ATRX(ΔE2) mice. In a contextual fear conditioning test, however, total freezing time was decreased in ATRX(ΔE2) mice compared to wild-type mice, suggesting that ATRX(ΔE2) mice have impaired contextual fear memory. ATRX(ΔE2) mice showed significantly reduced long-term potentiation in the hippocampal CA1 region evoked by high-frequency stimulation. Moreover, autophosphorylation of calcium-calmodulin-dependent kinase II (αCaMKII) and phosphorylation of glutamate receptor, ionotropic, AMPA 1 (GluR1) were decreased in the hippocampi of the ATRX(ΔE2) mice compared to wild-type mice. These findings suggest that ATRX(ΔE2) mice may have fear-associated learning impairment with the dysfunction of αCaMKII and GluR1. The ATRX(ΔE2) mice would be useful tools to investigate the role of the chromatin-remodeling factor in the pathogenesis of abnormal behaviors and learning impairment.
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Affiliation(s)
- Tatsuya Nogami
- Department of Clinical Laboratory and Molecular Pathology, University of Toyama, Japan
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115
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Kernohan KD, Jiang Y, Tremblay DC, Bonvissuto AC, Eubanks JH, Mann MRW, Bérubé NG. ATRX partners with cohesin and MeCP2 and contributes to developmental silencing of imprinted genes in the brain. Dev Cell 2010; 18:191-202. [PMID: 20159591 DOI: 10.1016/j.devcel.2009.12.017] [Citation(s) in RCA: 128] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2009] [Revised: 10/12/2009] [Accepted: 12/17/2009] [Indexed: 11/27/2022]
Abstract
Human developmental disorders caused by chromatin dysfunction often display overlapping clinical manifestations, such as cognitive deficits, but the underlying molecular links are poorly defined. Here, we show that ATRX, MeCP2, and cohesin, chromatin regulators implicated in ATR-X, RTT, and CdLS syndromes, respectively, interact in the brain and colocalize at the H19 imprinting control region (ICR) with preferential binding on the maternal allele. Importantly, we show that ATRX loss of function alters enrichment of cohesin, CTCF, and histone modifications at the H19 ICR, without affecting DNA methylation on the paternal allele. ATRX also affects cohesin, CTCF, and MeCP2 occupancy within the Gtl2/Dlk1 imprinted domain. Finally, we show that loss of ATRX interferes with the postnatal silencing of the maternal H19 gene along with a larger network of imprinted genes. We propose that ATRX, cohesin, and MeCP2 cooperate to silence a subset of imprinted genes in the postnatal mouse brain.
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Affiliation(s)
- Kristin D Kernohan
- Department of Paediatrics, 800 Commissioners Road East, London, ON N6C 2V5, Canada
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116
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Cohn DM, Pagon RA, Hudgins L, Schwartz CE, Stevenson RE, Friez MJ. Partial ATRX gene duplication causes ATR-X syndrome. Am J Med Genet A 2009; 149A:2317-20. [PMID: 19764021 DOI: 10.1002/ajmg.a.33006] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- Dianne M Cohn
- Greenwood Genetic Center, Greenwood, South Carolina 29646, USA
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117
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Urdinguio RG, Sanchez-Mut JV, Esteller M. Epigenetic mechanisms in neurological diseases: genes, syndromes, and therapies. Lancet Neurol 2009; 8:1056-72. [PMID: 19833297 DOI: 10.1016/s1474-4422(09)70262-5] [Citation(s) in RCA: 340] [Impact Index Per Article: 22.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Epigenetic mechanisms such as DNA methylation and modifications to histone proteins regulate high-order DNA structure and gene expression. Aberrant epigenetic mechanisms are involved in the development of many diseases, including cancer. The neurological disorder most intensely studied with regard to epigenetic changes is Rett syndrome; patients with Rett syndrome have neurodevelopmental defects associated with mutations in MeCP2, which encodes the methyl CpG binding protein 2, that binds to methylated DNA. Other mental retardation disorders are also linked to the disruption of genes involved in epigenetic mechanisms; such disorders include alpha thalassaemia/mental retardation X-linked syndrome, Rubinstein-Taybi syndrome, and Coffin-Lowry syndrome. Moreover, aberrant DNA methylation and histone modification profiles of discrete DNA sequences, and those at a genome-wide level, have just begun to be described for neurodegenerative disorders such as Alzheimer's disease, Parkinson's disease, and Huntington's disease, and in other neurological disorders such as multiple sclerosis, epilepsy, and amyotrophic lateral sclerosis. In this Review, we describe epigenetic changes present in neurological diseases and discuss the therapeutic potential of epigenetic drugs, such as histone deacetylase inhibitors.
