1
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Sahrhage M, Paul NB, Beißbarth T, Haubrock M. The importance of DNA sequence for nucleosome positioning in transcriptional regulation. Life Sci Alliance 2024; 7:e202302380. [PMID: 38830772 PMCID: PMC11147951 DOI: 10.26508/lsa.202302380] [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: 09/18/2023] [Revised: 05/15/2024] [Accepted: 05/16/2024] [Indexed: 06/05/2024] Open
Abstract
Nucleosome positioning is a key factor for transcriptional regulation. Nucleosomes regulate the dynamic accessibility of chromatin and interact with the transcription machinery at every stage. Influences to steer nucleosome positioning are diverse, and the according importance of the DNA sequence in contrast to active chromatin remodeling has been the subject of long discussion. In this study, we evaluate the functional role of DNA sequence for all major elements along the process of transcription. We developed a random forest classifier based on local DNA structure that assesses the sequence-intrinsic support for nucleosome positioning. On this basis, we created a simple data resource that we applied genome-wide to the human genome. In our comprehensive analysis, we found a special role of DNA in mediating the competition of nucleosomes with cis-regulatory elements, in enabling steady transcription, for positioning of stable nucleosomes in exons, and for repelling nucleosomes during transcription termination. In contrast, we relate these findings to concurrent processes that generate strongly positioned nucleosomes in vivo that are not mediated by sequence, such as energy-dependent remodeling of chromatin.
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Affiliation(s)
- Malte Sahrhage
- Department of Medical Bioinformatics, University Medical Center, Göttingen, Germany
| | - Niels Benjamin Paul
- Department of Medical Bioinformatics, University Medical Center, Göttingen, Germany
- Department of Cardiology and Pneumology, University Medical Center, Göttingen, Germany
| | - Tim Beißbarth
- Department of Medical Bioinformatics, University Medical Center, Göttingen, Germany
| | - Martin Haubrock
- Department of Medical Bioinformatics, University Medical Center, Göttingen, Germany
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2
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Bonnell VA, Zhang Y, Brown AS, Horton J, Josling GA, Chiu TP, Rohs R, Mahony S, Gordân R, Llinás M. DNA sequence and chromatin differentiate sequence-specific transcription factor binding in the human malaria parasite Plasmodium falciparum. Nucleic Acids Res 2024:gkae585. [PMID: 38966997 DOI: 10.1093/nar/gkae585] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2023] [Revised: 05/30/2024] [Accepted: 06/27/2024] [Indexed: 07/06/2024] Open
Abstract
Development of the malaria parasite, Plasmodium falciparum, is regulated by a limited number of sequence-specific transcription factors (TFs). However, the mechanisms by which these TFs recognize genome-wide binding sites is largely unknown. To address TF specificity, we investigated the binding of two TF subsets that either bind CACACA or GTGCAC DNA sequence motifs and further characterized two additional ApiAP2 TFs, PfAP2-G and PfAP2-EXP, which bind unique DNA motifs (GTAC and TGCATGCA). We also interrogated the impact of DNA sequence and chromatin context on P. falciparum TF binding by integrating high-throughput in vitro and in vivo binding assays, DNA shape predictions, epigenetic post-translational modifications, and chromatin accessibility. We found that DNA sequence context minimally impacts binding site selection for paralogous CACACA-binding TFs, while chromatin accessibility, epigenetic patterns, co-factor recruitment, and dimerization correlate with differential binding. In contrast, GTGCAC-binding TFs prefer different DNA sequence context in addition to chromatin dynamics. Finally, we determined that TFs that preferentially bind divergent DNA motifs may bind overlapping genomic regions due to low-affinity binding to other sequence motifs. Our results demonstrate that TF binding site selection relies on a combination of DNA sequence and chromatin features, thereby contributing to the complexity of P. falciparum gene regulatory mechanisms.
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Affiliation(s)
- Victoria A Bonnell
- Department of Biochemistry and Molecular Biology, University of Southern California, Los Angeles, CA 90089, USA
- Huck Institutes Center for Eukaryotic Gene Regulation, University of Southern California, Los Angeles, CA 90089, USA
- Huck Institutes Center for Malaria Research, University of Southern California, Los Angeles, CA 90089, USA
| | - Yuning Zhang
- Center for Genomic and Computational Biology, University of Southern California, Los Angeles, CA 90089, USA
- Department of Biostatistics and Bioinformatics, University of Southern California, Los Angeles, CA 90089, USA
- Program in Computational Biology and Bioinformatics, University of Southern California, Los Angeles, CA 90089, USA
| | - Alan S Brown
- Department of Biochemistry and Molecular Biology, University of Southern California, Los Angeles, CA 90089, USA
- Huck Institutes Center for Eukaryotic Gene Regulation, University of Southern California, Los Angeles, CA 90089, USA
- Huck Institutes Center for Malaria Research, University of Southern California, Los Angeles, CA 90089, USA
| | - John Horton
- Center for Genomic and Computational Biology, University of Southern California, Los Angeles, CA 90089, USA
- Department of Biostatistics and Bioinformatics, University of Southern California, Los Angeles, CA 90089, USA
| | - Gabrielle A Josling
- Department of Biochemistry and Molecular Biology, University of Southern California, Los Angeles, CA 90089, USA
- Huck Institutes Center for Eukaryotic Gene Regulation, University of Southern California, Los Angeles, CA 90089, USA
- Huck Institutes Center for Malaria Research, University of Southern California, Los Angeles, CA 90089, USA
| | - Tsu-Pei Chiu
- Department of Quantitative and Computational Biology, University of Southern California, Los Angeles, CA 90089, USA
| | - Remo Rohs
- Department of Quantitative and Computational Biology, University of Southern California, Los Angeles, CA 90089, USA
- Department of Chemistry, University of Southern California, Los Angeles, CA 90089, USA
- Department of Physics and Astronomy, University of Southern California, Los Angeles, CA 90089, USA
- Thomas Lord Department of Computer Science, University of Southern California, Los Angeles, CA 90089, USA
| | - Shaun Mahony
- Department of Biochemistry and Molecular Biology, University of Southern California, Los Angeles, CA 90089, USA
- Huck Institutes Center for Eukaryotic Gene Regulation, University of Southern California, Los Angeles, CA 90089, USA
| | - Raluca Gordân
- Center for Genomic and Computational Biology, University of Southern California, Los Angeles, CA 90089, USA
- Department of Biostatistics and Bioinformatics, University of Southern California, Los Angeles, CA 90089, USA
- Department of Computer Science, Durham, NC 27708, USA
- Department of Molecular Genetics and Microbiology, Duke University, Durham, NC 27708, USA
| | - Manuel Llinás
- Department of Biochemistry and Molecular Biology, University of Southern California, Los Angeles, CA 90089, USA
- Huck Institutes Center for Eukaryotic Gene Regulation, University of Southern California, Los Angeles, CA 90089, USA
- Huck Institutes Center for Malaria Research, University of Southern California, Los Angeles, CA 90089, USA
- Department of Chemistry, The Pennsylvania State University, University Park, PA 16802, USA
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3
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Kumar KK, Aburawi EH, Ljubisavljevic M, Leow MKS, Feng X, Ansari SA, Emerald BS. Exploring histone deacetylases in type 2 diabetes mellitus: pathophysiological insights and therapeutic avenues. Clin Epigenetics 2024; 16:78. [PMID: 38862980 PMCID: PMC11167878 DOI: 10.1186/s13148-024-01692-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2024] [Accepted: 06/04/2024] [Indexed: 06/13/2024] Open
Abstract
Diabetes mellitus is a chronic disease that impairs metabolism, and its prevalence has reached an epidemic proportion globally. Most people affected are with type 2 diabetes mellitus (T2DM), which is caused by a decline in the numbers or functioning of pancreatic endocrine islet cells, specifically the β-cells that release insulin in sufficient quantity to overcome any insulin resistance of the metabolic tissues. Genetic and epigenetic factors have been implicated as the main contributors to the T2DM. Epigenetic modifiers, histone deacetylases (HDACs), are enzymes that remove acetyl groups from histones and play an important role in a variety of molecular processes, including pancreatic cell destiny, insulin release, insulin production, insulin signalling, and glucose metabolism. HDACs also govern other regulatory processes related to diabetes, such as oxidative stress, inflammation, apoptosis, and fibrosis, revealed by network and functional analysis. This review explains the current understanding of the function of HDACs in diabetic pathophysiology, the inhibitory role of various HDAC inhibitors (HDACi), and their functional importance as biomarkers and possible therapeutic targets for T2DM. While their role in T2DM is still emerging, a better understanding of the role of HDACi may be relevant in improving insulin sensitivity, protecting β-cells and reducing T2DM-associated complications, among others.
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Affiliation(s)
- Kukkala Kiran Kumar
- Department of Anatomy, College of Medicine and Health Sciences, United Arab Emirates University, PO Box 15551, Al Ain, Abu Dhabi, United Arab Emirates
| | - Elhadi Husein Aburawi
- Department of Pediatrics, College of Medicine and Health Sciences, United Arab Emirates University, Al Ain, Abu Dhabi, United Arab Emirates
| | - Milos Ljubisavljevic
- Department of Physiology, College of Medicine and Health Sciences, United Arab Emirates University, Al Ain, Abu Dhabi, United Arab Emirates
- Duke-NUS Medical School, Cardiovascular and Metabolic Disorders Program, Singapore, Singapore
| | - Melvin Khee Shing Leow
- LKC School of Medicine, Nanyang Technological University, Singapore, Singapore
- Dept of Endocrinology, Tan Tock Seng Hospital, Singapore, Singapore
- Duke-NUS Medical School, Cardiovascular and Metabolic Disorders Program, Singapore, Singapore
| | - Xu Feng
- Department of Biochemistry, YLL School of Medicine, National University of Singapore, Singapore, Singapore
| | - Suraiya Anjum Ansari
- Department of Biochemistry, College of Medicine and Health Sciences, United Arab Emirates University, Al Ain, Abu Dhabi, United Arab Emirates
- Zayed Center for Health Sciences, United Arab Emirates University, Abu Dhabi, United Arab Emirates
- ASPIRE Precision Medicine Research Institute, Abu Dhabi, United Arab Emirates
| | - Bright Starling Emerald
- Department of Anatomy, College of Medicine and Health Sciences, United Arab Emirates University, PO Box 15551, Al Ain, Abu Dhabi, United Arab Emirates.
- Zayed Center for Health Sciences, United Arab Emirates University, Abu Dhabi, United Arab Emirates.
- ASPIRE Precision Medicine Research Institute, Abu Dhabi, United Arab Emirates.
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4
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Rudenko V, Korotkov E. Study of Dispersed Repeats in the Cyanidioschyzon merolae Genome. Int J Mol Sci 2024; 25:4441. [PMID: 38674025 PMCID: PMC11050394 DOI: 10.3390/ijms25084441] [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: 02/19/2024] [Revised: 04/08/2024] [Accepted: 04/15/2024] [Indexed: 04/28/2024] Open
Abstract
In this study, we applied the iterative procedure (IP) method to search for families of highly diverged dispersed repeats in the genome of Cyanidioschyzon merolae, which contains over 16 million bases. The algorithm included the construction of position weight matrices (PWMs) for repeat families and the identification of more dispersed repeats based on the PWMs using dynamic programming. The results showed that the C. merolae genome contained 20 repeat families comprising a total of 33,938 dispersed repeats, which is significantly more than has been previously found using other methods. The repeats varied in length from 108 to 600 bp (522.54 bp in average) and occupied more than 72% of the C. merolae genome, whereas previously identified repeats, including tandem repeats, have been shown to constitute only about 28%. The high genomic content of dispersed repeats and their location in the coding regions suggest a significant role in the regulation of the functional activity of the genome.
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Affiliation(s)
- Valentina Rudenko
- Institute of Bioengineering, Research Center of Biotechnology of the Russian Academy of Sciences, Moscow 119071, Russia;
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5
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Tonsager AJ, Zukowski A, Radebaugh CA, Weirich A, Stargell LA, Ramachandran S. THE HISTONE CHAPERONE SPN1 PRESERVES SUBNUCLEOSOMAL STRUCTURES AT PROMOTERS AND NUCLEOSOME POSITIONING IN OPEN READING FRAMES. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.03.14.585010. [PMID: 38559248 PMCID: PMC10979989 DOI: 10.1101/2024.03.14.585010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/04/2024]
Abstract
Spn1 is a multifunctional histone chaperone essential for life in eukaryotes. While previous work has elucidated regions of the protein important for its many interactions, it is unknown how these domains contribute to the maintenance of chromatin structure. Here, we employ digestion by micrococcal nuclease followed by single-stranded library preparation and sequencing (MNase-SSP) to characterize chromatin structure in yeast expressing wild-type or mutants of Spn1. We mapped nucleosome and subnucleosomal protections genome-wide, and surprisingly, we observed a genome-wide loss of subnucleosomal protection over nucleosome-depleted regions (NDRs) in the Spn1-K192N-containing strain, indicating critical functions of Spn1 in maintaining normal chromatin architecture in promoter regions. Additionally, alterations in nucleosome and hexasome positioning were observed in markedly different mutant Spn1 strains, demonstrating that multiple functions of Spn1 are required to maintain proper chromatin structure in open reading frames, particularly at higher expressed and longer genes. Taken together, our results reveal a previously unknown role of Spn1 in the maintenance of NDR architecture and deepen our understanding of Spn1-dependent chromatin maintenance over transcribed regions.
