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Zare A, Salehpour A, Khoradmehr A, Bakhshalizadeh S, Najafzadeh V, Almasi-Turk S, Mahdipour M, Shirazi R, Tamadon A. Epigenetic Modification Factors and microRNAs Network Associated with Differentiation of Embryonic Stem Cells and Induced Pluripotent Stem Cells toward Cardiomyocytes: A Review. Life (Basel) 2023; 13:life13020569. [PMID: 36836926 PMCID: PMC9965891 DOI: 10.3390/life13020569] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2022] [Revised: 11/16/2022] [Accepted: 11/16/2022] [Indexed: 02/22/2023] Open
Abstract
More research is being conducted on myocardial cell treatments utilizing stem cell lines that can develop into cardiomyocytes. All of the forms of cardiac illnesses have shown to be quite amenable to treatments using embryonic (ESCs) and induced pluripotent stem cells (iPSCs). In the present study, we reviewed the differentiation of these cell types into cardiomyocytes from an epigenetic standpoint. We also provided a miRNA network that is devoted to the epigenetic commitment of stem cells toward cardiomyocyte cells and related diseases, such as congenital heart defects, comprehensively. Histone acetylation, methylation, DNA alterations, N6-methyladenosine (m6a) RNA methylation, and cardiac mitochondrial mutations are explored as potential tools for precise stem cell differentiation.
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Affiliation(s)
- Afshin Zare
- The Persian Gulf Marine Biotechnology Research Center, The Persian Gulf Biomedical Sciences Research Institute, Bushehr University of Medical Sciences, Bushehr 7514633196, Iran
| | - Aria Salehpour
- The Persian Gulf Marine Biotechnology Research Center, The Persian Gulf Biomedical Sciences Research Institute, Bushehr University of Medical Sciences, Bushehr 7514633196, Iran
| | - Arezoo Khoradmehr
- The Persian Gulf Marine Biotechnology Research Center, The Persian Gulf Biomedical Sciences Research Institute, Bushehr University of Medical Sciences, Bushehr 7514633196, Iran
| | - Shabnam Bakhshalizadeh
- Reproductive Development, Murdoch Children’s Research Institute, Melbourne, VIC 3052, Australia
- Department of Paediatrics, University of Melbourne, Melbourne, VIC 3010, Australia
| | - Vahid Najafzadeh
- Department of Veterinary and Animal Sciences, University of Copenhagen, 1870 Frederiksberg C, Denmark
| | - Sahar Almasi-Turk
- Department of Basic Sciences, School of Medicine, Bushehr University of Medical Sciences, Bushehr 7514633341, Iran
| | - Mahdi Mahdipour
- Stem Cell Research Center, Tabriz University of Medical Sciences, Tabriz 5166653431, Iran
- Department of Reproductive Biology, Faculty of Advanced Medical Sciences, Tabriz University of Medical Sciences, Tabriz 5166653431, Iran
- Correspondence: (M.M.); (R.S.); (A.T.)
| | - Reza Shirazi
- Department of Anatomy, School of Medical Sciences, Medicine & Health, UNSW Sydney, Sydney, NSW 2052, Australia
- Correspondence: (M.M.); (R.S.); (A.T.)
| | - Amin Tamadon
- PerciaVista R&D Co., Shiraz 7135644144, Iran
- Correspondence: (M.M.); (R.S.); (A.T.)
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2
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Monteagudo-Mesas P, Brönner C, Kohvaei P, Amedi H, Canzar S, Halic M. Ccr4-Not complex reduces transcription efficiency in heterochromatin. Nucleic Acids Res 2022; 50:5565-5576. [PMID: 35640578 PMCID: PMC9177971 DOI: 10.1093/nar/gkac403] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2021] [Revised: 04/14/2022] [Accepted: 05/06/2022] [Indexed: 11/18/2022] Open
Abstract
Heterochromatic silencing is thought to occur through a combination of transcriptional silencing and RNA degradation, but the relative contribution of each pathway is not known. In this study, we analyzed RNA Polymerase II (RNA Pol II) occupancy and levels of nascent and steady-state RNA in different mutants of Schizosaccharomyces pombe, in order to quantify the contribution of each pathway to heterochromatic silencing. We found that transcriptional silencing consists of two components, reduced RNA Pol II accessibility and, unexpectedly, reduced transcriptional efficiency. Heterochromatic loci showed lower transcriptional output compared to euchromatic loci, even when comparable amounts of RNA Pol II were present in both types of regions. We determined that the Ccr4-Not complex and H3K9 methylation are required for reduced transcriptional efficiency in heterochromatin and that a subset of heterochromatic RNA is degraded more rapidly than euchromatic RNA. Finally, we quantified the contribution of different chromatin modifiers, RNAi and RNA degradation to each silencing pathway. Our data show that several pathways contribute to heterochromatic silencing in a locus-specific manner and reveal transcriptional efficiency as a new mechanism of silencing.
