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Ungerleider NA, Roberts C, O’Grady TM, Nguyen TT, Baddoo M, Wang J, Ishaq E, Concha M, Lam M, Bass J, Nguyen T, Van Otterloo N, Wickramarachchige-Dona N, Wyczechowska D, Morales M, Ma T, Dong Y, Flemington E. Viral reprogramming of host transcription initiation. Nucleic Acids Res 2024; 52:5016-5032. [PMID: 38471819 PMCID: PMC11109974 DOI: 10.1093/nar/gkae175] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2023] [Revised: 01/13/2024] [Accepted: 02/28/2024] [Indexed: 03/14/2024] Open
Abstract
Viruses are master remodelers of the host cell environment in support of infection and virus production. For example, viruses typically regulate cell gene expression through modulating canonical cell promoter activity. Here, we show that Epstein Barr virus (EBV) replication causes 'de novo' transcription initiation at 29674 new transcription start sites throughout the cell genome. De novo transcription initiation is facilitated in part by the unique properties of the viral pre-initiation complex (vPIC) that binds a TATT[T/A]AA, TATA box-like sequence and activates transcription with minimal support by additional transcription factors. Other de novo promoters are driven by the viral transcription factors, Zta and Rta and are influenced by directional proximity to existing canonical cell promoters, a configuration that fosters transcription through existing promoters and transcriptional interference. These studies reveal a new way that viruses interact with the host transcriptome to inhibit host gene expression and they shed light on primal features driving eukaryotic promoter function.
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Affiliation(s)
- Nathan A Ungerleider
- Department of Pathology & Laboratory Medicine, Tulane University School of Medicine, Tulane Cancer Center, New Orleans, LA, USA
| | - Claire Roberts
- Department of Pathology & Laboratory Medicine, Tulane University School of Medicine, Tulane Cancer Center, New Orleans, LA, USA
| | - Tina M O’Grady
- Department of Pathology & Laboratory Medicine, Tulane University School of Medicine, Tulane Cancer Center, New Orleans, LA, USA
| | - Trang T Nguyen
- Department of Pathology & Laboratory Medicine, Tulane University School of Medicine, Tulane Cancer Center, New Orleans, LA, USA
| | - Melody Baddoo
- Department of Pathology & Laboratory Medicine, Tulane University School of Medicine, Tulane Cancer Center, New Orleans, LA, USA
| | - Jia Wang
- Department of Pathology & Laboratory Medicine, Tulane University School of Medicine, Tulane Cancer Center, New Orleans, LA, USA
| | - Eman Ishaq
- Department of Pathology & Laboratory Medicine, Tulane University School of Medicine, Tulane Cancer Center, New Orleans, LA, USA
| | - Monica Concha
- Department of Pathology & Laboratory Medicine, Tulane University School of Medicine, Tulane Cancer Center, New Orleans, LA, USA
| | - Meggie Lam
- Department of Pathology & Laboratory Medicine, Tulane University School of Medicine, Tulane Cancer Center, New Orleans, LA, USA
| | - Jordan Bass
- Department of Pathology & Laboratory Medicine, Tulane University School of Medicine, Tulane Cancer Center, New Orleans, LA, USA
| | - Truong D Nguyen
- Department of Pathology & Laboratory Medicine, Tulane University School of Medicine, Tulane Cancer Center, New Orleans, LA, USA
| | - Nick Van Otterloo
- Department of Pathology & Laboratory Medicine, Tulane University School of Medicine, Tulane Cancer Center, New Orleans, LA, USA
| | | | - Dorota Wyczechowska
- Stanley S. Scott Cancer Center, Louisiana State University Health Sciences Center, New Orleans, LA, USA
| | | | - Tianfang Ma
- Dana-Farber Cancer Institute, Boston, MA, USA
| | - Yan Dong
- Department of Structural and Cellular Biology, Tulane University School of Medicine, Tulane Cancer Center, New Orleans, LA, USA
| | - Erik K Flemington
- Department of Pathology & Laboratory Medicine, Tulane University School of Medicine, Tulane Cancer Center, New Orleans, LA, USA
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2