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Affiliation(s)
- Andrew J. Tonsager
- Department of Biochemistry and Molecular Biology, Colorado State University, Fort Collins, CO, 80523-1870, USA
| | | | - Catherine A. Radebaugh
- Department of Biochemistry and Molecular Biology, Colorado State University, Fort Collins, CO, 80523-1870, USA
| | | | - Laurie A. Stargell
- Department of Biochemistry and Molecular Biology, Colorado State University, Fort Collins, CO, 80523-1870, USA
| | - Srinivas Ramachandran
- Department of Biochemistry and Molecular Genetics
- RNA Bioscience Initiative, University of Colorado School of Medicine, Aurora, CO, U80045, USA
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6
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Li L, Chen K, Sia Y, Hu P, Ye Y, Chen Z. Structure of the ISW1a complex bound to the dinucleosome. Nat Struct Mol Biol 2024; 31:266-274. [PMID: 38177688 DOI: 10.1038/s41594-023-01174-6] [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: 04/13/2022] [Accepted: 11/03/2023] [Indexed: 01/06/2024]
Abstract
Nucleosomes are basic repeating units of chromatin and form regularly spaced arrays in cells. Chromatin remodelers alter the positions of nucleosomes and are vital in regulating chromatin organization and gene expression. Here we report the cryo-EM structure of chromatin remodeler ISW1a complex from Saccharomyces cerevisiae bound to the dinucleosome. Each subunit of the complex recognizes a different nucleosome. The motor subunit binds to the mobile nucleosome and recognizes the acidic patch through two arginine residues, while the DNA-binding module interacts with the entry DNA at the nucleosome edge. This nucleosome-binding mode provides the structural basis for linker DNA sensing of the motor. Notably, the Ioc3 subunit recognizes the disk face of the adjacent nucleosome through interacting with the H4 tail, the acidic patch and the nucleosomal DNA, which plays a role in the spacing activity in vitro and in nucleosome organization and cell fitness in vivo. Together, these findings support the nucleosome spacing activity of ISW1a and add a new mode of nucleosome remodeling in the context of a chromatin environment.
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Affiliation(s)
- Lifei Li
- MOE Key Laboratory of Protein Science, Tsinghua University, Beijing, P.R. China
- School of Life Science, Tsinghua University, Beijing, P.R. China
- Tsinghua-Peking Joint Center for Life Sciences, Beijing, P.R. China
- Beijing Frontier Research Center for Biological Structure, Beijing, P.R. China
| | - Kangjing Chen
- MOE Key Laboratory of Protein Science, Tsinghua University, Beijing, P.R. China
- School of Life Science, Tsinghua University, Beijing, P.R. China
- Tsinghua-Peking Joint Center for Life Sciences, Beijing, P.R. China
- Beijing Frontier Research Center for Biological Structure, Beijing, P.R. China
| | - Youyang Sia
- MOE Key Laboratory of Protein Science, Tsinghua University, Beijing, P.R. China
- School of Life Science, Tsinghua University, Beijing, P.R. China
- Tsinghua-Peking Joint Center for Life Sciences, Beijing, P.R. China
- Beijing Frontier Research Center for Biological Structure, Beijing, P.R. China
| | - Pengjing Hu
- MOE Key Laboratory of Protein Science, Tsinghua University, Beijing, P.R. China
- School of Life Science, Tsinghua University, Beijing, P.R. China
- Tsinghua-Peking Joint Center for Life Sciences, Beijing, P.R. China
- Beijing Frontier Research Center for Biological Structure, Beijing, P.R. China
| | - Youpi Ye
- MOE Key Laboratory of Protein Science, Tsinghua University, Beijing, P.R. China
- School of Life Science, Tsinghua University, Beijing, P.R. China
- Tsinghua-Peking Joint Center for Life Sciences, Beijing, P.R. China
- Beijing Frontier Research Center for Biological Structure, Beijing, P.R. China
| | - Zhucheng Chen
- MOE Key Laboratory of Protein Science, Tsinghua University, Beijing, P.R. China.
- School of Life Science, Tsinghua University, Beijing, P.R. China.
- Tsinghua-Peking Joint Center for Life Sciences, Beijing, P.R. China.
- Beijing Frontier Research Center for Biological Structure, Beijing, P.R. China.
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7
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Nishimura M, Fujii T, Tanaka H, Maehara K, Morishima K, Shimizu M, Kobayashi Y, Nozawa K, Takizawa Y, Sugiyama M, Ohkawa Y, Kurumizaka H. Genome-wide mapping and cryo-EM structural analyses of the overlapping tri-nucleosome composed of hexasome-hexasome-octasome moieties. Commun Biol 2024; 7:61. [PMID: 38191828 PMCID: PMC10774305 DOI: 10.1038/s42003-023-05694-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2023] [Accepted: 12/11/2023] [Indexed: 01/10/2024] Open
Abstract
The nucleosome is a fundamental unit of chromatin in which about 150 base pairs of DNA are wrapped around a histone octamer. The overlapping di-nucleosome has been proposed as a product of chromatin remodeling around the transcription start site, and previously found as a chromatin unit, in which about 250 base pairs of DNA continuously bind to the histone core composed of a hexamer and an octamer. In the present study, our genome-wide analysis of human cells suggests another higher nucleosome stacking structure, the overlapping tri-nucleosome, which wraps about 300-350 base-pairs of DNA in the region downstream of certain transcription start sites of actively transcribed genes. We determine the cryo-electron microscopy (cryo-EM) structure of the overlapping tri-nucleosome, in which three subnucleosome moieties, hexasome, hexasome, and octasome, are associated by short connecting DNA segments. Small angle X-ray scattering and coarse-grained molecular dynamics simulation analyses reveal that the cryo-EM structure of the overlapping tri-nucleosome may reflect its structure in solution. Our findings suggest that nucleosome stacking structures composed of hexasome and octasome moieties may be formed by nucleosome remodeling factors around transcription start sites for gene regulation.
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Affiliation(s)
- Masahiro Nishimura
- Laboratory of Chromatin Structure and Function, Institute for Quantitative Biosciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo, 113-0032, Japan
- Epigenetics and Stem Cell Biology Laboratory, National Institute of Environmental Health Sciences, 111 TW, Alexander Drive, Research Triangle Park, NC, 27707, USA
| | - Takeru Fujii
- Division of Transcriptomics, Medical Institute of Bioregulation, Kyushu University, 3-1-1 Maidashi, Higashi, Fukuoka, 812-0054, Japan
| | - Hiroki Tanaka
- Laboratory of Chromatin Structure and Function, Institute for Quantitative Biosciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo, 113-0032, Japan
- Department of Structural Virology, National Center for Global Health and Medicine, 1-21-1 Toyama, Shinjuku-ku, Tokyo, 162-8655, Japan
| | - Kazumitsu Maehara
- Division of Transcriptomics, Medical Institute of Bioregulation, Kyushu University, 3-1-1 Maidashi, Higashi, Fukuoka, 812-0054, Japan
| | - Ken Morishima
- Institute for Integrated Radiation and Nuclear Science, Kyoto University, Kumatori, Sennan-gun, Osaka, 590-0494, Japan
| | - Masahiro Shimizu
- Institute for Integrated Radiation and Nuclear Science, Kyoto University, Kumatori, Sennan-gun, Osaka, 590-0494, Japan
| | - Yuki Kobayashi
- Laboratory of Chromatin Structure and Function, Institute for Quantitative Biosciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo, 113-0032, Japan
| | - Kayo Nozawa
- Laboratory of Chromatin Structure and Function, Institute for Quantitative Biosciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo, 113-0032, Japan
- School of Life Science and Technology, Tokyo Institute of Technology, 4259 Nagatsuta-cho, Midori-ku, Yokohama, Kanagawa, 226-8501, Japan
| | - Yoshimasa Takizawa
- Laboratory of Chromatin Structure and Function, Institute for Quantitative Biosciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo, 113-0032, Japan
| | - Masaaki Sugiyama
- Institute for Integrated Radiation and Nuclear Science, Kyoto University, Kumatori, Sennan-gun, Osaka, 590-0494, Japan
| | - Yasuyuki Ohkawa
- Division of Transcriptomics, Medical Institute of Bioregulation, Kyushu University, 3-1-1 Maidashi, Higashi, Fukuoka, 812-0054, Japan.
| | - Hitoshi Kurumizaka
- Laboratory of Chromatin Structure and Function, Institute for Quantitative Biosciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo, 113-0032, Japan.
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8
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Biernat E, Khan U, Govind CK. Measuring occupancies of the nucleosome and nucleosome-interacting factors in vivo in Saccharomyces cerevisiae genome-wide. Methods 2023; 218:167-175. [PMID: 37598811 PMCID: PMC10529416 DOI: 10.1016/j.ymeth.2023.08.007] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2023] [Revised: 07/26/2023] [Accepted: 08/11/2023] [Indexed: 08/22/2023] Open
Abstract
Nucleosomes are the repeating units of chromatin. The presence of nucleosomes poses a major impediment to all DNA-dependent processes. As a result, access to DNA in chromatin is dynamically regulated by many factors, including ATP-dependent chromatin remodeling complexes. Digestion of chromatin by micrococcal nuclease (MNase) followed by chromatin immunoprecipitation (ChIP) and sequencing can be leveraged to determine nucleosome occupancy, positioning, and the ability of chromatin interacting factors to alter chromatin accessibility. Here we describe the procedure for performing MNase and MNase ChIP-seq in detail.
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Affiliation(s)
- Emily Biernat
- Department of Biological Sciences, Oakland University, Rochester, MI 48309, USA
| | - Uzair Khan
- Department of Biological Sciences, Oakland University, Rochester, MI 48309, USA
| | - Chhabi K Govind
- Department of Biological Sciences, Oakland University, Rochester, MI 48309, USA.
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9
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Schuette G, Ding X, Zhang B. Efficient Hi-C inversion facilitates chromatin folding mechanism discovery and structure prediction. Biophys J 2023; 122:3425-3438. [PMID: 37496267 PMCID: PMC10502442 DOI: 10.1016/j.bpj.2023.07.017] [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: 03/17/2023] [Revised: 07/10/2023] [Accepted: 07/24/2023] [Indexed: 07/28/2023] Open
Abstract
Genome-wide chromosome conformation capture (Hi-C) experiments have revealed many structural features of chromatin across multiple length scales. Further understanding genome organization requires relating these discoveries to the mechanisms that establish chromatin structures and reconstructing these structures in three dimensions, but both objectives are difficult to achieve with existing algorithms that are often computationally expensive. To alleviate this challenge, we present an algorithm that efficiently converts Hi-C data into contact energies, which measure the interaction strength between genomic loci brought into proximity. Contact energies are local quantities unaffected by the topological constraints that correlate Hi-C contact probabilities. Thus, extracting contact energies from Hi-C contact probabilities distills the biologically unique information contained in the data. We show that contact energies reveal the location of chromatin loop anchors, support a phase separation mechanism for genome compartmentalization, and parameterize polymer simulations that predict three-dimensional chromatin structures. Therefore, we anticipate that contact energy extraction will unleash the full potential of Hi-C data and that our inversion algorithm will facilitate the widespread adoption of contact energy analysis.
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Affiliation(s)
- Greg Schuette
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts
| | - Xinqiang Ding
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts
| | - Bin Zhang
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts.
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10
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Kleinschmidt H, Xu C, Bai L. Using Synthetic DNA Libraries to Investigate Chromatin and Gene Regulation. Chromosoma 2023; 132:167-189. [PMID: 37184694 PMCID: PMC10542970 DOI: 10.1007/s00412-023-00796-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2023] [Revised: 04/25/2023] [Accepted: 04/26/2023] [Indexed: 05/16/2023]
Abstract
Despite the recent explosion in genome-wide studies in chromatin and gene regulation, we are still far from extracting a set of genetic rules that can predict the function of the regulatory genome. One major reason for this deficiency is that gene regulation is a multi-layered process that involves an enormous variable space, which cannot be fully explored using native genomes. This problem can be partially solved by introducing synthetic DNA libraries into cells, a method that can test the regulatory roles of thousands to millions of sequences with limited variables. Here, we review recent applications of this method to study transcription factor (TF) binding, nucleosome positioning, and transcriptional activity. We discuss the design principles, experimental procedures, and major findings from these studies and compare the pros and cons of different approaches.
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Affiliation(s)
- Holly Kleinschmidt
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, PA, 16802, USA
- Center for Eukaryotic Gene Regulation, The Pennsylvania State University, University Park, PA, 16802, USA
| | - Cheng Xu
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, PA, 16802, USA
- Center for Eukaryotic Gene Regulation, The Pennsylvania State University, University Park, PA, 16802, USA
| | - Lu Bai
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, PA, 16802, USA.
- Center for Eukaryotic Gene Regulation, The Pennsylvania State University, University Park, PA, 16802, USA.
- Department of Physics, The Pennsylvania State University, University Park, PA, 16802, USA.
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11
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Mondal A, Kolomeisky AB. Role of Nucleosome Sliding in the Protein Target Search for Covered DNA Sites. J Phys Chem Lett 2023; 14:7073-7082. [PMID: 37527481 DOI: 10.1021/acs.jpclett.3c01704] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/03/2023]
Abstract
Associations of transcription factors (TFs) with specific sites on DNA initiate major cellular processes. But DNA in eukaryotic cells is covered by nucleosomes which prevent TFs from binding. However, nucleosome structures on DNA are not static and exhibit breathing and sliding. We develop a theoretical framework to investigate the effect of nucleosome sliding on a protein target search. By analysis of a discrete-state stochastic model of nucleosome sliding, search dynamics are explicitly evaluated. It is found that for long sliding lengths the target search dynamics are faster for normal TFs that cannot enter the nucleosomal DNA. But for more realistic short sliding lengths, the so-called pioneer TFs, which can invade nucleosomal DNA, locate specific sites faster. It is also suggested that nucleosome breathing, which is a faster process, has a stronger effect on protein search dynamics than that of nucleosome sliding. Theoretical arguments to explain these observations are presented.