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Affiliation(s)
| | - Cornelia Brönner
- Gene Center, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Parastou Kohvaei
- Gene Center, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Haris Amedi
- Gene Center, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Stefan Canzar
- Gene Center, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Mario Halic
- Department of Structural Biology, St. Jude Children's Research Hospital, 263 Danny Thomas Place, Memphis, TN 38105, USA
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3
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Brothers M, Rine J. Distinguishing between recruitment and spread of silent chromatin structures in Saccharomyces cerevisiae. eLife 2022; 11:75653. [PMID: 35073254 PMCID: PMC8830885 DOI: 10.7554/elife.75653] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2021] [Accepted: 01/21/2022] [Indexed: 11/13/2022] Open
Abstract
The formation of heterochromatin at HML, HMR, and telomeres in Saccharomyces cerevisiae involves two main steps: Recruitment of Sir proteins to silencers and their spread throughout the silenced domain. We developed a method to study these two processes at single base-pair resolution. Using a fusion protein between the heterochromatin protein Sir3 and the non-site-specific bacterial adenine methyltransferase M.EcoGII, we mapped sites of Sir3-chromatin interactions genome-wide using long-read Nanopore sequencing to detect adenines methylated by the fusion protein and by ChIP-seq to map the distribution of Sir3-M.EcoGII. A silencing-deficient mutant of Sir3 lacking its Bromo-Adjacent Homology (BAH) domain, sir3-bah∆, was still recruited to HML, HMR, and telomeres. However, in the absence of the BAH domain, it was unable to spread away from those recruitment sites. Overexpression of Sir3 did not lead to further spreading at HML, HMR, and most telomeres. A few exceptional telomeres, like 6R, exhibited a small amount of Sir3 spreading, suggesting that boundaries at telomeres responded variably to Sir3 overexpression. Finally, by using a temperature-sensitive allele of SIR3 fused to M.ECOGII, we tracked the positions first methylated after induction and found that repression of genes at HML and HMR began before Sir3 occupied the entire locus.
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Affiliation(s)
- Molly Brothers
- Department of Molecular and Cell Biology, University of California, Berkeley
| | - Jasper Rine
- Department of Molecular and Cell Biology, University of California, Berkeley
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4
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Chiu YC, Tseng MC, Hsu CH. Expanding the Substrate Specificity of Macro Domains toward 3″-Isomer of O-Acetyl-ADP-ribose. ACS Catal 2021. [DOI: 10.1021/acscatal.1c01943] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Yi-Chih Chiu
- Genome and Systems Biology Degree Program, National Taiwan University and Academia Sinica, Taipei 10617, Taiwan
| | - Mei-Chun Tseng
- Institute of Chemistry, Academia Sinica, Taipei 11529, Taiwan
| | - Chun-Hua Hsu
- Genome and Systems Biology Degree Program, National Taiwan University and Academia Sinica, Taipei 10617, Taiwan
- Department of Agricultural Chemistry, National Taiwan University, Taipei 10617, Taiwan
- Institute of Biochemical Sciences, National Taiwan University, Taipei 10617, Taiwan
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5
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Kim YJ, Tamadon A, Kim YY, Kang BC, Ku SY. Epigenetic Regulation of Cardiomyocyte Differentiation from Embryonic and Induced Pluripotent Stem Cells. Int J Mol Sci 2021; 22:8599. [PMID: 34445302 PMCID: PMC8395249 DOI: 10.3390/ijms22168599] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2021] [Revised: 08/05/2021] [Accepted: 08/06/2021] [Indexed: 12/17/2022] Open
Abstract
With the intent to achieve the best modalities for myocardial cell therapy, different cell types are being evaluated as potent sources for differentiation into cardiomyocytes. Embryonic stem cells and induced pluripotent stem cells have great potential for future progress in the treatment of myocardial diseases. We reviewed aspects of epigenetic mechanisms that play a role in the differentiation of these cells into cardiomyocytes. Cardiomyocytes proliferate during fetal life, and after birth, they undergo permanent terminal differentiation. Upregulation of cardiac-specific genes in adults induces hypertrophy due to terminal differentiation. The repression or expression of these genes is controlled by chromatin structural and epigenetic changes. However, few studies have reviewed and analyzed the epigenetic aspects of the differentiation of embryonic stem cells and induced pluripotent stem cells into cardiac lineage cells. In this review, we focus on the current knowledge of epigenetic regulation of cardiomyocyte proliferation and differentiation from embryonic and induced pluripotent stem cells through histone modification and microRNAs, the maintenance of pluripotency, and its alteration during cardiac lineage differentiation.
