1
|
Ferreira ACF, Szeto ACH, Clark PA, Crisp A, Kozik P, Jolin HE, McKenzie ANJ. Neuroprotective protein ADNP-dependent histone remodeling complex promotes T helper 2 immune cell differentiation. Immunity 2023; 56:1468-1484.e7. [PMID: 37285842 PMCID: PMC10501989 DOI: 10.1016/j.immuni.2023.05.010] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2022] [Revised: 03/31/2023] [Accepted: 05/12/2023] [Indexed: 06/09/2023]
Abstract
Type 2 immune responses are critical in tissue homeostasis, anti-helminth immunity, and allergy. T helper 2 (Th2) cells produce interleukin-4 (IL-4), IL-5, and IL-13 from the type 2 gene cluster under regulation by transcription factors (TFs) including GATA3. To better understand transcriptional regulation of Th2 cell differentiation, we performed CRISPR-Cas9 screens targeting 1,131 TFs. We discovered that activity-dependent neuroprotector homeobox protein (ADNP) was indispensable for immune reactions to allergen. Mechanistically, ADNP performed a previously unappreciated role in gene activation, forming a critical bridge in the transition from pioneer TFs to chromatin remodeling by recruiting the helicase CHD4 and ATPase BRG1. Although GATA3 and AP-1 bound the type 2 cytokine locus in the absence of ADNP, they were unable to initiate histone acetylation or DNA accessibility, resulting in highly impaired type 2 cytokine expression. Our results demonstrate an important role for ADNP in promoting immune cell specialization.
Collapse
Affiliation(s)
| | | | - Paula A Clark
- MRC Laboratory of Molecular Biology, Cambridge CB2 0QH, UK
| | - Alastair Crisp
- MRC Laboratory of Molecular Biology, Cambridge CB2 0QH, UK
| | - Patrycja Kozik
- MRC Laboratory of Molecular Biology, Cambridge CB2 0QH, UK
| | - Helen E Jolin
- MRC Laboratory of Molecular Biology, Cambridge CB2 0QH, UK
| | | |
Collapse
|
2
|
Moena D, Vargas E, Montecino M. Epigenetic regulation during 1,25-dihydroxyvitamin D 3-dependent gene transcription. VITAMINS AND HORMONES 2023; 122:51-74. [PMID: 36863801 DOI: 10.1016/bs.vh.2023.01.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/10/2023]
Abstract
Multiple evidence accumulated over the years, demonstrates that vitamin D-dependent physiological control in vertebrates occurs primarily through the regulation of target gene transcription. In addition, there has been an increasing appreciation of the role of the chromatin organization of the genome on the ability of the active form of vitamin D, 1,25(OH)2D3, and its specific receptor VDR to regulate gene expression. Chromatin structure in eukaryotic cells is principally modulated through epigenetic mechanisms including, but not limited to, a wide number of post-translational modifications of histone proteins and ATP-dependent chromatin remodelers, which are operative in different tissues during response to physiological cues. Hence, there is necessity to understand in depth the epigenetic control mechanisms that operate during 1,25(OH)2D3-dependent gene regulation. This chapter provides a general overview about epigenetic mechanisms functioning in mammalian cells and discusses how some of these mechanisms represent important components during transcriptional regulation of the model gene system CYP24A1 in response to 1,25(OH)2D3.
Collapse
Affiliation(s)
- Daniel Moena
- School of Bachelor in Science, Faculty of Life Sciences, Universidad Andres Bello, Concepcion, Chile
| | - Esther Vargas
- School of Medicine, Universidad Andres Bello, Santiago, Chile
| | - Martin Montecino
- Institute of Biomedical Sciences, Faculty of Medicine, Universidad Andres Bello, Santiago, Chile; Millenium Institute Center for Genome Regulation (CRG), Santiago, Chile.
| |
Collapse
|
3
|
van Zundert B, Montecino M. Epigenetic Changes and Chromatin Reorganization in Brain Function: Lessons from Fear Memory Ensemble and Alzheimer’s Disease. Int J Mol Sci 2022; 23:ijms232012081. [PMID: 36292933 PMCID: PMC9602769 DOI: 10.3390/ijms232012081] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2022] [Revised: 10/03/2022] [Accepted: 10/05/2022] [Indexed: 11/16/2022] Open
Abstract
Healthy brain functioning in mammals requires a continuous fine-tuning of gene expression. Accumulating evidence over the last three decades demonstrates that epigenetic mechanisms and dynamic changes in chromatin organization are critical components during the control of gene transcription in neural cells. Recent genome-wide analyses show that the regulation of brain genes requires the contribution of both promoter and long-distance enhancer elements, which must functionally interact with upregulated gene expression in response to physiological cues. Hence, a deep comprehension of the mechanisms mediating these enhancer–promoter interactions (EPIs) is critical if we are to understand the processes associated with learning, memory and recall. Moreover, the onset and progression of several neurodegenerative diseases and neurological alterations are found to be strongly associated with changes in the components that support and/or modulate the dynamics of these EPIs. Here, we overview relevant discoveries in the field supporting the role of the chromatin organization and of specific epigenetic mechanisms during the control of gene transcription in neural cells from healthy mice subjected to the fear conditioning paradigm, a relevant model to study memory ensemble. Additionally, special consideration is dedicated to revising recent results generated by investigators working with animal models and human postmortem brain tissue to address how changes in the epigenome and chromatin architecture contribute to transcriptional dysregulation in Alzheimer’s disease, a widely studied neurodegenerative disease. We also discuss recent developments of potential new therapeutic strategies involving epigenetic editing and small chromatin-modifying molecules (or epidrugs).
Collapse
Affiliation(s)
- Brigitte van Zundert
- Institute of Biomedical Sciences, Faculty of Medicine and Faculty of Life Sciences, Universidad Andres Bello, Santiago 8370186, Chile
- CARE Biomedical Research Center, Santiago 8330005, Chile
- Correspondence: (B.v.Z.); (M.M.)
| | - Martin Montecino
- Institute of Biomedical Sciences, Faculty of Medicine and Faculty of Life Sciences, Universidad Andres Bello, Santiago 8370186, Chile
- Millennium Institute Center for Genome Regulation CRG, Santiago 8370186, Chile
- Correspondence: (B.v.Z.); (M.M.)
| |
Collapse
|
4
|
Piatek P, Tarkowski M, Namiecinska M, Riva A, Wieczorek M, Michlewska S, Dulska J, Domowicz M, Kulińska-Michalska M, Lewkowicz N, Lewkowicz P. H3K4me3 Histone ChIP-Seq Analysis Reveals Molecular Mechanisms Responsible for Neutrophil Dysfunction in HIV-Infected Individuals. Front Immunol 2021; 12:682094. [PMID: 34335583 PMCID: PMC8320512 DOI: 10.3389/fimmu.2021.682094] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2021] [Accepted: 05/25/2021] [Indexed: 01/15/2023] Open
Abstract
Peripheral neutrophils in HIV-infected individuals are characterized by impairment of chemotaxis, phagocytosis, bactericidal activity, and oxidative burst ability regardless of whether patients are receiving antiretroviral therapy or not. Neutrophil dysfunction leads not only to increased susceptibility to opportunistic infections but also to tissue damage through the release of reactive oxygen species (ROS), proteases, and other potentially harmful effector molecules contributing to AIDS progression. In this study, we demonstrated high levels of histone H3 lysine K4 trimethylated (H3K4me3) and dysregulation of DNA transcription in circulating neutrophils of HIV-infected subjects. This dysregulation was accompanied by a deficient response of neutrophils to LPS, impaired cytokine/chemokine/growth factor synthesis, and increased apoptosis. Chromatin immunoprecipitation sequencing (ChIPseq) H3K4me3 histone analysis revealed that the most spectacular abnormalities were observed in the exons, introns, and promoter-TSS regions. Bioinformatic analysis of Gene Ontology, including biological processes, molecular function, and cellular components, demonstrated that the main changes were related to the genes responsible for cell activation, cytokine production, adhesive molecule expression, histone remodeling via upregulation of methyltransferase process, and downregulation of NF-κB transcription factor in canonical pathways. Abnormalities within H3K4me3 implicated LPS-mediated NF-κB canonical activation pathway that was a result of low amounts of κB DNA sites within histone H3K4me3, low NF-κB (p65 RelA) and TLR4 mRNA expression, and reduced free NF-κB (p65 RelA) accumulation in the nucleus. Genome-wide survey of H3K4me3 provided evidence that chromatin modifications lead to an impairment within the canonical NF-κB cell activation pathway causing the neutrophil dysfunction observed in HIV-infected individuals.