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Affiliation(s)
- Anupam Mondal
- Center for Theoretical Biological Physics, Rice University, Houston, Texas 77005, United States
- Department of Chemistry, Rice University, Houston, Texas 77005, United States
| | - Anatoly B Kolomeisky
- Center for Theoretical Biological Physics, Rice University, Houston, Texas 77005, United States
- Department of Chemistry, Rice University, Houston, Texas 77005, United States
- Department of Chemical and Biomolecular Engineering, Rice University, Houston, Texas 77005, United States
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12
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Senapati S, Irshad IU, Sharma AK, Kumar H. Fundamental insights into the correlation between chromosome configuration and transcription. Phys Biol 2023; 20:051002. [PMID: 37467757 DOI: 10.1088/1478-3975/ace8e5] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2023] [Accepted: 07/19/2023] [Indexed: 07/21/2023]
Abstract
Eukaryotic chromosomes exhibit a hierarchical organization that spans a spectrum of length scales, ranging from sub-regions known as loops, which typically comprise hundreds of base pairs, to much larger chromosome territories that can encompass a few mega base pairs. Chromosome conformation capture experiments that involve high-throughput sequencing methods combined with microscopy techniques have enabled a new understanding of inter- and intra-chromosomal interactions with unprecedented details. This information also provides mechanistic insights on the relationship between genome architecture and gene expression. In this article, we review the recent findings on three-dimensional interactions among chromosomes at the compartment, topologically associating domain, and loop levels and the impact of these interactions on the transcription process. We also discuss current understanding of various biophysical processes involved in multi-layer structural organization of chromosomes. Then, we discuss the relationships between gene expression and genome structure from perturbative genome-wide association studies. Furthermore, for a better understanding of how chromosome architecture and function are linked, we emphasize the role of epigenetic modifications in the regulation of gene expression. Such an understanding of the relationship between genome architecture and gene expression can provide a new perspective on the range of potential future discoveries and therapeutic research.
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Affiliation(s)
- Swayamshree Senapati
- School of Basic Sciences, Indian Institute of Technology, Bhubaneswar, Argul, Odisha 752050, India
| | - Inayat Ullah Irshad
- Department of Physics, Indian Institute of Technology, Jammu, Jammu 181221, India
| | - Ajeet K Sharma
- Department of Physics, Indian Institute of Technology, Jammu, Jammu 181221, India
- Department of Biosciences and Bioengineering, Indian Institute of Technology Jammu, Jammu 181221, India
| | - Hemant Kumar
- School of Basic Sciences, Indian Institute of Technology, Bhubaneswar, Argul, Odisha 752050, India
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13
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Schuette G, Ding X, Zhang B. Efficient Hi-C inversion facilitates chromatin folding mechanism discovery and structure prediction. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.03.17.533194. [PMID: 36993500 PMCID: PMC10055272 DOI: 10.1101/2023.03.17.533194] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/31/2023]
Abstract
Genome-wide chromosome conformation capture (Hi-C) experiments have revealed many structural features of chromatin across multiple length scales. Further understanding genome organization requires relating these discoveries to the mechanisms that establish chromatin structures and reconstructing these structures in three dimensions, but both objectives are difficult to achieve with existing algorithms that are often computationally expensive. To alleviate this challenge, we present an algorithm that efficiently converts Hi-C data into contact energies, which measure the interaction strength between genomic loci brought into proximity. Contact energies are local quantities unaffected by the topological constraints that correlate Hi-C contact probabilities. Thus, extracting contact energies from Hi-C contact probabilities distills the biologically unique information contained in the data. We show that contact energies reveal the location of chromatin loop anchors, support a phase separation mechanism for genome compartmentalization, and parameterize polymer simulations that predict three-dimensional chromatin structures. Therefore, we anticipate that contact energy extraction will unleash the full potential of Hi-C data and that our inversion algorithm will facilitate the widespread adoption of contact energy analysis.
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Affiliation(s)
- Greg Schuette
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Xinqiang Ding
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Bin Zhang
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
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14
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Gòdia M, Lian Y, Naval-Sanchez M, Ponte I, Rodríguez-Gil JE, Sanchez A, Clop A. Micrococcal nuclease sequencing of porcine sperm suggests enriched co-location between retained histones and genomic regions related to semen quality and early embryo development. PeerJ 2023; 11:e15520. [PMID: 37361042 PMCID: PMC10290446 DOI: 10.7717/peerj.15520] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2022] [Accepted: 05/16/2023] [Indexed: 06/28/2023] Open
Abstract
The mammalian spermatozoon has a unique chromatin structure in which the majority of histones are replaced by protamines during spermatogenesis and a small fraction of nucleosomes are retained at specific locations of the genome. The sperm's chromatin structure remains unresolved in most animal species, including the pig. However, mapping the genomic locations of retained nucleosomes in sperm could help understanding the molecular basis of both sperm development and function as well as embryo development. This information could then be useful to identify molecular markers for sperm quality and fertility traits. Here, micrococcal nuclease digestion coupled with high throughput sequencing was performed on pig sperm to map the genomic location of mono- and sub-nucleosomal chromatin fractions in relation to a set of diverse functional elements of the genome, some of which were related to semen quality and early embryogenesis. In particular, the investigated elements were promoters, the different sections of the gene body, coding and non-coding RNAs present in the pig sperm, potential transcription factor binding sites, genomic regions associated to semen quality traits and repeat elements. The analysis yielded 25,293 and 4,239 peaks in the mono- and sub-nucleosomal fractions, covering 0.3% and 0.02% of the porcine genome, respectively. A cross-species comparison revealed positional conservation of the nucleosome retention in sperm between the pig data and a human dataset that found nucleosome enrichment in genomic regions of importance in development. Both gene ontology analysis of the genes mapping nearby the mono-nucleosomal peaks and the identification of putative transcription factor binding motifs within the mono- and the sub- nucleosomal peaks showed enrichment for processes related to sperm function and embryo development. There was significant motif enrichment for Znf263, which in humans was suggested to be a key regulator of genes with paternal preferential expression during early embryogenesis. Moreover, enriched positional intersection was found in the genome between the mono-nucleosomal peaks and both the RNAs present in pig sperm and the RNAs related to sperm quality. There was no co-location between GWAS hits for semen quality in swine and the nucleosomal sites. Finally, the data evidenced depletion of mono-nucleosomes in long interspersed nuclear elements and enrichment of sub-nucleosomes in short interspersed repeat elements.These results suggest that retained nucleosomes in sperm could both mark regulatory elements or genes expressed during spermatogenesis linked to semen quality and fertility and act as transcriptional guides during early embryogenesis. The results of this study support the undertaking of ambitious research using a larger number of samples to robustly assess the positional relationship between histone retention in sperm and the reproductive ability of boars.
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Affiliation(s)
- Marta Gòdia
- Centre for Research in Agricultural Genomics CRAG (CSIC-IRTA-UAB-UB), Cerdanyola del Vallés, Catalonia, Spain
- Animal Breeding and Genomics, Wageningen University and Research, Wageninger, Netherlands
| | - Yu Lian
- Centre for Research in Agricultural Genomics CRAG (CSIC-IRTA-UAB-UB), Cerdanyola del Vallés, Catalonia, Spain
| | | | - Inma Ponte
- Biochemistry and Molecular Biology, Universitat Autònoma de Barcelona, Cerdanyola del Vallés, Catalonia, Spain
| | - Joan Enric Rodríguez-Gil
- Animal Medicine and Surgery, Universitat Autònoma de Barcelona, Cerdanyola del Vallés, Catalonia, Spain
| | - Armand Sanchez
- Centre for Research in Agricultural Genomics CRAG (CSIC-IRTA-UAB-UB), Cerdanyola del Vallés, Catalonia, Spain
- Animal and food sciences, Universitat Autònoma de Barcelona, Cerdanyola del Vallés, Catalonia, Spain
| | - Alex Clop
- Centre for Research in Agricultural Genomics CRAG (CSIC-IRTA-UAB-UB), Cerdanyola del Vallés, Catalonia, Spain
- Consejo Superior de Investigaciones Científicas, Barcelona, Catalonia, Spain
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15
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Weiß E, Hennig T, Graßl P, Djakovic L, Whisnant AW, Jürges CS, Koller F, Kluge M, Erhard F, Dölken L, Friedel CC. HSV-1 Infection Induces a Downstream Shift of Promoter-Proximal Pausing for Host Genes. J Virol 2023; 97:e0038123. [PMID: 37093003 PMCID: PMC10231138 DOI: 10.1128/jvi.00381-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2023] [Accepted: 04/03/2023] [Indexed: 04/25/2023] Open
Abstract
Herpes simplex virus 1 (HSV-1) infection exerts a profound shutoff of host gene expression at multiple levels. Recently, HSV-1 infection was reported to also impact promoter-proximal RNA polymerase II (Pol II) pausing, a key step in the eukaryotic transcription cycle, with decreased and increased Pol II pausing observed for activated and repressed genes, respectively. Here, we demonstrate that HSV-1 infection induces more complex alterations in promoter-proximal pausing than previously suspected for the vast majority of cellular genes. While pausing is generally retained, it is shifted to more downstream and less well-positioned sites for most host genes. The downstream shift of Pol II pausing was established between 1.5 and 3 h of infection, remained stable until at least 6 hours postinfection, and was observed in the absence of ICP22. The shift in Pol II pausing does not result from alternative de novo transcription initiation at downstream sites or read-in transcription originating from disruption of transcription termination of upstream genes. The use of downstream secondary pause sites associated with +1 nucleosomes was previously observed upon negative elongation factor (NELF) depletion. However, downstream shifts of Pol II pausing in HSV-1 infection were much more pronounced than observed upon NELF depletion. Thus, our study reveals a novel aspect in which HSV-1 infection fundamentally reshapes host transcriptional processes, providing new insights into the regulation of promoter-proximal Pol II pausing in eukaryotic cells. IMPORTANCE This study provides a genome-wide analysis of changes in promoter-proximal polymerase II (Pol II) pausing on host genes induced by HSV-1 infection. It shows that standard measures of pausing, i.e., pausing indices, do not properly capture the complex and unsuspected alterations in Pol II pausing occurring in HSV-1 infection. Instead of a reduction of pausing with increased elongation, as suggested by pausing index analysis, HSV-1 infection leads to a shift of pausing to downstream and less well-positioned sites than in uninfected cells for the majority of host genes. Thus, HSV-1 infection fundamentally reshapes a key regulatory step at the beginning of the host transcriptional cycle on a genome-wide scale.
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Affiliation(s)
- Elena Weiß
- Institute of Informatics, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Thomas Hennig
- Institute for Virology and Immunobiology, Julius-Maximilians-University Würzburg, Würzburg, Germany
| | - Pilar Graßl
- Institute of Informatics, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Lara Djakovic
- Institute for Virology and Immunobiology, Julius-Maximilians-University Würzburg, Würzburg, Germany
| | - Adam W. Whisnant
- Institute for Virology and Immunobiology, Julius-Maximilians-University Würzburg, Würzburg, Germany
| | - Christopher S. Jürges
- Institute for Virology and Immunobiology, Julius-Maximilians-University Würzburg, Würzburg, Germany
| | - Franziska Koller
- Institute of Informatics, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Michael Kluge
- Institute of Informatics, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Florian Erhard
- Institute for Virology and Immunobiology, Julius-Maximilians-University Würzburg, Würzburg, Germany
| | - Lars Dölken
- Institute for Virology and Immunobiology, Julius-Maximilians-University Würzburg, Würzburg, Germany
- Helmholtz Institute for RNA-based Infection Research (HIRI), Helmholtz-Center for Infection Research (HZI), Würzburg, Germany
| | - Caroline C. Friedel
- Institute of Informatics, Ludwig-Maximilians-Universität München, Munich, Germany
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16
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Morse K, Swerdlow S, Ünal E. Swi/Snf Chromatin Remodeling Regulates Transcriptional Interference and Gene Repression. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.04.27.538572. [PMID: 37162931 PMCID: PMC10168381 DOI: 10.1101/2023.04.27.538572] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
Alternative transcription start sites can affect transcript isoform diversity and translation levels. In a recently described form of gene regulation, coordinated transcriptional and translational interference results in transcript isoform-dependent changes in protein expression. Specifically, a long undecoded transcript isoform (LUTI) is transcribed from a gene-distal promoter, interfering with expression of the gene-proximal promoter. While transcriptional and chromatin features associated with LUTI expression have been described, the mechanism underlying LUTI-based transcriptional interference is not well understood. Using an unbiased genetic approach followed by integrated genomic analysis, we uncovered that the Swi/Snf chromatin remodeling complex is required for co-transcriptional nucleosome remodeling that leads to LUTI-based repression. We identified genes with tandem promoters that rely on Swi/Snf function for transcriptional interference during protein folding stress, including LUTI-regulated genes. To our knowledge, this study is the first to observe Swi/Snf's direct involvement in gene repression via a cis transcriptional interference mechanism.
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Affiliation(s)
- Kaitlin Morse
- Department of Molecular and Cell Biology, Barker Hall, University of California, Berkeley, CA, USA, 94720
| | - Sarah Swerdlow
- Department of Molecular and Cell Biology, Barker Hall, University of California, Berkeley, CA, USA, 94720
| | - Elçin Ünal
- Department of Molecular and Cell Biology, Barker Hall, University of California, Berkeley, CA, USA, 94720
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17
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Donovan BT, Chen H, Eek P, Meng Z, Jipa C, Tan S, Bai L, Poirier MG. Basic helix-loop-helix pioneer factors interact with the histone octamer to invade nucleosomes and generate nucleosome-depleted regions. Mol Cell 2023; 83:1251-1263.e6. [PMID: 36996811 PMCID: PMC10182836 DOI: 10.1016/j.molcel.2023.03.006] [Citation(s) in RCA: 17] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2022] [Revised: 01/13/2023] [Accepted: 03/06/2023] [Indexed: 03/31/2023]
Abstract
Nucleosomes drastically limit transcription factor (TF) occupancy, while pioneer transcription factors (PFs) somehow circumvent this nucleosome barrier. In this study, we compare nucleosome binding of two conserved S. cerevisiae basic helix-loop-helix (bHLH) TFs, Cbf1 and Pho4. A cryo-EM structure of Cbf1 in complex with the nucleosome reveals that the Cbf1 HLH region can electrostatically interact with exposed histone residues within a partially unwrapped nucleosome. Single-molecule fluorescence studies show that the Cbf1 HLH region facilitates efficient nucleosome invasion by slowing its dissociation rate relative to DNA through interactions with histones, whereas the Pho4 HLH region does not. In vivo studies show that this enhanced binding provided by the Cbf1 HLH region enables nucleosome invasion and ensuing repositioning. These structural, single-molecule, and in vivo studies reveal the mechanistic basis of dissociation rate compensation by PFs and how this translates to facilitating chromatin opening inside cells.
