101
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BAF180 regulates cellular senescence and hematopoietic stem cell homeostasis through p21. Oncotarget 2017; 7:19134-46. [PMID: 26992241 PMCID: PMC4991371 DOI: 10.18632/oncotarget.8102] [Citation(s) in RCA: 46] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2016] [Accepted: 03/04/2016] [Indexed: 12/22/2022] Open
Abstract
BAF180 (also called PBRM1), a subunit of the SWI/SNF complex, plays critical roles in the regulation of chromatin remodeling and gene transcription, and is frequently mutated in several human cancers. However, the role of mammalian BAF180 in tumor suppression and tissue maintenance in vivo remains largely unknown. Here, using a conditional somatic knockout approach, we explored the cellular and organismal functions of BAF180 in mouse. BAF180 deletion in primary mouse embryonic fibroblasts (MEFs) triggers profound cell cycle arrest, premature cellular senescence, without affecting DNA damage response or chromosomal integrity. While somatic deletion of BAF180 in adult mice does not provoke tumor development, BAF180 deficient mice exhibit defects in hematopoietic system characterized by progressive reduction of hematopoietic stem cells (HSCs), defective long-term repopulating potential, and hematopoietic lineage developmental aberrations. BAF180 deletion results in elevated p21 expression in both MEFs and HSCs. Mechanistically, we showed that BAF180 binds to p21 promoter, and BAF180 deletion enhances the binding of modified histones associated with transcriptional activation on p21 promoter. Deletion of p21 rescues cell cycle arrest and premature senescence in BAF180 deficient MEFs, and partially rescues hematopoietic defects in BAF180 deficient mice. Together, our study identifies BAF180 as a critical regulator of cellular senescence and HSC homeostasis, which is at least partially regulated through BAF180-mediated suppression of p21 expression. Our results also suggest that senescence triggered by BAF180 inactivation may serve as a failsafe mechanism to restrain BAF180 deficiency-associated tumor development, providing a conceptual framework to further understand BAF180 function in tumor biology.
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102
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Temporal regulation of chromatin during myoblast differentiation. Semin Cell Dev Biol 2017; 72:77-86. [PMID: 29079444 DOI: 10.1016/j.semcdb.2017.10.022] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2017] [Revised: 10/06/2017] [Accepted: 10/22/2017] [Indexed: 11/23/2022]
Abstract
The commitment to and execution of differentiation programmes involves a significant change in gene expression in the precursor cell to facilitate development of the mature cell type. In addition to being regulated by lineage-determining and auxiliary transcription factors that drive these changes, the structural status of the chromatin has a considerable impact on the transcriptional competence of differentiation-specific genes, which is clearly demonstrated by the large number of cofactors and the extraordinary complex mechanisms by which these genes become activated. The terminal differentiation of myoblasts to myotubes and mature skeletal muscle is an excellent system to illustrate these points. The MyoD family of closely related, lineage-determining transcription factors directs, largely through targeting to chromatin, a cascade of cooperating transcription factors and enzymes that incorporate or remove variant histones, post-translationally modify histones, and alter nucleosome structure and positioning via energy released by ATP hydrolysis. The coordinated action of these transcription factors and enzymes prevents expression of differentiation-specific genes in myoblasts and facilitates the transition of these genes from transcriptionally repressed to activated during the differentiation process. Regulation is achieved in both a temporal as well as spatial manner, as at least some of these factors and enzymes affect local chromatin structure at myogenic gene regulatory sequences as well as higher-order genome organization. Here we discuss the transition of genes that promote myoblast differentiation from the silenced to the activated state with an emphasis on the changes that occur to individual histones and the chromatin structure present at these loci.
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103
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Christopher MA, Kyle SM, Katz DJ. Neuroepigenetic mechanisms in disease. Epigenetics Chromatin 2017; 10:47. [PMID: 29037228 PMCID: PMC5644115 DOI: 10.1186/s13072-017-0150-4] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2017] [Accepted: 08/23/2017] [Indexed: 02/08/2023] Open
Abstract
Epigenetics allows for the inheritance of information in cellular lineages during differentiation, independent of changes to the underlying genetic sequence. This raises the question of whether epigenetic mechanisms also function in post-mitotic neurons. During the long life of the neuron, fluctuations in gene expression allow the cell to pass through stages of differentiation, modulate synaptic activity in response to environmental cues, and fortify the cell through age-related neuroprotective pathways. Emerging evidence suggests that epigenetic mechanisms such as DNA methylation and histone modification permit these dynamic changes in gene expression throughout the life of a neuron. Accordingly, recent studies have revealed the vital importance of epigenetic players in the central nervous system and during neurodegeneration. Here, we provide a review of several of these recent findings, highlighting novel functions for epigenetics in the fields of Rett syndrome, Fragile X syndrome, and Alzheimer’s disease research. Together, these discoveries underscore the vital importance of epigenetics in human neurological disorders.
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Affiliation(s)
- Michael A Christopher
- Department of Cell Biology, Emory University School of Medicine, 615 Michael Street, Atlanta, GA, 30322, USA.,Department of Molecular, Cell and Developmental Biology, University of California, Los Angeles, Los Angeles, CA, 90095-7239, USA
| | - Stephanie M Kyle
- Department of Cell Biology, Emory University School of Medicine, 615 Michael Street, Atlanta, GA, 30322, USA
| | - David J Katz
- Department of Cell Biology, Emory University School of Medicine, 615 Michael Street, Atlanta, GA, 30322, USA.
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104
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Kelso TWR, Porter DK, Amaral ML, Shokhirev MN, Benner C, Hargreaves DC. Chromatin accessibility underlies synthetic lethality of SWI/SNF subunits in ARID1A-mutant cancers. eLife 2017; 6:30506. [PMID: 28967863 PMCID: PMC5643100 DOI: 10.7554/elife.30506] [Citation(s) in RCA: 121] [Impact Index Per Article: 17.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2017] [Accepted: 09/28/2017] [Indexed: 02/06/2023] Open
Abstract
ARID1A, a subunit of the SWI/SNF chromatin remodeling complex, is frequently mutated in cancer. Deficiency in its homolog ARID1B is synthetically lethal with ARID1A mutation. However, the functional relationship between these homologs has not been explored. Here, we use ATAC-seq, genome-wide histone modification mapping, and expression analysis to examine colorectal cancer cells lacking one or both ARID proteins. We find that ARID1A has a dominant role in maintaining chromatin accessibility at enhancers, while the contribution of ARID1B is evident only in the context of ARID1A mutation. Changes in accessibility are predictive of changes in expression and correlate with loss of H3K4me and H3K27ac marks, nucleosome spacing, and transcription factor binding, particularly at growth pathway genes including MET. We find that ARID1B knockdown in ARID1A mutant ovarian cancer cells causes similar loss of enhancer architecture, suggesting that this is a conserved function underlying the synthetic lethality between ARID1A and ARID1B.
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Affiliation(s)
- Timothy W R Kelso
- Molecular and Cell Biology Laboratory, Salk Institute for Biological Studies, California, United States
| | - Devin K Porter
- Molecular and Cell Biology Laboratory, Salk Institute for Biological Studies, California, United States
| | - Maria Luisa Amaral
- The Razavi Newman Integrative Genomics and Bioinformatics Core Facility, Salk Institute for Biological Studies, California, United States
| | - Maxim N Shokhirev
- The Razavi Newman Integrative Genomics and Bioinformatics Core Facility, Salk Institute for Biological Studies, California, United States
| | - Christopher Benner
- Department of Medicine, University of California San Diego, California, United States
| | - Diana C Hargreaves
- Molecular and Cell Biology Laboratory, Salk Institute for Biological Studies, California, United States
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105
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Nakayama RT, Pulice JL, Valencia AM, McBride MJ, McKenzie ZM, Gillespie MA, Ku WL, Teng M, Cui K, Williams RT, Cassel SH, Qing H, Widmer CJ, Demetri GD, Irizarry RA, Zhao K, Ranish JA, Kadoch C. SMARCB1 is required for widespread BAF complex-mediated activation of enhancers and bivalent promoters. Nat Genet 2017; 49:1613-1623. [PMID: 28945250 PMCID: PMC5803080 DOI: 10.1038/ng.3958] [Citation(s) in RCA: 183] [Impact Index Per Article: 26.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2016] [Accepted: 08/29/2017] [Indexed: 12/15/2022]
Abstract
Perturbations to mammalian SWI/SNF (BAF) complexes contribute to over 20% of human cancers, with driving roles first identified in malignant rhabdoid tumor (MRT), an aggressive pediatric cancer characterized by biallelic inactivation of the core BAF complex subunit SMARCB1 (BAF47). However, the mechanism by which this alteration contributes to tumorigenesis remains poorly understood. We find that BAF47 loss destabilizes BAF complexes on chromatin, absent significant changes in intra-complex integrity. Rescue of BAF47 in BAF47-deficient sarcoma cell lines results in increased genome-wide BAF complex occupancy, facilitating widespread enhancer activation and opposition of polycomb-mediated repression at bivalent promoters. We demonstrate differential regulation by BAF and PBAF complexes at enhancers and promoters, respectively, suggesting distinct functions of each complex which are perturbed upon BAF47 loss. Our results demonstrate collaborative mechanisms of mSWI/SNF-mediated gene activation, identifying functions that are coopted or abated to drive human cancers and developmental disorders.
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Affiliation(s)
- Robert T Nakayama
- Department of Pediatric Oncology, Dana-Farber Cancer Institute and Harvard Medical School, Boston, Massachusetts, USA.,Ludwig Center at Dana-Farber/Harvard and Center for Sarcoma and Bone Oncology, Department of Medical Oncology, Harvard Medical School, Boston, Massachusetts, USA
| | - John L Pulice
- Department of Pediatric Oncology, Dana-Farber Cancer Institute and Harvard Medical School, Boston, Massachusetts, USA.,Broad Institute of MIT and Harvard, Cambridge, Massachusetts, USA
| | - Alfredo M Valencia
- Department of Pediatric Oncology, Dana-Farber Cancer Institute and Harvard Medical School, Boston, Massachusetts, USA.,Program in Chemical Biology, Harvard University, Cambridge, Massachusetts, USA
| | - Matthew J McBride
- Department of Pediatric Oncology, Dana-Farber Cancer Institute and Harvard Medical School, Boston, Massachusetts, USA.,Program in Chemical Biology, Harvard University, Cambridge, Massachusetts, USA
| | - Zachary M McKenzie
- Department of Pediatric Oncology, Dana-Farber Cancer Institute and Harvard Medical School, Boston, Massachusetts, USA
| | | | - Wai Lim Ku
- Systems Biology Center, NHLBI, National Institutes of Health, Bethesda, Maryland, USA
| | - Mingxiang Teng
- Department of Biostatistics and Computational Biology, Dana-Farber Cancer Institute, Boston, Massachusetts, USA
| | - Kairong Cui
- Systems Biology Center, NHLBI, National Institutes of Health, Bethesda, Maryland, USA
| | - Robert T Williams
- Department of Pediatric Oncology, Dana-Farber Cancer Institute and Harvard Medical School, Boston, Massachusetts, USA
| | - Seth H Cassel
- Department of Pediatric Oncology, Dana-Farber Cancer Institute and Harvard Medical School, Boston, Massachusetts, USA.,Medical Scientist Training Program, Harvard Medical School, Boston, Massachusetts, USA
| | - He Qing
- Department of Pediatric Oncology, Dana-Farber Cancer Institute and Harvard Medical School, Boston, Massachusetts, USA
| | - Christian J Widmer
- Department of Pediatric Oncology, Dana-Farber Cancer Institute and Harvard Medical School, Boston, Massachusetts, USA
| | - George D Demetri
- Ludwig Center at Dana-Farber/Harvard and Center for Sarcoma and Bone Oncology, Department of Medical Oncology, Harvard Medical School, Boston, Massachusetts, USA
| | - Rafael A Irizarry
- Department of Biostatistics and Computational Biology, Dana-Farber Cancer Institute, Boston, Massachusetts, USA
| | - Keji Zhao
- Systems Biology Center, NHLBI, National Institutes of Health, Bethesda, Maryland, USA
| | | | - Cigall Kadoch
- Department of Pediatric Oncology, Dana-Farber Cancer Institute and Harvard Medical School, Boston, Massachusetts, USA.,Broad Institute of MIT and Harvard, Cambridge, Massachusetts, USA
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106
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Wiest NE, Houghtaling S, Sanchez JC, Tomkinson AE, Osley MA. The SWI/SNF ATP-dependent nucleosome remodeler promotes resection initiation at a DNA double-strand break in yeast. Nucleic Acids Res 2017; 45:5887-5900. [PMID: 28398510 PMCID: PMC5449591 DOI: 10.1093/nar/gkx221] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2017] [Accepted: 04/06/2017] [Indexed: 12/27/2022] Open
Abstract
DNA double-strand breaks (DSBs) are repaired by either the non-homologous end joining (NHEJ) or homologous recombination (HR) pathway. Pathway choice is determined by the generation of 3΄ single-strand DNA overhangs at the break that are initiated by the action of the Mre11-Rad50-Xrs2 (MRX) complex to direct repair toward HR. DSB repair occurs in the context of chromatin, and multiple chromatin regulators have been shown to play important roles in the repair process. We have investigated the role of the SWI/SNF ATP-dependent nucleosome-remodeling complex in the repair of a defined DNA DSB. SWI/SNF was previously shown to regulate presynaptic events in HR, but its function in these events is unknown. We find that in the absence of functional SWI/SNF, the initiation of DNA end resection is significantly delayed. The delay in resection initiation is accompanied by impaired recruitment of MRX to the DSB, and other functions of MRX in HR including the recruitment of long-range resection factors and activation of the DNA damage response are also diminished. These phenotypes are correlated with a delay in the eviction of nucleosomes surrounding the DSB. We propose that SWI/SNF orchestrates the recruitment of a pool of MRX that is specifically dedicated to HR.
