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Struhl K. Non-canonical functions of enhancers: regulation of RNA polymerase III transcription, DNA replication, and V(D)J recombination. Trends Genet 2024; 40:471-479. [PMID: 38643034 DOI: 10.1016/j.tig.2024.04.001] [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: 02/28/2024] [Accepted: 04/02/2024] [Indexed: 04/22/2024]
Abstract
Enhancers are the key regulators of other DNA-based processes by virtue of their unique ability to generate nucleosome-depleted regions in a highly regulated manner. Enhancers regulate cell-type-specific transcription of tRNA genes by RNA polymerase III (Pol III). They are also responsible for the binding of the origin replication complex (ORC) to DNA replication origins, thereby regulating origin utilization, replication timing, and replication-dependent chromosome breaks. Additionally, enhancers regulate V(D)J recombination by increasing access of the recombination-activating gene (RAG) recombinase to target sites and by generating non-coding enhancer RNAs and localized regions of trimethylated histone H3-K4 recognized by the RAG2 PHD domain. Thus, enhancers represent the first step in decoding the genome, and hence they regulate biological processes that, unlike RNA polymerase II (Pol II) transcription, do not have dedicated regulatory proteins.
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Affiliation(s)
- Kevin Struhl
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02115, USA.
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2
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Yang JH, Hansen AS. Enhancer selectivity in space and time: from enhancer-promoter interactions to promoter activation. Nat Rev Mol Cell Biol 2024:10.1038/s41580-024-00710-6. [PMID: 38413840 DOI: 10.1038/s41580-024-00710-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/30/2024] [Indexed: 02/29/2024]
Abstract
The primary regulators of metazoan gene expression are enhancers, originally functionally defined as DNA sequences that can activate transcription at promoters in an orientation-independent and distance-independent manner. Despite being crucial for gene regulation in animals, what mechanisms underlie enhancer selectivity for promoters, and more fundamentally, how enhancers interact with promoters and activate transcription, remain poorly understood. In this Review, we first discuss current models of enhancer-promoter interactions in space and time and how enhancers affect transcription activation. Next, we discuss different mechanisms that mediate enhancer selectivity, including repression, biochemical compatibility and regulation of 3D genome structure. Through 3D polymer simulations, we illustrate how the ability of 3D genome folding mechanisms to mediate enhancer selectivity strongly varies for different enhancer-promoter interaction mechanisms. Finally, we discuss how recent technical advances may provide new insights into mechanisms of enhancer-promoter interactions and how technical biases in methods such as Hi-C and Micro-C and imaging techniques may affect their interpretation.
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Affiliation(s)
- Jin H Yang
- Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, MA, USA
- Gene Regulation Observatory, Broad Institute of MIT and Harvard, Cambridge, MA, USA
- Koch Institute for Integrative Cancer Research, Cambridge, MA, USA
| | - Anders S Hansen
- Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, MA, USA.
- Gene Regulation Observatory, Broad Institute of MIT and Harvard, Cambridge, MA, USA.
- Koch Institute for Integrative Cancer Research, Cambridge, MA, USA.
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3
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Kondoh H. Enhancer Arrays Regulating Developmental Genes: Sox2 Enhancers as a Paradigm. Results Probl Cell Differ 2024; 72:145-166. [PMID: 38509257 DOI: 10.1007/978-3-031-39027-2_9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/22/2024]
Abstract
Enhancers are the primary regulatory DNA sequences in eukaryotes and are mostly located in the non-coding sequences of genes, namely, intergenic regions and introns. The essential characteristic of an enhancer is the ability to activate proximal genes, e.g., a reporter gene in a reporter assay, regardless of orientation, relative position, and distance from the gene. These characteristics are ascribed to the interaction (spatial proximity) of the enhancer sequence and the gene promoter via DNA looping, discussed in the latter part of this chapter.Developmentally regulated genes are associated with multiple enhancers carrying distinct cell and developmental stage specificities, which form arrays on the genome. We discuss the array of enhancers regulating the Sox2 gene as a paradigm. Sox2 enhancers are the best studied enhancers of a single gene in developmental regulation. In addition, the Sox2 gene is located in a genomic region with a very sparse gene distribution (no other protein-coding genes in ~1.6 Mb in the mouse genome), termed a "gene desert," which means that most identified enhancers in the region are associated with Sox2 regulation. Furthermore, the importance of the Sox2 gene in stem cell regulation and neural development justifies focusing on Sox2-associated enhancers.
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Affiliation(s)
- Hisato Kondoh
- Osaka University, Suita, Osaka, Japan
- Biohistory Research Hall, Takatsuki, Osaka, Japan
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4
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Mulet-Lazaro R, Delwel R. From Genotype to Phenotype: How Enhancers Control Gene Expression and Cell Identity in Hematopoiesis. Hemasphere 2023; 7:e969. [PMID: 37953829 PMCID: PMC10635615 DOI: 10.1097/hs9.0000000000000969] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2023] [Accepted: 09/11/2023] [Indexed: 11/14/2023] Open
Abstract
Blood comprises a wide array of specialized cells, all of which share the same genetic information and ultimately derive from the same precursor, the hematopoietic stem cell (HSC). This diversity of phenotypes is underpinned by unique transcriptional programs gradually acquired in the process known as hematopoiesis. Spatiotemporal regulation of gene expression depends on many factors, but critical among them are enhancers-sequences of DNA that bind transcription factors and increase transcription of genes under their control. Thus, hematopoiesis involves the activation of specific enhancer repertoires in HSCs and their progeny, driving the expression of sets of genes that collectively determine morphology and function. Disruption of this tightly regulated process can have catastrophic consequences: in hematopoietic malignancies, dysregulation of transcriptional control by enhancers leads to misexpression of oncogenes that ultimately drive transformation. This review attempts to provide a basic understanding of enhancers and their role in transcriptional regulation, with a focus on normal and malignant hematopoiesis. We present examples of enhancers controlling master regulators of hematopoiesis and discuss the main mechanisms leading to enhancer dysregulation in leukemia and lymphoma.