Collapse
Affiliation(s)
- Paweł Piatek
- Department of Neurology, Laboratory of Neuroimmunology, Medical University of Lodz, Lodz, Poland
| | - Maciej Tarkowski
- Department of Biomedical and Clinical Sciences, 'Luigi Sacco', University of Milan, Milan, Italy
| | - Magdalena Namiecinska
- Department of Neurology, Laboratory of Neuroimmunology, Medical University of Lodz, Lodz, Poland
| | - Agostino Riva
- Department of Biomedical and Clinical Sciences, 'Luigi Sacco', University of Milan, Milan, Italy
| | - Marek Wieczorek
- Department of Neurobiology, Faculty of Biology and Environmental Protection, University of Lodz, Lodz, Poland
| | - Sylwia Michlewska
- Laboratory of Microscopic Imaging and Specialized Biological Techniques, Faculty of Biology and Environmental Protection, University of Lodz, Lodz, Poland
| | | | - Małgorzata Domowicz
- Department of Neurology, Laboratory of Neuroimmunology, Medical University of Lodz, Lodz, Poland
| | | | - Natalia Lewkowicz
- Department of Periodontology and Oral Mucosal Diseases, Medical University of Lodz, Lodz, Poland
| | - Przemysław Lewkowicz
- Department of Neurology, Laboratory of Neuroimmunology, Medical University of Lodz, Lodz, Poland
| |
Collapse
|
5
|
Dual Regulatory Role of Chromatin Remodeler ISW1 in Coordinating Cellulase and Secondary Metabolite Biosynthesis in Trichoderma reesei. mBio 2021; 13:e0345621. [PMID: 35130719 PMCID: PMC8822348 DOI: 10.1128/mbio.03456-21] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
The saprophytic filamentous fungus Trichoderma reesei represents one of the most prolific cellulase producers isolated from nature. T. reesei also produces a typical yellow pigment identified as sorbicillinoids during cultivation. Here, we identified an evolutionarily conserved histone remodeling factor, ISW1, in T. reesei that simultaneously participates in regulating cellulase and the yellow pigment biosynthesis. Trisw1 deletion almost abolished vegetable growth, asexual spore formation, and cellulase gene expression. However, its absence significantly enhanced the production of the yellow pigment. The observed dual regulatory role of TrISW1 was dependent on its ATPase activity. We demonstrated that Trisw1 disruption elevated the transcription of ypr1 coding for the transcriptional activator of sor genes encoding the polyketide synthases catalyzing the biosynthesis of sorbicillinoids but compromised that of xyr1 encoding the key transcriptional activator of cellulase genes. Discrete T. reesei homologous ISW1 accessory factors were also found to exert differential effects on the expression of these two types of genes. Further analyses showed that TrISW1 was recruited to cellulase gene promoters, and its absence interfered with loss of histone H4 at the cbh1 and eg1 promoters upon cellulose induction. To the contrary, Trisw1 deletion facilitated loss of H4 at the sor locus. These data indicate that TrISW1 represents an important chromatin remodeler with a dual role in coordinating the cellulolytic response and biosynthesis of the major secondary metabolite in T. reesei. IMPORTANCE Microorganisms, including Trichoderma reesei, constantly face the challenge to outcompete other species to ensure efficient colonization in their natural habitat. They achieve this usually by adopting two alternative strategies by either maintaining fast growth on limited nutrient resources or producing a versatile array of secondary metabolites to fight against competitors. These two strategies, however, have to be subtly controlled to balance the assignment of and thus make the best use of cellular resources. Here, we identified a chromatin remodeling factor, TrISW1, with a dual role in coordinating the cellulolytic response and biosynthesis of the major secondary metabolite in T. reesei. The data also provide a novel insight into how T. reesei takes advantage of a chromatin remodeler to exquisitely balance two different adaptive strategies to ensure an efficient allocation of cellular resources to achieve efficient colonization in a specific environment.
Collapse
|
6
|
Montecino M, Carrasco ME, Nardocci G. Epigenetic Control of Osteogenic Lineage Commitment. Front Cell Dev Biol 2021; 8:611197. [PMID: 33490076 PMCID: PMC7820369 DOI: 10.3389/fcell.2020.611197] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2020] [Accepted: 12/11/2020] [Indexed: 12/22/2022] Open
Abstract
Within the eukaryotic nucleus the genomic DNA is organized into chromatin by stably interacting with the histone proteins as well as with several other nuclear components including non-histone proteins and non-coding RNAs. Together these interactions distribute the genetic material into chromatin subdomains which can exhibit higher and lower compaction levels. This organization contributes to differentially control the access to genomic sequences encoding key regulatory genetic information. In this context, epigenetic mechanisms play a critical role in the regulation of gene expression as they modify the degree of chromatin compaction to facilitate both activation and repression of transcription. Among the most studied epigenetic mechanisms we find the methylation of DNA, ATP-dependent chromatin remodeling, and enzyme-mediated deposition and elimination of post-translational modifications at histone and non-histone proteins. In this mini review, we discuss evidence that supports the role of these epigenetic mechanisms during transcriptional control of osteoblast-related genes. Special attention is dedicated to mechanisms of epigenetic control operating at the Runx2 and Sp7 genes coding for the two principal master regulators of the osteogenic lineage during mesenchymal stem cell commitment.
Collapse
Affiliation(s)
- Martin Montecino
- Faculty of Medicine and Faculty of Life Sciences, Institute of Biomedical Sciences and FONDAP Center for Genome Regulation, Universidad Andres Bello, Santiago, Chile
| | - Margarita E Carrasco
- Faculty of Medicine and Faculty of Life Sciences, Institute of Biomedical Sciences and FONDAP Center for Genome Regulation, Universidad Andres Bello, Santiago, Chile
| | - Gino Nardocci
- Faculty of Medicine, Universidad de los Andes, Santiago, Chile.,Molecular Biology and Bioinformatic Lab, Program in Molecular Biology and Bioinformatics, Center for Biomedical Research and Innovation (CIIB), Universidad de los Andes, Santiago, Chile
| |
Collapse
|
7
|
Regulation of KDM2B and Brg1 on Inflammatory Response of Nasal Mucosa in CRSwNP. Inflammation 2019; 42:1389-1400. [DOI: 10.1007/s10753-019-01000-6] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
|
8
|
Characterizing the role of SWI/SNF-related chromatin remodeling complexes in planarian regeneration and stem cell function. Stem Cell Res 2018; 32:91-103. [DOI: 10.1016/j.scr.2018.09.004] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/08/2018] [Revised: 08/18/2018] [Accepted: 09/06/2018] [Indexed: 11/21/2022] Open
|
9
|
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.