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Affiliation(s)
- Nathaniel E Wiest
- Department of Molecular Genetics and Microbiology, University of New Mexico Health Sciences Center, Albuquerque, NM 87131, USA.,Department of Internal Medicine, University of New Mexico Health Sciences Center, Albuquerque, NM 87131, USA
| | - Scott Houghtaling
- Department of Molecular Genetics and Microbiology, University of New Mexico Health Sciences Center, Albuquerque, NM 87131, USA
| | - Joseph C Sanchez
- Department of Biology, University of New Mexico, Albuquerque, NM 87131, USA
| | - Alan E Tomkinson
- Department of Molecular Genetics and Microbiology, University of New Mexico Health Sciences Center, Albuquerque, NM 87131, USA.,Department of Internal Medicine, University of New Mexico Health Sciences Center, Albuquerque, NM 87131, USA
| | - Mary Ann Osley
- Department of Molecular Genetics and Microbiology, University of New Mexico Health Sciences Center, Albuquerque, NM 87131, USA
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107
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Abstract
Four studies in this issue report new mechanisms underlying the function of the chromatin remodeling SWI/SNF complex in controlling gene expression and suppressing tumor development, providing valuable insights into the treatment of cancers harboring mutations in genes encoding SWI/SNF complex subunits.
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Affiliation(s)
- Chao Lu
- Laboratory of Chromatin Biology and Epigenetics, Rockefeller University, New York, New York, USA
| | - C David Allis
- Laboratory of Chromatin Biology and Epigenetics, Rockefeller University, New York, New York, USA
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108
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Wu Q, Lian JB, Stein JL, Stein GS, Nickerson JA, Imbalzano AN. The BRG1 ATPase of human SWI/SNF chromatin remodeling enzymes as a driver of cancer. Epigenomics 2017; 9:919-931. [PMID: 28521512 PMCID: PMC5705788 DOI: 10.2217/epi-2017-0034] [Citation(s) in RCA: 85] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Mammalian SWI/SNF enzymes are ATP-dependent remodelers of chromatin structure. These multisubunit enzymes are heterogeneous in composition; there are two catalytic ATPase subunits, BRM and BRG1, that are mutually exclusive, and additional subunits are incorporated in a combinatorial manner. Recent findings indicate that approximately 20% of human cancers contain mutations in SWI/SNF enzyme subunits, leading to the conclusion that the enzyme subunits are critical tumor suppressors. However, overexpression of specific subunits without apparent mutation is emerging as an alternative mechanism by which cellular transformation may occur. Here we highlight recent evidence linking elevated expression of the BRG1 ATPase to tissue-specific cancers and work suggesting that inhibiting BRG1 may be an effective therapeutic strategy.
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Affiliation(s)
- Qiong Wu
- Department of Pediatrics, University of Massachusetts Medical School, 55 Lake Avenue North, Worcester, MA 01655, USA
| | - Jane B Lian
- Department of Biochemistry, University of Vermont College of Medicine, 89 Beaumont Avenue, Burlington, VT 05405, USA
| | - Janet L Stein
- Department of Biochemistry, University of Vermont College of Medicine, 89 Beaumont Avenue, Burlington, VT 05405, USA
| | - Gary S Stein
- Department of Biochemistry, University of Vermont College of Medicine, 89 Beaumont Avenue, Burlington, VT 05405, USA
| | - Jeffrey A Nickerson
- Department of Pediatrics, University of Massachusetts Medical School, 55 Lake Avenue North, Worcester, MA 01655, USA
| | - Anthony N Imbalzano
- Department of Biochemistry & Molecular Pharmacology, University of Massachusetts Medical School, 364 Plantation Street, Worcester, MA 01605, USA
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109
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Nickerson JA, Wu Q, Imbalzano AN. Mammalian SWI/SNF Enzymes and the Epigenetics of Tumor Cell Metabolic Reprogramming. Front Oncol 2017; 7:49. [PMID: 28421159 PMCID: PMC5378717 DOI: 10.3389/fonc.2017.00049] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2017] [Accepted: 03/09/2017] [Indexed: 01/27/2023] Open
Abstract
Tumor cells reprogram their metabolism to survive and grow in a challenging microenvironment. Some of this reprogramming is performed by epigenetic mechanisms. Epigenetics is in turn affected by metabolism; chromatin modifying enzymes are dependent on substrates that are also key metabolic intermediates. We have shown that the chromatin remodeling enzyme Brahma-related gene 1 (BRG1), an epigenetic regulator, is necessary for rapid breast cancer cell proliferation. The mechanism for this requirement is the BRG1-dependent transcription of key lipogenic enzymes and regulators. Reduction in lipid synthesis lowers proliferation rates, which can be restored by palmitate supplementation. This work has established BRG1 as an attractive target for breast cancer therapy. Unlike genetic alterations, epigenetic mechanisms are reversible, promising gentler therapies without permanent off-target effects at distant sites.
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Affiliation(s)
- Jeffrey A Nickerson
- Department of Cell and Developmental Biology, University of Massachusetts Medical School, Worcester, MA, USA
| | - Qiong Wu
- Department of Pediatrics, University of Massachusetts Medical School, Worcester, MA, USA
| | - Anthony N Imbalzano
- Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, MA, USA
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110
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The BAF45a/PHF10 subunit of SWI/SNF-like chromatin remodeling complexes is essential for hematopoietic stem cell maintenance. Exp Hematol 2017; 48:58-71.e15. [DOI: 10.1016/j.exphem.2016.11.008] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2016] [Revised: 11/12/2016] [Accepted: 11/25/2016] [Indexed: 11/22/2022]
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111
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Al-Maqtari T, Hong KU, Vajravelu BN, Moktar A, Cao P, Moore JB, Bolli R. Transcription factor-induced activation of cardiac gene expression in human c-kit+ cardiac progenitor cells. PLoS One 2017; 12:e0174242. [PMID: 28355297 PMCID: PMC5371315 DOI: 10.1371/journal.pone.0174242] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2015] [Accepted: 03/06/2017] [Indexed: 12/11/2022] Open
Abstract
Although transplantation of c-kit+ cardiac progenitor cells (CPCs) significantly alleviates post-myocardial infarction left ventricular dysfunction, generation of cardiomyocytes by exogenous CPCs in the recipient heart has often been limited. Inducing robust differentiation would be necessary for improving the efficacy of the regenerative cardiac cell therapy. We assessed the hypothesis that differentiation of human c-kit+ CPCs can be enhanced by priming them with cardiac transcription factors (TFs). We introduced five different TFs (Gata4, MEF2C, NKX2.5, TBX5, and BAF60C) into CPCs, either alone or in combination, and then examined the expression of marker genes associated with the major cardiac cell types using quantitative RT-PCR. When introduced individually, Gata4 and TBX5 induced a subset of myocyte markers. Moreover, Gata4 alone significantly induced smooth muscle cell and fibroblast markers. Interestingly, these gene expression changes brought by Gata4 were also accompanied by morphological changes. In contrast, MEF2C and NKX2.5 were largely ineffective in initiating cardiac gene expression in CPCs. Surprisingly, introduction of multiple TFs in different combinations mostly failed to act synergistically. Likewise, addition of BAF60C to Gata4 and/or TBX5 did not further potentiate their effects on cardiac gene expression. Based on our results, it appears that GATA4 is able to potentiate gene expression programs associated with multiple cardiovascular lineages in CPCs, suggesting that GATA4 may be effective in priming CPCs for enhanced differentiation in the setting of stem cell therapy.
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Affiliation(s)
- Tareq Al-Maqtari
- Institute of Molecular Cardiology, Department of Medicine, University of Louisville, Louisville, KY, United States of America
| | - Kyung U. Hong
- Institute of Molecular Cardiology, Department of Medicine, University of Louisville, Louisville, KY, United States of America
| | - Bathri N. Vajravelu
- Institute of Molecular Cardiology, Department of Medicine, University of Louisville, Louisville, KY, United States of America
| | - Afsoon Moktar
- Institute of Molecular Cardiology, Department of Medicine, University of Louisville, Louisville, KY, United States of America
| | - Pengxiao Cao
- Institute of Molecular Cardiology, Department of Medicine, University of Louisville, Louisville, KY, United States of America
| | - Joseph B. Moore
- Institute of Molecular Cardiology, Department of Medicine, University of Louisville, Louisville, KY, United States of America
| | - Roberto Bolli
- Institute of Molecular Cardiology, Department of Medicine, University of Louisville, Louisville, KY, United States of America
- * E-mail:
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112
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Pfister NT, Prives C. Transcriptional Regulation by Wild-Type and Cancer-Related Mutant Forms of p53. Cold Spring Harb Perspect Med 2017; 7:cshperspect.a026054. [PMID: 27836911 DOI: 10.1101/cshperspect.a026054] [Citation(s) in RCA: 90] [Impact Index Per Article: 12.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
TP53 missense mutations produce a mutant p53 protein that cannot activate the p53 tumor suppressive transcriptional response, which is the primary selective pressure for TP53 mutation. Specific codons of TP53, termed hotspot mutants, are mutated at elevated frequency. Hotspot forms of mutant p53 possess oncogenic properties in addition to being deficient in tumor suppression. Such p53 mutants accumulate to high levels in the cells they inhabit, causing transcriptional alterations that produce pro-oncogenic activities, such as increased pro-growth signaling, invasiveness, and metastases. These forms of mutant p53 very likely use features of wild-type p53, such as interactions with the transcriptional machinery, to produce oncogenic effects. In this review, we discuss commonalities between wild-type and mutant p53 proteins with an emphasis on transcriptional processes.
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Affiliation(s)
- Neil T Pfister
- Department of Biological Sciences, Columbia University, New York, New York 10027
| | - Carol Prives
- Department of Biological Sciences, Columbia University, New York, New York 10027
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113
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Smith DK, Yang J, Liu ML, Zhang CL. Small Molecules Modulate Chromatin Accessibility to Promote NEUROG2-Mediated Fibroblast-to-Neuron Reprogramming. Stem Cell Reports 2016; 7:955-969. [PMID: 28157484 PMCID: PMC5106529 DOI: 10.1016/j.stemcr.2016.09.013] [Citation(s) in RCA: 81] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2016] [Revised: 09/28/2016] [Accepted: 09/29/2016] [Indexed: 11/20/2022] Open
Abstract
Pro-neural transcription factors and small molecules can induce the reprogramming of fibroblasts into functional neurons; however, the immediate-early molecular events that catalyze this conversion have not been well defined. We previously demonstrated that neurogenin 2 (NEUROG2), forskolin (F), and dorsomorphin (D) can reprogram fibroblasts into functional neurons with high efficiency. Here, we used this model to define the genetic and epigenetic events that initiate an acquisition of neuronal identity. We demonstrate that NEUROG2 is a pioneer factor, FD enhances chromatin accessibility and H3K27 acetylation, and synergistic transcription activated by these factors is essential to successful reprogramming. CREB1 promotes neuron survival and acts with NEUROG2 to upregulate SOX4, which co-activates NEUROD1 and NEUROD4. In addition, SOX4 targets SWI/SNF subunits and SOX4 knockdown results in extensive loss of open chromatin and abolishes reprogramming. Applying these insights, adult human glioblastoma cell and skin fibroblast reprogramming can be improved using SOX4 or chromatin-modifying chemicals. NEUROG2 acts as a pioneer factor to drive neuronal reprogramming ATAC-, ChIP-, and RNA-seq profiling reveals genome-wide mechanisms for reprogramming SOX4 is a critical mediator of chromatin remodeling during reprogramming SOX4 or FK228 can enhance adult human glioblastoma and skin fibroblast reprogramming
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Affiliation(s)
- Derek K Smith
- Department of Molecular Biology, The University of Texas Southwestern Medical Center, 6000 Harry Hines Boulevard, Dallas, TX 75390-9148, USA; Hamon Center for Regenerative Science and Medicine, The University of Texas Southwestern Medical Center, 6000 Harry Hines Boulevard, Dallas, TX 75390-9148, USA
| | - Jianjing Yang
- Department of Molecular Biology, The University of Texas Southwestern Medical Center, 6000 Harry Hines Boulevard, Dallas, TX 75390-9148, USA; Hamon Center for Regenerative Science and Medicine, The University of Texas Southwestern Medical Center, 6000 Harry Hines Boulevard, Dallas, TX 75390-9148, USA
| | - Meng-Lu Liu
- Department of Molecular Biology, The University of Texas Southwestern Medical Center, 6000 Harry Hines Boulevard, Dallas, TX 75390-9148, USA; Hamon Center for Regenerative Science and Medicine, The University of Texas Southwestern Medical Center, 6000 Harry Hines Boulevard, Dallas, TX 75390-9148, USA
| | - Chun-Li Zhang
- Department of Molecular Biology, The University of Texas Southwestern Medical Center, 6000 Harry Hines Boulevard, Dallas, TX 75390-9148, USA; Hamon Center for Regenerative Science and Medicine, The University of Texas Southwestern Medical Center, 6000 Harry Hines Boulevard, Dallas, TX 75390-9148, USA.