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Affiliation(s)
- Yong-Jin Kim
- Department of Obstetrics and Gynecology, Korea University College of Medicine, Seoul 08308, Korea;
| | - Amin Tamadon
- Department of Marine Stem Cell and Tissue Engineering, Bushehr University of Medical Sciences, Bushehr 14174, Iran;
| | - Yoon-Young Kim
- Department of Obstetrics and Gynecology, Seoul National University College of Medicine, Seoul 03080, Korea;
- Biomedical Research Institute, Seoul National University Hospital, Seoul 03080, Korea;
- Institute of Reproductive Medicine and Population, Medical Research Center, Seoul National University, Seoul 03080, Korea
| | - Byeong-Cheol Kang
- Biomedical Research Institute, Seoul National University Hospital, Seoul 03080, Korea;
| | - Seung-Yup Ku
- Department of Obstetrics and Gynecology, Seoul National University College of Medicine, Seoul 03080, Korea;
- Institute of Reproductive Medicine and Population, Medical Research Center, Seoul National University, Seoul 03080, Korea
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6
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Goodnight D, Rine J. S-phase-independent silencing establishment in Saccharomyces cerevisiae. eLife 2020; 9:58910. [PMID: 32687055 PMCID: PMC7398696 DOI: 10.7554/elife.58910] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2020] [Accepted: 07/18/2020] [Indexed: 02/06/2023] Open
Abstract
The establishment of silent chromatin, a heterochromatin-like structure at HML and HMR in Saccharomyces cerevisiae, depends on progression through S phase of the cell cycle, but the molecular nature of this requirement has remained elusive despite intensive study. Using high-resolution chromatin immunoprecipitation and single-molecule RNA analysis, we found that silencing establishment proceeded via gradual repression of transcription in individual cells over several cell cycles, and that the cell-cycle-regulated step was downstream of Sir protein recruitment. In contrast to prior results, HML and HMR had identical cell-cycle requirements for silencing establishment, with no apparent contribution from a tRNA gene adjacent to HMR. We identified the cause of the S-phase requirement for silencing establishment: removal of transcription-favoring histone modifications deposited by Dot1, Sas2, and Rtt109. These results revealed that silencing establishment was absolutely dependent on the cell-cycle-regulated interplay between euchromatic and heterochromatic histone modifications.
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Affiliation(s)
- Davis Goodnight
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, United States
| | - Jasper Rine
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, United States
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7
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Corless S, Höcker S, Erhardt S. Centromeric RNA and Its Function at and Beyond Centromeric Chromatin. J Mol Biol 2020; 432:4257-4269. [DOI: 10.1016/j.jmb.2020.03.027] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2019] [Revised: 03/26/2020] [Accepted: 03/27/2020] [Indexed: 12/21/2022]
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Swygert SG, Senapati S, Bolukbasi MF, Wolfe SA, Lindsay S, Peterson CL. SIR proteins create compact heterochromatin fibers. Proc Natl Acad Sci U S A 2018; 115:12447-12452. [PMID: 30455303 PMCID: PMC6298083 DOI: 10.1073/pnas.1810647115] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Heterochromatin is a silenced chromatin region essential for maintaining genomic stability and driving developmental processes. The complicated structure and dynamics of heterochromatin have rendered it difficult to characterize. In budding yeast, heterochromatin assembly requires the SIR proteins-Sir3, believed to be the primary structural component of SIR heterochromatin, and the Sir2-4 complex, responsible for the targeted recruitment of SIR proteins and the deacetylation of lysine 16 of histone H4. Previously, we found that Sir3 binds but does not compact nucleosomal arrays. Here we reconstitute chromatin fibers with the complete complement of SIR proteins and use sedimentation velocity, molecular modeling, and atomic force microscopy to characterize the stoichiometry and conformation of SIR chromatin fibers. In contrast to fibers with Sir3 alone, our results demonstrate that SIR arrays are highly compact. Strikingly, the condensed structure of SIR heterochromatin fibers requires both the integrity of H4K16 and an interaction between Sir3 and Sir4. We propose a model in which a dimer of Sir3 bridges and stabilizes two adjacent nucleosomes, while a Sir2-4 heterotetramer interacts with Sir3 associated with a nucleosomal trimer, driving fiber compaction.
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Affiliation(s)
- Sarah G Swygert
- Program in Molecular Medicine, University of Massachusetts Medical School, Worcester, MA 01605
| | - Subhadip Senapati
- Center for Single Molecule Biophysics, Biodesign Institute, Arizona State University, Tempe, AZ 85287
| | - Mehmet F Bolukbasi
- Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, MA 01655
| | - Scot A Wolfe
- Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, MA 01655
| | - Stuart Lindsay
- Center for Single Molecule Biophysics, Biodesign Institute, Arizona State University, Tempe, AZ 85287
| | - Craig L Peterson
- Program in Molecular Medicine, University of Massachusetts Medical School, Worcester, MA 01605;
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9
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Zukowski A, Phillips J, Park S, Wu R, Gygi SP, Johnson AM. Proteomic profiling of yeast heterochromatin connects direct physical and genetic interactions. Curr Genet 2018; 65:495-505. [PMID: 30310994 DOI: 10.1007/s00294-018-0889-6] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2018] [Revised: 09/10/2018] [Accepted: 10/03/2018] [Indexed: 11/27/2022]
Abstract
Heterochromatin domains are stably repressed chromatin structures composed of a core assembly of silencing proteins that condense adjacent nucleosomes. The minimal heterochromatin structure can serve as a platform for recruitment of complementary regulatory factors. We find that a reconstituted budding yeast heterochromatin domain can act as a platform to recruit multiple factors that play a role in regulating heterochromatin function. We uncover the direct interaction between the SIR heterochromatin complex and a chromosomal boundary protein that restricts the spread of heterochromatin. We find that the SIR complex relieves a mechanism of auto-inhibition within the boundary protein Yta7, allowing the Yta7 bromodomain to engage chromatin. Our results suggest that budding yeast shares with other eukaryotes the ability to establish complex heterochromatin domains that coordinate multiple mechanisms of silencing regulation through physical interactions.