Collapse
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
| |
Collapse
|
10
|
Lee A, Miller D, Henry R, Paruchuri VDP, O'Meally RN, Boronina T, Cole RN, Zachara NE. Combined Antibody/Lectin Enrichment Identifies Extensive Changes in the O-GlcNAc Sub-proteome upon Oxidative Stress. J Proteome Res 2016; 15:4318-4336. [PMID: 27669760 DOI: 10.1021/acs.jproteome.6b00369] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
O-Linked N-acetyl-β-d-glucosamine (O-GlcNAc) is a dynamic post-translational modification that modifies and regulates over 3000 nuclear, cytoplasmic, and mitochondrial proteins. Upon exposure to stress and injury, cells and tissues increase the O-GlcNAc modification, or O-GlcNAcylation, of numerous proteins promoting the cellular stress response and thus survival. The aim of this study was to identify proteins that are differentially O-GlcNAcylated upon acute oxidative stress (H2O2) to provide insight into the mechanisms by which O-GlcNAc promotes survival. We achieved this goal by employing Stable Isotope Labeling of Amino Acids in Cell Culture (SILAC) and a novel "G5-lectibody" immunoprecipitation strategy that combines four O-GlcNAc-specific antibodies (CTD110.6, RL2, HGAC39, and HGAC85) and the lectin WGA. Using the G5-lectibody column in combination with basic reversed phase chromatography and C18 RPLC-MS/MS, 990 proteins were identified and quantified. Hundreds of proteins that were identified demonstrated increased (>250) or decreased (>110) association with the G5-lectibody column upon oxidative stress, of which we validated the O-GlcNAcylation status of 24 proteins. Analysis of proteins with altered glycosylation suggests that stress-induced changes in O-GlcNAcylation cluster into pathways known to regulate the cell's response to injury and include protein folding, transcriptional regulation, epigenetics, and proteins involved in RNA biogenesis. Together, these data suggest that stress-induced O-GlcNAcylation regulates numerous and diverse cellular pathways to promote cell and tissue survival.
Collapse
Affiliation(s)
- Albert Lee
- Department of Biological Chemistry, The Johns Hopkins University School of Medicine , 725 North Wolfe Street, Baltimore, Maryland 21205-2185, United States
| | - Devin Miller
- Department of Biological Chemistry, The Johns Hopkins University School of Medicine , 725 North Wolfe Street, Baltimore, Maryland 21205-2185, United States
| | - Roger Henry
- Department of Biological Chemistry, The Johns Hopkins University School of Medicine , 725 North Wolfe Street, Baltimore, Maryland 21205-2185, United States
| | - Venkata D P Paruchuri
- Department of Biological Chemistry, The Johns Hopkins University School of Medicine , 725 North Wolfe Street, Baltimore, Maryland 21205-2185, United States
| | - Robert N O'Meally
- Mass Spectrometry and Proteomics Facility, The Johns Hopkins University School of Medicine , 733 North Broadway Street, Baltimore, Maryland 21205-2185, United States
| | - Tatiana Boronina
- Mass Spectrometry and Proteomics Facility, The Johns Hopkins University School of Medicine , 733 North Broadway Street, Baltimore, Maryland 21205-2185, United States
| | - Robert N Cole
- Department of Biological Chemistry, The Johns Hopkins University School of Medicine , 725 North Wolfe Street, Baltimore, Maryland 21205-2185, United States.,Mass Spectrometry and Proteomics Facility, The Johns Hopkins University School of Medicine , 733 North Broadway Street, Baltimore, Maryland 21205-2185, United States
| | - Natasha E Zachara
- Department of Biological Chemistry, The Johns Hopkins University School of Medicine , 725 North Wolfe Street, Baltimore, Maryland 21205-2185, United States
| |
Collapse
|
11
|
Tyagi M, Weber J, Bukrinsky M, Simon GL. The effects of cocaine on HIV transcription. J Neurovirol 2015; 22:261-74. [PMID: 26572787 DOI: 10.1007/s13365-015-0398-z] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2015] [Revised: 10/01/2015] [Accepted: 10/21/2015] [Indexed: 11/29/2022]
Abstract
Illicit drug users are a high-risk population for infection with the human immunodeficiency virus (HIV). A strong correlation exists between prohibited drug use and an increased rate of HIV transmission. Cocaine stands out as one of the most frequently abused illicit drugs, and its use is correlated with HIV infection and disease progression. The central nervous system (CNS) is a common target for both drugs of abuse and HIV, and cocaine intake further accelerates neuronal injury in HIV patients. Although the high incidence of HIV infection in illicit drug abusers is primarily due to high-risk activities such as needle sharing and unprotected sex, several studies have demonstrated that cocaine enhances the rate of HIV gene expression and replication by activating various signal transduction pathways and downstream transcription factors. In order to generate mature HIV genomic transcript, HIV gene expression has to pass through both the initiation and elongation phases of transcription, which requires discrete transcription factors. In this review, we will provide a detailed analysis of the molecular mechanisms that regulate HIV transcription and discuss how cocaine modulates those mechanisms to upregulate HIV transcription and eventually HIV replication.
Collapse
Affiliation(s)
- Mudit Tyagi
- Division of Infectious Diseases, Department of Medicine, The George Washington University, 2300 Eye Street, N.W., Washington, DC, 20037, USA. .,Department of Microbiology, Immunology and Tropical Medicine, The George Washington University, Washington, DC, 20037, USA.
| | - Jaime Weber
- Division of Infectious Diseases, Department of Medicine, The George Washington University, 2300 Eye Street, N.W., Washington, DC, 20037, USA
| | - Michael Bukrinsky
- Department of Microbiology, Immunology and Tropical Medicine, The George Washington University, Washington, DC, 20037, USA
| | - Gary L Simon
- Division of Infectious Diseases, Department of Medicine, The George Washington University, 2300 Eye Street, N.W., Washington, DC, 20037, USA
| |
Collapse
|
12
|
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 PMCID: PMC4516601 DOI: 10.1002/jcp.24991] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [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.
Collapse
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
| |
Collapse
|
13
|
Galvani A, Thiriet C. Nucleosome Dancing at the Tempo of Histone Tail Acetylation. Genes (Basel) 2015; 6:607-21. [PMID: 26184324 PMCID: PMC4584320 DOI: 10.3390/genes6030607] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2015] [Revised: 06/26/2015] [Accepted: 07/08/2015] [Indexed: 12/12/2022] Open
Abstract
The impact of histone acetylation on transcription was revealed over 50 years ago by Allfrey and colleagues. However, it took decades for an understanding of the fine mechanism by which this posttranslational modification affects chromatin structure and promotes transcription. Here, we review breakthroughs linking histone tail acetylation, histone dynamics, and transcription. We also discuss the histone exchange during transcription and highlight the important function of a pool of non-chromatinized histones in chromatin dynamics.
Collapse
Affiliation(s)
- Angélique Galvani
- UMR CNRS 6286 UFIP, Université de Nantes, Epigénétique: Proliferation et Différenciation, 2 rue de Houssinière, 44322 Nantes Cedex 03, France.
| | - Christophe Thiriet
- UMR CNRS 6286 UFIP, Université de Nantes, Epigénétique: Proliferation et Différenciation, 2 rue de Houssinière, 44322 Nantes Cedex 03, France.
| |
Collapse
|
14
|
Tartey S, Matsushita K, Imamura T, Wakabayashi A, Ori D, Mino T, Takeuchi O. Essential Function for the Nuclear Protein Akirin2 in B Cell Activation and Humoral Immune Responses. THE JOURNAL OF IMMUNOLOGY 2015; 195:519-27. [DOI: 10.4049/jimmunol.1500373] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/13/2015] [Accepted: 05/07/2015] [Indexed: 02/06/2023]
|
15
|
Wiley MM, Muthukumar V, Griffin TM, Griffin CT. SWI/SNF chromatin-remodeling enzymes Brahma-related gene 1 (BRG1) and Brahma (BRM) are dispensable in multiple models of postnatal angiogenesis but are required for vascular integrity in infant mice. J Am Heart Assoc 2015; 4:jah3948. [PMID: 25904594 PMCID: PMC4579958 DOI: 10.1161/jaha.115.001972] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Background Mammalian SWItch/Sucrose NonFermentable (SWI/SNF) adenosine triphosphate (ATP)‐dependent chromatin‐remodeling complexes play important roles in embryonic vascular development by modulating transcription of specific target genes. We sought to determine whether SWI/SNF complexes likewise impact postnatal physiological and pathological angiogenesis. Methods and Results Brahma‐related gene 1 (BRG1) and Brahma gene (BRM) are ATPases within mammalian SWI/SNF complexes and are essential for the complexes to function. Using mice with vascular‐specific mutations in Brg1 or with a global mutation in Brm, we employed 3 models to test the role of these ATPases in postnatal angiogenesis. We analyzed neonatal retinal angiogenesis, exercise‐induced angiogenesis in adult quadriceps muscles, and tumor angiogenesis in control and mutant animals. We found no evidence of defective angiogenesis in Brg1 or Brm mutants using these 3 models. Brg1/Brm double mutants likewise show no evidence of vascular defects in the neonatal retina or tumor angiogenesis models. However, 100% of Brg1/Brm‐double mutants in which Brg1 deletion is induced at postnatal day 3 (P3) die by P19 with hemorrhaging in the small intestine and heart. Conclusions Despite their important roles in embryonic vascular development, SWI/SNF chromatin‐remodeling complexes display a surprising lack of participation in the 3 models of postnatal angiogenesis we analyzed. However, these complexes are essential for maintaining vascular integrity in specific tissue beds before weaning. These findings highlight the temporal and spatial specificity of SWI/SNF activities in the vasculature and may indicate that other chromatin‐remodeling complexes play redundant or more essential roles during physiological and pathological postnatal vascular development.