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114
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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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115
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Romero OA, Verdura S, Torres-Diz M, Gomez A, Moran S, Condom E, Esteller M, Villanueva A, Sanchez-Cespedes M. Sensitization of retinoids and corticoids to epigenetic drugs in MYC-activated lung cancers by antitumor reprogramming. Oncogene 2016; 36:1287-1296. [PMID: 27593925 DOI: 10.1038/onc.2016.296] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2016] [Revised: 07/06/2016] [Accepted: 07/15/2016] [Indexed: 12/12/2022]
Abstract
Components of the SWI/SNF chromatin remodeling complex, including BRG1 (also SMARCA4), are inactivated in cancer. Among other functions, SWI/SNF orchestrates the response to retinoid acid (RA) and glucocorticoids (GC) involving downregulation of MYC. The epigenetic drugs SAHA and azacytidine, as well as RA and GC, are currently being used to treat some malignancies but their therapeutic potential in lung cancer is not well established. Here we aimed to determine the possible therapeutic effects of azacytidine and SAHA (A/S) alone or in combination with GC plus RA (GC/RA) in lung cancers with either BRG1 inactivation or MYC amplification. In vitro, responses to GC/RA treatment were more effective in MYC-amplified cells. These effects were mediated by BRG1 and involved a reprogramming towards prodifferentiation gene expression signatures and downregulation of MYC. In MYC-amplified cells, administration of GC/RA enhanced the cell growth inhibitory effects of A/S which, in turn, accentuated the prodifferentiation features promoted by GC/RA. Finally, these treatments improved overall survival of mice orthotopically implanted with MYC-amplified, but not BRG1-mutant, cells and reduced tumor cell viability and proliferation. We propose that the combination of epigenetic treatments with retinoids and corticoids of MYC-driven lung tumors constitute a strategy for therapeutic intervention in this otherwise incurable disease.
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Affiliation(s)
- O A Romero
- Genes and Cancer Group, Cancer Epigenetics and Biology Program (PEBC), Bellvitge Biomedical Research Institute-IDIBELL, Barcelona, Spain
| | - S Verdura
- Genes and Cancer Group, Cancer Epigenetics and Biology Program (PEBC), Bellvitge Biomedical Research Institute-IDIBELL, Barcelona, Spain
| | - M Torres-Diz
- Genes and Cancer Group, Cancer Epigenetics and Biology Program (PEBC), Bellvitge Biomedical Research Institute-IDIBELL, Barcelona, Spain
| | - A Gomez
- Cancer Epigenetics Groups, Cancer Epigenetics and Biology Program (PEBC), Bellvitge Biomedical Research Institute-IDIBELL, Barcelona, Spain
| | - S Moran
- Cancer Epigenetics Groups, Cancer Epigenetics and Biology Program (PEBC), Bellvitge Biomedical Research Institute-IDIBELL, Barcelona, Spain
| | - E Condom
- Pathology Department, Bellvitge Hospital, Barcelona, Spain
| | - M Esteller
- Cancer Epigenetics Groups, Cancer Epigenetics and Biology Program (PEBC), Bellvitge Biomedical Research Institute-IDIBELL, Barcelona, Spain
| | - A Villanueva
- Translational Research Laboratory, Catalan Institute of Oncology (ICO), Bellvitge Biomedical Research Institute-IDIBELL, Barcelona, Spain
| | - M Sanchez-Cespedes
- Genes and Cancer Group, Cancer Epigenetics and Biology Program (PEBC), Bellvitge Biomedical Research Institute-IDIBELL, Barcelona, Spain
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116
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Abstract
The nucleosome serves as a general gene repressor by the occlusion of regulatory and promoter DNA sequences. Repression is relieved by the SWI/SNF-RSC family of chromatin-remodeling complexes. Research reviewed here has revealed the essential features of the remodeling process.
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117
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Abstract
Chromatin is a highly dynamic structure that imparts structural organization to the genome and regulates the gene expression underneath. The decade long research in deciphering the significance of epigenetics in maintaining cellular integrity has embarked the focus on chromatin remodeling enzymes. These drivers have been categorized as readers, writers and erasers with each having significance of their own. Largely, on the basis of structure, ATP dependent chromatin remodelers have been grouped into 4 families; SWI/SNF, ISWI, IN080 and CHD. It is still unclear to what degree these enzymes are swayed by local DNA sequences when shifting a nucleosome to different positions. The ability of regulating active and repressive transcriptional state via open and close chromatin architecture has been well studied however, the significance of chromatin remodelers in regulating transcription at each step i.e. initiation, elongation and termination require further attention. The authors have highlighted the significance and role of different chromatin remodelers in transcription, DNA repair and histone variant deposition.
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Affiliation(s)
- Monica Tyagi
- a Kusuma School of Biological Sciences, Indian Institute of Technology Delhi Hauz Khas , New Delhi , India
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118
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Abstract
Over the past 20 years, breakthrough discoveries of chromatin-modifying enzymes and associated mechanisms that alter chromatin in response to physiological or pathological signals have transformed our knowledge of epigenetics from a collection of curious biological phenomena to a functionally dissected research field. Here, we provide a personal perspective on the development of epigenetics, from its historical origins to what we define as 'the modern era of epigenetic research'. We primarily highlight key molecular mechanisms of and conceptual advances in epigenetic control that have changed our understanding of normal and perturbed development.
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Affiliation(s)
- C David Allis
- Laboratory of Chromatin Biology and Epigenetics, The Rockefeller University, 1230 York Avenue, New York 10065, New York, USA
| | - Thomas Jenuwein
- Max Planck Institute of Immunobiology and Epigenetics, Stübeweg 51, Freiburg D-79108, Germany
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119
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Zhang P, Li L, Bao Z, Huang F. Role of BAF60a/BAF60c in chromatin remodeling and hepatic lipid metabolism. Nutr Metab (Lond) 2016; 13:30. [PMID: 27127533 PMCID: PMC4848843 DOI: 10.1186/s12986-016-0090-1] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2016] [Accepted: 04/19/2016] [Indexed: 02/07/2023] Open
Abstract
The switching defective/sucrose non-fermenting (SWI/SNF) complexes play an important role in hepatic lipid metabolism regulating both transcriptional activation and repression. BAF60a is a core subunit of the SWI/SNF chromatin-remodeling complexes that activates the transcription of fatty acid oxidation genes during fasting/glucagon. BAF60c, another subunit of SWI/SNF complexes, is recruited to form the lipoBAF complex that activates lipogenic genes, promoting lipogenesis and increasing the triglyceride level in response to feeding/insulin. Interestingly, hepatocytes located in the periportal and perivenous zones of the liver display a remarkable heterogeneity in the activity of various enzymes, metabolic functions and gene expression. Especially, fatty-acid oxidation was shown to be mostly periportal, whereas lipogenesis was mostly perivenous. Therefore, the present review highlights the role of of SWI/SNF regulating lipid metabolism under nutritional and hormonal control, which may be associated with hepatocyte heterogeneity.
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Affiliation(s)
- Ping Zhang
- Department of Animal Nutrition and Feed Science, College of Animal Science and Technology, Huazhong Agricultural University, Wuhan, 430070 China
| | - Lulu Li
- Department of Animal Nutrition and Feed Science, College of Animal Science and Technology, Huazhong Agricultural University, Wuhan, 430070 China
| | - Zhengxi Bao
- Department of Animal Nutrition and Feed Science, College of Animal Science and Technology, Huazhong Agricultural University, Wuhan, 430070 China
| | - Feiruo Huang
- Department of Animal Nutrition and Feed Science, College of Animal Science and Technology, Huazhong Agricultural University, Wuhan, 430070 China
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120
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Krasnov AN, Mazina MY, Nikolenko JV, Vorobyeva NE. On the way of revealing coactivator complexes cross-talk during transcriptional activation. Cell Biosci 2016; 6:15. [PMID: 26913181 PMCID: PMC4765067 DOI: 10.1186/s13578-016-0081-y] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2015] [Accepted: 02/09/2016] [Indexed: 08/07/2023] Open
Abstract
Transcriptional activation is a complex, multistage process implemented by hundreds of proteins. Many transcriptional proteins are organized into coactivator complexes, which participate in transcription regulation at numerous genes and are a driver of this process. The molecular action mechanisms of coactivator complexes remain largely understudied. Relevant publications usually deal with the involvement of these complexes in the entire process of transcription, and only a few studies are aimed to elucidate their functions at its particular stages. This review summarizes available information on the participation of key coactivator complexes in transcriptional activation. The timing of coactivator complex binding/removal has been used for restructuring previously described information about the transcriptional process. Several major stages of transcriptional activation have been distinguished based on the presence of covalent histone modifications and general transcriptional factors, and the recruitment and/or removal phases have been determined for each coactivator included in analysis. Recruitment of Mediator, SWItch/Sucrose Non-Fermentable and NUcleosome Remodeling Factor complexes during transcription activation has been investigated thoroughly; CHD and INOsitol auxotrophy 80 families are less well studied. In most cases, the molecular mechanisms responsible for the removal of certain coactivator complexes after the termination of their functions at the promoters are still not understood. On the basis of the summarized information, we propose a scheme that illustrates the involvement of coactivator complexes in different stages of the transcription activation process. This scheme may help to gain a deeper insight into the molecular mechanism of functioning of coactivator complexes, find novel participants of the process, and reveal novel structural or functional connections between different coactivators.
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Affiliation(s)
- Aleksey N Krasnov
- Department of Transcription Regulation and Chromatin Dynamic, Institute of Gene Biology, Russian Academy of Sciences, Moscow, 119334 Russia
| | - Marina Yu Mazina
- Department of Transcription Regulation and Chromatin Dynamic, Institute of Gene Biology, Russian Academy of Sciences, Moscow, 119334 Russia
| | - Julia V Nikolenko
- Department of Transcription Regulation and Chromatin Dynamic, Institute of Gene Biology, Russian Academy of Sciences, Moscow, 119334 Russia
| | - Nadezhda E Vorobyeva
- Department of Transcription Regulation and Chromatin Dynamic, Institute of Gene Biology, Russian Academy of Sciences, Moscow, 119334 Russia
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121
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Kadoch C, Copeland RA, Keilhack H. PRC2 and SWI/SNF Chromatin Remodeling Complexes in Health and Disease. Biochemistry 2016; 55:1600-14. [DOI: 10.1021/acs.biochem.5b01191] [Citation(s) in RCA: 86] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Affiliation(s)
- Cigall Kadoch
- Dana-Farber Cancer Institute and Harvard Medical School, 450 Brookline Avenue, Boston, Massachusetts 02215, United States
| | - Robert A. Copeland
- Epizyme Inc., 400 Technology
Square, 4th floor, Cambridge, Massachusetts 02139, United States
| | - Heike Keilhack
- Epizyme Inc., 400 Technology
Square, 4th floor, Cambridge, Massachusetts 02139, United States
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122
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Pulice JL, Kadoch C. Composition and Function of Mammalian SWI/SNF Chromatin Remodeling Complexes in Human Disease. COLD SPRING HARBOR SYMPOSIA ON QUANTITATIVE BIOLOGY 2016; 81:53-60. [PMID: 28408647 DOI: 10.1101/sqb.2016.81.031021] [Citation(s) in RCA: 62] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/14/2023]
Abstract
Mammalian SWI/SNF (BAF) chromatin remodeling complexes play critical roles in maintaining chromatin architecture and gene expression. Genomic sequencing efforts over the past several years have unveiled a major role for these complexes in the development of human cancer as well as neurologic disease, prompting the need to interrogate underlying mechanisms and to develop new methods to comprehensively understand mSWI/SNF complex function. Here we discuss the emerging insights from genetic, biochemical, and functional genomic studies in the field and suggest approaches toward further basic investigations, as well as therapeutic targeting of chromatin remodeling machinery.