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Affiliation(s)
- Roger Mulet-Lazaro
- Department of Hematology, Erasmus MC Cancer Institute, Rotterdam, the Netherlands
- Oncode Institute, Utrecht, the Netherlands
| | - Ruud Delwel
- Department of Hematology, Erasmus MC Cancer Institute, Rotterdam, the Netherlands
- Oncode Institute, Utrecht, the Netherlands
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Bubnova AN, Yakovleva IV, Korotkov EV, Kamionskaya AM. In Silico Verification of Predicted Potential Promoter Sequences in the Rice ( Oryza sativa) Genome. PLANTS (BASEL, SWITZERLAND) 2023; 12:3573. [PMID: 37896036 PMCID: PMC10609952 DOI: 10.3390/plants12203573] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/12/2023] [Revised: 10/09/2023] [Accepted: 10/12/2023] [Indexed: 10/29/2023]
Abstract
The exact identification of promoter sequences remains a serious problem in computational biology, as the promoter prediction algorithms under development continue to produce false-positive results. Therefore, to fully assess the validity of predicted sequences, it is necessary to perform a comprehensive test of their properties, such as the presence of downstream transcribed DNA regions behind them, or chromatin accessibility for transcription factor binding. In this paper, we examined the promoter sequences of chromosome 1 of the rice Oryza sativa genome from the Database of Potential Promoter Sequences predicted using a mathematical algorithm based on the derivation and calculation of statistically significant promoter classes. In this paper TATA motifs and cis-regulatory elements were identified in the predicted promoter sequences. We also verified the presence of potential transcription start sites near the predicted promoters by analyzing CAGE-seq data. We searched for unannotated transcripts behind the predicted sequences by de novo assembling transcripts from RNA-seq data. We also examined chromatin accessibility in the region of the predicted promoters by analyzing ATAC-seq data. As a result of this work, we identified the predicted sequences that are most likely to be promoters for further experimental validation in an in vivo or in vitro system.
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Affiliation(s)
- Anastasiya N. Bubnova
- Federal State Institution Federal Research Centre «Fundamentals of Biotechnology», Russian Academy of Sciences, 119071 Moscow, Russia (A.M.K.)
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6
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Li Q, Liu X, Wen J, Chen X, Xie B, Zhao Y. Enhancer RNAs: mechanisms in transcriptional regulation and functions in diseases. Cell Commun Signal 2023; 21:191. [PMID: 37537618 PMCID: PMC10398997 DOI: 10.1186/s12964-023-01206-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2023] [Accepted: 06/23/2023] [Indexed: 08/05/2023] Open
Abstract
In recent years, increasingly more non-coding RNAs have been detected with the development of high-throughput sequencing technology, including microRNAs (miRNAs), long non-coding RNAs (lncRNAs), circular RNAs (circRNAs), small nucleolar RNAs (snoRNAs), and piwi-interacting RNA (piRNAs). The discovery of enhancer RNAs (eRNAs) in 2010 has further broadened the range of non-coding RNAs revealed. eRNAs are non-coding RNA molecules produced by the transcription of DNA cis-acting elements, enhancer fragments. Recent studies revealed that the transcription of eRNAs may be a biological marker responding to enhancer activity that can participate in the regulation of coding gene transcription. In this review, we discussed the biological characteristics of eRNAs, their functions in transcriptional regulation, the regulation factors of eRNAs production, and the research progress of eRNAs in different diseases. Video Abstract.
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Affiliation(s)
- Qianhui Li
- Department of Obstetrics and Gynecology, Department of Gynecologic Oncology Research Office, Guangzhou Key Laboratory of Targeted Therapy for Gynecologic Oncology, Guangdong Provincial Key Laboratory of Major Obstetric Diseases, The Third Affiliated Hospital of Guangzhou Medical University, No.63 Duobao Road, Liwan District, Guangdong Province, Guangzhou City, 510150, People's Republic of China
| | - Xin Liu
- Department of Obstetrics and Gynecology, Department of Gynecologic Oncology Research Office, Guangzhou Key Laboratory of Targeted Therapy for Gynecologic Oncology, Guangdong Provincial Key Laboratory of Major Obstetric Diseases, The Third Affiliated Hospital of Guangzhou Medical University, No.63 Duobao Road, Liwan District, Guangdong Province, Guangzhou City, 510150, People's Republic of China
| | - Jingtao Wen
- Department of Obstetrics and Gynecology, Department of Gynecologic Oncology Research Office, Guangzhou Key Laboratory of Targeted Therapy for Gynecologic Oncology, Guangdong Provincial Key Laboratory of Major Obstetric Diseases, The Third Affiliated Hospital of Guangzhou Medical University, No.63 Duobao Road, Liwan District, Guangdong Province, Guangzhou City, 510150, People's Republic of China
| | - Xi Chen
- Department of Obstetrics and Gynecology, Department of Gynecologic Oncology Research Office, Guangzhou Key Laboratory of Targeted Therapy for Gynecologic Oncology, Guangdong Provincial Key Laboratory of Major Obstetric Diseases, The Third Affiliated Hospital of Guangzhou Medical University, No.63 Duobao Road, Liwan District, Guangdong Province, Guangzhou City, 510150, People's Republic of China
| | - Bumin Xie
- Department of Obstetrics and Gynecology, Department of Gynecologic Oncology Research Office, Guangzhou Key Laboratory of Targeted Therapy for Gynecologic Oncology, Guangdong Provincial Key Laboratory of Major Obstetric Diseases, The Third Affiliated Hospital of Guangzhou Medical University, No.63 Duobao Road, Liwan District, Guangdong Province, Guangzhou City, 510150, People's Republic of China
| | - Yang Zhao
- Department of Obstetrics and Gynecology, Department of Gynecologic Oncology Research Office, Guangzhou Key Laboratory of Targeted Therapy for Gynecologic Oncology, Guangdong Provincial Key Laboratory of Major Obstetric Diseases, The Third Affiliated Hospital of Guangzhou Medical University, No.63 Duobao Road, Liwan District, Guangdong Province, Guangzhou City, 510150, People's Republic of China.
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7
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Wang X, Liu D, Luo J, Kong D, Zhang Y. Exploring the Role of Enhancer-Mediated Transcriptional Regulation in Precision Biology. Int J Mol Sci 2023; 24:10843. [PMID: 37446021 PMCID: PMC10342031 DOI: 10.3390/ijms241310843] [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: 05/10/2023] [Revised: 06/18/2023] [Accepted: 06/25/2023] [Indexed: 07/15/2023] Open
Abstract
The emergence of precision biology has been driven by the development of advanced technologies and techniques in high-resolution biological research systems. Enhancer-mediated transcriptional regulation, a complex network of gene expression and regulation in eukaryotes, has attracted significant attention as a promising avenue for investigating the underlying mechanisms of biological processes and diseases. To address biological problems with precision, large amounts of data, functional information, and research on the mechanisms of action of biological molecules is required to address biological problems with precision. Enhancers, including typical enhancers and super enhancers, play a crucial role in gene expression and regulation within this network. The identification and targeting of disease-associated enhancers hold the potential to advance precision medicine. In this review, we present the concepts, progress, importance, and challenges in precision biology, transcription regulation, and enhancers. Furthermore, we propose a model of transcriptional regulation for multi-enhancers and provide examples of their mechanisms in mammalian cells, thereby enhancing our understanding of how enhancers achieve precise regulation of gene expression in life processes. Precision biology holds promise in providing new tools and platforms for discovering insights into gene expression and disease occurrence, ultimately benefiting individuals and society as a whole.