Collapse
Affiliation(s)
- Mandi M. Wiley
- Cardiovascular Biology Research Program, Oklahoma Medical Research Foundation, Oklahoma City, OK (M.M.W., V.M., C.T.G.)
| | - Vijay Muthukumar
- Cardiovascular Biology Research Program, Oklahoma Medical Research Foundation, Oklahoma City, OK (M.M.W., V.M., C.T.G.)
| | - Timothy M. Griffin
- Free Radical Biology and Aging Program, Oklahoma Medical Research Foundation, Oklahoma City, OK (T.M.G.)
- Department of Biochemistry and Molecular Biology, University of Oklahoma Health Sciences Center, Oklahoma City, OK (T.M.G.)
| | - Courtney T. Griffin
- Cardiovascular Biology Research Program, Oklahoma Medical Research Foundation, Oklahoma City, OK (M.M.W., V.M., C.T.G.)
- Department of Cell Biology, University of Oklahoma Health Sciences Center, Oklahoma City, OK (C.T.G.)
| |
Collapse
|
16
|
Sim JCH, White SM, Lockhart PJ. ARID1B-mediated disorders: Mutations and possible mechanisms. Intractable Rare Dis Res 2015; 4:17-23. [PMID: 25674384 PMCID: PMC4322591 DOI: 10.5582/irdr.2014.01021] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/19/2014] [Revised: 12/02/2014] [Accepted: 12/03/2014] [Indexed: 12/22/2022] Open
Abstract
Mutations in the gene encoding AT-rich interactive domain-containing protein 1B (ARID1B) were recently associated with multiple syndromes characterized by developmental delay and intellectual disability, in addition to nonsyndromic intellectual disability. While the majority of ARID1B mutations identified to date are predicted to result in haploinsufficiency, the underlying pathogenic mechanisms have yet to be fully understood. ARID1B is a DNA-binding subunit of the Brahma-associated factor chromatin remodelling complexes, which play a key role in the regulation of gene activity. The function of remodelling complexes can be regulated by their subunit composition, and there is some evidence that ARID1B is a component of the neuron-specific chromatin remodelling complex. This complex is involved in the regulation of stem/progenitor cells exiting the cell cycle and differentiating into postmitotic neurons. Recent research has indicated that alterations in the cell cycle contribute to the underlying pathogenesis of syndromes associated with ARID1B haploinsufficiency in fibroblasts derived from affected individuals. This review describes studies linking ARID1B to neurodevelopmental disorders and it summarizes the function of ARID1B to provide insights into the pathogenic mechanisms underlying ARID1B-mediated disorders. In conclusion, ARID1B is likely to play a key role in neurodevelopment and reduced levels of wild-type protein compromise normal brain development. Additional studies are required to determine the mechanisms by which impaired neural development contributes to the intellectual disability and speech impairment that are consistently observed in individuals with ARID1B haploinsufficiency.
Collapse
Affiliation(s)
- Joe C. H. Sim
- Bruce Lefroy Centre for Genetic Health Research, Murdoch Childrens Research Institute, Melbourne, Victoria, Australia
| | - Susan M White
- Bruce Lefroy Centre for Genetic Health Research, Murdoch Childrens Research Institute, Melbourne, Victoria, Australia
- Department of Paediatrics, The University of Melbourne, Melbourne, Victoria, Australia
| | - Paul J. Lockhart
- Bruce Lefroy Centre for Genetic Health Research, Murdoch Childrens Research Institute, Melbourne, Victoria, Australia
- Department of Paediatrics, The University of Melbourne, Melbourne, Victoria, Australia
- Address correspondence to: Dr. Paul J. Lockhart, Murdoch Childrens Research Institute, The Royal Children's Hospital, Flemington Road Parkville, Victoria 3052, Australia. E-mail:
| |
Collapse
|
17
|
The histone-fold complex MHF is remodeled by FANCM to recognize branched DNA and protect genome stability. Cell Res 2014; 24:560-75. [PMID: 24699063 DOI: 10.1038/cr.2014.42] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2013] [Revised: 02/10/2014] [Accepted: 02/24/2014] [Indexed: 01/19/2023] Open
Abstract
Histone-fold proteins typically assemble in multiprotein complexes to bind duplex DNA. However, one histone-fold complex, MHF, associates with Fanconi anemia (FA) protein FANCM to form a branched DNA remodeling complex that senses and repairs stalled replication forks and activates FA DNA damage response network. How the FANCM-MHF complex recognizes branched DNA is unclear. Here, we solved the crystal structure of MHF and its complex with the MHF-interaction domain (referred to as MID) of FANCM, and performed structure-guided mutagenesis. We found that the MID-MHF complex consists of one histone H3-H4-like MHF heterotetramer wrapped by a single polypeptide of MID. We identified a zinc atom-liganding structure at the central interface between MID and MHF that is critical for stabilization of the complex. Notably, the DNA-binding surface of MHF was altered by MID in both electrostatic charges and allosteric conformation. This leads to a switch in the DNA-binding preference - from duplex DNA by MHF alone, to branched DNA by the MID-MHF complex. Mutations that disrupt either the composite DNA-binding surface or the protein-protein interface of the MID-MHF complex impaired activation of the FA network and genome stability. Our data provide the structural basis of how FANCM and MHF work together to recognize branched DNA, and suggest a novel mechanism by which histone-fold complexes can be remodeled by their partners to bind special DNA structures generated during DNA metabolism.
Collapse
|
18
|
Sim JCH, White SM, Fitzpatrick E, Wilson GR, Gillies G, Pope K, Mountford HS, Torring PM, McKee S, Vulto-van Silfhout AT, Jhangiani SN, Muzny DM, Leventer RJ, Delatycki MB, Amor DJ, Lockhart PJ. Expanding the phenotypic spectrum of ARID1B-mediated disorders and identification of altered cell-cycle dynamics due to ARID1B haploinsufficiency. Orphanet J Rare Dis 2014; 9:43. [PMID: 24674232 PMCID: PMC4022252 DOI: 10.1186/1750-1172-9-43] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2013] [Accepted: 03/10/2014] [Indexed: 12/12/2022] Open
Abstract
Background Mutations in genes encoding components of the Brahma-associated factor (BAF) chromatin remodeling complex have recently been shown to contribute to multiple syndromes characterised by developmental delay and intellectual disability. ARID1B mutations have been identified as the predominant cause of Coffin-Siris syndrome and have also been shown to be a frequent cause of nonsyndromic intellectual disability. Here, we investigate the molecular basis of a patient with an overlapping but distinctive phenotype of intellectual disability, plantar fat pads and facial dysmorphism. Methods/results High density microarray analysis of the patient demonstrated a heterozygous deletion at 6q25.3, which resulted in the loss of four genes including AT Rich Interactive Domain 1B (ARID1B). Subsequent quantitative real-time PCR analysis revealed ARID1B haploinsufficiency in the patient. Analysis of both patient-derived and ARID1B knockdown fibroblasts after serum starvation demonstrated delayed cell cycle re-entry associated with reduced cell number in the S1 phase. Based on the patient’s distinctive phenotype, we ascertained four additional patients and identified heterozygous de novo ARID1B frameshift or nonsense mutations in all of them. Conclusions This study broadens the spectrum of ARID1B associated phenotypes by describing a distinctive phenotype including plantar fat pads but lacking the hypertrichosis or fifth nail hypoplasia associated with Coffin-Siris syndrome. We present the first direct evidence in patient-derived cells that alterations in cell cycle contribute to the underlying pathogenesis of syndromes associated with ARID1B haploinsufficiency.