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Contreras A, Perea-Resa C. Transcriptional repression across mitosis: mechanisms and functions. Biochem Soc Trans 2024; 52:455-464. [PMID: 38372373 PMCID: PMC10903446 DOI: 10.1042/bst20231071] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2023] [Revised: 02/05/2024] [Accepted: 02/06/2024] [Indexed: 02/20/2024]
Abstract
Transcription represents a central aspect of gene expression with RNA polymerase machineries (RNA Pol) driving the synthesis of RNA from DNA template molecules. In eukaryotes, a total of three RNA Pol enzymes generate the plethora of RNA species and RNA Pol II is the one transcribing all protein-coding genes. A high number of cis- and trans-acting factors orchestrates RNA Pol II-mediated transcription by influencing the chromatin recruitment, activation, elongation, and/or termination steps. The levels of DNA accessibility, defining open-euchromatin versus close-heterochromatin, delimits RNA Pol II activity as well as the encounter with other factors acting on chromatin such as the DNA replication or DNA repair machineries. The stage of the cell cycle highly influences RNA Pol II activity with mitosis representing the major challenge. In fact, there is a massive inhibition of transcription during the mitotic entry coupled with chromatin dissociation of most of the components of the transcriptional machinery. Mitosis, as a consequence, highly compromises the transcriptional memory and the perpetuation of cellular identity. Once mitosis ends, transcription levels immediately recover to define the cell fate and to safeguard the proper progression of daughter cells through the cell cycle. In this review, we evaluate our current understanding of the transcriptional repression associated with mitosis with a special focus on the molecular mechanisms involved, on the potential function behind the general repression, and on the transmission of the transcriptional machinery into the daughter cells. We finally discuss the contribution that errors in the inheritance of the transcriptional machinery across mitosis might play in stem cell aging.
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Affiliation(s)
- A. Contreras
- Centro de Biología Molecular Severo Ochoa (CBMSO-CSIC), C/Nicolas Cabrera 1, 28049 Madrid, Spain
| | - C. Perea-Resa
- Centro de Biología Molecular Severo Ochoa (CBMSO-CSIC), C/Nicolas Cabrera 1, 28049 Madrid, Spain
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3
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Khamwachirapithak P, Guillaume-Schoepfer D, Chansongkrow P, Teichmann SA, Wigge PA, Charoensawan V. Characterizing Different Modes of Interplay Between Rap1 and H3 Using Inducible H3-depletion Yeast. J Mol Biol 2023; 435:168355. [PMID: 37935256 DOI: 10.1016/j.jmb.2023.168355] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2023] [Revised: 10/31/2023] [Accepted: 11/01/2023] [Indexed: 11/09/2023]
Abstract
Histones and transcription factors (TFs) are two important DNA-binding proteins that interact, compete, and together regulate transcriptional processes in response to diverse internal and external stimuli. Condition-specific depletion of histones in Saccharomyces cerevisiae using a galactose-inducible H3 promoter provides a suitable framework for examining transcriptional alteration resulting from reduced nucleosome content. However, the effect on DNA binding activities of TFs is yet to be fully explored. In this work, we combine ChIP-seq of H3 with RNA-seq to elucidate the genome-scale relationships between H3 occupancy patterns and transcriptional dynamics before and after global H3 depletion. ChIP-seq of Rap1 is also conducted in the H3-depletion and control treatments, to investigate the interplay between this master regulator TF and nucleosomal H3, and to explore the impact on diverse transcriptional responses of different groups of target genes and functions. Ultimately, we propose a working model and testable hypotheses regarding the impact of global and local H3 depletion on transcriptional changes. We also demonstrate different potential modes of interaction between Rap1 and H3, which sheds light on the potential multifunctional regulatory capabilities of Rap1 and potentially other pioneer factors.