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Affiliation(s)
- Alexis Zukowski
- Department of Biochemistry and Molecular Genetics, University of Colorado School of Medicine, 12801 E. 17th Ave, Aurora, CO, 80045, USA
- Molecular Biology Program, University of Colorado, Denver, Anschutz Medical Campus, Aurora, CO, 80045, USA
| | - Juliana Phillips
- Department of Biochemistry and Molecular Genetics, University of Colorado School of Medicine, 12801 E. 17th Ave, Aurora, CO, 80045, USA
- Molecular Biology Program, University of Colorado, Denver, Anschutz Medical Campus, Aurora, CO, 80045, USA
| | - Soyeon Park
- Department of Molecular, Cellular, and Developmental Biology, University of Colorado, Boulder, Boulder, CO, 80309, USA
| | - Ronghu Wu
- Department of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, GA, 30332, USA
| | - Steven P Gygi
- Department of Cell Biology, Harvard Medical School, Boston, MA, 02115, USA
| | - Aaron M Johnson
- Department of Biochemistry and Molecular Genetics, University of Colorado School of Medicine, 12801 E. 17th Ave, Aurora, CO, 80045, USA.
- Molecular Biology Program, University of Colorado, Denver, Anschutz Medical Campus, Aurora, CO, 80045, USA.
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10
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Balas MM, Porman AM, Hansen KC, Johnson AM. SILAC-MS Profiling of Reconstituted Human Chromatin Platforms for the Study of Transcription and RNA Regulation. J Proteome Res 2018; 17:3475-3484. [PMID: 30192551 DOI: 10.1021/acs.jproteome.8b00395] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
DNA packaged into chromatin is the core structure of the human genome. Nearly all eukaryotic genome regulation must interface with this genomic structure, and modification of the chromatin can influence molecular mechanisms that regulate the underlying DNA. Many processes are governed by regulated stepwise assembly mechanisms that build complex machinery on chromatin to license a specific activity such as transcription. Transcriptional activators drive the initial steps of gene expression, regulated in part by chromatin. Here we describe tools to study the stepwise assembly of protein complexes on chromatin in a highly controlled manner using reconstituted human chromatin platforms and quantitative proteomic profiling. We profile the early steps in transcriptional activation and highlight the potential for understanding the multiple ways chromatin can influence transcriptional regulation. We also describe modifications of this approach to study the activity of a long noncoding RNA to act as a dynamic scaffold for proteins to be recruited to chromatin. This approach has the potential to provide a more comprehensive understanding of important macromolecular complex assembly that occurs on the human genome. The reconstituted nature of the chromatin substrate offers a tunable system that can be trapped at specific substeps to understand how chromatin interfaces with genome regulation machinery.
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11
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Zukowski A, Al-Afaleq NO, Duncan ED, Yao T, Johnson AM. Recruitment and allosteric stimulation of a histone-deubiquitinating enzyme during heterochromatin assembly. J Biol Chem 2017; 293:2498-2509. [PMID: 29288197 DOI: 10.1074/jbc.ra117.000498] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2017] [Revised: 12/22/2017] [Indexed: 02/02/2023] Open
Abstract
Heterochromatin formation in budding yeast is regulated by the silent information regulator (SIR) complex. The SIR complex comprises the NAD-dependent deacetylase Sir2, the scaffolding protein Sir4, and the nucleosome-binding protein Sir3. Transcriptionally active regions present a challenge to SIR complex-mediated de novo heterochromatic silencing due to the presence of antagonistic histone post-translational modifications, including acetylation and methylation. Methylation of histone H3K4 and H3K79 is dependent on monoubiquitination of histone H2B (H2B-Ub). The SIR complex cannot erase H2B-Ub or histone methylation on its own. The deubiquitinase (DUB) Ubp10 is thought to promote heterochromatic silencing by maintaining low H2B-Ub at sub-telomeres. Here, we biochemically characterized the interactions between Ubp10 and the SIR complex machinery. We demonstrate that a direct interaction between Ubp10 and the Sir2/4 sub-complex facilitates Ubp10 recruitment to chromatin via a co-assembly mechanism. Using hydrolyzable H2B-Ub analogs, we show that Ubp10 activity is lower on nucleosomes compared with H2B-Ub in solution. We find that Sir2/4 stimulates Ubp10 DUB activity on nucleosomes, likely through a combination of targeting and allosteric regulation. This coupling mechanism between the silencing machinery and its DUB partner allows erasure of active PTMs and the de novo transition of a transcriptionally active DNA region to a silent chromatin state.