Collapse
Affiliation(s)
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | - Paul J Lockhart
- Bruce Lefroy Centre for Genetic Health Research, Murdoch Childrens Research Institute, Parkville, Victoria 3052, Australia.
| |
Collapse
|
19
|
North JA, Šimon M, Ferdinand MB, Shoffner MA, Picking JW, Howard CJ, Mooney AM, van Noort J, Poirier MG, Ottesen JJ. Histone H3 phosphorylation near the nucleosome dyad alters chromatin structure. Nucleic Acids Res 2014; 42:4922-33. [PMID: 24561803 PMCID: PMC4005658 DOI: 10.1093/nar/gku150] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
Nucleosomes contain ∼146 bp of DNA wrapped around a histone protein octamer that controls DNA accessibility to transcription and repair complexes. Posttranslational modification (PTM) of histone proteins regulates nucleosome function. To date, only modest changes in nucleosome structure have been directly attributed to histone PTMs. Histone residue H3(T118) is located near the nucleosome dyad and can be phosphorylated. This PTM destabilizes nucleosomes and is implicated in the regulation of transcription and repair. Here, we report gel electrophoretic mobility, sucrose gradient sedimentation, thermal disassembly, micrococcal nuclease digestion and atomic force microscopy measurements of two DNA–histone complexes that are structurally distinct from nucleosomes. We find that H3(T118ph) facilitates the formation of a nucleosome duplex with two DNA molecules wrapped around two histone octamers, and an altosome complex that contains one DNA molecule wrapped around two histone octamers. The nucleosome duplex complex forms within short ∼150 bp DNA molecules, whereas altosomes require at least ∼250 bp of DNA and form repeatedly along 3000 bp DNA molecules. These results are the first report of a histone PTM significantly altering the nucleosome structure.
Collapse
Affiliation(s)
- Justin A North
- Department of Physics, The Ohio State University, Columbus, OH 43210, USA, Department of Chemistry and Biochemistry, The Ohio State University, Columbus, OH 43210, USA, Ohio State Biochemistry Program, The Ohio State University, Columbus, OH 43210, USA and Huygens-Kamerlingh Onnes Laboratory, Leiden University, The Netherlands
| | | | | | | | | | | | | | | | | | | |
Collapse
|
20
|
Abstract
The skin is the first line of defense against dehydration and external environmental aggressions. It constantly renews itself throughout adult life mainly due to the activity of tissue-specific stem cells. In this review, we discuss fundamental characteristics of different stem cell populations within the skin and how they are able to contribute to normal skin homeostasis. We also examine the most recent results regarding the cell-intrinsic and -extrinsic components of the stem cell niche within the adult skin epithelium. Finally, we address the recent efforts to understand how abnormal regulation of stem cell activity contributes to the initiation and progression of skin-associated cancers.
Collapse
Affiliation(s)
| | - Valerie Horsley
- Department of Molecular, Cell and Developmental Biology, Yale University, New Haven, Connecticut, USA.
| |
Collapse
|
21
|
Chandler RL, Zhang Y, Magnuson T, Bultman SJ. Characterization of a Brg1 hypomorphic allele demonstrates that genetic and biochemical activity are tightly correlated. Epigenetics 2013; 9:249-56. [PMID: 24172864 DOI: 10.4161/epi.26879] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Mammalian SWI/SNF-related complexes are recruited to the promoters of numerous target genes, and the BRG1 catalytic subunit confers ATPase activity necessary to slide or evict nucleosomes and to regulate transcription. Based on gene-targeting experiments in mice, BRG1 is essential for early embryonic development. However, Brg1 null mutants have provided limited insight into gene-dosage considerations and structure-function relationships. To extend our knowledge of BRG1 function, we describe the genetic and biochemical characteristics of an ENU-induced hypomorphic mutation that encodes a protein with a single amino-acid substitution (E1083G) within the bilobal ATPase/chromatin-remodeling domain. Brg1(ENU1/ENU1) mice have ~50% genetic activity and survive embryogenesis but exhibit a postnatal developmental phenotype associated with runting and incompletely penetrant lethality. The E1083G mutant protein is stable, and experiments with recombinant FLAG-tagged BRG1 proteins demonstrated that it retains full ATPase activity. Yet the biochemical activity of the mutant protein is diminished to ~50% of normal in chromatin-remodeling assays. Consistent with these findings, the E1083G substitution is predicted to disrupt a structurally conserved α-helix within the lobe that participates in DNA translocation but does not contain the ATPase catalytic site. We propose that this α-helix participates in the DNA translocation cycle by mechanistically linking DNA interaction surfaces at the DNA entry/anchor point to those within the Helicase C domain of lobe 2 of the bilobal ATPase motor. Taken together, these results demonstrate that BRG1 genetic and biochemical activities are tightly correlated. They also indicate that BRG1 ATPase activity is necessary but not sufficient for chromatin remodeling.
Collapse
Affiliation(s)
- Ronald L Chandler
- Department of Genetics; Lineberger Comprehensive Cancer Center; University of North Carolina; Chapel Hill, NC USA
| | - Ying Zhang
- Department of Genetics; Lineberger Comprehensive Cancer Center; University of North Carolina; Chapel Hill, NC USA
| | - Terry Magnuson
- Department of Genetics; Lineberger Comprehensive Cancer Center; University of North Carolina; Chapel Hill, NC USA
| | - Scott J Bultman
- Department of Genetics; Lineberger Comprehensive Cancer Center; University of North Carolina; Chapel Hill, NC USA
| |
Collapse
|
22
|
Wieczorek D, Bögershausen N, Beleggia F, Steiner-Haldenstätt S, Pohl E, Li Y, Milz E, Martin M, Thiele H, Altmüller J, Alanay Y, Kayserili H, Klein-Hitpass L, Böhringer S, Wollstein A, Albrecht B, Boduroglu K, Caliebe A, Chrzanowska K, Cogulu O, Cristofoli F, Czeschik JC, Devriendt K, Dotti MT, Elcioglu N, Gener B, Goecke TO, Krajewska-Walasek M, Guillén-Navarro E, Hayek J, Houge G, Kilic E, Simsek-Kiper PÖ, López-González V, Kuechler A, Lyonnet S, Mari F, Marozza A, Mathieu Dramard M, Mikat B, Morin G, Morice-Picard F, Ozkinay F, Rauch A, Renieri A, Tinschert S, Utine GE, Vilain C, Vivarelli R, Zweier C, Nürnberg P, Rahmann S, Vermeesch J, Lüdecke HJ, Zeschnigk M, Wollnik B. A comprehensive molecular study on Coffin-Siris and Nicolaides-Baraitser syndromes identifies a broad molecular and clinical spectrum converging on altered chromatin remodeling. Hum Mol Genet 2013; 22:5121-35. [PMID: 23906836 DOI: 10.1093/hmg/ddt366] [Citation(s) in RCA: 166] [Impact Index Per Article: 15.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
Chromatin remodeling complexes are known to modify chemical marks on histones or to induce conformational changes in the chromatin in order to regulate transcription. De novo dominant mutations in different members of the SWI/SNF chromatin remodeling complex have recently been described in individuals with Coffin-Siris (CSS) and Nicolaides-Baraitser (NCBRS) syndromes. Using a combination of whole-exome sequencing, NGS-based sequencing of 23 SWI/SNF complex genes, and molecular karyotyping in 46 previously undescribed individuals with CSS and NCBRS, we identified a de novo 1-bp deletion (c.677delG, p.Gly226Glufs*53) and a de novo missense mutation (c.914G>T, p.Cys305Phe) in PHF6 in two individuals diagnosed with CSS. PHF6 interacts with the nucleosome remodeling and deacetylation (NuRD) complex implicating dysfunction of a second chromatin remodeling complex in the pathogenesis of CSS-like phenotypes. Altogether, we identified mutations in 60% of the studied individuals (28/46), located in the genes ARID1A, ARID1B, SMARCB1, SMARCE1, SMARCA2, and PHF6. We show that mutations in ARID1B are the main cause of CSS, accounting for 76% of identified mutations. ARID1B and SMARCB1 mutations were also found in individuals with the initial diagnosis of NCBRS. These individuals apparently belong to a small subset who display an intermediate CSS/NCBRS phenotype. Our proposed genotype-phenotype correlations are important for molecular screening strategies.