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Affiliation(s)
- Peerapat Khamwachirapithak
- Doctor of Philosophy Program in Biochemistry (International Program), Faculty of Science, Mahidol University, Bangkok, Thailand; Department of Biochemistry, Faculty of Science, Mahidol University, Bangkok, Thailand
| | | | - Pakkanan Chansongkrow
- Department of Biochemistry, Faculty of Science, Mahidol University, Bangkok, Thailand
| | - Sarah A Teichmann
- Wellcome Sanger Institute, Wellcome Genome Campus, Cambridge, UK; Department of Physics, Cavendish Laboratory, University of Cambridge, Cambridge, UK.
| | - Philip A Wigge
- Sainsbury Laboratory, University of Cambridge, Cambridge, United Kingdom; University Potsdam, Institute for Biochemistry and Biology, Molecular Biology, Karl-Liebknecht-Str, Potsdam-Golm, Germany; Institute of Biochemistry and Biology, University of Potsdam, Potsdam-Golm, Germany.
| | - Varodom Charoensawan
- Department of Biochemistry, Faculty of Science, Mahidol University, Bangkok, Thailand; Sainsbury Laboratory, University of Cambridge, Cambridge, United Kingdom; Systems Biology of Diseases Research Unit, Faculty of Science, Mahidol University, Bangkok, Thailand; Integrative Computational BioScience (ICBS) center, Mahidol University, Nakhon Pathom, Thailand; School of Chemistry, Institute of Science, Suranaree University of Technology, Nakhon Ratchasima, Thailand.
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4
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De Sarkar N, Patton RD, Doebley AL, Hanratty B, Adil M, Kreitzman AJ, Sarthy JF, Ko M, Brahma S, Meers MP, Janssens DH, Ang LS, Coleman IM, Bose A, Dumpit RF, Lucas JM, Nunez TA, Nguyen HM, McClure HM, Pritchard CC, Schweizer MT, Morrissey C, Choudhury AD, Baca SC, Berchuck JE, Freedman ML, Ahmad K, Haffner MC, Montgomery RB, Corey E, Henikoff S, Nelson PS, Ha G. Nucleosome Patterns in Circulating Tumor DNA Reveal Transcriptional Regulation of Advanced Prostate Cancer Phenotypes. Cancer Discov 2023; 13:632-653. [PMID: 36399432 PMCID: PMC9976992 DOI: 10.1158/2159-8290.cd-22-0692] [Citation(s) in RCA: 10] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2022] [Revised: 10/01/2022] [Accepted: 11/16/2022] [Indexed: 11/19/2022]
Abstract
Advanced prostate cancers comprise distinct phenotypes, but tumor classification remains clinically challenging. Here, we harnessed circulating tumor DNA (ctDNA) to study tumor phenotypes by ascertaining nucleosome positioning patterns associated with transcription regulation. We sequenced plasma ctDNA whole genomes from patient-derived xenografts representing a spectrum of androgen receptor active (ARPC) and neuroendocrine (NEPC) prostate cancers. Nucleosome patterns associated with transcriptional activity were reflected in ctDNA at regions of genes, promoters, histone modifications, transcription factor binding, and accessible chromatin. We identified the activity of key phenotype-defining transcriptional regulators from ctDNA, including AR, ASCL1, HOXB13, HNF4G, and GATA2. To distinguish NEPC and ARPC in patient plasma samples, we developed prediction models that achieved accuracies of 97% for dominant phenotypes and 87% for mixed clinical phenotypes. Although phenotype classification is typically assessed by IHC or transcriptome profiling from tumor biopsies, we demonstrate that ctDNA provides comparable results with diagnostic advantages for precision oncology. SIGNIFICANCE This study provides insights into the dynamics of nucleosome positioning and gene regulation associated with cancer phenotypes that can be ascertained from ctDNA. New methods for classification in phenotype mixtures extend the utility of ctDNA beyond assessments of somatic DNA alterations with important implications for molecular classification and precision oncology. This article is highlighted in the In This Issue feature, p. 517.