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Affiliation(s)
- John L Pulice
- Department of Pediatric Oncology, Dana-Farber Cancer Institute and Harvard Medical School, Boston, Massachusetts 02215
- Broad Institute of MIT and Harvard, Cambridge, Massachusetts 02142
| | - Cigall Kadoch
- Department of Pediatric Oncology, Dana-Farber Cancer Institute and Harvard Medical School, Boston, Massachusetts 02215
- Broad Institute of MIT and Harvard, Cambridge, Massachusetts 02142
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123
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Bao X, Rubin AJ, Qu K, Zhang J, Giresi PG, Chang HY, Khavari PA. A novel ATAC-seq approach reveals lineage-specific reinforcement of the open chromatin landscape via cooperation between BAF and p63. Genome Biol 2015; 16:284. [PMID: 26683334 PMCID: PMC4699366 DOI: 10.1186/s13059-015-0840-9] [Citation(s) in RCA: 104] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2015] [Accepted: 11/19/2015] [Indexed: 01/04/2023] Open
Abstract
Background Open chromatin regions are correlated with active regulatory elements in development and are dysregulated in diseases. The BAF (SWI/SNF) complex is essential for development, and has been demonstrated to remodel reconstituted chromatin in vitro and to control the accessibility of a few individual regions in vivo. However, it remains unclear where and how BAF controls the open chromatin landscape to regulate developmental processes, such as human epidermal differentiation. Results Using a novel “on-plate” ATAC-sequencing approach for profiling open chromatin landscapes with a low number of adherent cells, we demonstrate that the BAF complex is essential for maintaining 11.6 % of open chromatin regions in epidermal differentiation. These BAF-dependent open chromatin regions are highly cell-type-specific and are strongly enriched for binding sites for p63, a master epidermal transcription factor. The DNA sequences of p63 binding sites intrinsically favor nucleosome formation and are inaccessible in other cell types without p63 to prevent ectopic activation. In epidermal cells, BAF and p63 mutually recruit each other to maintain 14,853 open chromatin regions. We further demonstrate that BAF and p63 cooperatively position nucleosomes away from p63 binding sites and recruit transcriptional machinery to control tissue differentiation. Conclusions BAF displays high specificity in controlling the open chromatin landscape during epidermal differentiation by cooperating with the master transcription factor p63 to maintain lineage-specific open chromatin regions. Electronic supplementary material The online version of this article (doi:10.1186/s13059-015-0840-9) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Xiaomin Bao
- Program in Epithelial Biology, Stanford University, 269 Campus Drive, Stanford, CA, 94305, USA.
| | - Adam J Rubin
- Program in Epithelial Biology, Stanford University, 269 Campus Drive, Stanford, CA, 94305, USA
| | - Kun Qu
- Program in Epithelial Biology, Stanford University, 269 Campus Drive, Stanford, CA, 94305, USA
| | - Jiajing Zhang
- Program in Epithelial Biology, Stanford University, 269 Campus Drive, Stanford, CA, 94305, USA
| | - Paul G Giresi
- Program in Epithelial Biology, Stanford University, 269 Campus Drive, Stanford, CA, 94305, USA.,Howard Hughes Medical Institute, Stanford University, Stanford, CA, 94305, USA
| | - Howard Y Chang
- Program in Epithelial Biology, Stanford University, 269 Campus Drive, Stanford, CA, 94305, USA.,Howard Hughes Medical Institute, Stanford University, Stanford, CA, 94305, USA
| | - Paul A Khavari
- Program in Epithelial Biology, Stanford University, 269 Campus Drive, Stanford, CA, 94305, USA. .,Veterans Affairs Palo Alto Healthcare System, 3801 Miranda Ave, Palo Alto, CA, 94304, USA.
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124
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Padilla-Benavides T, Nasipak BT, Imbalzano AN. Brg1 Controls the Expression of Pax7 to Promote Viability and Proliferation of Mouse Primary Myoblasts. J Cell Physiol 2015; 230:2990-7. [PMID: 26036967 DOI: 10.1002/jcp.25031] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2015] [Accepted: 05/04/2015] [Indexed: 12/29/2022]
Abstract
Brg1 (Brahma-related gene 1) is a catalytic component of the evolutionarily conserved mammalian SWI/SNF ATP-dependent chromatin remodeling enzymes that disrupt histone-DNA contacts on the nucleosome. While the requirement for the SWI/SNF enzymes in cell differentiation has been extensively studied, its role in precursor cell proliferation and survival is not as well defined. Muscle satellite cells constitute the stem cell pool that sustains and regenerates myofibers in adult skeletal muscle. Here, we show that deletion of Brg1 in primary mouse myoblasts derived from muscle satellite cells cultured ex vivo leads to a cell proliferation defect and apoptosis. We determined that Brg1 regulates cell proliferation and survival by controlling chromatin remodeling and activating transcription at the Pax7 promoter, which is expressed during somite development and is required for controlling viability of the satellite cell population. Reintroduction of catalytically active Brg1 or of Pax7 into Brg1-deficient satellite cells rescued the apoptotic phenotype and restored proliferation. These data demonstrate that Brg1 functions as a positive regulator for cellular proliferation and survival of primary myoblasts. Therefore, the regulation of gene expression through Brg1-mediated chromatin remodeling is critical not just for skeletal muscle differentiation but for maintaining the myoblast population as well.
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Affiliation(s)
- Teresita Padilla-Benavides
- Department of Cell and Developmental Biology, University of Massachusetts Medical School, Worcester, Massachusetts
| | - Brian T Nasipak
- Department of Cell and Developmental Biology, University of Massachusetts Medical School, Worcester, Massachusetts
| | - Anthony N Imbalzano
- Department of Cell and Developmental Biology, University of Massachusetts Medical School, Worcester, Massachusetts
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125
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Transcriptional Activation of Inflammatory Genes: Mechanistic Insight into Selectivity and Diversity. Biomolecules 2015; 5:3087-111. [PMID: 26569329 PMCID: PMC4693271 DOI: 10.3390/biom5043087] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2015] [Revised: 09/11/2015] [Accepted: 10/28/2015] [Indexed: 12/11/2022] Open
Abstract
Acute inflammation, an integral part of host defence and immunity, is a highly conserved cellular response to pathogens and other harmful stimuli. An inflammatory stimulation triggers transcriptional activation of selective pro-inflammatory genes that carry out specific functions such as anti-microbial activity or tissue healing. Based on the nature of inflammatory stimuli, an extensive exploitation of selective transcriptional activations of pro-inflammatory genes is performed by the host to ensure a defined inflammatory response. Inflammatory signal transductions are initiated by the recognition of inflammatory stimuli by transmembrane receptors, followed by the transmission of the signals to the nucleus for differential gene activations. The differential transcriptional activation of pro-inflammatory genes is precisely controlled by the selective binding of transcription factors to the promoters of these genes. Among a number of transcription factors identified to date, NF-κB still remains the most prominent and studied factor for its diverse range of selective transcriptional activities. Differential transcriptional activities of NF-κB are dictated by post-translational modifications, specificities in dimer formation, and variability in activation kinetics. Apart from the differential functions of transcription factors, the transcriptional activation of selective pro-inflammatory genes is also governed by chromatin structures, epigenetic markers, and other regulators as the field is continuously expanding.
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126
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Wu Q, Madany P, Akech J, Dobson JR, Douthwright S, Browne G, Colby JL, Winter GE, Bradner JE, Pratap J, Sluder G, Bhargava R, Chiosea SI, van Wijnen AJ, Stein JL, Stein GS, Lian JB, Nickerson JA, Imbalzano AN. The SWI/SNF ATPases Are Required for Triple Negative Breast Cancer Cell Proliferation. J Cell Physiol 2015; 230:2683-94. [PMID: 25808524 DOI: 10.1002/jcp.24991] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2015] [Accepted: 03/18/2015] [Indexed: 12/30/2022]
Abstract
The Brahma (BRM) and Brahma-related Gene 1 (BRG1) ATPases are highly conserved homologs that catalyze the chromatin remodeling functions of the multi-subunit human SWI/SNF chromatin remodeling enzymes in a mutually exclusive manner. SWI/SNF enzyme subunits are mutated or missing in many cancer types, but are overexpressed without apparent mutation in other cancers. Here, we report that both BRG1 and BRM are overexpressed in most primary breast cancers independent of the tumor's receptor status. Knockdown of either ATPase in a triple negative breast cancer cell line reduced tumor formation in vivo and cell proliferation in vitro. Fewer cells in S phase and an extended cell cycle progression time were observed without any indication of apoptosis, senescence, or alterations in migration or attachment properties. Combined knockdown of BRM and BRG1 showed additive effects in the reduction of cell proliferation and time required for completion of cell cycle, suggesting that these enzymes promote cell cycle progression through independent mechanisms. Knockout of BRG1 or BRM using CRISPR/Cas9 technology resulted in the loss of viability, consistent with a requirement for both enzymes in triple negative breast cancer cells.
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Affiliation(s)
- Qiong Wu
- Department of Cell and Developmental Biology, University of Massachusetts Medical School, Worcester, Massachusetts
| | - Pasil Madany
- Department of Cell and Developmental Biology, University of Massachusetts Medical School, Worcester, Massachusetts
| | - Jacqueline Akech
- Department of Cell and Developmental Biology, University of Massachusetts Medical School, Worcester, Massachusetts
| | - Jason R Dobson
- Department of Cell and Developmental Biology, University of Massachusetts Medical School, Worcester, Massachusetts
- Department of Molecular Biology, Cell Biology and Biochemistry, Center for Computational Molecular Biology, Brown University, Providence, Rhode Island
- Department of Computer Science, Brown University, Providence, Rhode Island
| | - Stephen Douthwright
- Department of Cell and Developmental Biology, University of Massachusetts Medical School, Worcester, Massachusetts
| | - Gillian Browne
- Department of Cell and Developmental Biology, University of Massachusetts Medical School, Worcester, Massachusetts
- Department of Biochemistry and Vermont Cancer Center for Basic and Translational Research, University of Vermont College of Medicine, Burlington, Vermont
| | - Jennifer L Colby
- Department of Cell and Developmental Biology, University of Massachusetts Medical School, Worcester, Massachusetts
| | - Georg E Winter
- Department of Medical Oncology, Dana-Farber Cancer Institute, Boston, Massachusetts
| | - James E Bradner
- Department of Medical Oncology, Dana-Farber Cancer Institute, Boston, Massachusetts
- Department of Medicine, Harvard Medical School, Boston, Massachusetts
| | - Jitesh Pratap
- Department of Cell and Developmental Biology, University of Massachusetts Medical School, Worcester, Massachusetts
- Department of Anatomy and Cell Biology, Rush University, Chicago, Illinois
| | - Greenfield Sluder
- Department of Cell and Developmental Biology, University of Massachusetts Medical School, Worcester, Massachusetts
| | - Rohit Bhargava
- Department of Pathology, Magee-Womens Hospital, Pittsburgh, Pennsylvania
| | - Simion I Chiosea
- Department of Pathology, University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania
| | - Andre J van Wijnen
- Department of Cell and Developmental Biology, University of Massachusetts Medical School, Worcester, Massachusetts
- Departments of Orthopedic Surgery & Biochemistry and Molecular Biology, Mayo Clinic, Rochester, Minnesota
| | - Janet L Stein
- Department of Cell and Developmental Biology, University of Massachusetts Medical School, Worcester, Massachusetts
- Department of Biochemistry and Vermont Cancer Center for Basic and Translational Research, University of Vermont College of Medicine, Burlington, Vermont
| | - Gary S Stein
- Department of Cell and Developmental Biology, University of Massachusetts Medical School, Worcester, Massachusetts
- Department of Biochemistry and Vermont Cancer Center for Basic and Translational Research, University of Vermont College of Medicine, Burlington, Vermont
| | - Jane B Lian
- Department of Cell and Developmental Biology, University of Massachusetts Medical School, Worcester, Massachusetts
- Department of Biochemistry and Vermont Cancer Center for Basic and Translational Research, University of Vermont College of Medicine, Burlington, Vermont
- Department of Orthopedics and Physical Rehabilitation, University of Massachusetts Medical School, Worcester, Massachusetts
| | - Jeffrey A Nickerson
- Department of Cell and Developmental Biology, University of Massachusetts Medical School, Worcester, Massachusetts
| | - Anthony N Imbalzano
- Department of Cell and Developmental Biology, University of Massachusetts Medical School, Worcester, Massachusetts
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127
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128
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Wade SL, Langer LF, Ward JM, Archer TK. MiRNA-Mediated Regulation of the SWI/SNF Chromatin Remodeling Complex Controls Pluripotency and Endodermal Differentiation in Human ESCs. Stem Cells 2015; 33:2925-35. [PMID: 26119756 DOI: 10.1002/stem.2084] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2014] [Accepted: 06/15/2015] [Indexed: 01/07/2023]
Abstract
MicroRNAs and chromatin remodeling complexes represent powerful epigenetic mechanisms that regulate the pluripotent state. miR-302 is a strong inducer of pluripotency, which is characterized by a distinct chromatin architecture. This suggests that miR-302 regulates global chromatin structure; however, a direct relationship between miR-302 and chromatin remodelers has not been established. Here, we provide data to show that miR-302 regulates Brg1 chromatin remodeling complex composition in human embryonic stem cells (hESCs) through direct repression of the BAF53a and BAF170 subunits. With the subsequent overexpression of BAF170 in hESCs, we show that miR-302's inhibition of BAF170 protein levels can affect the expression of genes involved in cell proliferation. Furthermore, miR-302-mediated repression of BAF170 regulates pluripotency by positively influencing mesendodermal differentiation. Overexpression of BAF170 in hESCs led to biased differentiation toward the ectoderm lineage during EB formation and severely hindered directed definitive endoderm differentiation. Taken together, these data uncover a direct regulatory relationship between miR-302 and the Brg1 chromatin remodeling complex that controls gene expression and cell fate decisions in hESCs and suggests that similar mechanisms are at play during early human development.