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Affiliation(s)
- Benjamin T Donovan
- Biophysics Graduate Program, The Ohio State University, Columbus, OH 43210, USA
| | - Hengye Chen
- Department of Biochemistry and Molecular Biology, Center for Eukaryotic Gene Regulation, The Pennsylvania State University, University Park, PA 16802, USA
| | - Priit Eek
- Department of Biochemistry and Molecular Biology, Center for Eukaryotic Gene Regulation, The Pennsylvania State University, University Park, PA 16802, USA
| | - Zhiyuan Meng
- Biophysics Graduate Program, The Ohio State University, Columbus, OH 43210, USA
| | - Caroline Jipa
- Department of Physics, The Ohio State University, Columbus, OH 43210, USA
| | - Song Tan
- Department of Biochemistry and Molecular Biology, Center for Eukaryotic Gene Regulation, The Pennsylvania State University, University Park, PA 16802, USA; Huck Institutes of the Life Sciences, The Pennsylvania State University, University Park, PA 16802, USA.
| | - Lu Bai
- Department of Biochemistry and Molecular Biology, Center for Eukaryotic Gene Regulation, The Pennsylvania State University, University Park, PA 16802, USA; Department of Physics, The Pennsylvania State University, University Park, PA 16802, USA.
| | - Michael G Poirier
- Biophysics Graduate Program, The Ohio State University, Columbus, OH 43210, USA; Department of Physics, The Ohio State University, Columbus, OH 43210, USA; Department of Chemistry & Biochemistry, The Ohio State University, Columbus, OH 43210, USA.
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18
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Song H, Wang Q, Zhang Z, Lin K, Pang E. Identification of clade-wide putative cis-regulatory elements from conserved non-coding sequences in Cucurbitaceae genomes. HORTICULTURE RESEARCH 2023; 10:uhad038. [PMID: 37799630 PMCID: PMC10548412 DOI: 10.1093/hr/uhad038] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/22/2022] [Accepted: 02/20/2023] [Indexed: 10/07/2023]
Abstract
Cis-regulatory elements regulate gene expression and play an essential role in the development and physiology of organisms. Many conserved non-coding sequences (CNSs) function as cis-regulatory elements. They control the development of various lineages. However, predicting clade-wide cis-regulatory elements across several closely related species remains challenging. Based on the relationship between CNSs and cis-regulatory elements, we present a computational approach that predicts the clade-wide putative cis-regulatory elements in 12 Cucurbitaceae genomes. Using 12-way whole-genome alignment, we first obtained 632 112 CNSs in Cucurbitaceae. Next, we identified 16 552 Cucurbitaceae-wide cis-regulatory elements based on collinearity among all 12 Cucurbitaceae plants. Furthermore, we predicted 3 271 potential regulatory pairs in the cucumber genome, of which 98 were verified using integrative RNA sequencing and ChIP sequencing datasets from samples collected during various fruit development stages. The CNSs, Cucurbitaceae-wide cis-regulatory elements, and their target genes are accessible at http://cmb.bnu.edu.cn/cisRCNEs_cucurbit/. These elements are valuable resources for functionally annotating CNSs and their regulatory roles in Cucurbitaceae genomes.
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Affiliation(s)
- Hongtao Song
- MOE Key Laboratory for Biodiversity Science and Ecological Engineering and Beijing Key Laboratory of Gene Resource and Molecular Development, College of Life Sciences, Beijing Normal University, Beijing 100875, China
| | - Qi Wang
- MOE Key Laboratory for Biodiversity Science and Ecological Engineering and Beijing Key Laboratory of Gene Resource and Molecular Development, College of Life Sciences, Beijing Normal University, Beijing 100875, China
| | - Zhonghua Zhang
- College of Horticulture, Qingdao Agricultural University, Qingdao 266109, China
| | - Kui Lin
- MOE Key Laboratory for Biodiversity Science and Ecological Engineering and Beijing Key Laboratory of Gene Resource and Molecular Development, College of Life Sciences, Beijing Normal University, Beijing 100875, China
| | - Erli Pang
- MOE Key Laboratory for Biodiversity Science and Ecological Engineering and Beijing Key Laboratory of Gene Resource and Molecular Development, College of Life Sciences, Beijing Normal University, Beijing 100875, China
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19
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Interaction preferences between protein side chains and key epigenetic modifications 5-methylcytosine, 5-hydroxymethycytosine and N 6-methyladenine. Sci Rep 2022; 12:19583. [PMID: 36380112 PMCID: PMC9666514 DOI: 10.1038/s41598-022-23585-z] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2022] [Accepted: 11/02/2022] [Indexed: 11/16/2022] Open
Abstract
Covalent modifications of standard DNA/RNA nucleobases affect epigenetic regulation of gene expression by modulating interactions between nucleic acids and protein readers. We derive here the absolute binding free energies and analyze the binding modalities between key modified nucleobases 5-methylcytosine (5mC), 5-hydroxymethylcytosine (5hmC) and N6-methyladenine (m6A) and all non-prolyl/non-glycyl protein side chains using molecular dynamics simulations and umbrella sampling in both water and methanol, the latter mimicking the low dielectric environment at the dehydrated nucleic-acid/protein interfaces. We verify the derived affinities by comparing against a comprehensive set of high-resolution structures of nucleic-protein complexes involving 5mC. Our analysis identifies protein side chains that are highly tuned for detecting cytosine methylation as a function of the environment and can thus serve as microscopic readers of epigenetic marks. Conversely, we show that the relative ordering of sidechain affinities for 5hmC and m6A does not differ significantly from those for their precursor bases, cytosine and adenine, respectively, especially in the low dielectric environment. For those two modified bases, the effect is more nuanced and manifests itself primarily at the level of absolute changes in the binding free energy. Our results contribute towards establishing a quantitative foundation for understanding, predicting and modulating the interactions between modified nucleic acids and proteins at the atomistic level.
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20
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Ghoshdastidar D, Bansal M. Flexibility of flanking DNA is a key determinant of transcription factor affinity for the core motif. Biophys J 2022; 121:3987-4000. [PMID: 35978548 PMCID: PMC9674967 DOI: 10.1016/j.bpj.2022.08.015] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2022] [Revised: 07/28/2022] [Accepted: 08/15/2022] [Indexed: 11/02/2022] Open
Abstract
Selective gene regulation is mediated by recognition of specific DNA sequences by transcription factors (TFs). The extremely challenging task of searching out specific cognate DNA binding sites among several million putative sites within the eukaryotic genome is achieved by complex molecular recognition mechanisms. Elements of this recognition code include the core binding sequence, the flanking sequence context, and the shape and conformational flexibility of the composite binding site. To unravel the extent to which DNA flexibility modulates TF binding, in this study, we employed experimentally guided molecular dynamics simulations of ternary complex of closely related Hox heterodimers Exd-Ubx and Exd-Scr with DNA. Results demonstrate that flexibility signatures embedded in the flanking sequences impact TF binding at the cognate binding site. A DNA sequence has intrinsic shape and flexibility features. While shape features are localized, our analyses reveal that flexibility features of the flanking sequences percolate several basepairs and allosterically modulate TF binding at the core. We also show that lack of flexibility in the motif context can render the cognate site resistant to protein-induced shape changes and subsequently lower TF binding affinity. Overall, this study suggests that flexibility-guided DNA shape, and not merely the static shape, is a key unexplored component of the complex DNA-TF recognition code.
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Affiliation(s)
| | - Manju Bansal
- Molecular Biophysics Unit, Indian Institute of Science, Bangalore 560012, Karnataka, India.
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21
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Corcoran ET, LeBlanc C, Huang YC, Arias Tsang M, Sarkiss A, Hu Y, Pedmale UV, Jacob Y. Systematic histone H4 replacement in Arabidopsis thaliana reveals a role for H4R17 in regulating flowering time. THE PLANT CELL 2022; 34:3611-3631. [PMID: 35879829 PMCID: PMC9516085 DOI: 10.1093/plcell/koac211] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/18/2022] [Accepted: 07/15/2022] [Indexed: 06/13/2023]
Abstract
Despite the broad array of roles for epigenetic mechanisms on regulating diverse processes in eukaryotes, no experimental system is currently available in plants for the direct assessment of histone function. In this work, we present the development of a genetic strategy in Arabidopsis (Arabidopsis thaliana) whereby modified histone H4 transgenes can completely replace the expression of endogenous histone H4 genes. Accordingly, we established a collection of plants expressing different H4 point mutants targeting residues that may be post-translationally modified in vivo. To demonstrate its utility, we screened this new H4 mutant collection to uncover substitutions in H4 that alter flowering time. We identified different mutations in the H4 tail (H4R17A) and the H4 globular domain (H4R36A, H4R39K, H4R39A, and H4K44A) that strongly accelerate the floral transition. Furthermore, we identified a conserved regulatory relationship between H4R17 and the ISWI chromatin remodeling complex in plants: As with other biological systems, H4R17 regulates nucleosome spacing via ISWI. Overall, this work provides a large set of H4 mutants to the plant epigenetics community that can be used to systematically assess histone H4 function in Arabidopsis and a roadmap to replicate this strategy for studying other histone proteins in plants.
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Affiliation(s)
- Emma Tung Corcoran
- Faculty of Arts and Sciences, Department of Molecular, Cellular and Developmental Biology, Yale University, New Haven, CT 06511, USA
| | - Chantal LeBlanc
- Faculty of Arts and Sciences, Department of Molecular, Cellular and Developmental Biology, Yale University, New Haven, CT 06511, USA
| | - Yi-Chun Huang
- Faculty of Arts and Sciences, Department of Molecular, Cellular and Developmental Biology, Yale University, New Haven, CT 06511, USA
| | - Mia Arias Tsang
- Faculty of Arts and Sciences, Department of Molecular, Cellular and Developmental Biology, Yale University, New Haven, CT 06511, USA
| | - Anthony Sarkiss
- Faculty of Arts and Sciences, Department of Molecular, Cellular and Developmental Biology, Yale University, New Haven, CT 06511, USA
| | - Yuzhao Hu
- Cold Spring Harbor Laboratory, Cold Spring Harbor, NY 11724, USA
| | - Ullas V Pedmale
- Cold Spring Harbor Laboratory, Cold Spring Harbor, NY 11724, USA
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22
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A study of strong nucleosomes in the human genome. iScience 2022; 25:104593. [PMID: 35789840 PMCID: PMC9249913 DOI: 10.1016/j.isci.2022.104593] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2021] [Revised: 03/03/2022] [Accepted: 06/08/2022] [Indexed: 11/30/2022] Open
Abstract
Micrococcal nuclease (MNase) is widely used to map nucleosomes. However, nucleosomes are highly dynamic and susceptible to experimental conditions, resulting in extreme variability across nucleosome maps, which complicates the generation of accurate nucleosome organization data. We mapped nucleosomes from different individuals using improved MNase-seq. The improvements included setting different digestion levels (low, medium, high) and naked DNA correction to remove the noise caused by experimental manipulation and comparing maps to obtain the accurate position and occupancy of strong nucleosomes (SNs) in the whole genome. In addition, the characteristics of SNs were further excavated. SNs were enriched in Alu elements and near the centromere of Chr12. SNs contain some specific sequences, and the GC content of SNs is different from that of dynamic nucleosomes. The findings suggest that nucleosome location in the genome and the DNA sequence may affect nucleosome stability. Naked DNA correction improved the accuracy of nucleosome map in partial digestion Level of MNase digestion has effects on nucleosome organization A type of strong nucleosomes (SNs) exist across different nucleosome maps Nucleosome stability may be related to its location and the DNA sequence
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23
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Han GS, Li Q, Li Y. Nucleosome positioning based on DNA sequence embedding and deep learning. BMC Genomics 2022; 23:301. [PMID: 35418074 PMCID: PMC9006412 DOI: 10.1186/s12864-022-08508-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2022] [Accepted: 03/28/2022] [Indexed: 11/25/2022] Open
Abstract
Background Nucleosome positioning is the precise determination of the location of nucleosomes on DNA sequence. With the continuous advancement of biotechnology and computer technology, biological data is showing explosive growth. It is of practical significance to develop an efficient nucleosome positioning algorithm. Indeed, convolutional neural networks (CNN) can capture local features in DNA sequences, but ignore the order of bases. While the bidirectional recurrent neural network can make up for CNN's shortcomings in this regard and extract the long-term dependent features of DNA sequence. Results In this work, we use word vectors to represent DNA sequences and propose three new deep learning models for nucleosome positioning, and the integrative model NP_CBiR reaches a better prediction performance. The overall accuracies of NP_CBiR on H. sapiens, C. elegans, and D. melanogaster datasets are 86.18%, 89.39%, and 85.55% respectively. Conclusions Benefited by different network structures, NP_CBiR can effectively extract local features and bases order features of DNA sequences, thus can be considered as a complementary tool for nucleosome positioning.