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Affiliation(s)
- Alexis Zukowski
- From the Department of Biochemistry and Molecular Genetics and.,Molecular Biology Program, University of Colorado, Denver-Anschutz Medical Campus, Aurora, Colorado 80045 and
| | - Nouf Omar Al-Afaleq
- the Department of Biochemistry and Molecular Biology, Colorado State University, Fort Collins, Colorado 80523
| | - Emily D Duncan
- From the Department of Biochemistry and Molecular Genetics and.,Molecular Biology Program, University of Colorado, Denver-Anschutz Medical Campus, Aurora, Colorado 80045 and
| | - Tingting Yao
- the Department of Biochemistry and Molecular Biology, Colorado State University, Fort Collins, Colorado 80523
| | - Aaron M Johnson
- From the Department of Biochemistry and Molecular Genetics and .,Molecular Biology Program, University of Colorado, Denver-Anschutz Medical Campus, Aurora, Colorado 80045 and
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The Nuts and Bolts of Transcriptionally Silent Chromatin in Saccharomyces cerevisiae. Genetics 2017; 203:1563-99. [PMID: 27516616 DOI: 10.1534/genetics.112.145243] [Citation(s) in RCA: 88] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2016] [Accepted: 05/30/2016] [Indexed: 12/31/2022] Open
Abstract
Transcriptional silencing in Saccharomyces cerevisiae occurs at several genomic sites including the silent mating-type loci, telomeres, and the ribosomal DNA (rDNA) tandem array. Epigenetic silencing at each of these domains is characterized by the absence of nearly all histone modifications, including most prominently the lack of histone H4 lysine 16 acetylation. In all cases, silencing requires Sir2, a highly-conserved NAD(+)-dependent histone deacetylase. At locations other than the rDNA, silencing also requires additional Sir proteins, Sir1, Sir3, and Sir4 that together form a repressive heterochromatin-like structure termed silent chromatin. The mechanisms of silent chromatin establishment, maintenance, and inheritance have been investigated extensively over the last 25 years, and these studies have revealed numerous paradigms for transcriptional repression, chromatin organization, and epigenetic gene regulation. Studies of Sir2-dependent silencing at the rDNA have also contributed to understanding the mechanisms for maintaining the stability of repetitive DNA and regulating replicative cell aging. The goal of this comprehensive review is to distill a wide array of biochemical, molecular genetic, cell biological, and genomics studies down to the "nuts and bolts" of silent chromatin and the processes that yield transcriptional silencing.
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Prindull G. Potential Gene Interactions in the Cell Cycles of Gametes, Zygotes, Embryonic Stem Cells and the Development of Cancer. Front Oncol 2015; 5:200. [PMID: 26442212 PMCID: PMC4585297 DOI: 10.3389/fonc.2015.00200] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2014] [Accepted: 08/31/2015] [Indexed: 11/13/2022] Open
Abstract
OBJECTIVES This review is to explore whether potential gene interactions in the cell cycles of gametes, zygotes, and embryonic stem (ES) cells are associated with the development of cancer. METHODS MEDPILOT at the Central Library of the University of Cologne, Germany (Zentralbibliothek Köln) that covers 5,800 international medical journals and 4,300 E-journals was used to collect data. The initial searches were done in December 2012 and additional searches in October 2013-May 2015. The search terms included "cancer development," "gene interaction," and "ES cells," and the time period was between 1998 and 2015. A total of 147 articles in English language only were included in this review. RESULTS Transgenerational gene translation is implemented in the zygote through interactions of epigenetic isoforms of transcription factors (TFs) from parental gametes, predominantly during the first two zygote cleavages. Pluripotent transcription factors may provide interacting links with mutated genes during zygote-to-ES cell switches. Translation of post-transcriptional carcinogenic genes is implemented by abnormally spliced, tumor-specific isoforms of gene-encoded mRNA/non-coding RNA variants of TFs employing de novo gene synthesis and neofunctionalization. Post-translationally, mutated genes are preserved in pre-neoplastic ES cell subpopulations that can give rise to overt cancer stem cells. Thus, TFs operate as cell/disease-specific epigenetic messengers triggering clinical expression of neoplasms. CONCLUSION Potential gene interactions in the cell cycle of gametes, zygotes, and ES cells may play some roles in the development of cancer.