Collapse
|
23
|
Swi/Snf chromatin remodeling/tumor suppressor complex establishes nucleosome occupancy at target promoters. Proc Natl Acad Sci U S A 2013; 110:10165-70. [PMID: 23723349 DOI: 10.1073/pnas.1302209110] [Citation(s) in RCA: 137] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
Precise nucleosome-positioning patterns at promoters are thought to be crucial for faithful transcriptional regulation. However, the mechanisms by which these patterns are established, are dynamically maintained, and subsequently contribute to transcriptional control are poorly understood. The switch/sucrose non-fermentable chromatin remodeling complex, also known as the Brg1 associated factors complex, is a master developmental regulator and tumor suppressor capable of mobilizing nucleosomes in biochemical assays. However, its role in establishing the nucleosome landscape in vivo is unclear. Here we have inactivated Snf5 and Brg1, core subunits of the mammalian Swi/Snf complex, to evaluate their effects on chromatin structure and transcription levels genomewide. We find that inactivation of either subunit leads to disruptions of specific nucleosome patterning combined with a loss of overall nucleosome occupancy at a large number of promoters, regardless of their association with CpG islands. These rearrangements are accompanied by gene expression changes that promote cell proliferation. Collectively, these findings define a direct relationship between chromatin-remodeling complexes, chromatin structure, and transcriptional regulation.
Collapse
|
24
|
Abstract
HIV-1 can establish a state of latent infection at the level of individual T cells. Latently infected cells are rare in vivo and appear to arise when activated CD4(+) T cells, the major targets cells for HIV-1, become infected and survive long enough to revert back to a resting memory state, which is nonpermissive for viral gene expression. Because latent virus resides in memory T cells, it persists indefinitely even in patients on potent antiretroviral therapy. This latent reservoir is recognized as a major barrier to curing HIV-1 infection. The molecular mechanisms of latency are complex and include the absence in resting CD4(+) T cells of nuclear forms of key host transcription factors (e.g., NFκB and NFAT), the absence of Tat and associated host factors that promote efficient transcriptional elongation, epigenetic changes inhibiting HIV-1 gene expression, and transcriptional interference. The presence of a latent reservoir for HIV-1 helps explain the presence of very low levels of viremia in patients on antiretroviral therapy. These viruses are released from latently infected cells that have become activated and perhaps from other stable reservoirs but are blocked from additional rounds of replication by the drugs. Several approaches are under exploration for reactivating latent virus with the hope that this will allow elimination of the latent reservoir.
Collapse
Affiliation(s)
- Robert F Siliciano
- Department of Medicine, Johns Hopkins University School of Medicine, Howard Hughes Medical Institute, Baltimore, Maryland 21205, USA.
| | | |
Collapse
|
25
|
Abstract
In the eukaryotic nucleus, processes of DNA metabolism such as transcription, DNA replication, and repair occur in the context of DNA packaged into nucleosomes and higher order chromatin structures. In order to overcome the barrier presented by chromatin structures to the protein machinery carrying out these processes, the cell relies on a class of enzymes called chromatin remodeling complexes which catalyze ATP-dependent restructuring and repositioning of nucleosomes. Chromatin remodelers are large multi-subunit complexes which all share a common SF2 helicase ATPase domain in their catalytic subunit, and are classified into four different families-SWI/SNF, ISWI, CHD, INO80-based on the arrangement of other domains in their catalytic subunit as well as their non-catalytic subunit composition. A large body of structural, biochemical, and biophysical evidence suggests chromatin remodelers operate as histone octamer-anchored directional DNA translocases in order to disrupt DNA-histone interactions and catalyze nucleosome sliding. Remodeling mechanisms are family-specific and depend on factors such as how the enzyme engages with nucleosomal and linker DNA, features of DNA loop intermediates, specificity for mono- or oligonucleosomal substrates, and ability to remove histones and exchange histone variants. Ultimately, the biological function of chromatin remodelers and their genomic targeting in vivo is regulated by each complex's subunit composition, association with chromatin modifiers and histone chaperones, and affinity for chromatin signals such as histone posttranslational modifications.
Collapse
|
26
|
Beyer DC, Ghoneim MK, Spies M. Structure and Mechanisms of SF2 DNA Helicases. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2013; 767:47-73. [PMID: 23161006 DOI: 10.1007/978-1-4614-5037-5_3] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Effective transcription, replication, and maintenance of the genome require a diverse set of molecular machines to perform the many chemical transactions that constitute these processes. Many of these machines use single-stranded nucleic acids as templates, and their actions are often regulated by the participation of nucleic acids in multimeric structures and macromolecular assemblies that restrict access to chemical information. Superfamily II (SF2) DNA helicases and translocases are a group of molecular machines that remodel nucleic acid lattices and enable essential cellular processes to use the information stored in the duplex DNA of the packaged genome. Characteristic accessory domains associated with the subgroups of the superfamily direct the activity of the common motor core and expand the repertoire of activities and substrates available to SF2 DNA helicases, translocases, and large multiprotein complexes containing SF2 motors. In recent years, single-molecule studies have contributed extensively to the characterization of this ubiquitous and essential class of enzymes.
Collapse
Affiliation(s)
- David C Beyer
- Department of Biochemistry, University of Iowa Carver College of Medicine, Iowa City, IA, USA
| | | | | |
Collapse
|
27
|
Smith-Roe SL, Bultman SJ. Combined gene dosage requirement for SWI/SNF catalytic subunits during early mammalian development. Mamm Genome 2012; 24:21-9. [PMID: 23076393 DOI: 10.1007/s00335-012-9433-z] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2012] [Accepted: 09/10/2012] [Indexed: 01/17/2023]
Abstract
Mammalian SWI/SNF complexes utilize either BRG1 or BRM as alternative catalytic subunits with DNA-dependent ATPase activity to remodel chromatin. Although the two proteins are 75 % identical, broadly expressed, and have similar biochemical activities in vitro, BRG1 is essential for mouse embryonic development, while BRM is dispensable. To investigate whether BRG1 and BRM have overlapping functions during mouse embryogenesis, we performed double-heterozygous intercrosses using constitutive null mutations previously created by gene targeting. The progeny of these crosses had a distribution of genotypes that was significantly skewed relative to their combined gene dosage. This was most pronounced at the top and bottom of the gene dosage hierarchy, with a 1.5-fold overrepresentation of Brg1 (+/+) ;Brm (+/+) mice and a corresponding 1.6-fold underrepresentation of Brg1 (+/-) ;Brm (-/-) mice. To account for the underrepresentation of Brg1 (+/-) ;Brm (-/-) mice, timed matings and blastocyst outgrowth assays demonstrated that ~50 % of these embryos failed to develop beyond the peri-implantation stage. These results challenge the idea that BRG1 is the exclusive catalytic subunit of SWI/SNF complexes in ES cells and suggest that BRM also interacts with the pluripotency transcription factors to facilitate self-renewal of the inner cell mass. In contrast to implantation, the Brm genotype did not influence an exencephaly phenotype that arises because of Brg1 haploinsufficiency during neural tube closure and that results in peri-natal lethality. Taken together, these results support the idea that BRG1 and BRM have overlapping functions for certain developmental processes but not others during embryogenesis.