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Affiliation(s)
- Guo-Sheng Han
- Department of Mathematics and Computational Science, Xiangtan University, Xiangtan, 411105, Hunan, China. .,Key Laboratory of Intelligent Computing and Information Processing of Ministry of Education and Hunan Key Laboratory for Computation and Simulation in Science and Engineering, Xiangtan University, Xiangtan, 411105, Hunan, China.
| | - Qi Li
- Department of Mathematics and Computational Science, Xiangtan University, Xiangtan, 411105, Hunan, China.,Xiangtan Medicine Health Vocational College, Xiangtan, 411102, Hunan, China
| | - Ying Li
- Department of Mathematics and Computational Science, Xiangtan University, Xiangtan, 411105, Hunan, China.,Key Laboratory of Intelligent Computing and Information Processing of Ministry of Education and Hunan Key Laboratory for Computation and Simulation in Science and Engineering, Xiangtan University, Xiangtan, 411105, Hunan, China
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24
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Trotta E. GC content strongly influences the role of poly(dA) in the intrinsic nucleosome positioning in Saccharomyces cerevisiae. Yeast 2022; 39:262-271. [PMID: 35348238 PMCID: PMC9541940 DOI: 10.1002/yea.3701] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2021] [Revised: 02/21/2022] [Accepted: 02/22/2022] [Indexed: 11/08/2022] Open
Abstract
The nucleosome is the basic structural element of genomic DNA packaging and plays a role in transcription, replication, and recombination. Poly(dA) tracts are considered major sequence determinants of nucleosome positioning, although their role is not well understood. Here, we show that the homopolymeric character and the low GC content of poly(dA)s play different roles in nucleosome formation. We found that the inherent low GC content of poly(dA) alone can account for the deep and anisotropic nucleosome depletion at structurally and functionally important regions of promoters and origins of replication. We also show that the level of nucleosome occupancy at poly(dA) is strongly related to the local nucleotide background and its high frequency of occurrence in Saccharomyces cerevisiae does not appear merely to be associated with its intrinsic nucleosome-excluding properties. In addition, we show that the GC content alone can predict more than 60% of the in vitro nucleosome map, providing further evidence that the intrinsic nucleosome positioning is more greatly determined by GC content than poly(dA) stretches. Our results are consistent with a model in which poly(dA) stretches act at two distinct levels: first, by its low GC content, which intrinsically contributes to hinder nucleosome formation, and second, by its contiguous runs of dA that selectively drive the recruitment of non-histone proteins with structural and functional roles.
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Affiliation(s)
- Edoardo Trotta
- Institute of Translational Pharmacology, Consiglio Nazionale delle Ricerche (CNR), Rome, Italy
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25
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Schmitz RJ, Grotewold E, Stam M. Cis-regulatory sequences in plants: Their importance, discovery, and future challenges. THE PLANT CELL 2022; 34:718-741. [PMID: 34918159 PMCID: PMC8824567 DOI: 10.1093/plcell/koab281] [Citation(s) in RCA: 110] [Impact Index Per Article: 55.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/04/2021] [Accepted: 10/20/2021] [Indexed: 05/19/2023]
Abstract
The identification and characterization of cis-regulatory DNA sequences and how they function to coordinate responses to developmental and environmental cues is of paramount importance to plant biology. Key to these regulatory processes are cis-regulatory modules (CRMs), which include enhancers and silencers. Despite the extraordinary advances in high-quality sequence assemblies and genome annotations, the identification and understanding of CRMs, and how they regulate gene expression, lag significantly behind. This is especially true for their distinguishing characteristics and activity states. Here, we review the current knowledge on CRMs and breakthrough technologies enabling identification, characterization, and validation of CRMs; we compare the genomic distributions of CRMs with respect to their target genes between different plant species, and discuss the role of transposable elements harboring CRMs in the evolution of gene expression. This is an exciting time to study cis-regulomes in plants; however, significant existing challenges need to be overcome to fully understand and appreciate the role of CRMs in plant biology and in crop improvement.
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Affiliation(s)
- Robert J Schmitz
- Department of Genetics, University of Georgia, Athens, Georgia 30602, USA
| | - Erich Grotewold
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, Michigan 48824, USA
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26
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Giniūnaitė R, Petkevičiūtė-Gerlach D. Predicting the configuration and energy of DNA in a nucleosome by coarse-grain modelling. Phys Chem Chem Phys 2022; 24:26124-26133. [DOI: 10.1039/d2cp03553g] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
We present a novel algorithm which uses a coarse-grained model and an energy minimisation procedure to predict the sequence-dependent DNA configuration in a nucleosome together with its energetic cost.
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Affiliation(s)
- Rasa Giniūnaitė
- Department of Applied Mathematics, Kaunas University of Technology, Studentų 50-318, 51368, Kaunas, Lithuania
- Institute of Applied Mathematics, Vilnius University, Naugarduko 24, 03225, Vilnius, Lithuania
| | - Daiva Petkevičiūtė-Gerlach
- Department of Applied Mathematics, Kaunas University of Technology, Studentų 50-318, 51368, Kaunas, Lithuania
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27
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Watson GD, Chan EW, Leake MC, Noy A. Structural interplay between DNA-shape protein recognition and supercoiling: The case of IHF. Comput Struct Biotechnol J 2022; 20:5264-5274. [PMID: 36212531 PMCID: PMC9519438 DOI: 10.1016/j.csbj.2022.09.020] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2022] [Revised: 09/12/2022] [Accepted: 09/12/2022] [Indexed: 11/03/2022] Open
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28
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Hirai S, Tomimatsu K, Miyawaki-Kuwakado A, Takizawa Y, Komatsu T, Tachibana T, Fukushima Y, Takeda Y, Negishi L, Kujirai T, Koyama M, Ohkawa Y, Kurumizaka H. Unusual nucleosome formation and transcriptome influence by the histone H3mm18 variant. Nucleic Acids Res 2021; 50:72-91. [PMID: 34929737 PMCID: PMC8855299 DOI: 10.1093/nar/gkab1137] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2021] [Revised: 10/22/2021] [Accepted: 10/29/2021] [Indexed: 11/14/2022] Open
Abstract
Histone H3mm18 is a non-allelic H3 variant expressed in skeletal muscle and brain
in mice. However, its function has remained enigmatic. We found that H3mm18 is
incorporated into chromatin in cells with low efficiency, as compared to H3.3.
We determined the structures of the nucleosome core particle (NCP) containing
H3mm18 by cryo-electron microscopy, which revealed that the entry/exit DNA
regions are drastically disordered in the H3mm18 NCP. Consistently, the H3mm18
NCP is substantially unstable in vitro. The forced expression
of H3mm18 in mouse myoblast C2C12 cells markedly suppressed muscle
differentiation. A transcriptome analysis revealed that the forced expression of
H3mm18 affected the expression of multiple genes, and suppressed a group of
genes involved in muscle development. These results suggest a novel gene
expression regulation system in which the chromatin landscape is altered by the
formation of unusual nucleosomes with a histone variant, H3mm18, and provide
important insight into understanding transcription regulation by chromatin.
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Affiliation(s)
- Seiya Hirai
- Laboratory of Chromatin Structure and Function, Institute for Quantitative Biosciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo113-0032, Japan.,Department of Biological Sciences, Graduate School of Science, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo113-0032, Japan
| | - Kosuke Tomimatsu
- Division of Transcriptomics, Medical Institute of Bioregulation, Kyushu University, 3-1-1 Maidashi, Higashi, Fukuoka812-0054, Japan
| | - Atsuko Miyawaki-Kuwakado
- Division of Transcriptomics, Medical Institute of Bioregulation, Kyushu University, 3-1-1 Maidashi, Higashi, Fukuoka812-0054, Japan
| | - Yoshimasa Takizawa
- Laboratory of Chromatin Structure and Function, Institute for Quantitative Biosciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo113-0032, Japan
| | - Tetsuro Komatsu
- Institute for Molecular and Cellular Regulation, Gunma University, 3-39-15, Showa-machi, Maebashi, Gunma371-8512, Japan
| | - Taro Tachibana
- Department of Bioengineering, Graduate School of Engineering, Osaka City University, Sugimoto, Sumiyoshi-ku, Osaka558-8585, Japan
| | - Yutaro Fukushima
- Laboratory of Chromatin Structure and Function, Institute for Quantitative Biosciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo113-0032, Japan.,Department of Biological Sciences, Graduate School of Science, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo113-0032, Japan
| | - Yasuko Takeda
- Laboratory of Chromatin Structure and Function, Institute for Quantitative Biosciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo113-0032, Japan
| | - Lumi Negishi
- Laboratory of Chromatin Structure and Function, Institute for Quantitative Biosciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo113-0032, Japan
| | - Tomoya Kujirai
- Laboratory of Chromatin Structure and Function, Institute for Quantitative Biosciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo113-0032, Japan
| | - Masako Koyama
- Laboratory of Chromatin Structure and Function, Institute for Quantitative Biosciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo113-0032, Japan
| | - Yasuyuki Ohkawa
- Division of Transcriptomics, Medical Institute of Bioregulation, Kyushu University, 3-1-1 Maidashi, Higashi, Fukuoka812-0054, Japan
| | - Hitoshi Kurumizaka
- Laboratory of Chromatin Structure and Function, Institute for Quantitative Biosciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo113-0032, Japan.,Department of Biological Sciences, Graduate School of Science, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo113-0032, Japan
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29
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Levings DC, Lacher SE, Palacios-Moreno J, Slattery M. Transcriptional reprogramming by oxidative stress occurs within a predefined chromatin accessibility landscape. Free Radic Biol Med 2021; 171:319-331. [PMID: 33992677 PMCID: PMC8608001 DOI: 10.1016/j.freeradbiomed.2021.05.016] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/31/2021] [Revised: 05/06/2021] [Accepted: 05/07/2021] [Indexed: 01/16/2023]
Abstract
Reactive oxygen species (ROS) are important signaling molecules in many physiological processes, yet excess ROS leads to cell damage and can lead to pathology. Accordingly, cells need to maintain tight regulation of ROS levels, and ROS-responsive transcriptional reprogramming is central to this process. Although it has long been recognized that oxidative stress leads to rapid, significant changes in gene expression, the impact of oxidative stress on the underlying chromatin accessibility landscape remained unclear. Here, we asked whether ROS-responsive transcriptional reprogramming is accompanied by reprogramming of the chromatin environment in MCF7 human breast cancer cells. Using a time-course exposure to multiple inducers of oxidative stress, we determined that the widespread ROS-responsive changes in gene expression induced by ROS occur with minimal changes to the chromatin environment. While we did observe changes in chromatin accessibility, these changes were: (1) far less numerous than gene expression changes after oxidative stress, and (2) occur within pre-existing regions of accessible chromatin. Transcription factor (TF) footprinting analysis of our ATAC-seq experiments identified 5 TFs or TF families with evidence for ROS-responsive changes in DNA binding: NRF2, AP-1, p53, NFY, and SP/KLF. Importantly, several of these (AP-1, NF-Y, and SP/KLF factors) have not been previously implicated as widespread regulators in the response to ROS. In summary, we have characterized genome-wide changes in gene expression and chromatin accessibility in response to ROS treatment of MCF7 cells, and we have found that regulation of the large-scale transcriptional response to excess ROS is primarily constrained by the cell's pre-existing chromatin landscape.
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Affiliation(s)
- Daniel C Levings
- Department of Biomedical Sciences, University of Minnesota Medical School, Duluth, MN, 55812, USA
| | - Sarah E Lacher
- Department of Biomedical Sciences, University of Minnesota Medical School, Duluth, MN, 55812, USA
| | - Juan Palacios-Moreno
- Department of Biomedical Sciences, University of Minnesota Medical School, Duluth, MN, 55812, USA
| | - Matthew Slattery
- Department of Biomedical Sciences, University of Minnesota Medical School, Duluth, MN, 55812, USA.
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30
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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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31
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Han GS, Li Q, Li Y. Comparative analysis and prediction of nucleosome positioning using integrative feature representation and machine learning algorithms. BMC Bioinformatics 2021; 22:129. [PMID: 34078256 PMCID: PMC8170966 DOI: 10.1186/s12859-021-04006-w] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2021] [Accepted: 02/08/2021] [Indexed: 12/01/2022] Open
Abstract
Background Nucleosome plays an important role in the process of genome expression, DNA replication, DNA repair and transcription. Therefore, the research of nucleosome positioning has invariably received extensive attention. Considering the diversity of DNA sequence representation methods, we tried to integrate multiple features to analyze its effect in the process of nucleosome positioning analysis. This process can also deepen our understanding of the theoretical analysis of nucleosome positioning. Results Here, we not only used frequency chaos game representation (FCGR) to construct DNA sequence features, but also integrated it with other features and adopted the principal component analysis (PCA) algorithm. Simultaneously, support vector machine (SVM), extreme learning machine (ELM), extreme gradient boosting (XGBoost), multilayer perceptron (MLP) and convolutional neural networks (CNN) are used as predictors for nucleosome positioning prediction analysis, respectively. The integrated feature vector prediction quality is significantly superior to a single feature. After using principal component analysis (PCA) to reduce the feature dimension, the prediction quality of H. sapiens dataset has been significantly improved. Conclusions Comparative analysis and prediction on H. sapiens, C. elegans, D. melanogaster and S. cerevisiae datasets, demonstrate that the application of FCGR to nucleosome positioning is feasible, and we also found that integrative feature representation would be better.
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Affiliation(s)
- Guo-Sheng Han
- Department of Mathematics and Computational Science, Xiangtan University, Xiangtan, 411105, Hunan, China. .,Key Laboratory of Intelligent Computing and Information Processing of Ministry of Education and Hunan Key Laboratory for Computation and Simulation in Science and Engineering, Xiangtan University, Xiangtan, 411105, Hunan, China.
| | - Qi Li
- Department of Mathematics and Computational Science, Xiangtan University, Xiangtan, 411105, Hunan, China.,Key Laboratory of Intelligent Computing and Information Processing of Ministry of Education and Hunan Key Laboratory for Computation and Simulation in Science and Engineering, Xiangtan University, Xiangtan, 411105, Hunan, China
| | - Ying Li
- Department of Mathematics and Computational Science, Xiangtan University, Xiangtan, 411105, Hunan, China.,Key Laboratory of Intelligent Computing and Information Processing of Ministry of Education and Hunan Key Laboratory for Computation and Simulation in Science and Engineering, Xiangtan University, Xiangtan, 411105, Hunan, China
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32
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Nishimura M, Arimura Y, Nozawa K, Kurumizaka H. Linker DNA and histone contributions in nucleosome binding by p53. J Biochem 2021; 168:669-675. [PMID: 32702132 PMCID: PMC7763433 DOI: 10.1093/jb/mvaa081] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2020] [Accepted: 07/13/2020] [Indexed: 02/07/2023] Open
Abstract
The tumour suppressor protein p53 regulates various genes involved in cell-cycle arrest, apoptosis and DNA repair in response to cellular stress, and apparently functions as a pioneer transcription factor. The pioneer transcription factors can bind nucleosomal DNA, where many transcription factors are largely restricted. However, the mechanisms by which p53 recognizes the nucleosomal DNA are poorly understood. In the present study, we found that p53 requires linker DNAs for the efficient formation of p53-nucleosome complexes. p53 forms an additional specific complex with the nucleosome, when the p53 binding sequence is located around the entry/exit region of the nucleosomal DNA. We also showed that p53 directly binds to the histone H3-H4 complex via its N-terminal 1–93 amino acid region. These results shed light on the mechanism of nucleosome recognition by p53.