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Affiliation(s)
- Gregor Prindull
- Medical Faculty, University of Göttingen , Göttingen , Germany
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14
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Tatavosian R, Zhen CY, Duc HN, Balas MM, Johnson AM, Ren X. Distinct Cellular Assembly Stoichiometry of Polycomb Complexes on Chromatin Revealed by Single-molecule Chromatin Immunoprecipitation Imaging. J Biol Chem 2015; 290:28038-28054. [PMID: 26381410 DOI: 10.1074/jbc.m115.671115] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2015] [Indexed: 12/11/2022] Open
Abstract
Epigenetic complexes play an essential role in regulating chromatin structure, but information about their assembly stoichiometry on chromatin within cells is poorly understood. The cellular assembly stoichiometry is critical for appreciating the initiation, propagation, and maintenance of epigenetic inheritance during normal development and in cancer. By combining genetic engineering, chromatin biochemistry, and single-molecule fluorescence imaging, we developed a novel and sensitive approach termed single-molecule chromatin immunoprecipitation imaging (Sm-ChIPi) to enable investigation of the cellular assembly stoichiometry of epigenetic complexes on chromatin. Sm-ChIPi was validated by using chromatin complexes with known stoichiometry. The stoichiometry of subunits within a polycomb complex and the assembly stoichiometry of polycomb complexes on chromatin have been extensively studied but reached divergent views. Moreover, the cellular assembly stoichiometry of polycomb complexes on chromatin remains unexplored. Using Sm-ChIPi, we demonstrated that within mouse embryonic stem cells, one polycomb repressive complex (PRC) 1 associates with multiple nucleosomes, whereas two PRC2s can bind to a single nucleosome. Furthermore, we obtained direct physical evidence that the nucleoplasmic PRC1 is monomeric, whereas PRC2 can dimerize in the nucleoplasm. We showed that ES cell differentiation induces selective alteration of the assembly stoichiometry of Cbx2 on chromatin but not other PRC1 components. We additionally showed that the PRC2-mediated trimethylation of H3K27 is not required for the assembly stoichiometry of PRC1 on chromatin. Thus, these findings uncover that PRC1 and PRC2 employ distinct mechanisms to assemble on chromatin, and the novel Sm-ChIPi technique could provide single-molecule insight into other epigenetic complexes.
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Affiliation(s)
- Roubina Tatavosian
- Department of Chemistry, University of Colorado Denver, Denver, Colorado 80217-3364
| | - Chao Yu Zhen
- Department of Chemistry, University of Colorado Denver, Denver, Colorado 80217-3364
| | - Huy Nguyen Duc
- Department of Chemistry, University of Colorado Denver, Denver, Colorado 80217-3364
| | - Maggie M Balas
- Department of Biochemistry and Molecular Genetics, University of Colorado School of Medicine, Aurora, Colorado 80045
| | - Aaron M Johnson
- Department of Biochemistry and Molecular Genetics, University of Colorado School of Medicine, Aurora, Colorado 80045
| | - Xiaojun Ren
- Department of Chemistry, University of Colorado Denver, Denver, Colorado 80217-3364.
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15
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Foda BM, Singh U. Dimethylated H3K27 Is a Repressive Epigenetic Histone Mark in the Protist Entamoeba histolytica and Is Significantly Enriched in Genes Silenced via the RNAi Pathway. J Biol Chem 2015; 290:21114-21130. [PMID: 26149683 DOI: 10.1074/jbc.m115.647263] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2015] [Indexed: 01/02/2023] Open
Abstract
RNA interference (RNAi) is a fundamental biological process that plays a crucial role in regulation of gene expression in many organisms. Transcriptional gene silencing (TGS) is one of the important nuclear roles of RNAi. Our previous data show that Entamoeba histolytica has a robust RNAi pathway that links to TGS via Argonaute 2-2 (Ago2-2) associated 27-nucleotide small RNAs with 5'-polyphosphate termini. Here, we report the first repressive histone mark to be identified in E. histolytica, dimethylation of H3K27 (H3K27Me2), and demonstrate that it is enriched at genes that are silenced by RNAi-mediated TGS. An RNAi-silencing trigger can induce H3K27Me2 deposits at both episomal and chromosomal loci, mediating gene silencing. Our data support two phases of RNAi-mediated TGS: an active silencing phase where the RNAi trigger is present and both H3K27Me2 and Ago2-2 concurrently enrich at chromosomal loci; and an established silencing phase in which the RNAi trigger is removed, but gene silencing with H3K27Me2 enrichment persist independently of Ago2-2 deposition. Importantly, some genes display resistance to chromosomal silencing despite induction of functional small RNAs. In those situations, the RNAi-triggering plasmid that is maintained episomally gets partially silenced and has H3K27Me2 enrichment, but the chromosomal copy displays no repressive histone enrichment. Our data are consistent with a model in which H3K27Me2 is a repressive histone modification, which is strongly associated with transcriptional repression. This is the first example of an epigenetic histone modification that functions to mediate RNAi-mediated TGS in the deep-branching eukaryote E. histolytica.