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Affiliation(s)
- Staton L Wade
- Chromatin and Gene Expression Group, Epigenetics and Stem Cell Biology Laboratory, Department of Health and Human Services
| | - Lee F Langer
- Chromatin and Gene Expression Group, Epigenetics and Stem Cell Biology Laboratory, Department of Health and Human Services
| | - James M Ward
- Integrative Bioinformatics Resource, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, North Carolina, USA
| | - Trevor K Archer
- Chromatin and Gene Expression Group, Epigenetics and Stem Cell Biology Laboratory, Department of Health and Human Services
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129
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Shen J, Peng Y, Wei L, Zhang W, Yang L, Lan L, Kapoor P, Ju Z, Mo Q, Shih IM, Uray IP, Wu X, Brown PH, Shen X, Mills GB, Peng G. ARID1A Deficiency Impairs the DNA Damage Checkpoint and Sensitizes Cells to PARP Inhibitors. Cancer Discov 2015; 5:752-67. [PMID: 26069190 DOI: 10.1158/2159-8290.cd-14-0849] [Citation(s) in RCA: 352] [Impact Index Per Article: 39.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2014] [Accepted: 05/06/2015] [Indexed: 02/05/2023]
Abstract
UNLABELLED ARID1A, SWI/SNF chromatin remodeling complex subunit, is a recently identified tumor suppressor that is mutated in a broad spectrum of human cancers. Thus, it is of fundamental clinical importance to understand its molecular functions and determine whether ARID1A deficiency can be exploited therapeutically. In this article, we report a key function of ARID1A in regulating the DNA damage checkpoint. ARID1A is recruited to DNA double-strand breaks (DSB) via its interaction with the upstream DNA damage checkpoint kinase ATR. At the molecular level, ARID1A facilitates efficient processing of DSB to single-strand ends and sustains DNA damage signaling. Importantly, ARID1A deficiency sensitizes cancer cells to PARP inhibitors in vitro and in vivo, providing a potential therapeutic strategy for patients with ARID1A-mutant tumors. SIGNIFICANCE ARID1A has been identified as one of the most frequently mutated genes across human cancers. Our data suggest that clinical utility of PARP inhibitors might be extended beyond patients with BRCA mutations to a larger group of patients with ARID1A-mutant tumors, which may exhibit therapeutic vulnerability to PARP inhibitors.
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Affiliation(s)
- Jianfeng Shen
- Department of Clinical Cancer Prevention, The University of Texas MD Anderson Cancer Center, Houston, Texas
| | - Yang Peng
- Department of Systems Biology, The University of Texas MD Anderson Cancer Center, Houston, Texas
| | - Leizhen Wei
- Department of Microbiology and Molecular Genetics, The University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania. The University of Pittsburgh Cancer Institute, Pittsburgh, Pennsylvania
| | - Wei Zhang
- Department of Clinical Cancer Prevention, The University of Texas MD Anderson Cancer Center, Houston, Texas
| | - Lin Yang
- Department of Clinical Cancer Prevention, The University of Texas MD Anderson Cancer Center, Houston, Texas. Department of Medical Oncology, Tongji Hospital, Tongji Medical College, The Huazhong University of Science and Technology, Wuhan, P.R. China
| | - Li Lan
- Department of Microbiology and Molecular Genetics, The University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania. The University of Pittsburgh Cancer Institute, Pittsburgh, Pennsylvania
| | - Prabodh Kapoor
- Department of Epigenetics and Molecular Carcinogenesis, The University of Texas MD Anderson Cancer Center, Houston, Texas
| | - Zhenlin Ju
- Department of Bioinformatics and Computational Biology, The University of Texas MD Anderson Cancer Center, Houston, Texas
| | - Qianxing Mo
- Division of Biostatistics, Dan L. Duncan Cancer Center, Baylor College of Medicine, Houston, Texas
| | - Ie-Ming Shih
- Department of Pathology, Johns Hopkins Medical Institutions, Baltimore, Maryland
| | - Ivan P Uray
- Department of Clinical Cancer Prevention, The University of Texas MD Anderson Cancer Center, Houston, Texas
| | - Xiangwei Wu
- Department of Clinical Cancer Prevention, The University of Texas MD Anderson Cancer Center, Houston, Texas
| | - Powel H Brown
- Department of Clinical Cancer Prevention, The University of Texas MD Anderson Cancer Center, Houston, Texas
| | - Xuetong Shen
- Department of Epigenetics and Molecular Carcinogenesis, The University of Texas MD Anderson Cancer Center, Houston, Texas
| | - Gordon B Mills
- Department of Systems Biology, The University of Texas MD Anderson Cancer Center, Houston, Texas
| | - Guang Peng
- Department of Clinical Cancer Prevention, The University of Texas MD Anderson Cancer Center, Houston, Texas. Department of Medical Oncology, Tongji Hospital, Tongji Medical College, The Huazhong University of Science and Technology, Wuhan, P.R. China.
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130
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Li M, Hada A, Sen P, Olufemi L, Hall MA, Smith BY, Forth S, McKnight JN, Patel A, Bowman GD, Bartholomew B, Wang MD. Dynamic regulation of transcription factors by nucleosome remodeling. eLife 2015; 4. [PMID: 26047462 PMCID: PMC4456607 DOI: 10.7554/elife.06249] [Citation(s) in RCA: 69] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2015] [Accepted: 05/11/2015] [Indexed: 12/27/2022] Open
Abstract
The chromatin landscape and promoter architecture are dominated by the interplay of nucleosome and transcription factor (TF) binding to crucial DNA sequence elements. However, it remains unclear whether nucleosomes mobilized by chromatin remodelers can influence TFs that are already present on the DNA template. In this study, we investigated the interplay between nucleosome remodeling, by either yeast ISW1a or SWI/SNF, and a bound TF. We found that a TF serves as a major barrier to ISW1a remodeling, and acts as a boundary for nucleosome repositioning. In contrast, SWI/SNF was able to slide a nucleosome past a TF, with concurrent eviction of the TF from the DNA, and the TF did not significantly impact the nucleosome positioning. Our results provide direct evidence for a novel mechanism for both nucleosome positioning regulation by bound TFs and TF regulation via dynamic repositioning of nucleosomes. DOI:http://dx.doi.org/10.7554/eLife.06249.001 Cells contain thousands of genes that are encoded by molecules of DNA. In yeast and other eukaryotic organisms, this DNA is wrapped around proteins called histones to make structures called nucleosomes. This compacts the DNA and allows it to fit inside the tiny nucleus within the cell. The positioning of the nucleosomes influences how tightly packed the DNA is, which in turn influences the activity of genes. Less active genes tend to be found within regions of DNA that are tightly packed, while more active genes are found in less tightly packed regions. To activate a gene, proteins called transcription factors bind to a section of DNA within the gene called the promoter. Enzymes known as ‘chromatin remodelers’ can alter the locations of nucleosomes on DNA to allow the transcription factors access to the promoters of particular genes. In yeast, the SWI/SNF family of chromatin remodelers can disassemble nucleosomes to promote gene activity, while the ISW1 family organises nucleosomes into closely spaced groups to repress gene activity. However, it is not clear if, or how, chromatin remodelers can influence transcription factors that are already bound to DNA. Here, Li et al. studied the interactions between a transcription factor and the chromatin remodelers in yeast. The experiment used a piece of DNA that contained a bound transcription factor and a single nucleosome. Li et al. used a technique called ‘single molecule DNA unzipping’, which enabled them to precisely locate the position of the nucleosome and transcription factor before and after the nucleosome was remodeled. The experiments found that a chromatin remodeler called ISW1a moved the nucleosome away from the transcription factor, while a SWI/SNF chromatin remodeler moved the nucleosome towards it. Significantly, Li et al. also found that a transcription factor is a major barrier to ISW1a's remodeling activity, suggesting that ISW1a may use transcription factors as reference points to position nucleosomes. In contrast, SWI/SNF was able to slide a nucleosome past the transcription factor, which led to the transcription factor falling off the DNA. Therefore, SWI/SNF is able to move transcription factors out of the way to deactivate genes. Li et al. propose a new model for how chromatin remodelers can move nucleosomes and regulate transcription factors to alter gene activity. A future challenge will be to observe these types of activities in living cells. DOI:http://dx.doi.org/10.7554/eLife.06249.002
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Affiliation(s)
- Ming Li
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, United States
| | - Arjan Hada
- Department of Biochemistry and Molecular Biology, Southern Illinois University School of Medicine, Carbondale, United States
| | - Payel Sen
- Department of Biochemistry and Molecular Biology, Southern Illinois University School of Medicine, Carbondale, United States
| | - Lola Olufemi
- Department of Biochemistry and Molecular Biology, Southern Illinois University School of Medicine, Carbondale, United States
| | - Michael A Hall
- Department of Physics, Laboratory of Atomic and Solid State Physics, Howard Hughes Medical Institute, Cornell University, Ithaca, United States
| | - Benjamin Y Smith
- Department of Physics, Laboratory of Atomic and Solid State Physics, Howard Hughes Medical Institute, Cornell University, Ithaca, United States
| | - Scott Forth
- Department of Physics, Laboratory of Atomic and Solid State Physics, Howard Hughes Medical Institute, Cornell University, Ithaca, United States
| | - Jeffrey N McKnight
- Thomas C. Jenkins Department of Biophysics, Johns Hopkins University, Baltimore, United States
| | - Ashok Patel
- Thomas C. Jenkins Department of Biophysics, Johns Hopkins University, Baltimore, United States
| | - Gregory D Bowman
- Thomas C. Jenkins Department of Biophysics, Johns Hopkins University, Baltimore, United States
| | - Blaine Bartholomew
- Department of Biochemistry and Molecular Biology, Southern Illinois University School of Medicine, Carbondale, United States
| | - Michelle D Wang
- Department of Physics, Laboratory of Atomic and Solid State Physics, Howard Hughes Medical Institute, Cornell University, Ithaca, United States
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131
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Kadoch C, Crabtree GR. Mammalian SWI/SNF chromatin remodeling complexes and cancer: Mechanistic insights gained from human genomics. SCIENCE ADVANCES 2015; 1:e1500447. [PMID: 26601204 PMCID: PMC4640607 DOI: 10.1126/sciadv.1500447] [Citation(s) in RCA: 571] [Impact Index Per Article: 63.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/08/2015] [Accepted: 04/26/2015] [Indexed: 05/25/2023]
Abstract
Over the past 4 years, nearly 100 exome sequencing studies have revealed the high frequency of mutations in the genes encoding the subunits of ATP-dependent chromatin remodelers in human cancer. Most of these mutations are within the genes encoding subunits of the BAF (Brg/Brahma-associated factors) or mSWI/SNF complex, which is one of two dozen predicted ATP-dependent chromatin remodeling complexes in mammals. Considering BAF complexes as a single entity, the 15 subunits encoded by 29 genes are mutated in >20% of human cancer, across a broad range of tumor types. These observations demonstrate that there is little redundancy in the oncogenic function of BAF complexes with the other remodeling complexes, underscoring their unique roles. Several important conclusions emerge from these genomic data: specific subunits appear to be mutated in specific cancers, highlighting tissue-specific protective roles; mutations can function as tumor suppressors or oncogenes; mutations can be homozygous or, more commonly, heterozygous, implying their dosage-sensitive roles in an unknown yet fundamental process used to suppress the genesis of cancer. These new human genetic findings paired with biochemical studies are challenging old ideas on how chromatin remodeling complexes function, generating new hypotheses with respect to their normal and oncogenic mechanisms and highlighting potential avenues for therapeutic intervention in human cancer.