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Affiliation(s)
- Xueyan Wang
- College of Life Science and Technology, Huazhong Agricultural University, Wuhan 430070, China;
- Shenzhen Branch, Guangdong Laboratory of Lingnan Modern Agriculture, Key Laboratory of Livestock and Poultry Multi-Omics of MARA, Agricultural Genomics Institute at Shenzhen, Chinese Academy of Agricultural Sciences, Shenzhen 518120, China; (D.L.); (J.L.); (D.K.)
| | - Danli Liu
- Shenzhen Branch, Guangdong Laboratory of Lingnan Modern Agriculture, Key Laboratory of Livestock and Poultry Multi-Omics of MARA, Agricultural Genomics Institute at Shenzhen, Chinese Academy of Agricultural Sciences, Shenzhen 518120, China; (D.L.); (J.L.); (D.K.)
| | - Jing Luo
- Shenzhen Branch, Guangdong Laboratory of Lingnan Modern Agriculture, Key Laboratory of Livestock and Poultry Multi-Omics of MARA, Agricultural Genomics Institute at Shenzhen, Chinese Academy of Agricultural Sciences, Shenzhen 518120, China; (D.L.); (J.L.); (D.K.)
| | - Dashuai Kong
- Shenzhen Branch, Guangdong Laboratory of Lingnan Modern Agriculture, Key Laboratory of Livestock and Poultry Multi-Omics of MARA, Agricultural Genomics Institute at Shenzhen, Chinese Academy of Agricultural Sciences, Shenzhen 518120, China; (D.L.); (J.L.); (D.K.)
| | - Yubo Zhang
- College of Life Science and Technology, Huazhong Agricultural University, Wuhan 430070, China;
- Shenzhen Branch, Guangdong Laboratory of Lingnan Modern Agriculture, Key Laboratory of Livestock and Poultry Multi-Omics of MARA, Agricultural Genomics Institute at Shenzhen, Chinese Academy of Agricultural Sciences, Shenzhen 518120, China; (D.L.); (J.L.); (D.K.)
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8
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Razin SV, Ulianov SV, Iarovaia OV. Enhancer Function in the 3D Genome. Genes (Basel) 2023; 14:1277. [PMID: 37372457 DOI: 10.3390/genes14061277] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2023] [Revised: 05/31/2023] [Accepted: 06/15/2023] [Indexed: 06/29/2023] Open
Abstract
In this review, we consider various aspects of enhancer functioning in the context of the 3D genome. Particular attention is paid to the mechanisms of enhancer-promoter communication and the significance of the spatial juxtaposition of enhancers and promoters in 3D nuclear space. A model of an activator chromatin compartment is substantiated, which provides the possibility of transferring activating factors from an enhancer to a promoter without establishing direct contact between these elements. The mechanisms of selective activation of individual promoters or promoter classes by enhancers are also discussed.
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Affiliation(s)
- Sergey V Razin
- Institute of Gene Biology Russian Academy of Sciences, 119334 Moscow, Russia
- Faculty of Biology, M.V. Lomonosov Moscow State University, 119234 Moscow, Russia
| | - Sergey V Ulianov
- Institute of Gene Biology Russian Academy of Sciences, 119334 Moscow, Russia
- Faculty of Biology, M.V. Lomonosov Moscow State University, 119234 Moscow, Russia
| | - Olga V Iarovaia
- Institute of Gene Biology Russian Academy of Sciences, 119334 Moscow, Russia
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9
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Zhu D, Yang W, Xu D, Li H, Zhao Y, Li D. A deep learning based two-layer predictor to identify enhancers and their strength. Methods 2023; 211:23-30. [PMID: 36740001 DOI: 10.1016/j.ymeth.2023.01.007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2022] [Revised: 01/03/2023] [Accepted: 01/30/2023] [Indexed: 02/05/2023] Open
Abstract
The enhancer is a DNA sequence that can increase the activity of promoters and thus speed up the frequency of gene transcription. The enhancer plays an essential role in activating gene expression. Currently, gene sequencing technology has been developed for 30 years from the first generation to the third generation, and a variety of biological sequence data have increased significantly every year. Due to the importance of enhancer functions, it is very expensive to identify enhancers through biochemical experiments. Therefore, we need to study new methods for the identification and classification of enhancers. Based on the K-mer principle this study proposed a feature extraction method that others have not used in convolutional neural networks. Then, we combined it with one-hot encoding to build an efficient one-dimensional convolutional neural network ensemble model for predicting enhancers and their strengths. Finally, we used five commonly used classification problem evaluation indicators to compare with the models proposed by other researchers. The model proposed in this paper has a better performance by using the same independent test dataset as other models.
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Affiliation(s)
- Di Zhu
- College of Information and Computer Engineering, Northeast Forestry University, Harbin, China
| | - Wen Yang
- International Medical Center, Shenzhen University General Hospital, Shenzhen, China
| | - Dali Xu
- College of Information and Computer Engineering, Northeast Forestry University, Harbin, China
| | - Hongfei Li
- College of Information and Computer Engineering, Northeast Forestry University, Harbin, China
| | - Yuming Zhao
- College of Information and Computer Engineering, Northeast Forestry University, Harbin, China.
| | - Dan Li
- College of Information and Computer Engineering, Northeast Forestry University, Harbin, China.
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10
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Lindhorst D, Halfon MS. Reporter gene assays and chromatin-level assays define substantially non-overlapping sets of enhancer sequences. BMC Genomics 2023; 24:17. [PMID: 36639739 PMCID: PMC9837977 DOI: 10.1186/s12864-023-09123-9] [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: 10/11/2022] [Accepted: 01/09/2023] [Indexed: 01/15/2023] Open
Abstract
BACKGROUND Transcriptional enhancers are essential for gene regulation, but how these regulatory elements are best defined remains a significant unresolved question. Traditional definitions rely on activity-based criteria such as reporter gene assays, while more recently, biochemical assays based on chromatin-level phenomena such as chromatin accessibility, histone modifications, and localized RNA transcription have gained prominence. RESULTS We examine here whether these two types of definitions, activity-based and chromatin-based, effectively identify the same sets of sequences. We find that, concerningly, the overlap between the two groups is strikingly limited. Few of the data sets we compared displayed statistically significant overlap, and even for those, the degree of overlap was typically small (below 40% of sequences). Moreover, a substantial batch effect was observed in which experiment set rather than experimental method was a primary driver of whether or not chromatin-defined enhancers showed a strong overlap with reporter gene-defined enhancers. CONCLUSIONS Our results raise important questions as to the appropriateness of both old and new enhancer definitions, and suggest that new approaches are required to reconcile the poor agreement among existing methods for defining enhancers.