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Affiliation(s)
- Bardees M Foda
- Departments of Internal Medicine, Division of Infectious Diseases, School of Medicine, Stanford University, Stanford, California 94305; Department of Molecular Genetics and Enzymology, National Research Centre, Dokki, Egypt
| | - Upinder Singh
- Departments of Internal Medicine, Division of Infectious Diseases, School of Medicine, Stanford University, Stanford, California 94305; Departments of Microbiology and Immunology, School of Medicine, Stanford University, Stanford, California 94305.
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16
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Steakley DL, Rine J. On the Mechanism of Gene Silencing in Saccharomyces cerevisiae. G3 (BETHESDA, MD.) 2015; 5:1751-63. [PMID: 26082137 PMCID: PMC4528331 DOI: 10.1534/g3.115.018515] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/11/2015] [Accepted: 06/15/2015] [Indexed: 11/18/2022]
Abstract
Multiple mechanisms have been proposed for gene silencing in Saccharomyces cerevisiae, ranging from steric occlusion of DNA binding proteins from their recognition sequences in silenced chromatin to a specific block in the formation of the preinitiation complex to a block in transcriptional elongation. This study provided strong support for the steric occlusion mechanism by the discovery that RNA polymerase of bacteriophage T7 could be substantially blocked from transcribing from its cognate promoter when embedded in silenced chromatin. Moreover, unlike previous suggestions, we found no evidence for stalled RNA polymerase II within silenced chromatin. The effectiveness of the Sir protein-based silencing mechanism to block transcription activated by Gal4 at promoters in the domain of silenced chromatin was marginal, yet it improved when tested against mutant forms of the Gal4 protein, highlighting a role for specific activators in their sensitivity to gene silencing.
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Affiliation(s)
- David Lee Steakley
- Department of Molecular and Cell Biology, California Institute of Quantitative Biosciences, Stanley Hall, University of California Berkeley, Berkeley, California 94720
| | - Jasper Rine
- Department of Molecular and Cell Biology, California Institute of Quantitative Biosciences, Stanley Hall, University of California Berkeley, Berkeley, California 94720
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17
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Abstract
Heterochromatin contributes to the dynamic range of eukaryotic gene expression. In yeast, its ability to suppress transcription is inversely proportional to activator strength. A recent study reveals that Sir silencing proteins enhance the avidity with which nucleosomes assemble, endowing heterochromatin with both repressive and dynamic characteristics.
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Affiliation(s)
- David S Gross
- Department of Biochemistry and Molecular Biology, Louisiana State University Health Sciences Center, Shreveport, LA 71130, USA.
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18
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Oyama K, El-Nachef D, Zhang Y, Sdek P, MacLellan WR. Epigenetic regulation of cardiac myocyte differentiation. Front Genet 2014; 5:375. [PMID: 25408700 PMCID: PMC4219506 DOI: 10.3389/fgene.2014.00375] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2014] [Accepted: 10/07/2014] [Indexed: 12/04/2022] Open
Abstract
Cardiac myocytes (CMs) proliferate robustly during fetal life but withdraw permanently from the cell cycle soon after birth and undergo terminal differentiation. This cell cycle exit is associated with the upregulation of a host of adult cardiac-specific genes. The vast majority of adult CMs (ACMs) do not reenter cell cycle even if subjected to mitogenic stimuli. The basis for this irreversible cell cycle exit is related to the stable silencing of cell cycle genes specifically involved in the progression of G2/M transition and cytokinesis. Studies have begun to clarify the molecular basis for this stable gene repression and have identified epigenetic and chromatin structural changes in this process. In this review, we summarize the current understanding of epigenetic regulation of CM cell cycle and cardiac-specific gene expression with a focus on histone modifications and the role of retinoblastoma family members.