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Affiliation(s)
- Cigall Kadoch
- Department of Pediatric Oncology, Dana-Farber Cancer Institute and Harvard Medical School, Boston, MA 02215, USA
- Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA
| | - Gerald R. Crabtree
- Howard Hughes Medical Institute, Departments of Pathology and Developmental Biology, Stanford University, Stanford, CA 94305, USA
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132
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Koster M, Snel B, Timmers H. Genesis of Chromatin and Transcription Dynamics in the Origin of Species. Cell 2015; 161:724-36. [DOI: 10.1016/j.cell.2015.04.033] [Citation(s) in RCA: 56] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2014] [Indexed: 11/15/2022]
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133
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Kongpetch S, Jusakul A, Ong CK, Lim WK, Rozen SG, Tan P, Teh BT. Pathogenesis of cholangiocarcinoma: From genetics to signalling pathways. Best Pract Res Clin Gastroenterol 2015; 29:233-44. [PMID: 25966424 DOI: 10.1016/j.bpg.2015.02.002] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/19/2014] [Accepted: 02/07/2015] [Indexed: 01/31/2023]
Abstract
Cholangiocarcinoma (CCA) is a malignant tumour of bile duct epithelial cells with dismal prognosis and rising incidence. Chronic inflammation resulting from liver fluke infection, hepatitis and other inflammatory bowel diseases is a major contributing factor to cholangiocarcinogenesis, likely through accumulation of serial genetic and epigenetic alterations resulting in aberration of oncogenes and tumour suppressors. Recent studies making use of advances in high-throughput genomics have revealed the genetic landscape of CCA, greatly increasing our understanding of its underlying biology. A series of highly recurrent mutations in genes such as TP53, KRAS, SMAD4, BRAF, MLL3, ARID1A, PBRM1 and BAP1, which are known to be involved in cell cycle control, cell signalling pathways and chromatin dynamics, have led to investigations of their roles, through molecular to mouse modelling studies, in cholangiocarcinogenesis. This review focuses on the landscape genetic alterations in CCA and its functional relevance to the formation and progression of CCA.
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Affiliation(s)
- Sarinya Kongpetch
- Laboratory of Cancer Epigenome, Division of Medical Sciences, National Cancer Centre Singapore, Singapore; Department of Pharmacology, Faculty of Medicine and Liver Fluke and Cholangiocarcinoma Research Center, Khon Kaen University, Khon Kaen, Thailand; Division of Cancer and Stem Cell Biology, Duke-National University of Singapore (NUS) Graduate Medical School, Singapore.
| | - Apinya Jusakul
- Laboratory of Cancer Epigenome, Division of Medical Sciences, National Cancer Centre Singapore, Singapore; Division of Cancer and Stem Cell Biology, Duke-National University of Singapore (NUS) Graduate Medical School, Singapore.
| | - Choon Kiat Ong
- Laboratory of Cancer Epigenome, Division of Medical Sciences, National Cancer Centre Singapore, Singapore; Division of Cancer and Stem Cell Biology, Duke-National University of Singapore (NUS) Graduate Medical School, Singapore.
| | - Weng Khong Lim
- Laboratory of Cancer Epigenome, Division of Medical Sciences, National Cancer Centre Singapore, Singapore; Division of Cancer and Stem Cell Biology, Duke-National University of Singapore (NUS) Graduate Medical School, Singapore.
| | - Steven G Rozen
- Division of Cancer and Stem Cell Biology, Duke-National University of Singapore (NUS) Graduate Medical School, Singapore; Centre for Computational Biology, Duke-NUS Graduate Medical School, Singapore.
| | - Patrick Tan
- Division of Cancer and Stem Cell Biology, Duke-National University of Singapore (NUS) Graduate Medical School, Singapore; Genome Institute of Singapore, Singapore; Cancer Science Institute of Singapore, National University of Singapore, Singapore.
| | - Bin Tean Teh
- Laboratory of Cancer Epigenome, Division of Medical Sciences, National Cancer Centre Singapore, Singapore; Division of Cancer and Stem Cell Biology, Duke-National University of Singapore (NUS) Graduate Medical School, Singapore; Cancer Science Institute of Singapore, National University of Singapore, Singapore.
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134
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Alexander JM, Hota SK, He D, Thomas S, Ho L, Pennacchio LA, Bruneau BG. Brg1 modulates enhancer activation in mesoderm lineage commitment. Development 2015; 142:1418-30. [PMID: 25813539 PMCID: PMC4392595 DOI: 10.1242/dev.109496] [Citation(s) in RCA: 70] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2014] [Accepted: 02/27/2015] [Indexed: 12/28/2022]
Abstract
The interplay between different levels of gene regulation in modulating developmental transcriptional programs, such as histone modifications and chromatin remodeling, is not well understood. Here, we show that the chromatin remodeling factor Brg1 is required for enhancer activation in mesoderm induction. In an embryonic stem cell-based directed differentiation assay, the absence of Brg1 results in a failure of cardiomyocyte differentiation and broad deregulation of lineage-specific gene expression during mesoderm induction. We find that Brg1 co-localizes with H3K27ac at distal enhancers and is required for robust H3K27 acetylation at distal enhancers that are activated during mesoderm induction. Brg1 is also required to maintain Polycomb-mediated repression of non-mesodermal developmental regulators, suggesting cooperativity between Brg1 and Polycomb complexes. Thus, Brg1 is essential for modulating active and repressive chromatin states during mesoderm lineage commitment, in particular the activation of developmentally important enhancers. These findings demonstrate interplay between chromatin remodeling complexes and histone modifications that, together, ensure robust and broad gene regulation during crucial lineage commitment decisions. SUMMARY: The chromatin remodeling factor Brg1 is essential for mesoderm induction and, by modulating active and repressive chromatin states, is involved in promoting the activation of dynamic enhancers.
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Affiliation(s)
- Jeffrey M Alexander
- Gladstone Institute of Cardiovascular Disease, San Francisco, CA 94158, USA Roddenberry Center for Stem Cell Biology and Medicine at Gladstone, San Francisco, CA 94158, USA
| | - Swetansu K Hota
- Gladstone Institute of Cardiovascular Disease, San Francisco, CA 94158, USA Roddenberry Center for Stem Cell Biology and Medicine at Gladstone, San Francisco, CA 94158, USA
| | - Daniel He
- Gladstone Institute of Cardiovascular Disease, San Francisco, CA 94158, USA Roddenberry Center for Stem Cell Biology and Medicine at Gladstone, San Francisco, CA 94158, USA
| | - Sean Thomas
- Gladstone Institute of Cardiovascular Disease, San Francisco, CA 94158, USA Roddenberry Center for Stem Cell Biology and Medicine at Gladstone, San Francisco, CA 94158, USA
| | - Lena Ho
- Institute of Medical Biology, A*STAR, Singapore 138648
| | - Len A Pennacchio
- Genomics Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA United States Department of Energy, Joint Genome Institute, Walnut Creek, CA 94598, USA
| | - Benoit G Bruneau
- Gladstone Institute of Cardiovascular Disease, San Francisco, CA 94158, USA Roddenberry Center for Stem Cell Biology and Medicine at Gladstone, San Francisco, CA 94158, USA Department of Pediatrics, University of California, San Francisco, CA 94143, USA Cardiovascular Research Institute, University of California, San Francisco, CA 94158, USA
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135
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Bowman GD, Poirier MG. Post-translational modifications of histones that influence nucleosome dynamics. Chem Rev 2015; 115:2274-95. [PMID: 25424540 PMCID: PMC4375056 DOI: 10.1021/cr500350x] [Citation(s) in RCA: 318] [Impact Index Per Article: 35.3] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2014] [Indexed: 12/12/2022]
Affiliation(s)
- Gregory D. Bowman
- T.
C. Jenkins Department of Biophysics, Johns
Hopkins University, Baltimore, Maryland 21218, United States
| | - Michael G. Poirier
- Department of Physics, and Department of
Chemistry and Biochemistry, The Ohio State
University, Columbus, Ohio 43210, United
States
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136
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Harada A, Mallappa C, Okada S, Butler JT, Baker SP, Lawrence JB, Ohkawa Y, Imbalzano AN. Spatial re-organization of myogenic regulatory sequences temporally controls gene expression. Nucleic Acids Res 2015; 43:2008-21. [PMID: 25653159 PMCID: PMC4344497 DOI: 10.1093/nar/gkv046] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2014] [Revised: 11/05/2014] [Accepted: 01/13/2015] [Indexed: 12/14/2022] Open
Abstract
During skeletal muscle differentiation, the activation of some tissue-specific genes occurs immediately while others are delayed. The molecular basis controlling temporal gene regulation is poorly understood. We show that the regulatory sequences, but not other regions of genes expressed at late times of myogenesis, are in close physical proximity in differentiating embryonic tissue and in differentiating culture cells, despite these genes being located on different chromosomes. Formation of these inter-chromosomal interactions requires the lineage-determinant MyoD and functional Brg1, the ATPase subunit of SWI/SNF chromatin remodeling enzymes. Ectopic expression of myogenin and a specific Mef2 isoform induced myogenic differentiation without activating endogenous MyoD expression. Under these conditions, the regulatory sequences of late gene loci were not in close proximity, and these genes were prematurely activated. The data indicate that the spatial organization of late genes contributes to temporal regulation of myogenic transcription by restricting late gene expression during the early stages of myogenesis.
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Affiliation(s)
- Akihito Harada
- Department of Advanced Medical Initiatives, JST-CREST, Faculty of Medicine, Kyushu University, Fukuoka 812-8582, Japan
| | - Chandrashekara Mallappa
- Department of Cell and Developmental Biology, University of Massachusetts Medical School, Worcester, MA 01655, USA
| | - Seiji Okada
- Department of Advanced Medical Initiatives, JST-CREST, Faculty of Medicine, Kyushu University, Fukuoka 812-8582, Japan
| | - John T Butler
- Department of Cell and Developmental Biology, University of Massachusetts Medical School, Worcester, MA 01655, USA
| | - Stephen P Baker
- Department of Cell and Developmental Biology, University of Massachusetts Medical School, Worcester, MA 01655, USA Department of Quantitative Health Sciences, University of Massachusetts Medical School, Worcester, MA 01655, USA
| | - Jeanne B Lawrence
- Department of Cell and Developmental Biology, University of Massachusetts Medical School, Worcester, MA 01655, USA
| | - Yasuyuki Ohkawa
- Department of Advanced Medical Initiatives, JST-CREST, Faculty of Medicine, Kyushu University, Fukuoka 812-8582, Japan Department of Cell and Developmental Biology, University of Massachusetts Medical School, Worcester, MA 01655, USA
| | - Anthony N Imbalzano
- Department of Cell and Developmental Biology, University of Massachusetts Medical School, Worcester, MA 01655, USA
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137
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Ryu SH, Jang MK, Kim WJ, Lee D, Chung YH. Metastatic tumor antigen in hepatocellular carcinoma: golden roads toward personalized medicine. Cancer Metastasis Rev 2014; 33:965-80. [PMID: 25325987 DOI: 10.1007/s10555-014-9522-4] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Hepatocellular carcinoma (HCC), a prototype of hypervascular tumors, is one of the most common malignancies in the world, especially hyperendemic in the Far East where chronic hepatitis B virus (HBV) infection is highly prevalent. It is characterized by the clinical feature of a poor prognosis or a high mortality due to its already far advanced stages at diagnosis. It is so multifactorial that hepatocarcinogenesis cannot be explained by a single molecular mechanism. To date, a number of pathways have been known to contribute to the development, growth, angiogenesis, and even metastasis of HCC. Among the various factors, metastatic tumor antigens (MTAs) or metastasis-associated proteins have been vigorously investigated as an intriguing target in the field of hepatocarcinogenesis. According to recent studies including ours, MTAs are not only involved in the HCC development and growth (molecular carcinogenesis), but also closely associated with the post-operative recurrence and a poor prognosis or a worse response to post-operative anti-cancer therapy (clinical significance). Herein, we review MTAs in light of their essential structure, functions, and molecular mechanism in hepatocarcinogenesis. We will also focus in detail on the interaction between hepatitis B x protein (HBx) of HBV and MTA in order to clarify the HBV-associated HCC development. Finally, we will discuss the prognostic significance and clinical application of MTA in HCC. We believe that this review will help clinicians to understand the meaning and use of the detection of MTA in order to more effectively manage their HCC patients.