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Affiliation(s)
- Daniel Lindhorst
- grid.273335.30000 0004 1936 9887Department of Biochemistry, University at Buffalo-State University of New York, 955 Main St. #5128, Buffalo, NY 14203 USA ,grid.21729.3f0000000419368729Present Address: Program in Biomedical Sciences, Columbia University, New York, NY 10032 USA
| | - Marc S. Halfon
- grid.273335.30000 0004 1936 9887Department of Biochemistry, University at Buffalo-State University of New York, 955 Main St. #5128, Buffalo, NY 14203 USA ,grid.273335.30000 0004 1936 9887Department of Biomedical Informatics, University at Buffalo-State University of New York, Buffalo, NY 14203 USA ,grid.273335.30000 0004 1936 9887Department of Biological Sciences, University at Buffalo-State University of New York, Buffalo, NY 14260 USA ,NY State Center of Excellence in Bioinformatics & Life Sciences, Buffalo, NY 14203 USA ,grid.240614.50000 0001 2181 8635Department of Molecular and Cellular Biology and Program in Cancer Genetics, Roswell Park Comprehensive Cancer Center, Buffalo, NY 14263 USA
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11
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Nair SJ, Suter T, Wang S, Yang L, Yang F, Rosenfeld MG. Transcriptional enhancers at 40: evolution of a viral DNA element to nuclear architectural structures. Trends Genet 2022; 38:1019-1047. [PMID: 35811173 PMCID: PMC9474616 DOI: 10.1016/j.tig.2022.05.015] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2022] [Revised: 05/05/2022] [Accepted: 05/31/2022] [Indexed: 02/08/2023]
Abstract
Gene regulation by transcriptional enhancers is the dominant mechanism driving cell type- and signal-specific transcriptional diversity in metazoans. However, over four decades since the original discovery, how enhancers operate in the nuclear space remains largely enigmatic. Recent multidisciplinary efforts combining real-time imaging, genome sequencing, and biophysical strategies provide insightful but conflicting models of enhancer-mediated gene control. Here, we review the discovery and progress in enhancer biology, emphasizing the recent findings that acutely activated enhancers assemble regulatory machinery as mesoscale architectural structures with distinct physical properties. These findings help formulate novel models that explain several mysterious features of the assembly of transcriptional enhancers and the mechanisms of spatial control of gene expression.
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Affiliation(s)
- Sreejith J Nair
- Department of Oncology, Lombardi Comprehensive Cancer Center, Georgetown University, Washington, DC 20057, USA.
| | - Tom Suter
- Howard Hughes Medical Institute, Department and School of Medicine, University of California, San Diego, La Jolla, CA 92093, USA
| | - Susan Wang
- Howard Hughes Medical Institute, Department and School of Medicine, University of California, San Diego, La Jolla, CA 92093, USA; Cellular and Molecular Medicine Graduate Program, University of California, San Diego, La Jolla, CA 92093, USA
| | - Lu Yang
- Howard Hughes Medical Institute, Department and School of Medicine, University of California, San Diego, La Jolla, CA 92093, USA
| | - Feng Yang
- Howard Hughes Medical Institute, Department and School of Medicine, University of California, San Diego, La Jolla, CA 92093, USA
| | - Michael G Rosenfeld
- Howard Hughes Medical Institute, Department and School of Medicine, University of California, San Diego, La Jolla, CA 92093, USA.
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12
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Popay TM, Dixon JR. Coming full circle: on the origin and evolution of the looping model for enhancer-promoter communication. J Biol Chem 2022; 298:102117. [PMID: 35691341 PMCID: PMC9283939 DOI: 10.1016/j.jbc.2022.102117] [Citation(s) in RCA: 16] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2022] [Revised: 05/26/2022] [Accepted: 05/27/2022] [Indexed: 11/05/2022] Open
Abstract
In mammalian organisms, enhancers can regulate transcription from great genomic distances. How enhancers affect distal gene expression has been a major question in the field of gene regulation. One model to explain how enhancers communicate with their target promoters, the chromatin looping model, posits that enhancers and promoters come in close spatial proximity to mediate communication. Chromatin looping has been broadly accepted as a means for enhancer–promoter communication, driven by accumulating in vitro and in vivo evidence. The genome is now known to be folded into a complex 3D arrangement, created and maintained in part by the interplay of the Cohesin complex and the DNA-binding protein CTCF. In the last few years, however, doubt over the relationship between looping and transcriptional activation has emerged, driven by studies finding that only a modest number of genes are perturbed with acute degradation of looping machinery components. In parallel, newer models describing distal enhancer action have also come to prominence. In this article, we explore the emergence and development of the looping model as a means for enhancer–promoter communication and review the contrasting evidence between historical gene-specific and current global data for the role of chromatin looping in transcriptional regulation. We also discuss evidence for alternative models to chromatin looping and their support in the literature. We suggest that, while there is abundant evidence for chromatin looping as a major mechanism for enhancer function, enhancer–promoter communication is likely mediated by more than one mechanism in an enhancer- and context-dependent manner.
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Affiliation(s)
- Tessa M Popay
- Gene Expression Laboratory, The Salk Institute for Biological Studies, La Jolla, CA 92037, USA
| | - Jesse R Dixon
- Gene Expression Laboratory, The Salk Institute for Biological Studies, La Jolla, CA 92037, USA.
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13
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Yang JF, You J. Merkel cell polyomavirus and associated Merkel cell carcinoma. Tumour Virus Res 2022; 13:200232. [PMID: 34920178 PMCID: PMC8715208 DOI: 10.1016/j.tvr.2021.200232] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2021] [Revised: 11/08/2021] [Accepted: 12/13/2021] [Indexed: 12/22/2022] Open
Abstract
Merkel cell polyomavirus (MCPyV) is a ubiquitous skin infection that can cause Merkel cell carcinoma (MCC), a highly lethal form of skin cancer with a nearly 50% mortality rate. Since the discovery of MCPyV in 2008, great advances have been made to improve our understanding of how the viral encoded oncoproteins contribute to MCC oncogenesis. However, our knowledge of the MCPyV infectious life cycle and its oncogenic mechanisms are still incomplete. The incidence of MCC has tripled over the past two decades, but effective treatments are lacking. Only recently have there been major victories in combatting metastatic MCC with the application of PD-1 immune checkpoint blockade. Still, these immune-based therapies are not ideal for patients with a medical need to maintain systemic immune suppression. As such, a better understanding of MCPyV's oncogenic mechanisms is needed in order to develop more effective and targeted therapies against virus-associated MCC. In this review, we discuss current areas of interest for MCPyV and MCC research and the progress made in elucidating both the natural host of MCPyV infection and the cell of origin for MCC. We also highlight the remaining gaps in our knowledge on the transcriptional regulation of MCPyV, which may be key to understanding and targeting viral oncogenesis for developing future therapies.