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Affiliation(s)
- Kyohei Oyama
- Division of Cardiology, Department of Medicine, Center for Cardiovascular Biology and Institute for Stem Cell and Regenerative Medicine, University of Washington Seattle, WA, USA
| | - Danny El-Nachef
- Division of Cardiology, Department of Medicine, Center for Cardiovascular Biology and Institute for Stem Cell and Regenerative Medicine, University of Washington Seattle, WA, USA
| | - Yiqiang Zhang
- Division of Cardiology, Department of Medicine, Center for Cardiovascular Biology and Institute for Stem Cell and Regenerative Medicine, University of Washington Seattle, WA, USA
| | - Patima Sdek
- Division of Cardiology, Department of Medicine, Center for Cardiovascular Biology and Institute for Stem Cell and Regenerative Medicine, University of Washington Seattle, WA, USA
| | - W Robb MacLellan
- Division of Cardiology, Department of Medicine, Center for Cardiovascular Biology and Institute for Stem Cell and Regenerative Medicine, University of Washington Seattle, WA, USA
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19
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Bi X. Heterochromatin structure: lessons from the budding yeast. IUBMB Life 2014; 66:657-66. [PMID: 25355678 DOI: 10.1002/iub.1322] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2014] [Revised: 10/12/2014] [Accepted: 10/14/2014] [Indexed: 12/28/2022]
Abstract
The eukaryotic genome can be roughly divided into euchromatin and heterochromatin domains that are structurally and functionally distinct. Heterochromatin is characterized by its high compactness and its inhibitory effect on DNA transactions such as gene expression. Formation of heterochromatin involves special histone modifications and the recruitment and spread of silencing complexes and causes changes in the primary and higher order structures of chromatin. The past two decades have seen dramatic advances in dissecting the molecular aspects of heterochromatin because of the identification of the histone code for heterochromatin as well as its writers and erasers (histone-modifying enzymes) and readers (silencing factors recognizing histone modifications). How heterochromatic histone modifications and silencing factors contribute to the special primary and higher order structures of heterochromatin has begun to be understood. The budding yeast Saccharomyces cerevisiae has long been used as a model organism for heterochromatin studies. Results from these studies have contributed significantly to the elucidation of the general principles governing the formation, maintenance, and function of heterochromatin. This review is focused on investigations into the structural aspects of heterochromatin in S. cerevisiae. Current understanding of other aspects of heterochromatin including how it promotes gene silencing and its epigenetic inheritance is briefly summarized.
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Affiliation(s)
- Xin Bi
- Department of Biology, University of Rochester, Rochester, NY, USA
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Zhang H, Gao L, Anandhakumar J, Gross DS. Uncoupling transcription from covalent histone modification. PLoS Genet 2014; 10:e1004202. [PMID: 24722509 PMCID: PMC3983032 DOI: 10.1371/journal.pgen.1004202] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2013] [Accepted: 01/08/2014] [Indexed: 12/04/2022] Open
Abstract
It is widely accepted that transcriptional regulation of eukaryotic genes is intimately coupled to covalent modifications of the underlying chromatin template, and in certain cases the functional consequences of these modifications have been characterized. Here we present evidence that gene activation in the silent heterochromatin of the yeast Saccharomyces cerevisiae can occur in the context of little, if any, covalent histone modification. Using a SIR-regulated heat shock-inducible transgene, hsp82-2001, and a natural drug-inducible subtelomeric gene, YFR057w, as models we demonstrate that substantial transcriptional induction (>200-fold) can occur in the context of restricted histone loss and negligible levels of H3K4 trimethylation, H3K36 trimethylation and H3K79 dimethylation, modifications commonly linked to transcription initiation and elongation. Heterochromatic gene activation can also occur with minimal H3 and H4 lysine acetylation and without replacement of H2A with the transcription-linked variant H2A.Z. Importantly, absence of histone modification does not stem from reduced transcriptional output, since hsp82-ΔTATA, a euchromatic promoter mutant lacking a TATA box and with threefold lower induced transcription than heterochromatic hsp82-2001, is strongly hyperacetylated in response to heat shock. Consistent with negligible H3K79 dimethylation, dot1Δ cells lacking H3K79 methylase activity show unimpeded occupancy of RNA polymerase II within activated heterochromatic promoter and coding regions. Our results indicate that large increases in transcription can be observed in the virtual absence of histone modifications often thought necessary for gene activation. The proper regulation of gene expression is of fundamental importance in the maintenance of normal growth and development. Misregulation of genes can lead to such outcomes as cancer, diabetes and neurodegenerative disease. A key step in gene regulation occurs during the transcription of the chromosomal DNA into messenger RNA by the enzyme, RNA polymerase II. Histones are small, positively charged proteins that package genomic DNA into arrays of bead-like particles termed nucleosomes, the principal components of chromatin. Increasing evidence suggests that nucleosomal histones play an active role in regulating transcription, and that this is derived in part from reversible chemical (“covalent”) modifications that take place on their amino acids. These histone modifications create novel surfaces on nucleosomes that can serve as docking sites for other proteins that control a gene's expression state. In this study we present evidence that contrary to the general case, covalent modifications typically associated with transcription are minimally used by genes embedded in a specialized, condensed chromatin structure termed heterochromatin in the model organism baker's yeast. Our observations are significant, for they suggest that gene transcription can occur in a living cell in the virtual absence of covalent modification of the chromatin template.
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Affiliation(s)
- Hesheng Zhang
- Department of Biochemistry and Molecular Biology, Louisiana State University Health Sciences Center, Shreveport, Louisiana, United States of America
| | - Lu Gao
- Department of Biochemistry and Molecular Biology, Louisiana State University Health Sciences Center, Shreveport, Louisiana, United States of America
| | - Jayamani Anandhakumar
- Department of Biochemistry and Molecular Biology, Louisiana State University Health Sciences Center, Shreveport, Louisiana, United States of America
| | - David S. Gross
- Department of Biochemistry and Molecular Biology, Louisiana State University Health Sciences Center, Shreveport, Louisiana, United States of America
- * E-mail:
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