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Affiliation(s)
- Masahiro Nishimura
- Laboratory of Chromatin Structure and Function, Institute for Quantitative Biosciences.,Department of Biological Sciences, Graduate School of Science, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-0032, Japan
| | - Yasuhiro Arimura
- Laboratory of Chromatin Structure and Function, Institute for Quantitative Biosciences
| | - Kayo Nozawa
- Laboratory of Chromatin Structure and Function, Institute for Quantitative Biosciences
| | - Hitoshi Kurumizaka
- Laboratory of Chromatin Structure and Function, Institute for Quantitative Biosciences.,Department of Biological Sciences, Graduate School of Science, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-0032, Japan
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33
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Jauregui-Lozano J, Bakhle K, Weake VM. In vivo tissue-specific chromatin profiling in Drosophila melanogaster using GFP-tagged nuclei. Genetics 2021; 218:6281219. [PMID: 34022041 DOI: 10.1093/genetics/iyab079] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2021] [Accepted: 05/17/2021] [Indexed: 12/23/2022] Open
Abstract
The chromatin landscape defines cellular identity in multicellular organisms with unique patterns of DNA accessibility and histone marks decorating the genome of each cell type. Thus, profiling the chromatin state of different cell types in an intact organism under disease or physiological conditions can provide insight into how chromatin regulates cell homeostasis in vivo. To overcome the many challenges associated with characterizing chromatin state in specific cell types, we developed an improved approach to isolate Drosophila melanogaster nuclei tagged with a GFPKASH protein. The perinuclear space-localized KASH domain anchors GFP to the outer nuclear membrane, and expression of UAS-GFPKASH can be controlled by tissue-specific Gal4 drivers. Using this protocol, we profiled chromatin accessibility using an improved version of Assay for Transposable Accessible Chromatin followed by sequencing (ATAC-seq), called Omni-ATAC. In addition, we examined the distribution of histone marks using Chromatin immunoprecipitation followed by sequencing (ChIP-seq) and Cleavage Under Targets and Tagmentation (CUT&Tag) in adult photoreceptor neurons. We show that the chromatin landscape of photoreceptors reflects the transcriptional state of these cells, demonstrating the quality and reproducibility of our approach for profiling the transcriptome and epigenome of specific cell types in Drosophila.
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Affiliation(s)
| | - Kimaya Bakhle
- Department of Biochemistry, Purdue University, West Lafayette, IN 47907, USA
| | - Vikki M Weake
- Department of Biochemistry, Purdue University, West Lafayette, IN 47907, USA.,Purdue University Center for Cancer Research, Purdue University, West Lafayette, IN 47907, USA
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34
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Wang SY, Pollina EA, Wang IH, Pino LK, Bushnell HL, Takashima K, Fritsche C, Sabin G, Garcia BA, Greer PL, Greer EL. Role of epigenetics in unicellular to multicellular transition in Dictyostelium. Genome Biol 2021; 22:134. [PMID: 33947439 PMCID: PMC8094536 DOI: 10.1186/s13059-021-02360-9] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2021] [Accepted: 04/22/2021] [Indexed: 11/26/2022] Open
Abstract
BACKGROUND The evolution of multicellularity is a critical event that remains incompletely understood. We use the social amoeba, Dictyostelium discoideum, one of the rare organisms that readily transits back and forth between both unicellular and multicellular stages, to examine the role of epigenetics in regulating multicellularity. RESULTS While transitioning to multicellular states, patterns of H3K4 methylation and H3K27 acetylation significantly change. By combining transcriptomics, epigenomics, chromatin accessibility, and orthologous gene analyses with other unicellular and multicellular organisms, we identify 52 conserved genes, which are specifically accessible and expressed during multicellular states. We validated that four of these genes, including the H3K27 deacetylase hdaD, are necessary and that an SMC-like gene, smcl1, is sufficient for multicellularity in Dictyostelium. CONCLUSIONS These results highlight the importance of epigenetics in reorganizing chromatin architecture to facilitate multicellularity in Dictyostelium discoideum and raise exciting possibilities about the role of epigenetics in the evolution of multicellularity more broadly.
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Affiliation(s)
- Simon Yuan Wang
- Division of Newborn Medicine, Boston Children's Hospital, 300 Longwood Avenue, Boston, MA, 02115, USA
- Department of Pediatrics, Harvard Medical School, Boston, MA, 02115, USA
| | | | - I-Hao Wang
- Program in Molecular Medicine, University of Massachusetts Medical School, Worcester, MA, 01605, USA
| | - Lindsay Kristina Pino
- Department of Biochemistry and Biophysics, University of Pennsylvania, Perelman School of Medicine, Philadelphia, PA, 19104, USA
| | - Henry L Bushnell
- Division of Newborn Medicine, Boston Children's Hospital, 300 Longwood Avenue, Boston, MA, 02115, USA
- Department of Pediatrics, Harvard Medical School, Boston, MA, 02115, USA
| | - Ken Takashima
- Division of Newborn Medicine, Boston Children's Hospital, 300 Longwood Avenue, Boston, MA, 02115, USA
- Department of Pediatrics, Harvard Medical School, Boston, MA, 02115, USA
| | - Colette Fritsche
- Division of Newborn Medicine, Boston Children's Hospital, 300 Longwood Avenue, Boston, MA, 02115, USA
| | - George Sabin
- Division of Newborn Medicine, Boston Children's Hospital, 300 Longwood Avenue, Boston, MA, 02115, USA
| | - Benjamin Aaron Garcia
- Department of Biochemistry and Biophysics, University of Pennsylvania, Perelman School of Medicine, Philadelphia, PA, 19104, USA
| | - Paul Lieberman Greer
- Program in Molecular Medicine, University of Massachusetts Medical School, Worcester, MA, 01605, USA
| | - Eric Lieberman Greer
- Division of Newborn Medicine, Boston Children's Hospital, 300 Longwood Avenue, Boston, MA, 02115, USA.
- Department of Pediatrics, Harvard Medical School, Boston, MA, 02115, USA.
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35
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Kharerin H, Bai L. Thermodynamic modeling of genome-wide nucleosome depleted regions in yeast. PLoS Comput Biol 2021; 17:e1008560. [PMID: 33428627 PMCID: PMC7822557 DOI: 10.1371/journal.pcbi.1008560] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2020] [Revised: 01/22/2021] [Accepted: 11/25/2020] [Indexed: 01/09/2023] Open
Abstract
Nucleosome positioning in the genome is essential for the regulation of many nuclear processes. We currently have limited capability to predict nucleosome positioning in vivo, especially the locations and sizes of nucleosome depleted regions (NDRs). Here, we present a thermodynamic model that incorporates the intrinsic affinity of histones, competitive binding of sequence-specific factors, and nucleosome remodeling to predict nucleosome positioning in budding yeast. The model shows that the intrinsic affinity of histones, at near-saturating histone concentration, is not sufficient in generating NDRs in the genome. However, the binding of a few factors, especially RSC towards GC-rich and poly(A/T) sequences, allows us to predict ~ 66% of genome-wide NDRs. The model also shows that nucleosome remodeling activity is required to predict the correct NDR sizes. The validity of the model was further supported by the agreement between the predicted and the measured nucleosome positioning upon factor deletion or on exogenous sequences introduced into yeast. Overall, our model quantitatively evaluated the impact of different genetic components on NDR formation and illustrated the vital roles of sequence-specific factors and nucleosome remodeling in this process. Nucleosome is the basic unit of chromatin, containing 147 base-pairs of DNA wrapped around a histone core. The positioning of nucleosomes, i.e., which parts of DNA are inside nucleosome and which parts are nucleosome-free, is highly regulated. In particular, regulatory sequences tend to be exposed in nucleosome-depleted regions (NDRs), and such exposure is crucial for a variety of processes including DNA replication, repair, and gene expression. Here, we used a thermodynamics model to predict nucleosome positioning on the yeast genome. The model shows that the intrinsic sequence preference of histones is not sufficient in generating NDRs. In contrast, binding of a few transcription factors, especially RSC, is largely responsible for NDR formation. Nucleosome remodeling activity is also required in the model to recapitulate the NDR sizes. This model contributes to our understanding of the mechanisms that regulate nucleosome positioning. It can also be used to predict nucleosome positioning in mutant yeast or on novel DNA sequences.
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Affiliation(s)
- Hungyo Kharerin
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, Pennsylvania, United States of America
- Center for Eukaryotic Gene Regulation, The Pennsylvania State University, University Park, Pennsylvania, United States of America
| | - Lu Bai
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, Pennsylvania, United States of America
- Center for Eukaryotic Gene Regulation, The Pennsylvania State University, University Park, Pennsylvania, United States of America
- Department of Physics, The Pennsylvania State University, University Park, Pennsylvania, United States of America
- * E-mail:
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36
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Jiang Z, Zhang B. On the role of transcription in positioning nucleosomes. PLoS Comput Biol 2021; 17:e1008556. [PMID: 33417594 PMCID: PMC7819601 DOI: 10.1371/journal.pcbi.1008556] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2020] [Revised: 01/21/2021] [Accepted: 11/23/2020] [Indexed: 12/12/2022] Open
Abstract
Nucleosome positioning is crucial for the genome’s function. Though the role of DNA sequence in positioning nucleosomes is well understood, a detailed mechanistic understanding on the impact of transcription remains lacking. Using numerical simulations, we investigated the dependence of nucleosome density profiles on transcription level across multiple species. We found that the low nucleosome affinity of yeast, but not mouse, promoters contributes to the formation of phased nucleosomes arrays for inactive genes. For the active genes, a heterogeneous distribution of +1 nucleosomes, caused by a tug-of-war between two types of remodeling enzymes, is essential for reproducing their density profiles. In particular, while positioning enzymes are known to remodel the +1 nucleosome and align it toward the transcription start site (TSS), spacer enzymes that use a pair of nucleosomes as their substrate can shift the nucleosome array away from the TSS. Competition between these enzymes results in two types of nucleosome density profiles with well- and ill-positioned +1 nucleosome. Finally, we showed that Pol II assisted histone exchange, if occurring at a fast speed, can abolish the impact of remodeling enzymes. By elucidating the role of individual factors, our study reconciles the seemingly conflicting results on the overall impact of transcription in positioning nucleosomes across species. Nucleosome positioning plays a key role in the genome’s function by regulating the accessibility of protein binding sites as well as higher-order chromatin organization. Though significant progress has been made towards studying the role of DNA sequence in positioning the nucleosomes, our understanding on the impact of transcription lags behind. Our study uses kinetic simulations to explore the role of DNA sequence specificity, transcription factor binding, enzyme remodeling, and Pol II elongation in positioning nucleosomes. It suggests that the differences in nucleosome density profiles observed at various transcription levels in yeast and mouse embryonic stem cells can be understood from a tug-of-war between two types of remodeling enzymes.
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Affiliation(s)
- Zhongling Jiang
- Departments of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
| | - Bin Zhang
- Departments of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
- * E-mail:
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37
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Abstract
Gene expression is needed for the maintenance of heart function under normal conditions and in response to stress. Each cell type of the heart has a specific program controlling transcription. Different types of stress induce modifications of these programs and, if prolonged, can lead to altered cardiac phenotype and, eventually, to heart failure. The transcriptional status of a gene is regulated by the epigenome, a complex network of DNA and histone modifications. Until a few years ago, our understanding of the role of the epigenome in heart disease was limited to that played by histone deacetylation. But over the last decade, the consequences for the maintenance of homeostasis in the heart and for the development of cardiac hypertrophy of a number of other modifications, including DNA methylation and hydroxymethylation, histone methylation and acetylation, and changes in chromatin architecture, have become better understood. Indeed, it is now clear that many levels of regulation contribute to defining the epigenetic landscape required for correct cardiomyocyte function, and that their perturbation is responsible for cardiac hypertrophy and fibrosis. Here, we review these aspects and draw a picture of what epigenetic modification may imply at the therapeutic level for heart failure.
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Affiliation(s)
- Roberto Papait
- Department of Biotechnology and Life Sciences, University of Insubria, Varese, Italy; Humanitas Clinical Research Center-IRCCS, Rozzano, Italy; Humanitas University, Department of Biomedical Sciences, Pieve Emanuele, Italy; and National Research Council of Italy, Institute of Genetics and Biomedical Research, Milan Unit, Rozzano, Italy
| | - Simone Serio
- Department of Biotechnology and Life Sciences, University of Insubria, Varese, Italy; Humanitas Clinical Research Center-IRCCS, Rozzano, Italy; Humanitas University, Department of Biomedical Sciences, Pieve Emanuele, Italy; and National Research Council of Italy, Institute of Genetics and Biomedical Research, Milan Unit, Rozzano, Italy
| | - Gianluigi Condorelli
- Department of Biotechnology and Life Sciences, University of Insubria, Varese, Italy; Humanitas Clinical Research Center-IRCCS, Rozzano, Italy; Humanitas University, Department of Biomedical Sciences, Pieve Emanuele, Italy; and National Research Council of Italy, Institute of Genetics and Biomedical Research, Milan Unit, Rozzano, Italy
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38
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Jenull S, Tscherner M, Mair T, Kuchler K. ATAC-Seq Identifies Chromatin Landscapes Linked to the Regulation of Oxidative Stress in the Human Fungal Pathogen Candida albicans. J Fungi (Basel) 2020; 6:jof6030182. [PMID: 32967096 PMCID: PMC7559329 DOI: 10.3390/jof6030182] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2020] [Revised: 09/15/2020] [Accepted: 09/15/2020] [Indexed: 12/12/2022] Open
Abstract
Human fungal pathogens often encounter fungicidal stress upon host invasion, but they can swiftly adapt by transcriptional reprogramming that enables pathogen survival. Fungal immune evasion is tightly connected to chromatin regulation. Hence, fungal chromatin modifiers pose alternative treatment options to combat fungal infections. Here, we present an assay for transposase-accessible chromatin using sequencing (ATAC-seq) protocol adapted for the opportunistic pathogen Candida albicans to gain further insight into the interplay of chromatin accessibility and gene expression mounted during fungal adaptation to oxidative stress. The ATAC-seq workflow not only facilitates the robust detection of genomic regions with accessible chromatin but also allows for the precise modeling of nucleosome positions in C. albicans. Importantly, the data reveal genes with altered chromatin accessibility in upstream regulatory regions, which correlate with transcriptional regulation during oxidative stress. Interestingly, many genes show increased chromatin accessibility without change in gene expression upon stress exposure. Such chromatin signatures could predict yet unknown regulatory factors under highly dynamic transcriptional control. Additionally, de novo motif analysis in genomic regions with increased chromatin accessibility upon H2O2 treatment shows significant enrichment for Cap1 binding sites, a major factor of oxidative stress responses in C. albicans. Taken together, the ATAC-seq workflow enables the identification of chromatin signatures and highlights the dynamics of regulatory mechanisms mediating environmental adaptation of C. albicans.