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Affiliation(s)
- Navonil De Sarkar
- Division of Public Health Sciences, Fred Hutchinson Cancer Center, Seattle, Washington
- Division of Human Biology, Fred Hutchinson Cancer Center, Seattle, Washington
- Division of Clinical Research, Fred Hutchinson Cancer Center, Seattle, Washington
- Department of Pathology and Prostate Cancer Center of Excellence, Medical College of Wisconsin, Milwaukee, Wisconsin
| | - Robert D. Patton
- Division of Public Health Sciences, Fred Hutchinson Cancer Center, Seattle, Washington
- Division of Human Biology, Fred Hutchinson Cancer Center, Seattle, Washington
| | - Anna-Lisa Doebley
- Division of Public Health Sciences, Fred Hutchinson Cancer Center, Seattle, Washington
- Division of Human Biology, Fred Hutchinson Cancer Center, Seattle, Washington
- Molecular and Cellular Biology Graduate Program, University of Washington, Seattle, Washington
- Medical Scientist Training Program, University of Washington, Seattle, Washington
| | - Brian Hanratty
- Division of Human Biology, Fred Hutchinson Cancer Center, Seattle, Washington
| | - Mohamed Adil
- Division of Public Health Sciences, Fred Hutchinson Cancer Center, Seattle, Washington
| | - Adam J. Kreitzman
- Division of Public Health Sciences, Fred Hutchinson Cancer Center, Seattle, Washington
- Division of Human Biology, Fred Hutchinson Cancer Center, Seattle, Washington
| | - Jay F. Sarthy
- Division of Basic Sciences, Fred Hutchinson Cancer Center, Seattle, Washington
| | - Minjeong Ko
- Division of Public Health Sciences, Fred Hutchinson Cancer Center, Seattle, Washington
- Division of Human Biology, Fred Hutchinson Cancer Center, Seattle, Washington
| | - Sandipan Brahma
- Division of Basic Sciences, Fred Hutchinson Cancer Center, Seattle, Washington
| | - Michael P. Meers
- Division of Basic Sciences, Fred Hutchinson Cancer Center, Seattle, Washington
| | - Derek H. Janssens
- Division of Basic Sciences, Fred Hutchinson Cancer Center, Seattle, Washington
| | - Lisa S. Ang
- Division of Human Biology, Fred Hutchinson Cancer Center, Seattle, Washington
| | - Ilsa M. Coleman
- Division of Human Biology, Fred Hutchinson Cancer Center, Seattle, Washington
| | - Arnab Bose
- Division of Human Biology, Fred Hutchinson Cancer Center, Seattle, Washington
| | - Ruth F. Dumpit
- Division of Human Biology, Fred Hutchinson Cancer Center, Seattle, Washington
| | - Jared M. Lucas
- Division of Human Biology, Fred Hutchinson Cancer Center, Seattle, Washington
| | - Talina A. Nunez
- Division of Human Biology, Fred Hutchinson Cancer Center, Seattle, Washington
| | - Holly M. Nguyen
- Department of Urology, University of Washington, Seattle, Washington
| | | | - Colin C. Pritchard
- Department of Laboratory Medicine and Pathology, University of Washington, Seattle, Washington
- Brotman Baty Institute for Precision Medicine, Seattle, Washington
| | - Michael T. Schweizer
- Division of Clinical Research, Fred Hutchinson Cancer Center, Seattle, Washington
- Division of Oncology, Department of Medicine, University of Washington, Seattle, Washington
| | - Colm Morrissey
- Department of Urology, University of Washington, Seattle, Washington
| | - Atish D. Choudhury
- Dana-Farber Cancer Institute, Boston, Massachusetts
- Broad Institute of MIT and Harvard, Cambridge, Massachusetts
| | - Sylvan C. Baca
- Dana-Farber Cancer Institute, Boston, Massachusetts
- Broad Institute of MIT and Harvard, Cambridge, Massachusetts
| | | | - Matthew L. Freedman
- Dana-Farber Cancer Institute, Boston, Massachusetts
- Broad Institute of MIT and Harvard, Cambridge, Massachusetts
| | - Kami Ahmad