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Affiliation(s)
- Soo Hyung Ryu
- Department of Internal Medicine, Inje University College of Medicine, Seoul Paik Hospital, Seoul, South Korea
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138
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Meier K, Brehm A. Chromatin regulation: how complex does it get? Epigenetics 2014; 9:1485-95. [PMID: 25482055 PMCID: PMC4622878 DOI: 10.4161/15592294.2014.971580] [Citation(s) in RCA: 86] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2014] [Revised: 08/18/2014] [Accepted: 09/29/2014] [Indexed: 12/16/2022] Open
Abstract
Gene transcription is tightly regulated at different levels to ensure that the transcriptome of the cell is appropriate for developmental stage and cell type. The chromatin state in which a gene is embedded determines its expression level to a large extent. Activation or repression of transcription is typically accomplished by the recruitment of chromatin-associated multisubunit protein complexes that combine several molecular tools, such as histone-binding and chromatin-modifying activities. Recent biochemical purifications of such complexes have revealed a substantial diversity. On the one hand, complexes that were thought to be unique have been revealed to be part of large complex families. On the other hand, protein subunits that were thought to only exist in separate complexes have been shown to coexist in novel assemblies. In this review we discuss our current knowledge of repressor complexes that contain MBT domain proteins and/or the CoREST co-repressor and use them as a paradigm to illustrate the unexpected heterogeneity and tool sharing of chromatin regulating protein complexes. These recent insights also challenge the ways we define and think about protein complexes in general.
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Key Words
- ATP, adenosine triphosphate
- BAP, brahma associated protein
- BHC80, BRAF-histone deacetylase complex 80
- BRG1, brahma Related Gene 1
- CHD, chromo domain helicase DNA binding
- CoREST
- CoREST REST, corepressor
- DNA, deoxyribonucleic acid
- DNMT, DNA methyltransferase
- DP-1, dimerization partner 1
- E2F, E2 transcription Factor
- ELM2, EGL-27 and MTA1 homology 2
- ES cell, embryonic stem cells
- H, histone
- HDAC, histone deacetylas
- HMTase, histone methylase
- HP1, heterochromatin protein 1
- K, lysine
- L3MBTL, lethal 3 malignant brain tumor-like
- LINT, l(3)mbt interacting
- LSD1, lysine-specific demethylase 1
- Lint-1, l(3)mbt interacting 1
- MBT protein
- MBT, malignant brain tumor
- MBTS, malignant brain tumor signature
- NPA1, nucleosome assembly protein
- NRSF, neural-restrictive silencing factor
- NuRD, nucleosome remodeling and deacetylase
- PBAP, polybromo-associated BAP
- PHD, plant homeo domain
- PRC1, polycomb repressive complex 1
- PRE, polycomb responsive element
- Pc, polycomb
- PcG, polycomb group
- Ph, polyhomeotic
- Pho, pleiohomeotic
- PhoRC, Pho repressive complex
- Psc, posterior sex combs
- RB, retinoblastoma
- REST, repressor element 1 silencing transcription factor
- RNA, ribonucleic acid
- Rpd3, reduced potassium dependency 3
- SANT, SWI/ADA2/N-CoR/TFIIIB
- SCML, sex combs on midleg-like
- SLC, SFMBT1, LSD1, CoREST
- SWH, Salvador-Warts-Hippo
- SWI/SNF, switching defective/sucrose non-fermenting
- Sce, sex combs extra
- Scm, sex combs on midleg
- Sfmbt, Scm-related gene containing 4 mbt domains
- TSS, transcription start site
- YY1, ying-yang 1
- ZNF, zinc finger
- complex family
- dL(3)mbt, Drosophila Lethal 3 malignant brain tumor
- hBRM, human Brahma
- l(3)mbt, lethal 3 malignant brain tumor
- protein complex
- transcriptional regulation
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Affiliation(s)
- Karin Meier
- Institut für Molekularbiologie und Tumorforschung; Philipps-Universität Marburg; Marburg, Germany
- Instituto de Fisiología Celular; Departamento de Genética Molecular; Universidad Nacional Autónoma de México; México City, México
| | - Alexander Brehm
- Institut für Molekularbiologie und Tumorforschung; Philipps-Universität Marburg; Marburg, Germany
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139
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Kingston RE, Tamkun JW. Transcriptional regulation by trithorax-group proteins. Cold Spring Harb Perspect Biol 2014; 6:a019349. [PMID: 25274705 DOI: 10.1101/cshperspect.a019349] [Citation(s) in RCA: 72] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
The trithorax group of genes (trxG) was identified in mutational screens that examined developmental phenotypes and suppression of Polycomb mutant phenotypes. The protein products of these genes are primarily involved in gene activation, although some can also have repressive effects. There is no central function for these proteins. Some move nucleosomes about on the genome in an ATP-dependent manner, some covalently modify histones such as methylating lysine 4 of histone H3, and some directly interact with the transcription machinery or are a part of that machinery. It is interesting to consider why these specific members of large families of functionally related proteins have strong developmental phenotypes.
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Affiliation(s)
- Robert E Kingston
- Department of Molecular Biology, Massachusetts General Hospital, Boston, Massachusetts 02114
| | - John W Tamkun
- Department of Molecular, Cell and Developmental Biology, University of California, Santa Cruz, Santa Cruz, California 95064
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140
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Wang B, Kettenbach AN, Gerber SA, Loros JJ, Dunlap JC. Neurospora WC-1 recruits SWI/SNF to remodel frequency and initiate a circadian cycle. PLoS Genet 2014; 10:e1004599. [PMID: 25254987 PMCID: PMC4177678 DOI: 10.1371/journal.pgen.1004599] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2013] [Accepted: 07/13/2014] [Indexed: 12/23/2022] Open
Abstract
In the negative feedback loop comprising the Neurospora circadian oscillator, the White Collar Complex (WCC) formed from White Collar-1 (WC-1) and White Collar-2 (WC-2) drives transcription of the circadian pacemaker gene frequency (frq). Although FRQ-dependent repression of WCC has been extensively studied, the mechanism by which the WCC initiates a circadian cycle remains elusive. Structure/function analysis of WC-1 eliminated domains previously thought to transactivate frq expression but instead identified amino acids 100–200 as essential for frq circadian expression. A proteomics-based search for coactivators with WCC uncovered the SWI/SNF (SWItch/Sucrose NonFermentable) complex: SWI/SNF interacts with WCC in vivo and in vitro, binds to the Clock box in the frq promoter, and is required both for circadian remodeling of nucleosomes at frq and for rhythmic frq expression; interestingly, SWI/SNF is not required for light-induced frq expression. These data suggest a model in which WC-1 recruits SWI/SNF to remodel and loop chromatin at frq, thereby activating frq expression to initiate the circadian cycle. Circadian clocks govern behavior in a wide variety of organisms. These clocks are assembled in such a way that proteins encoded by a few dedicated “clock genes” form a complex that acts to reduce their own expression. That is, the genes and proteins participate in a negative feedback loop, and so long as the feedback has delays built in, this system will oscillate. The feedback loops that underlie circadian rhythms in fungi and animals are quite similar in many ways, and while much is known about the proteins themselves, both those that activate the dedicated clock genes and the clock proteins that repress their own expression, relatively little is known about how the initial expression of the clock genes is activated. In Neurospora, a fungal model for these clocks, the proteins that activate expression of the clock gene “frequency” bind to DNA far away from where the coding part of the gene begins, and a mystery has been how this action-at-a-distance works. The answer revealed here is that the activating proteins recruit other proteins to unwrap the DNA and bring the distal site close to the place where the coding part of the gene begins.
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Affiliation(s)
- Bin Wang
- Department of Genetics, Geisel School of Medicine, Dartmouth, Hanover, New Hampshire, United States of America
| | - Arminja N. Kettenbach
- Department of Genetics, Geisel School of Medicine, Dartmouth, Hanover, New Hampshire, United States of America
- Norris Cotton Cancer Center, Geisel School of Medicine, Dartmouth, Hanover, New Hampshire, United States of America
| | - Scott A. Gerber
- Department of Genetics, Geisel School of Medicine, Dartmouth, Hanover, New Hampshire, United States of America
- Norris Cotton Cancer Center, Geisel School of Medicine, Dartmouth, Hanover, New Hampshire, United States of America
| | - Jennifer J. Loros
- Department of Genetics, Geisel School of Medicine, Dartmouth, Hanover, New Hampshire, United States of America
- Department of Biochemistry, Geisel School of Medicine, Dartmouth, Hanover, New Hampshire, United States of America
| | - Jay C. Dunlap
- Department of Genetics, Geisel School of Medicine, Dartmouth, Hanover, New Hampshire, United States of America
- * E-mail:
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141
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Hohmann AF, Vakoc CR. A rationale to target the SWI/SNF complex for cancer therapy. Trends Genet 2014; 30:356-63. [PMID: 24932742 PMCID: PMC4112150 DOI: 10.1016/j.tig.2014.05.001] [Citation(s) in RCA: 141] [Impact Index Per Article: 14.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2014] [Revised: 05/07/2014] [Accepted: 05/11/2014] [Indexed: 02/06/2023]
Abstract
SWI/SNF is a multisubunit chromatin-remodeling complex that performs fundamental roles in gene regulation, cell lineage specification, and organismal development. Mutations that inactivate SWI/SNF subunits are found in nearly 20% of human cancers, which indicates that the proper functioning of this complex is necessary to prevent tumor formation in diverse tissues. Recent studies show that SWI/SNF-mutant cancers depend on residual SWI/SNF complexes for their aberrant growth, thus revealing synthetic lethal interactions that could be exploited for therapeutic purposes. Other studies reveal that certain acute leukemias and small cell lung cancers, which lack SWI/SNF mutations, can be vulnerable to inhibition of the SWI/SNF ATPase subunit BRG1, whereas several normal and malignant cell types do not show this sensitivity. Here, we review the emerging evidence that implicates SWI/SNF as a tumor-dependency and candidate drug target in human cancer.
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Affiliation(s)
- Anja F Hohmann
- Cold Spring Harbor Laboratory, 1 Bungtown Road, Cold Spring Harbor, NY 11724, USA
| | - Christopher R Vakoc
- Cold Spring Harbor Laboratory, 1 Bungtown Road, Cold Spring Harbor, NY 11724, USA.
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142
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Damiano L, Stewart KM, Cohet N, Mouw JK, Lakins JN, Debnath J, Reisman D, Nickerson JA, Imbalzano AN, Weaver VM. Oncogenic targeting of BRM drives malignancy through C/EBPβ-dependent induction of α5 integrin. Oncogene 2014; 33:2441-53. [PMID: 23770848 PMCID: PMC3960370 DOI: 10.1038/onc.2013.220] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2012] [Revised: 05/04/2013] [Accepted: 05/07/2013] [Indexed: 02/06/2023]
Abstract
Integrin expression and activity are altered in tumors, and aberrant integrin signaling promotes malignancy. However, how integrins become altered in tumors remains poorly understood. We discovered that oncogenic activation of MEK signaling induces cell growth and survival, and promotes the malignant phenotype of mammary epithelial cells (MECs) by increasing α5 integrin expression. We determined that MEK activates c-Myc to reduce the transcription of the SWI/SNF chromatin remodeling enzyme Brahma (BRM). Our studies revealed that reduced BRM expression and/or activity drives the malignant behavior of MECs by epigenetically promoting C/EBPβ expression to directly induce α5 integrin transcription. Consistently, we could show that restoring BRM levels normalized the malignant behavior of transformed MECs in culture and in vivo by preventing C/EBPβ-dependent α5 integrin transcription. Our findings identify a novel mechanism whereby oncogenic signaling promotes malignant transformation by regulating transcription of a key chromatin remodeling molecule that regulates integrin-dependent stromal-epithelial interactions.
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Affiliation(s)
- L Damiano
- Department of Surgery, Center for Bioengineering and Tissue Regeneration, University of California–San Francisco, San Francisco, CA, USA
| | - KM Stewart
- Department of Surgery, Center for Bioengineering and Tissue Regeneration, University of California–San Francisco, San Francisco, CA, USA
| | - N Cohet
- Department of Cell and Developmental Biology, University of Massachusetts Medical School, Worcester, MA, USA
| | - JK Mouw
- Department of Surgery, Center for Bioengineering and Tissue Regeneration, University of California–San Francisco, San Francisco, CA, USA
| | - JN Lakins
- Department of Surgery, Center for Bioengineering and Tissue Regeneration, University of California–San Francisco, San Francisco, CA, USA
| | - J Debnath
- Department of Pathology, University of California–San Francisco, San Francisco, CA, USA
| | - D Reisman
- Division of Hematology/Oncology, Department of Medicine, University of Florida, Gainesville, FL, USA
| | - JA Nickerson
- Department of Cell and Developmental Biology, University of Massachusetts Medical School, Worcester, MA, USA
| | - AN Imbalzano
- Department of Cell and Developmental Biology, University of Massachusetts Medical School, Worcester, MA, USA
| | - VM Weaver
- Department of Surgery, Center for Bioengineering and Tissue Regeneration, University of California–San Francisco, San Francisco, CA, USA
- Department of Anatomy, Bioengineering and Therapeutic Sciences, Eli and Edythe Broad Center of Regeneration Medicine and Stem Cell Research, Helen Diller Family Comprehensive Cancer Center, University of California–San Francisco, San Francisco, CA, USA
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143
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Mechanisms by which SMARCB1 loss drives rhabdoid tumor growth. Cancer Genet 2014; 207:365-72. [PMID: 24853101 DOI: 10.1016/j.cancergen.2014.04.004] [Citation(s) in RCA: 99] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2014] [Revised: 04/01/2014] [Accepted: 04/02/2014] [Indexed: 02/02/2023]
Abstract
SMARCB1 (INI1/SNF5/BAF47), a core subunit of the SWI/SNF (BAF) chromatin-remodeling complex, is inactivated in the large majority of rhabdoid tumors, and germline heterozygous SMARCB1 mutations form the basis for rhabdoid predisposition syndrome. Mouse models validated Smarcb1 as a bona fide tumor suppressor, as Smarcb1 inactivation in mice results in 100% of the animals rapidly developing cancer. SMARCB1 was the first subunit of the SWI/SNF complex found mutated in cancer. More recently, at least seven other genes encoding SWI/SNF subunits have been identified as recurrently mutated in cancer. Collectively, 20% of all human cancers contain a SWI/SNF mutation. Consequently, investigation of the mechanisms by which SMARCB1 mutation causes cancer has relevance not only for rhabdoid tumors, but also potentially for the wide variety of SWI/SNF mutant cancers. Here we discuss normal functions of SMARCB1 and the SWI/SNF complex as well as mechanistic and potentially therapeutic insights that have emerged.