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Affiliation(s)
- Rocio G Urdinguio
- Cancer Epigenetics and Biology Program, Bellvitge Biomedical Research Institute, Catalonia, Spain
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118
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Solomon LA, Li JR, Bérubé NG, Beier F. Loss of ATRX in chondrocytes has minimal effects on skeletal development. PLoS One 2009; 4:e7106. [PMID: 19774083 PMCID: PMC2744333 DOI: 10.1371/journal.pone.0007106] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2009] [Accepted: 08/25/2009] [Indexed: 11/19/2022] Open
Abstract
Background Mutations in the human ATRX gene cause developmental defects, including skeletal deformities and dwarfism. ATRX encodes a chromatin remodeling protein, however the role of ATRX in skeletal development is currently unknown. Methodology/Principal Findings We induced Atrx deletion in mouse cartilage using the Cre-loxP system, with Cre expression driven by the collagen II (Col2a1) promoter. Growth rate, body size and weight, and long bone length did not differ in AtrxCol2cre mice compared to control littermates. Histological analyses of the growth plate did not reveal any differences between control and mutant mice. Expression patterns of Sox9, a transcription factor required for cartilage morphogenesis, and p57, a marker of cell cycle arrest and hypertrophic chondrocyte differentiation, was unaffected. However, loss of ATRX in cartilage led to a delay in the ossification of the hips in some mice. We also observed hindlimb polydactily in one out of 61 mutants. Conclusions/Significance These findings indicate that ATRX is not directly required for development or growth of cartilage in the mouse, suggesting that the short stature in ATR-X patients is caused by defects in cartilage-extrinsic mechanisms.
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Affiliation(s)
- Lauren A. Solomon
- Department of Biochemistry, University of Western Ontario, London, Ontario, Canada
- Children's Health Research Institute, Victoria Research Laboratories, London, Ontario, Canada
- Skeletal Biology Group, University of Western Ontario, London, Ontario, Canada
| | - Jennifer R. Li
- Department of Biochemistry, University of Western Ontario, London, Ontario, Canada
- Children's Health Research Institute, Victoria Research Laboratories, London, Ontario, Canada
- Skeletal Biology Group, University of Western Ontario, London, Ontario, Canada
| | - Nathalie G. Bérubé
- Department of Biochemistry, University of Western Ontario, London, Ontario, Canada
- Children's Health Research Institute, Victoria Research Laboratories, London, Ontario, Canada
- Department of Paediatrics, University of Western Ontario, London, Ontario, Canada
- * E-mail: (NB); (FB)
| | - Frank Beier
- Department of Biochemistry, University of Western Ontario, London, Ontario, Canada
- Skeletal Biology Group, University of Western Ontario, London, Ontario, Canada
- Department of Paediatrics, University of Western Ontario, London, Ontario, Canada
- Department of Physiology and Pharmacology, University of Western Ontario, London, Ontario, Canada
- * E-mail: (NB); (FB)
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Muntean AG, Hess JL. Epigenetic dysregulation in cancer. THE AMERICAN JOURNAL OF PATHOLOGY 2009; 175:1353-61. [PMID: 19717641 DOI: 10.2353/ajpath.2009.081142] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
One of the great paradoxes in cellular differentiation is how cells with identical DNA sequences differentiate into so many different cell types. The mechanisms underlying this process involve epigenetic regulation mediated by alterations in DNA methylation, histone posttranslational modifications, and nucleosome remodeling. It is becoming increasingly clear that disruption of the "epigenome" as a result of alterations in epigenetic regulators is a fundamental mechanism in cancer. This has major implications for the future of both molecular diagnostics as well as cancer chemotherapy.