- Division of Basic Sciences, Fred Hutchinson Cancer Center, Seattle, Washington
| | - Michael C. Haffner
- Division of Human Biology, Fred Hutchinson Cancer Center, Seattle, Washington
- Division of Clinical Research, Fred Hutchinson Cancer Center, Seattle, Washington
- Department of Laboratory Medicine and Pathology, University of Washington, Seattle, Washington
| | - R. Bruce Montgomery
- Division of Oncology, Department of Medicine, University of Washington, Seattle, Washington
| | - Eva Corey
- Department of Urology, University of Washington, Seattle, Washington
| | - Steven Henikoff
- Division of Basic Sciences, Fred Hutchinson Cancer Center, Seattle, Washington
- Howard Hughes Medical Institute, Chevy Chase, Maryland
| | - Peter S. Nelson
- Division of Human Biology, Fred Hutchinson Cancer Center, Seattle, Washington
- Division of Clinical Research, Fred Hutchinson Cancer Center, Seattle, Washington
- Department of Urology, University of Washington, Seattle, Washington
- Brotman Baty Institute for Precision Medicine, Seattle, Washington
- Division of Oncology, Department of Medicine, University of Washington, Seattle, Washington
- Corresponding Authors: Gavin Ha, Fred Hutchinson Cancer Center, 1100 Fairview Avenue North, Seattle, WA 98109. Phone: 206-667-2802; E-mail: ; and Peter S. Nelson, Fred Hutchinson Cancer Center, 1100 Fairview Avenue North, Seattle, WA 98109. Phone: 206-667-3377; E-mail:
| | - Gavin Ha
- Division of Public Health Sciences, Fred Hutchinson Cancer Center, Seattle, Washington
- Division of Human Biology, Fred Hutchinson Cancer Center, Seattle, Washington
- Brotman Baty Institute for Precision Medicine, Seattle, Washington
- Department of Genome Sciences, University of Washington, Seattle, Washington
- Corresponding Authors: Gavin Ha, Fred Hutchinson Cancer Center, 1100 Fairview Avenue North, Seattle, WA 98109. Phone: 206-667-2802; E-mail: ; and Peter S. Nelson, Fred Hutchinson Cancer Center, 1100 Fairview Avenue North, Seattle, WA 98109. Phone: 206-667-3377; E-mail:
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5
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Shu J, Ding N, Liu J, Cui Y, Chen C. Transcription elongator SPT6L regulates the occupancies of the SWI2/SNF2 chromatin remodelers SYD/BRM and nucleosomes at transcription start sites in Arabidopsis. Nucleic Acids Res 2022; 50:12754-12767. [PMID: 36453990 PMCID: PMC9825159 DOI: 10.1093/nar/gkac1126] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2022] [Revised: 10/10/2022] [Accepted: 11/08/2022] [Indexed: 12/03/2022] Open
Abstract
Chromatin remodelers have been thought to be crucial in creating an accessible chromatin environment before transcription activation. However, it is still unclear how chromatin remodelers recognize and bind to the active regions. In this study, we found that chromatin remodelers SPLAYED (SYD) and BRAHMA (BRM) interact and co-occupy with Suppressor of Ty6-like (SPT6L), a core subunit of the transcription machinery, at thousands of the transcription start sites (TSS). The association of SYD and BRM to chromatin is dramatically reduced in spt6l and can be restored mainly by SPT6LΔtSH2, which binds to TSS in a RNA polymerase II (Pol II)-independent manner. Furthermore, SPT6L and SYD/BRM are involved in regulating the nucleosome and Pol II occupancy around TSS. The presence of SPT6L is sufficient to restore the association of the chromatin remodeler SYD to chromatin and maintain normal nucleosome occupancy. Our findings suggest that the two chromatin remodelers can form protein complexes with the core subunit of the transcription machinery and regulate nucleosome occupancy in the early transcription stage.