Collapse
Affiliation(s)
- Stephanie L Smith-Roe
- Department of Genetics, University of North Carolina, Chapel Hill, NC 27599-7264, USA
| | | |
Collapse
|
28
|
Tyagi M, Bukrinsky M. Human immunodeficiency virus (HIV) latency: the major hurdle in HIV eradication. Mol Med 2012; 18:1096-108. [PMID: 22692576 DOI: 10.2119/molmed.2012.00194] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2012] [Accepted: 06/07/2012] [Indexed: 12/11/2022] Open
Abstract
Failure of highly active antiretroviral therapy to eradicate the human immunodeficiency virus (HIV), even in patients who suppress the virus to undetectable levels for many years, underscores the problems associated with fighting this infection. The existence of persistent infection in certain cellular and anatomical reservoirs appears to be the major hurdle in HIV eradication. The development of therapeutic interventions that eliminate or limit the latent viral pools or prevent the reemergence of the viruses from producing cells will therefore be required to enhance the effectiveness of current antiretroviral strategies. To achieve this goal, there is a pressing need to understand HIV latency at the molecular level to design novel and improved therapies to either eradicate HIV or find a functional cure in which patients could maintain a manageable viral pool without AIDS in the absence of antiretroviral therapy. The integrated proviral genome remains transcriptionally silent for a long period in certain subsets of T cells. This ability to infect cells latently helps HIV to establish a persistent infection despite strong humoral and cellular immune responses against the viral proteins. The main purpose of this report is to provide a general overview of the HIV latency. We will describe the hurdles being faced in eradicating latent HIV proviruses. We will also briefly discuss the ongoing strategies aimed toward curing HIV infection.
Collapse
Affiliation(s)
- Mudit Tyagi
- National Center for Biodefense and Infectious Disease, George Mason University, Manassas, Virginia 20109, United States of America.
| | | |
Collapse
|
29
|
Sampey GC, Guendel I, Das R, Jaworski E, Klase Z, Narayanan A, Kehn-Hall K, Kashanchi F. Transcriptional Gene Silencing (TGS) via the RNAi Machinery in HIV-1 Infections. BIOLOGY 2012; 1:339-69. [PMID: 24832229 PMCID: PMC4009781 DOI: 10.3390/biology1020339] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/29/2012] [Revised: 08/03/2012] [Accepted: 08/13/2012] [Indexed: 12/21/2022]
Abstract
Gene silencing via non-coding RNA, such as siRNA and miRNA, can occur at the transcriptional, post-transcriptional, and translational stages of expression. Transcriptional gene silencing (TGS) involving the RNAi machinery generally occurs through DNA methylation, as well as histone post-translational modifications, and corresponding remodeling of chromatin around the target gene into a heterochromatic state. The mechanism by which mammalian TGS occurs includes the recruitment of RNA-induced initiation of transcriptional gene silencing (RITS) complexes, DNA methyltransferases (DNMTs), and other chromatin remodelers. Additionally, virally infected cells encoding miRNAs have also been shown to manipulate the host cell RNAi machinery to induce TGS at the viral genome, thereby establishing latency. Furthermore, the introduction of exogenous siRNA and shRNA into infected cells that target integrated viral promoters can greatly suppress viral transcription via TGS. Here we examine the latest findings regarding mammalian TGS, specifically focusing on HIV-1 infected cells, and discuss future avenues of exploration in this field.
Collapse
Affiliation(s)
- Gavin C Sampey
- National Center for Biodefense and Infectious Disease, School of Systems Biology, George Mason University, 10900 University Blvd, Manassas, VA 20108, USA.
| | - Irene Guendel
- National Center for Biodefense and Infectious Disease, School of Systems Biology, George Mason University, 10900 University Blvd, Manassas, VA 20108, USA.
| | - Ravi Das
- National Center for Biodefense and Infectious Disease, School of Systems Biology, George Mason University, 10900 University Blvd, Manassas, VA 20108, USA.
| | - Elizabeth Jaworski
- National Center for Biodefense and Infectious Disease, School of Systems Biology, George Mason University, 10900 University Blvd, Manassas, VA 20108, USA.
| | - Zachary Klase
- Molecular Virology Section, Laboratory of Molecular Microbiology, National Institute of Allergy and Infectious Diseases, 9000 Rockville Pike, Bethesda, MD 20810, USA.
| | - Aarthi Narayanan
- National Center for Biodefense and Infectious Disease, School of Systems Biology, George Mason University, 10900 University Blvd, Manassas, VA 20108, USA.
| | - Kylene Kehn-Hall
- National Center for Biodefense and Infectious Disease, School of Systems Biology, George Mason University, 10900 University Blvd, Manassas, VA 20108, USA.
| | - Fatah Kashanchi
- National Center for Biodefense and Infectious Disease, School of Systems Biology, George Mason University, 10900 University Blvd, Manassas, VA 20108, USA.
| |
Collapse
|
30
|
Sequence-based prediction of single nucleosome positioning and genome-wide nucleosome occupancy. Proc Natl Acad Sci U S A 2012; 109:E2514-22. [PMID: 22908247 DOI: 10.1073/pnas.1205659109] [Citation(s) in RCA: 62] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Nucleosome positioning dictates eukaryotic DNA compaction and access. To predict nucleosome positions in a statistical mechanics model, we exploited the knowledge that nucleosomes favor DNA sequences with specific periodically occurring dinucleotides. Our model is the first to capture both dyad position within a few base pairs, and free binding energy within 2 k(B)T, for all the known nucleosome positioning sequences. By applying Percus's equation to the derived energy landscape, we isolate sequence effects on genome-wide nucleosome occupancy from other factors that may influence nucleosome positioning. For both in vitro and in vivo systems, three parameters suffice to predict nucleosome occupancy with correlation coefficients of respectively 0.74 and 0.66. As predicted, we find the largest deviations in vivo around transcription start sites. This relatively simple algorithm can be used to guide future studies on the influence of DNA sequence on chromatin organization.
Collapse
|
31
|
Willis MS, Homeister JW, Rosson GB, Annayev Y, Holley D, Holly SP, Madden VJ, Godfrey V, Parise LV, Bultman SJ. Functional redundancy of SWI/SNF catalytic subunits in maintaining vascular endothelial cells in the adult heart. Circ Res 2012; 111:e111-22. [PMID: 22740088 DOI: 10.1161/circresaha.112.265587] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
RATIONALE Mating type switching/sucrose non-fermenting (SWI/SNF) chromatin-remodeling complexes utilize either BRG1 or BRM as a catalytic subunit to alter nucleosome position and regulate gene expression. BRG1 is required for vascular endothelial cell (VEC) development and embryonic survival, whereas BRM is dispensable. OBJECTIVE To circumvent embryonic lethality and study Brg1 function in adult tissues, we used conditional gene targeting. To evaluate possible Brg1-Brm redundancy, we analyzed Brg1 mutant mice on wild-type and Brm-deficient backgrounds. METHODS AND RESULTS The inducible Mx1-Cre driver was used to mutate Brg1 in adult mice. These conditional-null mutants exhibited a tissue-specific phenotype and unanticipated functional compensation between Brg1 and Brm. Brg1 single mutants were healthy and had a normal lifespan, whereas Brg1/Brm double mutants exhibited cardiovascular defects and died within 1 month. BRG1 and BRM were required for the viability of VECs but not other cell types where both genes were also knocked out. The VEC phenotype was most evident in the heart, particularly in the microvasculature of the outer myocardium, and was recapitulated in primary cells ex vivo. VEC death resulted in vascular leakage, cardiac hemorrhage, secondary death of cardiomyocytes due to ischemia, and ventricular dissections. CONCLUSIONS BRG1-catalyzed SWI/SNF complexes are particularly important in cardiovascular tissues. However, in contrast to embryonic development, in which Brm does not compensate, Brg1 is required in adult VECs only when Brm is also mutated. These results demonstrate for the first time that Brm functionally compensates for Brg1 in vivo and that there are significant changes in the relative importance of BRG1- and BRM-catalyzed SWI/SNF complexes during the development of an essential cell lineage.