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Affiliation(s)
- June F Yang
- Department of Microbiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, 19104-6076, USA
| | - Jianxin You
- Department of Microbiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, 19104-6076, USA.
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Abstract
Enhancers control the establishment of spatiotemporal gene expression patterns throughout development. Over the past decade, the development of new technologies has improved our capacity to link enhancers with their target genes based on their colocalization within the same topological domains. However, the mechanisms that regulate how enhancers specifically activate some genes but not others within a given domain remain unclear. In this Review, we discuss recent insights into the factors controlling enhancer specificity, including the genetic composition of enhancers and promoters, the linear and 3D distance between enhancers and their target genes, and cell-type specific chromatin landscapes. We also discuss how elucidating the molecular principles of enhancer specificity might help us to better understand and predict the pathological consequences of human genetic, epigenetic and structural variants.
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Affiliation(s)
- Tomás Pachano
- Institute of Biomedicine and Biotechnology of Cantabria (IBBTEC), CSIC/Universidad de Cantabria/SODERCAN, Albert Einstein 22, 39011 Santander, Spain
| | - Endika Haro
- Institute of Biomedicine and Biotechnology of Cantabria (IBBTEC), CSIC/Universidad de Cantabria/SODERCAN, Albert Einstein 22, 39011 Santander, Spain
| | - Alvaro Rada-Iglesias
- Institute of Biomedicine and Biotechnology of Cantabria (IBBTEC), CSIC/Universidad de Cantabria/SODERCAN, Albert Einstein 22, 39011 Santander, Spain
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15
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Nollmann M, Bennabi I, Götz M, Gregor T. The Impact of Space and Time on the Functional Output of the Genome. Cold Spring Harb Perspect Biol 2022; 14:a040378. [PMID: 34230036 PMCID: PMC8733053 DOI: 10.1101/cshperspect.a040378] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Over the past two decades, it has become clear that the multiscale spatial and temporal organization of the genome has important implications for nuclear function. This review centers on insights gained from recent advances in light microscopy on our understanding of transcription. We discuss spatial and temporal aspects that shape nuclear order and their consequences on regulatory components, focusing on genomic scales most relevant to function. The emerging picture is that spatiotemporal constraints increase the complexity in transcriptional regulation, highlighting new challenges, such as uncertainty about how information travels from molecular factors through the genome and space to generate a functional output.
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Affiliation(s)
- Marcelo Nollmann
- Centre de Biologie Structurale, CNRS UMR5048, INSERM U1054, Univ Montpellier, 34090 Montpellier, France
| | - Isma Bennabi
- Department of Stem Cell and Developmental Biology, CNRS UMR3738, Institut Pasteur, 75015 Paris, France
| | - Markus Götz
- Centre de Biologie Structurale, CNRS UMR5048, INSERM U1054, Univ Montpellier, 34090 Montpellier, France
| | - Thomas Gregor
- Department of Stem Cell and Developmental Biology, CNRS UMR3738, Institut Pasteur, 75015 Paris, France
- Joseph Henry Laboratory of Physics & Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton, New Jersey 08544, USA
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16
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Kneppers J, Bergman AM, Zwart W. Prostate Cancer Epigenetic Plasticity and Enhancer Heterogeneity: Molecular Causes, Consequences and Clinical Implications. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2022; 1390:255-275. [DOI: 10.1007/978-3-031-11836-4_15] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/30/2023]
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17
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Ray-Jones H, Spivakov M. Transcriptional enhancers and their communication with gene promoters. Cell Mol Life Sci 2021; 78:6453-6485. [PMID: 34414474 PMCID: PMC8558291 DOI: 10.1007/s00018-021-03903-w] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2021] [Revised: 07/08/2021] [Accepted: 07/19/2021] [Indexed: 12/13/2022]
Abstract
Transcriptional enhancers play a key role in the initiation and maintenance of gene expression programmes, particularly in metazoa. How these elements control their target genes in the right place and time is one of the most pertinent questions in functional genomics, with wide implications for most areas of biology. Here, we synthesise classic and recent evidence on the regulatory logic of enhancers, including the principles of enhancer organisation, factors that facilitate and delimit enhancer-promoter communication, and the joint effects of multiple enhancers. We show how modern approaches building on classic insights have begun to unravel the complexity of enhancer-promoter relationships, paving the way towards a quantitative understanding of gene control.
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Affiliation(s)
- Helen Ray-Jones
- MRC London Institute of Medical Sciences, London, W12 0NN, UK
- Institute of Clinical Sciences, Faculty of Medicine, Imperial College, London, W12 0NN, UK
| | - Mikhail Spivakov
- MRC London Institute of Medical Sciences, London, W12 0NN, UK.
- Institute of Clinical Sciences, Faculty of Medicine, Imperial College, London, W12 0NN, UK.
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18
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Lee YE, Lee J, Lee YS, Jang JJ, Woo H, Choi HI, Chai YG, Kim TK, Kim T, Kim LK, Choi SS. Identification and Functional Characterization of Two Noncoding RNAs Transcribed from Putative Active Enhancers in Hepatocellular Carcinoma. Mol Cells 2021; 44:658-669. [PMID: 34588321 PMCID: PMC8490203 DOI: 10.14348/molcells.2021.0173] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2021] [Revised: 08/12/2021] [Accepted: 08/13/2021] [Indexed: 01/08/2023] Open
Abstract
Enhancers have been conventionally perceived as cis-acting elements that provide binding sites for trans-acting factors. However, recent studies have shown that enhancers are transcribed and that these transcripts, called enhancer RNAs (eRNAs), have a regulatory function. Here, we identified putative eRNAs by profiling and determining the overlap between noncoding RNA expression loci and eRNA-associated histone marks such as H3K27ac and H3K4me1 in hepatocellular carcinoma (HCC) cell lines. Of the 132 HCC-derived noncoding RNAs, 74 overlapped with the eRNA loci defined by the FANTOM consortium, and 65 were located in the proximal regions of genes differentially expressed between normal and tumor tissues in TCGA dataset. Interestingly, knockdown of two selected putative eRNAs, THUMPD3-AS1 and LINC01572, led to downregulation of their target mRNAs and to a reduction in the proliferation and migration of HCC cells. Additionally, the expression of these two noncoding RNAs and target mRNAs was elevated in tumor samples in the TCGA dataset, and high expression was associated with poor survival of patients. Collectively, our study suggests that noncoding RNAs such as THUMPD3-AS1 and LINC01572 (i.e., putative eRNAs) can promote the transcription of genes involved in cell proliferation and differentiation and that the dysregulation of these noncoding RNAs can cause cancers such as HCC.