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39
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Parmar JJ, Padinhateeri R. Nucleosome positioning and chromatin organization. Curr Opin Struct Biol 2020; 64:111-118. [PMID: 32731156 DOI: 10.1016/j.sbi.2020.06.021] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2020] [Revised: 05/31/2020] [Accepted: 06/23/2020] [Indexed: 11/24/2022]
Abstract
In our cells, DNA is folded and packed with the help of many proteins into chromatin whose basic unit is a nucleosome-DNA wrapped around octamer of histone proteins. The chain of nucleosomes is further folded and arranged into many layers and has a dynamic organization. How does the complex chromatin organization emerge from interactions among DNA, histones, and non-histone proteins have been a question of great interest. Here we review recent literature that investigated how nucleosome positioning and nucleosome-mediated interactions drive chromatin organization. Unlike our earlier understanding, chromatin is organized into 3D domains of various sizes having irregularly organized nucleosomes. These domains emerge due to heterogeneous nucleosome positioning and diverse inter-nucleosome interactions that vary in space and time.
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Affiliation(s)
- Jyotsana J Parmar
- Department of Biosciences and Bioengineering, Indian Institute of Technology Bombay, Mumbai 400 076, India
| | - Ranjith Padinhateeri
- Department of Biosciences and Bioengineering, Indian Institute of Technology Bombay, Mumbai 400 076, India.
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40
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Levings D, Shaw KE, Lacher SE. Genomic resources for dissecting the role of non-protein coding variation in gene-environment interactions. Toxicology 2020; 441:152505. [PMID: 32450112 DOI: 10.1016/j.tox.2020.152505] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2020] [Revised: 05/18/2020] [Accepted: 05/18/2020] [Indexed: 12/27/2022]
Abstract
The majority of single nucleotide variants (SNVs) identified in Genome Wide Association Studies (GWAS) fall within non-protein coding DNA and have the potential to alter gene expression. Non-protein coding DNA can control gene expression by acting as transcription factor (TF) binding sites or by regulating the organization of DNA into chromatin. SNVs in non-coding DNA sequences can disrupt TF binding and chromatin structure and this can result in pathology. Further, environmental health studies have shown that exposure to xenobiotics can disrupt the ability of TFs to regulate entire gene networks and result in pathology. However, there is a large amount of interindividual variability in exposure-linked health outcomes. One explanation for this heterogeneity is that genetic variation and exposure combine to disrupt gene regulation, and this eventually manifests in disease. Many resources exist that annotate common variants from GWAS and combine them with conservation, functional genomics, and TF binding data. These annotation tools provide clues regarding the biological implications of an SNV, as well as lead to the generation of hypotheses regarding potentially disrupted target genes, epigenetic markers, pathways, and cell types. Collectively this information can be used to predict how SNVs can alter an individual's response to exposure and disease risk. A basic understanding of the regulatory information contained within non-protein coding DNA is needed to predict the biological consequences of SNVs, and to determine how these SNVs impact exposure-related disease. We hope that this review will aid in the characterization of disease-associated genetic variation in the non-protein coding genome.
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Affiliation(s)
- Daniel Levings
- Department of Biomedical Sciences, University of Minnesota Medical School, Duluth Campus, 1035 University Drive, Duluth, MN, 55812, USA
| | - Kirsten E Shaw
- Department of Biomedical Sciences, University of Minnesota Medical School, Duluth Campus, 1035 University Drive, Duluth, MN, 55812, USA
| | - Sarah E Lacher
- Department of Biomedical Sciences, University of Minnesota Medical School, Duluth Campus, 1035 University Drive, Duluth, MN, 55812, USA.
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41
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Zhao Y, Wang J, Liang F, Liu Y, Wang Q, Zhang H, Jiang M, Zhang Z, Zhao W, Bao Y, Zhang Z, Wu J, Asmann YW, Li R, Xiao J. NucMap: a database of genome-wide nucleosome positioning map across species. Nucleic Acids Res 2020; 47:D163-D169. [PMID: 30335176 PMCID: PMC6323900 DOI: 10.1093/nar/gky980] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2018] [Accepted: 10/10/2018] [Indexed: 12/16/2022] Open
Abstract
Dynamics of nucleosome positioning affects chromatin state, transcription and all other biological processes occurring on genomic DNA. While MNase-Seq has been used to depict nucleosome positioning map in eukaryote in the past years, nucleosome positioning data is increasing dramatically. To facilitate the usage of published data across studies, we developed a database named nucleosome positioning map (NucMap, http://bigd.big.ac.cn/nucmap). NucMap includes 798 experimental data from 477 samples across 15 species. With a series of functional modules, users can search profile of nucleosome positioning at the promoter region of each gene across all samples and make enrichment analysis on nucleosome positioning data in all genomic regions. Nucleosome browser was built to visualize the profiles of nucleosome positioning. Users can also visualize multiple sources of omics data with the nucleosome browser and make side-by-side comparisons. All processed data in the database are freely available. NucMap is the first comprehensive nucleosome positioning platform and it will serve as an important resource to facilitate the understanding of chromatin regulation.
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Affiliation(s)
- Yongbing Zhao
- Department of Health Sciences Research, Mayo Clinic, Jacksonville, FL 32224, USA
| | - Jinyue Wang
- BIG Data Center, Beijing Institute of Genomics, Chinese Academy of Sciences, Beijing 100101, China.,CAS Key Laboratory of Genome Sciences and Information, Beijing Institute of Genomics, Chinese Academy of Sciences, Beijing 100101, China.,College of Life Sciences, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Fang Liang
- BIG Data Center, Beijing Institute of Genomics, Chinese Academy of Sciences, Beijing 100101, China
| | - Yanxia Liu
- BIG Data Center, Beijing Institute of Genomics, Chinese Academy of Sciences, Beijing 100101, China.,CAS Key Laboratory of Genome Sciences and Information, Beijing Institute of Genomics, Chinese Academy of Sciences, Beijing 100101, China.,College of Life Sciences, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Qi Wang
- BIG Data Center, Beijing Institute of Genomics, Chinese Academy of Sciences, Beijing 100101, China.,CAS Key Laboratory of Genome Sciences and Information, Beijing Institute of Genomics, Chinese Academy of Sciences, Beijing 100101, China.,College of Life Sciences, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Hao Zhang
- BIG Data Center, Beijing Institute of Genomics, Chinese Academy of Sciences, Beijing 100101, China.,CAS Key Laboratory of Genome Sciences and Information, Beijing Institute of Genomics, Chinese Academy of Sciences, Beijing 100101, China.,College of Life Sciences, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Meiye Jiang
- BIG Data Center, Beijing Institute of Genomics, Chinese Academy of Sciences, Beijing 100101, China.,CAS Key Laboratory of Genome Sciences and Information, Beijing Institute of Genomics, Chinese Academy of Sciences, Beijing 100101, China
| | - Zhewen Zhang
- BIG Data Center, Beijing Institute of Genomics, Chinese Academy of Sciences, Beijing 100101, China.,CAS Key Laboratory of Genome Sciences and Information, Beijing Institute of Genomics, Chinese Academy of Sciences, Beijing 100101, China
| | - Wenming Zhao
- BIG Data Center, Beijing Institute of Genomics, Chinese Academy of Sciences, Beijing 100101, China.,CAS Key Laboratory of Genome Sciences and Information, Beijing Institute of Genomics, Chinese Academy of Sciences, Beijing 100101, China
| | - Yiming Bao
- BIG Data Center, Beijing Institute of Genomics, Chinese Academy of Sciences, Beijing 100101, China.,CAS Key Laboratory of Genome Sciences and Information, Beijing Institute of Genomics, Chinese Academy of Sciences, Beijing 100101, China
| | - Zhang Zhang
- BIG Data Center, Beijing Institute of Genomics, Chinese Academy of Sciences, Beijing 100101, China.,CAS Key Laboratory of Genome Sciences and Information, Beijing Institute of Genomics, Chinese Academy of Sciences, Beijing 100101, China.,Collaborative Innovation Center of Genetics and Development, Fudan University, Shanghai 200438, China
| | - Jiayan Wu
- CAS Key Laboratory of Genome Sciences and Information, Beijing Institute of Genomics, Chinese Academy of Sciences, Beijing 100101, China
| | - Yan W Asmann
- Department of Health Sciences Research, Mayo Clinic, Jacksonville, FL 32224, USA
| | - Rujiao Li
- BIG Data Center, Beijing Institute of Genomics, Chinese Academy of Sciences, Beijing 100101, China
| | - Jingfa Xiao
- BIG Data Center, Beijing Institute of Genomics, Chinese Academy of Sciences, Beijing 100101, China.,CAS Key Laboratory of Genome Sciences and Information, Beijing Institute of Genomics, Chinese Academy of Sciences, Beijing 100101, China.,College of Life Sciences, University of Chinese Academy of Sciences, Beijing 100049, China.,Collaborative Innovation Center of Genetics and Development, Fudan University, Shanghai 200438, China
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42
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Takada S, Brandani GB, Tan C. Nucleosomes as allosteric scaffolds for genetic regulation. Curr Opin Struct Biol 2020; 62:93-101. [PMID: 31901887 DOI: 10.1016/j.sbi.2019.11.013] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2019] [Revised: 11/13/2019] [Accepted: 11/14/2019] [Indexed: 12/11/2022]
Abstract
Nucleosomes are stable yet highly dynamic complexes exhibiting diverse types of motions, such as sliding, DNA unwrapping, and disassembly, encoding a landscape with a large number of metastable states. In this review, describing recent studies on these nucleosome structure changes, we propose that the nucleosome can be viewed as an ideal allosteric scaffold: regulated by effector molecules such as transcription factors and chromatin remodelers, the nucleosome controls the downstream gene activity. Binding of transcription factors to the nucleosome can enhance DNA unwrapping or slide the DNA, altering either the binding or the unbinding of other transcription factors to nearby sites. ATP-dependent chromatin remodelers induce a series of DNA deformations, which allosterically propagate throughout the nucleosome to induce DNA sliding or histone exchange.
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Affiliation(s)
- Shoji Takada
- Department of Biophysics, Graduate School of Science, Kyoto University, Kitashirakawa-Oiwake, Sakyo Kyoto, 606-8502, Japan.
| | - Giovanni B Brandani
- Department of Biophysics, Graduate School of Science, Kyoto University, Kitashirakawa-Oiwake, Sakyo Kyoto, 606-8502, Japan
| | - Cheng Tan
- RIKEN Center for Computational Science, 7-1-26 Minatojima-minamimachi, Chuo, Kobe, 650-0047 Japan
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43
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Abstract
In eukaryotes, DNA is highly compacted within the nucleus into a structure known as chromatin. Modulation of chromatin structure allows for precise regulation of gene expression, and thereby controls cell fate decisions. Specific chromatin organization is established and preserved by numerous factors to generate desired cellular outcomes. In embryonic stem (ES) cells, chromatin is precisely regulated to preserve their two defining characteristics: self-renewal and pluripotent state. This action is accomplished by a litany of nucleosome remodelers, histone variants, epigenetic marks, and other chromatin regulatory factors. These highly dynamic regulatory factors come together to precisely define a chromatin state that is conducive to ES cell maintenance and development, where dysregulation threatens the survival and fitness of the developing organism.
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Affiliation(s)
- David C Klein
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, PA, United States
| | - Sarah J Hainer
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, PA, United States.
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44
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Q-Nuc: a bioinformatics pipeline for the quantitative analysis of nucleosomal profiles. Interdiscip Sci 2019; 12:69-81. [PMID: 31845186 DOI: 10.1007/s12539-019-00354-7] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2019] [Revised: 10/20/2019] [Accepted: 11/22/2019] [Indexed: 12/26/2022]
Abstract
Nucleosomal profiling is an effective method to determine the positioning and occupancy of nucleosomes, which is essential to understand their roles in genomic processes. However, the positional randomness across the genome and its relationship with nucleosome occupancy remains poorly understood. Here we present a computational method that segments the profile into nucleosomal domains and quantifies their randomness and relative occupancy level. Applying this method to published data, we find on average ~ 3-fold differences in the degree of positional randomness between regions typically considered "well-ordered", as well as an unexpected predominance of only two types of domains of positional randomness in yeast cells. Further, we find that occupancy levels between domains actually differ maximally by ~ 2-3-fold in both cells, which has not been described before. We also developed a procedure by which one can estimate the sequencing depth that is required to identify nucleosomal positions even when regional positional randomness is high. Overall, we have developed a pipeline to quantitatively characterize domain-level features of nucleosome randomness and occupancy genome-wide, enabling the identification of otherwise unknown features in nucleosomal organization.