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Affiliation(s)
- Andrew G Muntean
- Department of Pathology, University of Michigan Medical School, Ann Arbor MI 48109, USA
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120
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Jezela-Stanek A, Fisher C, Szarras-Czapnik M, Olczak-Kowalczyk D, Gibbons RJ, Słowikowska-Hilczer J, Krajewska-Walasek M. X-linked alpha thalassaemia/mental retardation syndrome: a case with gonadal dysgenesis, caused by a novel mutation in ATRX gene. Clin Dysmorphol 2009; 18:168-171. [PMID: 19444090 DOI: 10.1097/mcd.0b013e32832a9ea5] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Affiliation(s)
- Aleksandra Jezela-Stanek
- Departments of Medical Genetics Endocrinology Oral Pathology, The Children's Memorial Health Institute, Warsaw Department of Andrology and Reproductive Endocrinology, Institute of Endocrinology, Medical University of Lodz, Lodz, Poland MRC Molecular Haematology Unit, Weatherall Institute of Molecular Medicine, John Radcliffe Hospital, Oxford, UK
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121
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Mangelsdorf M, Chevrier E, Mustonen A, Picketts DJ. Börjeson-Forssman-Lehmann Syndrome due to a novel plant homeodomain zinc finger mutation in the PHF6 gene. J Child Neurol 2009; 24:610-4. [PMID: 19264739 DOI: 10.1177/0883073808327830] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
The Börjeson-Forssman-Lehmann syndrome is an X-linked mental retardation disorder caused by mutations in the PHF6 gene. The PHF6 gene contains 2 plant homeodomain zinc fingers, suggesting a role for the protein in chromatin remodeling. In this study, the authors report on a Finnish family with a classical Börjeson-Forssman-Lehmann syndrome phenotype caused by a G to T nucleotide substitution at position 266 within exon 4 within the PHF6 gene (c.266G>T). The resulting glycine to valine (p.G89V) change corresponds to a highly conserved residue within the first plant homeodomain zinc finger domain. This is a novel change that adds to the number of plant homeodomain zinc finger mutations identified, such that 23% of all Börjeson-Forssman-Lehmann syndrome mutations lie within this motif. Moreover, it highlights the functional importance of plant homeodomain zinc finger motifs to human disease and more specifically to PHF6 function.
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Affiliation(s)
- Marie Mangelsdorf
- Regenerative Medicine Program, Ottawa Health Research Institute, Ontario, Canada
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122
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Bitoun E, Davies KE. The robotic mouse: understanding the role of AF4, a cofactor of transcriptional elongation and chromatin remodelling, in purkinje cell function. THE CEREBELLUM 2009; 8:175-83. [PMID: 19340490 DOI: 10.1007/s12311-009-0101-0] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/26/2008] [Accepted: 03/11/2009] [Indexed: 10/20/2022]
Abstract
Neurological disorders represent a large share of the disease burden worldwide, and the incidence of age-related forms will continue to rise with life expectancy. Gene targeting has been and will remain a valuable approach to the generation of clinically relevant mouse models from which to elucidate the underlying molecular basis. However, as the aetiology of the majority of these conditions is still unknown, a reverse approach based on large-scale random chemical mutagenesis is now being used in an attempt to identify new genes and associated signalling pathways that control neuronal cell death and survival. Here, we review the characterisation of a novel model of autosomal dominant cerebellar ataxia which shows general growth retardation and develops adult-onset region-specific Purkinje cell loss as well as cataracts and defects in early T-cell maturation. We have previously established that the mutated protein Af4, which is a member of the AF4/LAF4/FMR2 (ALF) family of transcription cofactors frequently translocated in childhood leukaemia, undergoes slower proteasomal turnover through the ubiquitin pathway and abnormally accumulates in Purkinje cells of the cerebellum. We have also shown that Af4 functions as part of a large multiprotein complex that stimulates RNA polymerase II elongation and mediates chromatin remodelling during transcription. With the forthcoming identification of the gene targets that trigger Purkinje cell death in the robotic cerebellum, and the functional conservation among the ALF proteins, the robotic mouse promises to deliver important insights into the pathogenesis of human ataxia, but also of mental retardation to which FMR2 and LAF4 have been linked.