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Affiliation(s)
- Ye-Eun Lee
- Division of Biomedical Convergence, College of Biomedical Science, Institute of Bioscience & Biotechnology, Kangwon National University, Chuncheon 24341, Korea
| | - Jiyeon Lee
- Severance Biomedical Science Institute, Graduate School of Medical Science, Brain Korea 21 Project, Gangnam Severance Hospital, Yonsei University College of Medicine, Seoul 06230, Korea
| | - Yong Sun Lee
- Department of Cancer Biomedical Science, Graduate School of Cancer Science and Policy, National Cancer Center, Goyang 10408, Korea
| | - Jiyoung Joan Jang
- Department of Cancer Biomedical Science, Graduate School of Cancer Science and Policy, National Cancer Center, Goyang 10408, Korea
| | - Hyeonju Woo
- Department of Life Science and the Research Center for Cellular Homeostasis, Ewha Womans University, Seoul 03760, Korea
| | - Hae In Choi
- Department of Bionanotechnology, Hanyang University, Seoul 04673, Korea
| | - Young Gyu Chai
- Department of Molecular and Life Science, Hanyang University, Ansan 15588, Korea
| | - Tae-Kyung Kim
- Department of Life Sciences, Pohang University of Science and Technology (POSTECH), Pohang 37673, Korea
| | - TaeSoo Kim
- Department of Life Science and the Research Center for Cellular Homeostasis, Ewha Womans University, Seoul 03760, Korea
| | - Lark Kyun Kim
- Severance Biomedical Science Institute, Graduate School of Medical Science, Brain Korea 21 Project, Gangnam Severance Hospital, Yonsei University College of Medicine, Seoul 06230, Korea
| | - Sun Shim Choi
- Division of Biomedical Convergence, College of Biomedical Science, Institute of Bioscience & Biotechnology, Kangwon National University, Chuncheon 24341, Korea
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19
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Waymack R, Gad M, Wunderlich Z. Molecular competition can shape enhancer activity in the Drosophila embryo. iScience 2021; 24:103034. [PMID: 34568782 PMCID: PMC8449247 DOI: 10.1016/j.isci.2021.103034] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2021] [Revised: 07/27/2021] [Accepted: 08/20/2021] [Indexed: 01/12/2023] Open
Abstract
Transgenic reporters allow the measurement of regulatory DNA activity in vivo and consequently have long been useful tools for studying enhancers. Despite their utility, few studies have investigated the effects these reporters may have on the expression of other genes. Understanding these effects is required to accurately interpret reporter data and characterize gene regulatory mechanisms. By measuring the expression of Kruppel (Kr) enhancer reporters in live Drosophila embryos, we find reporters inhibit one another’s expression and that of a nearby endogenous gene. Using synthetic transcription factor (TF) binding site arrays, we present evidence that competition for TFs is partially responsible for the observed transcriptional inhibition. We develop a simple thermodynamic model that predicts competition of the measured magnitude specifically when TF binding is restricted to distinct nuclear subregions. Our findings underline an unexpected role of the non-homogenous nature of the nucleus in regulating gene expression. Live tracking of transcription reveals competition between transgenic reporters Transgenic reporters can also depress the expression of a neighboring gene Expression inhibition is in part because of competition for transcription factors (TFs) Competition is predicted with a model that restricts TFs to sub-nuclear “hubs”
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Affiliation(s)
- Rachel Waymack
- Department of Developmental and Cell Biology, University of California, Irvine, CA 92697, USA
| | - Mario Gad
- Department of Developmental and Cell Biology, University of California, Irvine, CA 92697, USA
| | - Zeba Wunderlich
- Department of Developmental and Cell Biology, University of California, Irvine, CA 92697, USA.,Department of Biology, Boston University, 610 Commonwealth Ave., Boston, MA 02215, USA.,Biological Design Center, Boston University, 610 Commonwealth Avenue, Boston, MA 02215, USA
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20
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Petrenko N, Struhl K. Comparison of transcriptional initiation by RNA polymerase II across eukaryotic species. eLife 2021; 10:67964. [PMID: 34515029 PMCID: PMC8463073 DOI: 10.7554/elife.67964] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2021] [Accepted: 09/10/2021] [Indexed: 01/17/2023] Open
Abstract
The preinitiation complex (PIC) for transcriptional initiation by RNA polymerase (Pol) II is composed of general transcription factors that are highly conserved. However, analysis of ChIP-seq datasets reveals kinetic and compositional differences in the transcriptional initiation process among eukaryotic species. In yeast, Mediator associates strongly with activator proteins bound to enhancers, but it transiently associates with promoters in a form that lacks the kinase module. In contrast, in human, mouse, and fly cells, Mediator with its kinase module stably associates with promoters, but not with activator-binding sites. This suggests that yeast and metazoans differ in the nature of the dynamic bridge of Mediator between activators and Pol II and the composition of a stable inactive PIC-like entity. As in yeast, occupancies of TATA-binding protein (TBP) and TBP-associated factors (Tafs) at mammalian promoters are not strictly correlated. This suggests that within PICs, TFIID is not a monolithic entity, and multiple forms of TBP affect initiation at different classes of genes. TFIID in flies, but not yeast and mammals, interacts strongly at regions downstream of the initiation site, consistent with the importance of downstream promoter elements in that species. Lastly, Taf7 and the mammalian-specific Med26 subunit of Mediator also interact near the Pol II pause region downstream of the PIC, but only in subsets of genes and often not together. Species-specific differences in PIC structure and function are likely to affect how activators and repressors affect transcriptional activity.