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144
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Swygert SG, Peterson CL. Chromatin dynamics: interplay between remodeling enzymes and histone modifications. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2014; 1839:728-36. [PMID: 24583555 DOI: 10.1016/j.bbagrm.2014.02.013] [Citation(s) in RCA: 166] [Impact Index Per Article: 16.6] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 01/08/2014] [Revised: 02/13/2014] [Accepted: 02/20/2014] [Indexed: 01/08/2023]
Abstract
Chromatin dynamics play an essential role in regulating the accessibility of genomic DNA for a variety of nuclear processes, including gene transcription and DNA repair. The posttranslational modification of the core histones and the action of ATP-dependent chromatin remodeling enzymes represent two primary mechanisms by which chromatin dynamics are controlled and linked to nuclear events. Although there are examples in which a histone modification or a remodeling enzyme may be sufficient to drive a chromatin transition, these mechanisms typically work in concert to integrate regulatory inputs, leading to a coordinated alteration in chromatin structure and function. Indeed, site-specific histone modifications can facilitate the recruitment of chromatin remodeling enzymes to particular genomic regions, or they can regulate the efficiency or the outcome of a chromatin remodeling reaction. Conversely, chromatin remodeling enzymes can also influence, and sometimes directly modulate, the modification state of histones. These functional interactions are generally complex, frequently transient, and often require the association of myriad additional factors. This article is part of a Special Issue entitled: Molecular mechanisms of histone modification function.
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Affiliation(s)
- Sarah G Swygert
- Program in Molecular Medicine, University of Massachusetts Medical School, Worcester, MA 01605, USA
| | - Craig L Peterson
- Program in Molecular Medicine, University of Massachusetts Medical School, Worcester, MA 01605, USA.
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145
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Le N, Ho T, Ho B, Tran D. A nucleosomal approach to inferring causal relationships of histone modifications. BMC Genomics 2014; 15 Suppl 1:S7. [PMID: 24564627 PMCID: PMC4046832 DOI: 10.1186/1471-2164-15-s1-s7] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
Motivation Histone proteins are subject to various posttranslational modifications (PTMs). Elucidating their functional relationships is crucial toward understanding many biological processes. Bayesian network (BN)-based approaches have shown the advantage of revealing causal relationships, rather than simple cooccurrences, of PTMs. Previous works employing BNs to infer causal relationships of PTMs require that all confounders should be included. This assumption, however, is unavoidably violated given the fact that several modifications are often regulated by a common but unobserved factor. An existing non-parametric method can be applied to tackle the problem but the complexity and inflexibility make it impractical. Results We propose a novel BN-based method to infer causal relationships of histone modifications. First, from the evidence that nucleosome organization in vivo significantly affects the activities of PTM regulators working on chromatin substrate, hidden confounders of PTMs are selectively introduced by an information-theoretic criterion. Causal relationships are then inferred from a network model of both PTMs and the derived confounders. Application on human epigenomic data shows the advantage of the proposed method, in terms of computational performance and support from literature. Requiring less strict data assumptions also makes it more practical. Interestingly, analysis of the most significant relationships suggests that the proposed method can recover biologically relevant causal effects between histone modifications, which should be important for future investigation of histone crosstalk.
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146
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Burd CJ, Archer TK. Chromatin architecture defines the glucocorticoid response. Mol Cell Endocrinol 2013; 380:25-31. [PMID: 23545159 PMCID: PMC3762934 DOI: 10.1016/j.mce.2013.03.020] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/26/2012] [Revised: 03/19/2013] [Accepted: 03/21/2013] [Indexed: 01/10/2023]
Abstract
The glucocorticoid receptor (GR) functions to regulate a wide group of physiological processes through hormone inducible interaction with genomic loci and subsequent manipulation of the transcriptional output of target genes. Despite expression in a wide variety of tissues, the GR has diverse roles that are regulated tightly in a cell type specific manner. With the advent of whole genome approaches, the details of that diversity and the mechanisms regulating them are beginning to be elucidated. This review aims describe the recent advances detailing the role chromatin structure plays in dictating GR specificity.
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Affiliation(s)
- Craig J Burd
- Department of Molecular Genetics, The Ohio State University, Columbus, OH 43210, United States.
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147
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Vogel-Ciernia A, Wood MA. Neuron-specific chromatin remodeling: a missing link in epigenetic mechanisms underlying synaptic plasticity, memory, and intellectual disability disorders. Neuropharmacology 2013; 80:18-27. [PMID: 24140580 DOI: 10.1016/j.neuropharm.2013.10.002] [Citation(s) in RCA: 60] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2013] [Revised: 09/29/2013] [Accepted: 10/04/2013] [Indexed: 01/09/2023]
Abstract
Long-term memory formation requires the coordinated regulation of gene expression. Until recently nucleosome remodeling, one of the major epigenetic mechanisms for controlling gene expression, had been largely unexplored in the field of neuroscience. Nucleosome remodeling is carried out by chromatin remodeling complexes (CRCs) that interact with DNA and histones to physically alter chromatin structure and ultimately regulate gene expression. Human exome sequencing and gene wide association studies have linked mutations in CRC subunits to intellectual disability disorders, autism spectrum disorder and schizophrenia. However, how mutations in CRC subunits were related to human cognitive disorders was unknown. There appears to be both developmental and adult specific roles for the neuron specific CRC nBAF (neuronal Brg1/hBrm Associated Factor). nBAF regulates gene expression required for dendritic arborization during development, and in the adult, contributes to long-term potentiation, a form of synaptic plasticity, and long-term memory. We propose that the nBAF complex is a novel epigenetic mechanism for regulating transcription required for long-lasting forms of synaptic plasticity and memory processes and that impaired nBAF function may result in human cognitive disorders.
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Affiliation(s)
- Annie Vogel-Ciernia
- University of California, Irvine, Department of Neurobiology & Behavior, Irvine, CA, USA; Center for the Neurobiology of Learning & Memory, Irvine, CA, USA
| | - Marcelo A Wood
- University of California, Irvine, Department of Neurobiology & Behavior, Irvine, CA, USA; Center for the Neurobiology of Learning & Memory, Irvine, CA, USA.
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148
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Torigoe SE, Patel A, Khuong MT, Bowman GD, Kadonaga JT. ATP-dependent chromatin assembly is functionally distinct from chromatin remodeling. eLife 2013; 2:e00863. [PMID: 23986862 PMCID: PMC3748710 DOI: 10.7554/elife.00863] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2013] [Accepted: 07/16/2013] [Indexed: 11/23/2022] Open
Abstract
Chromatin assembly involves the combined action of ATP-dependent motor proteins and histone chaperones. Because motor proteins in chromatin assembly also function as chromatin remodeling factors, we investigated the relationship between ATP-driven chromatin assembly and chromatin remodeling in the generation of periodic nucleosome arrays. We found that chromatin remodeling-defective Chd1 motor proteins are able to catalyze ATP-dependent chromatin assembly. The resulting nucleosomes are not, however, spaced in periodic arrays. Wild-type Chd1, but not chromatin remodeling-defective Chd1, can catalyze the conversion of randomly-distributed nucleosomes into periodic arrays. These results reveal a functional distinction between ATP-dependent nucleosome assembly and chromatin remodeling, and suggest a model for chromatin assembly in which randomly-distributed nucleosomes are formed by the nucleosome assembly function of Chd1, and then regularly-spaced nucleosome arrays are generated by the chromatin remodeling activity of Chd1. These findings uncover an unforeseen level of specificity in the role of motor proteins in chromatin assembly. DOI:http://dx.doi.org/10.7554/eLife.00863.001 In many cells, genomic DNA is wrapped around proteins known as histones to produce particles called nucleosomes. These particles then join together—like beads on a string—to form a highly periodic structure called chromatin. In the nucleus, chromatin is further folded and condensed into chromosomes. However, many important processes, including the replication of DNA and the transcription of genes, require access to the DNA. The cell must therefore be able to disassemble chromatin and remove the histones, and then, once these processes are complete, to reassemble the chromatin. Enzymes known as chromatin assembly factors are responsible for the disassembly and reassembly of chromatin. There are two main types of chromatin assembly factors in eukaryotic cells (i.e., cells with nuclei)—histone chaperones and motor proteins. The histone chaperones escort histones from the cytoplasm, where they are made, to the nucleus. The motor proteins—using energy supplied by ATP molecules—then catalyze the formation of nucleosomes. This involves two activities: the motor proteins assemble nucleosomes by helping the DNA to wrap around the histones, and they also remodel chromatin by altering the positions of nucleosomes along the DNA to ensure that they are periodic—that is, regularly spaced. A conserved motor protein called Chd1 performs chromatin assembly and remodeling in eukaryotic cells. Chd1 works in conjunction with histone chaperones—both are needed for chromatin assembly, and so are DNA, histones and ATP. However, whether or not chromatin assembly and chromatin remodeling by Chd1 are identical or distinct processes is not well understood. Torigoe et al. have now discovered a mutant Chd1 protein that has nucleosome assembly activity (i.e., it can make nucleosomes) but cannot remodel chromatin (i.e., it is unable to move nucleosomes), and thus have demonstrated that these two processes are functionally distinct. Torigoe et al. additionally have found that the mutant Chd1 proteins produce randomly distributed nucleosomes rather than the periodic arrays normally found in chromatin. Further analysis then revealed that the wild-type Chd1 protein, which can remodel chromatin, is able to convert randomly distributed nucleosomes into periodic arrays. These findings have led to a new model for chromatin assembly in which Chd1 initially generates randomly distributed nucleosomes (via its assembly function), and then converts them into periodic arrays of nucleosomes (via its remodeling function). Together, these studies shed light on the mechanisms by which chromatin is created and manipulated in cells. DOI:http://dx.doi.org/10.7554/eLife.00863.002
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Affiliation(s)
- Sharon E Torigoe
- Section of Molecular Biology , University of California, San Diego , La Jolla , United States
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149
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Torigoe SE, Patel A, Khuong MT, Bowman GD, Kadonaga JT. ATP-dependent chromatin assembly is functionally distinct from chromatin remodeling. eLife 2013. [PMID: 23986862 DOI: 10.7554/elife.00863.001] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Chromatin assembly involves the combined action of ATP-dependent motor proteins and histone chaperones. Because motor proteins in chromatin assembly also function as chromatin remodeling factors, we investigated the relationship between ATP-driven chromatin assembly and chromatin remodeling in the generation of periodic nucleosome arrays. We found that chromatin remodeling-defective Chd1 motor proteins are able to catalyze ATP-dependent chromatin assembly. The resulting nucleosomes are not, however, spaced in periodic arrays. Wild-type Chd1, but not chromatin remodeling-defective Chd1, can catalyze the conversion of randomly-distributed nucleosomes into periodic arrays. These results reveal a functional distinction between ATP-dependent nucleosome assembly and chromatin remodeling, and suggest a model for chromatin assembly in which randomly-distributed nucleosomes are formed by the nucleosome assembly function of Chd1, and then regularly-spaced nucleosome arrays are generated by the chromatin remodeling activity of Chd1. These findings uncover an unforeseen level of specificity in the role of motor proteins in chromatin assembly. DOI:http://dx.doi.org/10.7554/eLife.00863.001.
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Affiliation(s)
- Sharon E Torigoe
- Section of Molecular Biology , University of California, San Diego , La Jolla , United States
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150
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Oike T, Ogiwara H, Nakano T, Yokota J, Kohno T. Inactivating Mutations in SWI/SNF Chromatin Remodeling Genes in Human Cancer. Jpn J Clin Oncol 2013; 43:849-55. [DOI: 10.1093/jjco/hyt101] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
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