Collapse
Affiliation(s)
- Monte S Willis
- 120 Mason Farm Rd, Genetic Medicine Bldg, Room 5060, Chapel Hill, NC 27516-7264, USA
| | | | | | | | | | | | | | | | | | | |
Collapse
|
32
|
Hopfner KP, Gerhold CB, Lakomek K, Wollmann P. Swi2/Snf2 remodelers: hybrid views on hybrid molecular machines. Curr Opin Struct Biol 2012; 22:225-33. [PMID: 22445226 DOI: 10.1016/j.sbi.2012.02.007] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2012] [Accepted: 02/26/2012] [Indexed: 12/14/2022]
Abstract
Swi2/Snf2 (switch/sucrose non-fermentable) enzymes form a large and diverse class of proteins and multiprotein assemblies that remodel nucleic acid:protein complexes, using the energy of ATP hydrolysis. The core Swi2/Snf2 type ATPase domain belongs to the 'helicase and NTP driven nucleic acid translocase' superfamily 2 (SF2). It serves as a motor that functionally and structurally interacts with different targeting domains and functional modules to drive a plethora of remodeling activities in chromatin structure and dynamics, transcription regulation and DNA repair. Recent progress on the interaction of Swi2/Snf2 enzymes and multiprotein assemblies with their substrate nucleic acids and proteins, using hybrid structural biology methods, illuminates mechanisms for complex chemo-mechanical remodeling reactions. For Mot1, a hybrid mechanism of remodeler and chaperone emerged.
Collapse
Affiliation(s)
- Karl-Peter Hopfner
- Department of Biochemistry at the Gene Center, Ludwig-Maximilians-University Munich, Feodor-Lynen-Str. 25, 81377 Munich, Germany.
| | | | | | | |
Collapse
|
33
|
Yang Z, Hayes JJ. The divalent cations Ca2+ and Mg2+ play specific roles in stabilizing histone-DNA interactions within nucleosomes that are partially redundant with the core histone tail domains. Biochemistry 2011; 50:9973-81. [PMID: 22007636 DOI: 10.1021/bi201377x] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
We previously reported that reconstituted nucleosomes undergo sequence-dependent translational repositioning upon removal of the core histone tail domains under physiological conditions, indicating that the tails influence the choice of position. We report here that removal of the core histone tail domains increases the exposure of the DNA backbone in nucleosomes to hydroxyl radicals, a nonbiased chemical cleavage reagent, indicative of an increase in the motility of the DNA on the histone surface. Moreover, we demonstrate that the divalent cations Mg(2+) and Ca(2+) can replace the role of the tail domains with regard to stabilization of histone-DNA interactions within the nucleosome core and restrict repositioning of nucleosomes upon tail removal. However, when nucleosomes were incubated with Mg(2+) after tail removal, the original distribution of translational positions was not re-established, indicating that divalent cations increase the energy barrier between translational positions rather than altering the free energy differences between positions. Interestingly, other divalent cations such as Zn(2+), Fe(2+), Co(2+), and Mn(2+) had little or no effect on the stability of histone-DNA interactions within tailless nucleosomes. These results support the idea that specific binding sites for Mg(2+) and Ca(2+) ions exist within the nucleosome and play a critical role in nucleosome stability that is partially redundant with the core histone tail domains.
Collapse
Affiliation(s)
- Zungyoon Yang
- Department of Biochemistry and Biophysics, University of Rochester Medical Center, Rochester, New York 14642, USA
| | | |
Collapse
|
34
|
SWI/SNF- and RSC-catalyzed nucleosome mobilization requires internal DNA loop translocation within nucleosomes. Mol Cell Biol 2011; 31:4165-75. [PMID: 21859889 DOI: 10.1128/mcb.05605-11] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The multisubunit SWI/SNF and RSC complexes utilize energy derived from ATP hydrolysis to mobilize nucleosomes and render the DNA accessible for various nuclear processes. Here we test the idea that remodeling involves intermediates with mobile DNA bulges or loops within the nucleosome by cross-linking the H2A N- or C-terminal tails together to generate protein "loops" that constrict separation of the DNA from the histone surface. Analyses indicate that this intranucleosomal cross-linking causes little or no change in remodeling-dependent exposure of DNA sequences within the nucleosome to restriction enzymes. However, cross-linking inhibits nucleosome mobilization and blocks complete movement of nucleosomes to extreme end positions on the DNA fragments. These results are consistent with evidence that nucleosome remodeling involves intermediates with DNA loops on the nucleosome surface but indicate that such loops do not freely diffuse about the surface of the histone octamer. We propose a threading model for movement of DNA loops around the perimeter of the nucleosome core.
Collapse
|
35
|
Van Duyne R, Guendel I, Narayanan A, Gregg E, Shafagati N, Tyagi M, Easley R, Klase Z, Nekhai S, Kehn-Hall K, Kashanchi F. Varying modulation of HIV-1 LTR activity by Baf complexes. J Mol Biol 2011; 411:581-96. [PMID: 21699904 DOI: 10.1016/j.jmb.2011.06.001] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2011] [Revised: 05/25/2011] [Accepted: 06/01/2011] [Indexed: 01/08/2023]
Abstract
The human immunodeficiency virus type 1 (HIV-1) long terminal repeat is present on both ends of the integrated viral genome and contains regulatory elements needed for transcriptional initiation and elongation. Post-integration, a highly ordered chromatin structure consisting of at least five nucleosomes, is found at the 5' long terminal repeat, the location and modification state of which control the state of active viral replication as well as silencing of the latent HIV-1 provirus. In this context, the chromatin remodeling field rapidly emerges as having a critical role in the control of viral gene expression. In the current study, we focused on unique Baf subunits that are common to the most highly recognized of chromatin remodeling proteins, the SWI/SNF (switching-defective-sucrose non-fermenting) complexes. We find that at least two Baf proteins, Baf53 and Baf170, are highly regulated in HIV-1-infected cells. Previously, studies have shown that the depletion of Baf53 in uninfected cells leads to the expansion of chromosomal territories and the decompaction of the chromatin. Baf53, in the presence of HIV-1 infection, co-elutes off of a chromatographic column as a different-sized complex when compared to uninfected cells and appears to be predominantly phosphorylated. The innate function of Baf53-containing complexes appears to be transcriptionally suppressive, in that knocking down Baf53 increases viral gene expression from cells both transiently and chronically infected with HIV-1. Additionally, cdk9/cyclin T in the presence of Tat is able to phosphorylate Baf53 in vitro, implying that this posttranslationally modified form relieves the suppressive effect and allows for viral transcription to proceed.
Collapse
Affiliation(s)
- Rachel Van Duyne
- Department of Molecular and Microbiology, National Center for Biodefense and Infectious Diseases, George Mason University, Manassas, VA 20110, USA
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
36
|
Wang Y, Gao B, Xu W, Xiong S. BRG1 is indispensable for IFN-γ-induced TRIM22 expression, which is dependent on the recruitment of IRF-1. Biochem Biophys Res Commun 2011; 410:549-54. [PMID: 21683060 DOI: 10.1016/j.bbrc.2011.06.022] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2011] [Accepted: 06/01/2011] [Indexed: 12/24/2022]
Abstract
The modification of chromatin structure is increasingly recognized to be an important facet of transcriptional regulation. Here, we report that Brahma-related gene 1 (BRG1), a chromatin remodeling enzyme, plays a crucial role in IFN-γ-induced TRIM22 expression. Our results showed that IFN-γ failed to induce TRIM22 expression in BRG1-deficient SW-13 cells, and reconstitution of BRG1 in this cell line could restore IFN-γ induction of TRIM22. Furthermore, it was revealed that BRG1 absence, per se, did not impair IFN-γ-induced IRF-1 expression, but blocked its access to TRIM22 promoter, and BRG1-dependent induction of TRIM22 perfectly correlated with BRG1-dependent recruitment of IRF-1 to TRIM22 promoter. We also found that the DNA-dependent ATPase domain of BRG1 was required for TRIM22 expression and IRF-1 recruitment in response to IFN-γ stimulation, suggesting that BRG1-mediated chromatin remodeling is critical for the IFN-γ-inducibility of TRIM22 gene.
Collapse
Affiliation(s)
- Yaxin Wang
- Institute for Immunobiology, Department of Immunology, Shanghai Medical College of Fudan University, Shanghai 200032, PR China
| | | | | | | |
Collapse
|
37
|
Liu N, Balliano A, Hayes JJ. ChemInform Abstract: Mechanism(s) of SWI/SNF-Induced Nucleosome Mobilization. ACTA ACUST UNITED AC 2011. [DOI: 10.1002/chin.201115265] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
|