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Affiliation(s)
- Emmanuelle Bitoun
- MRC Functional Genomics Unit, Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford OX1 3QX, UK
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123
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Sanlaville D, Schluth-Bolard C, Turleau C. Distal Xq duplication and functional Xq disomy. Orphanet J Rare Dis 2009; 4:4. [PMID: 19232094 PMCID: PMC2649904 DOI: 10.1186/1750-1172-4-4] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2008] [Accepted: 02/20/2009] [Indexed: 11/10/2022] Open
Abstract
Distal Xq duplications refer to chromosomal disorders resulting from involvement of the long arm of the X chromosome (Xq). Clinical manifestations widely vary depending on the gender of the patient and on the gene content of the duplicated segment. Prevalence of Xq duplications remains unknown. About 40 cases of Xq28 functional disomy due to cytogenetically visible rearrangements, and about 50 cases of cryptic duplications encompassing the MECP2 gene have been reported. The most frequently reported distal duplications involve the Xq28 segment and yield a recognisable phenotype including distinctive facial features (premature closure of the fontanels or ridged metopic suture, broad face with full cheeks, epicanthal folds, large ears, small and open mouth, ear anomalies, pointed nose, abnormal palate and facial hypotonia), major axial hypotonia, severe developmental delay, severe feeding difficulties, abnormal genitalia and proneness to infections. Xq duplications may be caused either by an intrachromosomal duplication or an unbalanced X/Y or X/autosome translocation. In XY males, structural X disomy always results in functional disomy. In females, failure of X chromosome dosage compensation could result from a variety of mechanisms, including an unfavourable pattern of inactivation, a breakpoint separating an X segment from the X-inactivation centre in cis, or a small ring chromosome. The MECP2 gene in Xq28 is the most important dosage-sensitive gene responsible for the abnormal phenotype in duplications of distal Xq. Diagnosis is based on clinical features and is confirmed by CGH array techniques. Differential diagnoses include Prader-Willi syndrome and Alpha thalassaemia-mental retardation, X linked (ATR-X). The recurrence risk is significant if a structural rearrangement is present in one of the parent, the most frequent situation being that of an intrachromosomal duplication inherited from the mother. Prenatal diagnosis is performed by cytogenetic testing including FISH and/or DNA quantification methods. Management is multi-specialist and only symptomatic, with special attention to prevention of malnutrition and recurrent infections. Educational and rehabilitation support should be offered to all patients.
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Affiliation(s)
- Damien Sanlaville
- Hospices Civils de Lyon, Centre de Biologie et de Pathologie Est, Service de Cytogénétique Constitutionnelle, Lyon, France.
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Medina CF, Mazerolle C, Wang Y, Bérubé NG, Coupland S, Gibbons RJ, Wallace VA, Picketts DJ. Altered visual function and interneuron survival in Atrx knockout mice: inference for the human syndrome. Hum Mol Genet 2008; 18:966-77. [DOI: 10.1093/hmg/ddn424] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
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