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45
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Buitrago D, Codó L, Illa R, de Jorge P, Battistini F, Flores O, Bayarri G, Royo R, Del Pino M, Heath S, Hospital A, Gelpí JL, Heath IB, Orozco M. Nucleosome Dynamics: a new tool for the dynamic analysis of nucleosome positioning. Nucleic Acids Res 2019; 47:9511-9523. [PMID: 31504766 PMCID: PMC6765203 DOI: 10.1093/nar/gkz759] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2019] [Revised: 07/23/2019] [Accepted: 08/22/2019] [Indexed: 02/03/2023] Open
Abstract
We present Nucleosome Dynamics, a suite of programs integrated into a virtual research environment and created to define nucleosome architecture and dynamics from noisy experimental data. The package allows both the definition of nucleosome architectures and the detection of changes in nucleosomal organization due to changes in cellular conditions. Results are displayed in the context of genomic information thanks to different visualizers and browsers, allowing the user a holistic, multidimensional view of the genome/transcriptome. The package shows good performance for both locating equilibrium nucleosome architecture and nucleosome dynamics and provides abundant useful information in several test cases, where experimental data on nucleosome position (and for some cases expression level) have been collected for cells under different external conditions (cell cycle phase, yeast metabolic cycle progression, changes in nutrients or difference in MNase digestion level). Nucleosome Dynamics is a free software and is provided under several distribution models.
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Affiliation(s)
- Diana Buitrago
- Institute for Research in Biomedicine (IRB Barcelona), The Barcelona Institute of Science and Technology, Baldiri Reixac 10, Barcelona 08028, Spain
| | - Laia Codó
- Barcelona Supercomputing Center (BSC), Jordi Girona 31, Barcelona 08028. Spain
| | - Ricard Illa
- Institute for Research in Biomedicine (IRB Barcelona), The Barcelona Institute of Science and Technology, Baldiri Reixac 10, Barcelona 08028, Spain
| | - Pau de Jorge
- Institute for Research in Biomedicine (IRB Barcelona), The Barcelona Institute of Science and Technology, Baldiri Reixac 10, Barcelona 08028, Spain
| | - Federica Battistini
- Institute for Research in Biomedicine (IRB Barcelona), The Barcelona Institute of Science and Technology, Baldiri Reixac 10, Barcelona 08028, Spain
| | - Oscar Flores
- Institute for Research in Biomedicine (IRB Barcelona), The Barcelona Institute of Science and Technology, Baldiri Reixac 10, Barcelona 08028, Spain
| | - Genis Bayarri
- Institute for Research in Biomedicine (IRB Barcelona), The Barcelona Institute of Science and Technology, Baldiri Reixac 10, Barcelona 08028, Spain
| | - Romina Royo
- Barcelona Supercomputing Center (BSC), Jordi Girona 31, Barcelona 08028. Spain
| | - Marc Del Pino
- Barcelona Supercomputing Center (BSC), Jordi Girona 31, Barcelona 08028. Spain
| | - Simon Heath
- Centro Nacional de Análisis Genómico (CNAG-CRG), Centre de Regulacio Genómico (CRG), The Barcelona Institute of Science and Technology, Barcelona, Spain
| | - Adam Hospital
- Institute for Research in Biomedicine (IRB Barcelona), The Barcelona Institute of Science and Technology, Baldiri Reixac 10, Barcelona 08028, Spain
| | - Josep Lluís Gelpí
- Barcelona Supercomputing Center (BSC), Jordi Girona 31, Barcelona 08028. Spain.,Departament de Bioquímica i Biomedicina. Facultat de Biologia, Universitat de Barcelona, Avgda Diagonal 647, Barcelona 08028, Spain
| | - Isabelle Brun Heath
- Institute for Research in Biomedicine (IRB Barcelona), The Barcelona Institute of Science and Technology, Baldiri Reixac 10, Barcelona 08028, Spain
| | - Modesto Orozco
- Institute for Research in Biomedicine (IRB Barcelona), The Barcelona Institute of Science and Technology, Baldiri Reixac 10, Barcelona 08028, Spain.,Departament de Bioquímica i Biomedicina. Facultat de Biologia, Universitat de Barcelona, Avgda Diagonal 647, Barcelona 08028, Spain
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46
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Kameda T, Awazu A, Togashi Y. Histone Tail Dynamics in Partially Disassembled Nucleosomes During Chromatin Remodeling. Front Mol Biosci 2019; 6:133. [PMID: 31850366 PMCID: PMC6896900 DOI: 10.3389/fmolb.2019.00133] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2019] [Accepted: 11/11/2019] [Indexed: 11/13/2022] Open
Abstract
Nucleosomes are structural units of the chromosome consisting of DNA wrapped around histone proteins, and play important roles in compaction and regulation of the chromatin structure. While the structure and dynamics of canonical nucleosomes have been studied extensively, those of nucleosomes in intermediate states, that occur when their structure or positioning is modulated, have been less understood. In particular, the dynamic features of partially disassembled nucleosomes have not been discussed in previous studies. Using all-atom molecular dynamics simulations, in this study, we investigated the dynamics and stability of nucleosome structures lacking a histone-dimer. DNA in nucleosomes lacking a histone H2A/H2B dimer was drastically deformed due to loss of local interactions between DNA and histones. In contrast, conformation of DNA in nucleosomes lacking H3/H4 was similar to the canonical nucleosome, as the H2A C-terminal domain infiltrated the space originally occupied by the dissociated H3/H4 histones and restricted DNA dynamics in close proximity. Our results suggest that, besides histone chaperones, the intrinsic dynamics of nucleosomes support the exchange of H2A/H2B, which is significantly more frequent than that of H3/H4.
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Affiliation(s)
- Takeru Kameda
- Department of Mathematical and Life Sciences, Graduate School of Science, Hiroshima University, Higashi-Hiroshima, Japan
| | - Akinori Awazu
- Graduate School of Integrated Sciences for Life, Hiroshima University, Higashi-Hiroshima, Japan.,Research Center for the Mathematics on Chromatin Live Dynamics (RcMcD), Hiroshima University, Higashi-Hiroshima, Japan
| | - Yuichi Togashi
- Graduate School of Integrated Sciences for Life, Hiroshima University, Higashi-Hiroshima, Japan.,Research Center for the Mathematics on Chromatin Live Dynamics (RcMcD), Hiroshima University, Higashi-Hiroshima, Japan.,RIKEN Center for Biosystems Dynamics Research (BDR), Higashi-Hiroshima, Japan
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47
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Abstract
Nucleosome positioning controls the accessible regions of chromatin and plays essential roles in DNA-templated processes. ATP driven remodeling enzymes are known to be crucial for its establishment in vivo, but their nonequilibrium nature has hindered the development of a unified theoretical framework for nucleosome positioning. Using a perturbation theory, we show that the effect of these enzymes can be well approximated by effective equilibrium models with rescaled temperatures and interactions. Numerical simulations support the accuracy of the theory in predicting both kinetic and steady-state quantities, including the effective temperature and the radial distribution function, in biologically relevant regimes. The energy landscape view emerging from our study provides an intuitive understanding for the impact of remodeling enzymes in either reinforcing or overwriting intrinsic signals for nucleosome positioning, and may help improve the accuracy of computational models for its prediction in silico.
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48
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Hocher A, Rojec M, Swadling JB, Esin A, Warnecke T. The DNA-binding protein HTa from Thermoplasma acidophilum is an archaeal histone analog. eLife 2019; 8:52542. [PMID: 31710291 PMCID: PMC6877293 DOI: 10.7554/elife.52542] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2019] [Accepted: 11/10/2019] [Indexed: 02/06/2023] Open
Abstract
Histones are a principal constituent of chromatin in eukaryotes and fundamental to our understanding of eukaryotic gene regulation. In archaea, histones are widespread but not universal: several lineages have lost histone genes. What prompted or facilitated these losses and how archaea without histones organize their chromatin remains largely unknown. Here, we elucidate primary chromatin architecture in an archaeon without histones, Thermoplasma acidophilum, which harbors a HU family protein (HTa) that protects part of the genome from micrococcal nuclease digestion. Charting HTa-based chromatin architecture in vitro, in vivo and in an HTa-expressing E. coli strain, we present evidence that HTa is an archaeal histone analog. HTa preferentially binds to GC-rich sequences, exhibits invariant positioning throughout the growth cycle, and shows archaeal histone-like oligomerization behavior. Our results suggest that HTa, a DNA-binding protein of bacterial origin, has converged onto an architectural role filled by histones in other archaea.
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Affiliation(s)
- Antoine Hocher
- MRC London Institute of Medical Sciences (LMS), London, United Kingdom.,Institute of Clinical Sciences (ICS), Faculty of Medicine, Imperial College, London, United Kingdom
| | - Maria Rojec
- MRC London Institute of Medical Sciences (LMS), London, United Kingdom.,Institute of Clinical Sciences (ICS), Faculty of Medicine, Imperial College, London, United Kingdom
| | - Jacob B Swadling
- MRC London Institute of Medical Sciences (LMS), London, United Kingdom.,Institute of Clinical Sciences (ICS), Faculty of Medicine, Imperial College, London, United Kingdom
| | - Alexander Esin
- MRC London Institute of Medical Sciences (LMS), London, United Kingdom.,Institute of Clinical Sciences (ICS), Faculty of Medicine, Imperial College, London, United Kingdom
| | - Tobias Warnecke
- MRC London Institute of Medical Sciences (LMS), London, United Kingdom.,Institute of Clinical Sciences (ICS), Faculty of Medicine, Imperial College, London, United Kingdom
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49
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Kim N. The Interplay between G-quadruplex and Transcription. Curr Med Chem 2019; 26:2898-2917. [PMID: 29284393 PMCID: PMC6026074 DOI: 10.2174/0929867325666171229132619] [Citation(s) in RCA: 83] [Impact Index Per Article: 16.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2017] [Revised: 11/22/2017] [Accepted: 12/21/2017] [Indexed: 12/25/2022]
Abstract
G4 DNA is a non-canonical DNA structure consisting of a stacked array of Gquartets held together by base pairing between guanine bases. The formation of G4 DNA requires a cluster of guanine-runs within a strand of DNA. Even though the chemistry of this remarkable DNA structure has been under investigation for decades, evidence supporting the biological relevance of G4 DNA has only begun to emerge and point to very important and conserved biological functions. This review will specifically focus on the interplay between transcription and G4 DNA and discuss two alternative but interconnected perspectives. The first part of the review will describe the evidence substantiating the intriguing idea that a shift in DNA structural conformation could be another layer of non-genetic or epigenetic regulator of gene expression and thereby an important determinant of cell fate. The second part will describe the recent genetic studies showing that those genomic loci containing G4 DNA-forming guanine-rich sequences are potential hotspots of genome instability and that the level and orientation of transcription is critical in the materialization of genome instability associated with these sequences.
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Affiliation(s)
- Nayun Kim
- Department of Microbiology and Molecular Genetics, The University of Texas Health Science Center at Houston; The University of Texas Graduate School of Biomedical Sciences, Houston, TX, United States
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50
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Wang AW, Wang YJ, Zahm AM, Morgan AR, Wangensteen KJ, Kaestner KH. The Dynamic Chromatin Architecture of the Regenerating Liver. Cell Mol Gastroenterol Hepatol 2019; 9:121-143. [PMID: 31629814 PMCID: PMC6909351 DOI: 10.1016/j.jcmgh.2019.09.006] [Citation(s) in RCA: 33] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/21/2019] [Revised: 09/19/2019] [Accepted: 09/23/2019] [Indexed: 12/12/2022]
Abstract
BACKGROUND & AIMS The adult liver is the main detoxification organ and routinely is exposed to environmental insults but retains the ability to restore its mass and function upon tissue damage. However, extensive injury can lead to liver failure, and chronic injury causes fibrosis, cirrhosis, and hepatocellular carcinoma. Currently, the transcriptional regulation of organ repair in the adult liver is incompletely understood. METHODS We isolated nuclei from quiescent as well as repopulating hepatocytes in a mouse model of hereditary tyrosinemia, which recapitulates the injury and repopulation seen in toxic liver injury in human beings. We then performed the assay for transposase accessible chromatin with high-throughput sequencing specifically in repopulating hepatocytes to identify differentially accessible chromatin regions and nucleosome positioning. In addition, we used motif analysis to predict differential transcription factor occupancy and validated the in silico results with chromatin immunoprecipitation followed by sequencing for hepatocyte nuclear factor 4α (HNF4α) and CCCTC-binding factor (CTCF). RESULTS Chromatin accessibility in repopulating hepatocytes was increased in the regulatory regions of genes promoting proliferation and decreased in the regulatory regions of genes involved in metabolism. The epigenetic changes at promoters and liver enhancers correspond with the regulation of gene expression, with enhancers of many liver function genes showing a less accessible state during the regenerative process. Moreover, increased CTCF occupancy at promoters and decreased HNF4α binding at enhancers implicate these factors as key drivers of the transcriptomic changes in replicating hepatocytes that enable liver repopulation. CONCLUSIONS Our analysis of hepatocyte-specific epigenomic changes during liver repopulation identified CTCF and HNF4α as key regulators of hepatocyte proliferation and regulation of metabolic programs. Thus, liver repopulation in the setting of toxic injury makes use of both general transcription factors (CTCF) for promoter activation, and reduced binding by a hepatocyte-enriched factor (HNF4α) to temporarily limit enhancer activity. All sequencing data in this study were deposited to the Gene Expression Omnibus database and can be downloaded with accession number GSE109466.
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Affiliation(s)
- Amber W Wang
- Department of Genetics, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Yue J Wang
- Department of Genetics, University of Pennsylvania, Philadelphia, Pennsylvania; Department of Biomedical Sciences, Florida State University College of Medicine, Tallahassee, Florida
| | - Adam M Zahm
- Department of Genetics, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Ashleigh R Morgan
- Department of Genetics, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Kirk J Wangensteen
- Department of Genetics, University of Pennsylvania, Philadelphia, Pennsylvania; Department of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Klaus H Kaestner
- Department of Genetics, University of Pennsylvania, Philadelphia, Pennsylvania.
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