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Affiliation(s)
- Natalia Petrenko
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, United States
| | - Kevin Struhl
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, United States
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21
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Lee JH, Wang R, Xiong F, Krakowiak J, Liao Z, Nguyen PT, Moroz-Omori EV, Shao J, Zhu X, Bolt MJ, Wu H, Singh PK, Bi M, Shi CJ, Jamal N, Li G, Mistry R, Jung SY, Tsai KL, Ferreon JC, Stossi F, Caflisch A, Liu Z, Mancini MA, Li W. Enhancer RNA m6A methylation facilitates transcriptional condensate formation and gene activation. Mol Cell 2021; 81:3368-3385.e9. [PMID: 34375583 PMCID: PMC8383322 DOI: 10.1016/j.molcel.2021.07.024] [Citation(s) in RCA: 111] [Impact Index Per Article: 37.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2020] [Revised: 06/10/2021] [Accepted: 07/20/2021] [Indexed: 01/22/2023]
Abstract
The mechanistic understanding of nascent RNAs in transcriptional control remains limited. Here, by a high sensitivity method methylation-inscribed nascent transcripts sequencing (MINT-seq), we characterized the landscapes of N6-methyladenosine (m6A) on nascent RNAs. We uncover heavy but selective m6A deposition on nascent RNAs produced by transcription regulatory elements, including promoter upstream antisense RNAs and enhancer RNAs (eRNAs), which positively correlates with their length, inclusion of m6A motif, and RNA abundances. m6A-eRNAs mark highly active enhancers, where they recruit nuclear m6A reader YTHDC1 to phase separate into liquid-like condensates, in a manner dependent on its C terminus intrinsically disordered region and arginine residues. The m6A-eRNA/YTHDC1 condensate co-mixes with and facilitates the formation of BRD4 coactivator condensate. Consequently, YTHDC1 depletion diminished BRD4 condensate and its recruitment to enhancers, resulting in inhibited enhancer and gene activation. We propose that chemical modifications of eRNAs together with reader proteins play broad roles in enhancer activation and gene transcriptional control.
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Affiliation(s)
- Joo-Hyung Lee
- Department of Biochemistry and Molecular Biology, McGovern Medical School, University of Texas Health Science Center, Houston, TX 77030, USA
| | - Ruoyu Wang
- Department of Biochemistry and Molecular Biology, McGovern Medical School, University of Texas Health Science Center, Houston, TX 77030, USA; Graduate School of Biomedical Sciences, University of Texas MD Anderson Cancer Center and UTHealth, Houston, TX 77030, USA
| | - Feng Xiong
- Department of Biochemistry and Molecular Biology, McGovern Medical School, University of Texas Health Science Center, Houston, TX 77030, USA
| | - Joanna Krakowiak
- Department of Biochemistry and Molecular Biology, McGovern Medical School, University of Texas Health Science Center, Houston, TX 77030, USA
| | - Zian Liao
- Department of Biochemistry and Molecular Biology, McGovern Medical School, University of Texas Health Science Center, Houston, TX 77030, USA; Graduate School of Biomedical Sciences, University of Texas MD Anderson Cancer Center and UTHealth, Houston, TX 77030, USA
| | - Phuoc T Nguyen
- Department of Biochemistry and Molecular Biology, McGovern Medical School, University of Texas Health Science Center, Houston, TX 77030, USA; Graduate School of Biomedical Sciences, University of Texas MD Anderson Cancer Center and UTHealth, Houston, TX 77030, USA
| | - Elena V Moroz-Omori
- Department of Biochemistry, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland
| | - Jiaofang Shao
- Department of Biochemistry and Molecular Biology, McGovern Medical School, University of Texas Health Science Center, Houston, TX 77030, USA
| | - Xiaoyu Zhu
- Department of Biochemistry and Molecular Biology, McGovern Medical School, University of Texas Health Science Center, Houston, TX 77030, USA
| | - Michael J Bolt
- Institute of Biosciences and Technology, Texas A&M University Health Science Center, Houston, TX 77030, USA; Gulf Coast Consortia Center for Advanced Microscopy and Image Informatics, Houston, TX 77030, USA
| | - Haoyi Wu
- Department of Biochemistry and Molecular Biology, McGovern Medical School, University of Texas Health Science Center, Houston, TX 77030, USA; Graduate School of Biomedical Sciences, University of Texas MD Anderson Cancer Center and UTHealth, Houston, TX 77030, USA
| | - Pankaj K Singh
- Institute of Biosciences and Technology, Texas A&M University Health Science Center, Houston, TX 77030, USA; Gulf Coast Consortia Center for Advanced Microscopy and Image Informatics, Houston, TX 77030, USA
| | - Mingjun Bi
- Department of Molecular Medicine, Mays Cancer Center, University of Texas Health Science Center at San Antonio, San Antonio, TX 78229, USA
| | - Caleb J Shi
- Department of Biochemistry and Molecular Biology, McGovern Medical School, University of Texas Health Science Center, Houston, TX 77030, USA
| | - Naadir Jamal
- Department of Biochemistry and Molecular Biology, McGovern Medical School, University of Texas Health Science Center, Houston, TX 77030, USA
| | - Guojie Li
- Department of Biochemistry and Molecular Biology, McGovern Medical School, University of Texas Health Science Center, Houston, TX 77030, USA
| | - Ragini Mistry
- Gulf Coast Consortia Center for Advanced Microscopy and Image Informatics, Houston, TX 77030, USA; Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, TX 77030, USA
| | - Sung Yun Jung
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX 77030, USA
| | - Kuang-Lei Tsai
- Department of Biochemistry and Molecular Biology, McGovern Medical School, University of Texas Health Science Center, Houston, TX 77030, USA
| | - Josephine C Ferreon
- Department of Pharmacology and Chemical Biology, Baylor College of Medicine, Houston, TX 77030, USA
| | - Fabio Stossi
- Gulf Coast Consortia Center for Advanced Microscopy and Image Informatics, Houston, TX 77030, USA; Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, TX 77030, USA
| | - Amedeo Caflisch
- Department of Biochemistry, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland
| | - Zhijie Liu
- Department of Molecular Medicine, Mays Cancer Center, University of Texas Health Science Center at San Antonio, San Antonio, TX 78229, USA
| | - Michael A Mancini
- Institute of Biosciences and Technology, Texas A&M University Health Science Center, Houston, TX 77030, USA; Gulf Coast Consortia Center for Advanced Microscopy and Image Informatics, Houston, TX 77030, USA; Department of Pharmacology and Chemical Biology, Baylor College of Medicine, Houston, TX 77030, USA; Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, TX 77030, USA; Dan L. Duncan Comprehensive Cancer Center, Baylor College of Medicine, Houston, TX 77030, USA
| | - Wenbo Li
- Department of Biochemistry and Molecular Biology, McGovern Medical School, University of Texas Health Science Center, Houston, TX 77030, USA; Graduate School of Biomedical Sciences, University of Texas MD Anderson Cancer Center and UTHealth, Houston, TX 77030, USA.