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Affiliation(s)
- Jie Shu
- Key Laboratory of South China Agricultural Plant Molecular Analysis and Genetic Improvement & Guangdong Provincial Key Laboratory of Applied Botany, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou, Guangdong 510650, China
| | - Ning Ding
- Key Laboratory of South China Agricultural Plant Molecular Analysis and Genetic Improvement & Guangdong Provincial Key Laboratory of Applied Botany, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou, Guangdong 510650, China,University of the Chinese Academy of Sciences, Beijing 100049, China
| | - Jun Liu
- Agro-biological Gene Research Center, Guangdong Academy of Agricultural Sciences, Guangzhou, Guangdong 510640, China
| | - Yuhai Cui
- Agriculture and Agri-Food Canada, London Research and Development Centre, London, Ontario N5V 4T3, Canada,Department of Biology, Western University, London, Ontario N6A 5B7, Canada
| | - Chen Chen
- To whom correspondence should be addressed. Tel: +86 20 37252711;
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6
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Latham AP, Zhang B. Molecular Determinants for the Layering and Coarsening of Biological Condensates. AGGREGATE (HOBOKEN, N.J.) 2022; 3:e306. [PMID: 37065433 PMCID: PMC10101022 DOI: 10.1002/agt2.306] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/18/2023]
Abstract
Many membraneless organelles, or biological condensates, form through phase separation, and play key roles in signal sensing and transcriptional regulation. While the functional importance of these condensates has inspired many studies to characterize their stability and spatial organization, the underlying principles that dictate these emergent properties are still being uncovered. In this review, we examine recent work on biological condensates, especially multicomponent systems. We focus on connecting molecular factors such as binding energy, valency, and stoichiometry with the interfacial tension, explaining the nontrivial interior organization in many condensates. We further discuss mechanisms that arrest condensate coalescence by lowering the surface tension or introducing kinetic barriers to stabilize the multidroplet state.
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Affiliation(s)
- Andrew P Latham
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA, 02139
- Department of Bioengineering and Therapeutic Sciences, University of California at San Francisco, San Francisco, CA 94143
| | - Bin Zhang
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA, 02139
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7
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Jiang Z, Qi Y, Kamat K, Zhang B. Phase Separation and Correlated Motions in Motorized Genome. J Phys Chem B 2022; 126:5619-5628. [PMID: 35858189 PMCID: PMC9899348 DOI: 10.1021/acs.jpcb.2c03238] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
The human genome is arranged in the cell nucleus nonrandomly, and phase separation has been proposed as an important driving force for genome organization. However, the cell nucleus is an active system, and the contribution of nonequilibrium activities to phase separation and genome structure and dynamics remains to be explored. We simulated the genome using an energy function parametrized with chromosome conformation capture (Hi-C) data with the presence of active, nondirectional forces that break the detailed balance. We found that active forces that may arise from transcription and chromatin remodeling can dramatically impact the spatial localization of heterochromatin. When applied to euchromatin, active forces can drive heterochromatin to the nuclear envelope and compete with passive interactions among heterochromatin that tend to pull them in opposite directions. Furthermore, active forces induce long-range spatial correlations among genomic loci beyond single chromosome territories. We further showed that the impact of active forces could be understood from the effective temperature defined as the fluctuation-dissipation ratio. Our study suggests that nonequilibrium activities can significantly impact genome structure and dynamics, producing unexpected collective phenomena.
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Affiliation(s)
- Zhongling Jiang
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139-4307, United States
| | - Yifeng Qi
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139-4307, United States
| | - Kartik Kamat
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139-4307, United States
| | - Bin Zhang
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139-4307, United States
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8
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Kadam S, Bameta T, Padinhateeri R. Nucleosome sliding can influence the spreading of histone modifications. Phys Rev E 2022; 106:024408. [PMID: 36110002 DOI: 10.1103/physreve.106.024408] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2021] [Accepted: 07/25/2022] [Indexed: 06/15/2023]
Abstract
Nucleosomes are the fundamental building blocks of chromatin that not only help in the folding of chromatin, but also in carrying epigenetic information. It is known that nucleosome sliding is responsible for dynamically organizing chromatin structure and the resulting gene regulation. Since sliding can move two neighboring nucleosomes physically close or away, can it play a role in the spreading of histone modifications? We investigate this by simulating a stochastic model that couples nucleosome dynamics with the kinetics of histone modifications. We show that the sliding of nucleosomes can affect the modification pattern as well as the time it takes to modify a given region of chromatin. Exploring different nucleosome densities and modification kinetic parameters, we show that nucleosome sliding can be important for creating histone modification domains. Our model predicts that nucleosome density coupled with sliding dynamics can create an asymmetric histone modification profile around regulatory regions. We also compute the probability distribution of modified nucleosomes and relaxation kinetics of modifications. Our predictions are comparable with known experimental results.
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Affiliation(s)
- Shantanu Kadam
- Department of Biosciences and Bioengineering, Indian Institute of Technology Bombay, Mumbai 400076, India
| | - Tripti Bameta
- Department of Medical Oncology, Tata Memorial Centre, Homi Bhabha National Institute, Mumbai 410210, India
| | - Ranjith Padinhateeri
- Department of Biosciences and Bioengineering, Indian Institute of Technology Bombay, Mumbai 400076, India
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9
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Obstacles and Opportunities for Base Excision Repair in Chromatin. DNA Repair (Amst) 2022; 116:103345. [PMID: 35689883 PMCID: PMC9253077 DOI: 10.1016/j.dnarep.2022.103345] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2022] [Revised: 05/20/2022] [Accepted: 05/24/2022] [Indexed: 01/01/2023]
Abstract
Most eukaryotic DNA is packaged into chromatin, which is made up of tandemly repeating nucleosomes. This packaging of DNA poses a significant barrier to the various enzymes that must act on DNA, including DNA damage response enzymes that interact intimately with DNA to prevent mutations and cell death. To regulate access to certain DNA regions, chromatin remodeling, variant histone exchange, and histone post-translational modifications have been shown to assist several DNA repair pathways including nucleotide excision repair, single strand break repair, and double strand break repair. While these chromatin-level responses have been directly linked to various DNA repair pathways, how they modulate the base excision repair (BER) pathway remains elusive. This review highlights recent findings that demonstrate how BER is regulated by the packaging of DNA into nucleosome core particles (NCPs) and higher orders of chromatin structures. We also summarize the available data that indicate BER may be enabled by chromatin modifications and remodeling.
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10
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Lin X, Qi Y, Latham AP, Zhang B. Multiscale modeling of genome organization with maximum entropy optimization. J Chem Phys 2021; 155:010901. [PMID: 34241389 PMCID: PMC8253599 DOI: 10.1063/5.0044150] [Citation(s) in RCA: 30] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2021] [Accepted: 04/28/2021] [Indexed: 12/15/2022] Open
Abstract
Three-dimensional (3D) organization of the human genome plays an essential role in all DNA-templated processes, including gene transcription, gene regulation, and DNA replication. Computational modeling can be an effective way of building high-resolution genome structures and improving our understanding of these molecular processes. However, it faces significant challenges as the human genome consists of over 6 × 109 base pairs, a system size that exceeds the capacity of traditional modeling approaches. In this perspective, we review the progress that has been made in modeling the human genome. Coarse-grained models parameterized to reproduce experimental data via the maximum entropy optimization algorithm serve as effective means to study genome organization at various length scales. They have provided insight into the principles of whole-genome organization and enabled de novo predictions of chromosome structures from epigenetic modifications. Applications of these models at a near-atomistic resolution further revealed physicochemical interactions that drive the phase separation of disordered proteins and dictate chromatin stability in situ. We conclude with an outlook on the opportunities and challenges in studying chromosome dynamics.
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Affiliation(s)
- Xingcheng Lin
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - Yifeng Qi
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - Andrew P. Latham
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - Bin Zhang
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
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11
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Understanding transcription across scales: From base pairs to chromosomes. Mol Cell 2021; 81:1601-1616. [PMID: 33770487 DOI: 10.1016/j.molcel.2021.03.002] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2021] [Revised: 02/23/2021] [Accepted: 02/26/2021] [Indexed: 02/07/2023]
Abstract
The influence of genome organization on transcription is central to our understanding of cell type specification. Higher-order genome organization is established through short- and long-range DNA interactions. Coordination of these interactions, from single atoms to entire chromosomes, plays a fundamental role in transcriptional control of gene expression. Loss of this coupling can result in disease. Analysis of transcriptional regulation typically involves disparate experimental approaches, from structural studies that define angstrom-level interactions to cell-biological and genomic approaches that assess mesoscale relationships. Thus, to fully understand the mechanisms that regulate gene expression, it is critical to integrate the findings gained across these distinct size scales. In this review, I illustrate fundamental ways in which cells regulate transcription in the context of genome organization.
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