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22
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Enhancer RNA: biogenesis, function, and regulation. Essays Biochem 2021; 64:883-894. [PMID: 33034351 DOI: 10.1042/ebc20200014] [Citation(s) in RCA: 29] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2020] [Revised: 09/02/2020] [Accepted: 09/23/2020] [Indexed: 12/30/2022]
Abstract
Enhancers are noncoding DNA elements that are present upstream or downstream of a gene to control its spatial and temporal expression. Specific histone modifications, such as monomethylation on histone H3 lysine 4 (H3K4me1) and H3K27ac, have been widely used to assign enhancer regions in mammalian genomes. In recent years, emerging evidence suggests that active enhancers are bidirectionally transcribed to produce enhancer RNAs (eRNAs). This finding not only adds a new reliable feature to define enhancers but also raises a fundamental question of how eRNAs function to activate transcription. Although some believe that eRNAs are merely transcriptional byproducts, many studies have demonstrated that eRNAs execute crucial tasks in regulating chromatin conformation and transcription activation. In this review, we summarize the current understanding of eRNAs from their biogenesis, functions, and regulation to their pathological significance. Additionally, we discuss the challenges and possible mechanisms of eRNAs in regulated transcription.
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23
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Compe E, Egly JM. The Long Road to Understanding RNAPII Transcription Initiation and Related Syndromes. Annu Rev Biochem 2021; 90:193-219. [PMID: 34153211 DOI: 10.1146/annurev-biochem-090220-112253] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
In eukaryotes, transcription of protein-coding genes requires the assembly at core promoters of a large preinitiation machinery containing RNA polymerase II (RNAPII) and general transcription factors (GTFs). Transcription is potentiated by regulatory elements called enhancers, which are recognized by specific DNA-binding transcription factors that recruit cofactors and convey, following chromatin remodeling, the activating cues to the preinitiation complex. This review summarizes nearly five decades of work on transcription initiation by describing the sequential recruitment of diverse molecular players including the GTFs, the Mediator complex, and DNA repair factors that support RNAPII to enable RNA synthesis. The elucidation of the transcription initiation mechanism has greatly benefited from the study of altered transcription components associated with human diseases that could be considered transcription syndromes.
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Affiliation(s)
- Emmanuel Compe
- Institut de Génétique et de Biologie Moléculaire et Cellulaire, CNRS, INSERM, Université de Strasbourg, 67404 Illkirch CEDEX, Commune Urbaine de Strasbourg, France; ,
| | - Jean-Marc Egly
- Institut de Génétique et de Biologie Moléculaire et Cellulaire, CNRS, INSERM, Université de Strasbourg, 67404 Illkirch CEDEX, Commune Urbaine de Strasbourg, France; , .,College of Medicine, National Taiwan University, Taipei 10051, Taiwan
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24
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Grosveld F, van Staalduinen J, Stadhouders R. Transcriptional Regulation by (Super)Enhancers: From Discovery to Mechanisms. Annu Rev Genomics Hum Genet 2021; 22:127-146. [PMID: 33951408 DOI: 10.1146/annurev-genom-122220-093818] [Citation(s) in RCA: 39] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Accurate control of gene expression in the right cell at the right moment is of fundamental importance to animal development and homeostasis. At the heart of gene regulation lie the enhancers, a class of gene regulatory elements that ensures precise spatiotemporal activation of gene transcription. Mammalian genomes are littered with enhancers, which are frequently organized in cooperative clusters such as locus control regions and superenhancers. Here, we discuss our current knowledge of enhancer biology, including an overview of the discovery of the various enhancer subsets and the mechanistic models used to explain their gene regulatory function.
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Affiliation(s)
- Frank Grosveld
- Department of Cell Biology, Erasmus MC, 3000 CA Rotterdam, The Netherlands; ,
| | | | - Ralph Stadhouders
- Department of Cell Biology, Erasmus MC, 3000 CA Rotterdam, The Netherlands; , .,Department of Pulmonary Medicine, Erasmus MC, 3000 CA Rotterdam, The Netherlands
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25
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Giudicelli F, Roest Crollius H. On the importance of evolutionary constraint for regulatory sequence identification. Brief Funct Genomics 2021:elab015. [PMID: 33754633 DOI: 10.1093/bfgp/elab015] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2020] [Revised: 01/15/2021] [Accepted: 02/19/2021] [Indexed: 11/13/2022] Open
Abstract
Regulation of gene expression relies on the activity of specialized genomic elements, enhancers or silencers, distributed over sometimes large distance from their target gene promoters. A significant part of vertebrate genomes consists in such regulatory elements, but their identification and that of their target genes remains challenging, due to the lack of clear signature at the nucleotide level. For many years the main hallmark used for identifying functional elements has been their sequence conservation between genomes of distant species, indicative of purifying selection. More recently, genome-wide biochemical assays have opened new avenues for detecting regulatory regions, shifting attention away from evolutionary constraints. Here, we review the respective contributions of comparative genomics and biochemical assays for the definition of regulatory elements and their targets and advocate that both sequence conservation and preserved synteny, taken as signature of functional constraint, remain essential tools in this task.
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26
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Sun D, Sun W, Gao SQ, Wei C, Naderi A, Schilb AL, Scheidt J, Lee S, Kern TS, Palczewski K, Lu ZR. Formulation and efficacy of ECO/pRHO-ABCA4-SV40 nanoparticles for nonviral gene therapy of Stargardt disease in a mouse model. J Control Release 2021; 330:329-340. [PMID: 33358976 PMCID: PMC9066847 DOI: 10.1016/j.jconrel.2020.12.010] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2020] [Revised: 12/07/2020] [Accepted: 12/09/2020] [Indexed: 01/13/2023]
Abstract
It is still a challenge to develop gene replacement therapy for retinal disorders caused by mutations in large genes, such as Stargardt disease (STGD). STGD is caused by mutations in ABCA4 gene. Previously, we have developed an effective non-viral gene therapy using self-assembled nanoparticles of a multifunctional pH-sensitive amino lipid ECO and a therapeutic ABCA4 plasmid containing rhodopsin promoter (pRHO-ABCA4). In this study, we modified the ABCA4 plasmid with simian virus 40 enhancer (SV40, pRHO-ABCA4-SV40) for enhanced gene expression. We also prepared and assessed the formulations of ECO/pDNA nanoparticles using sucrose or sorbitol as a stablilizer to develop consistent and stable formulations. Results demonstrated that ECO formed stable nanoparticles with pRHO-ABCA4-SV40 in the presence of sucrose, but not with sorbitol. The transfection efficiency in vitro increased significantly after introduction of SV40 enhancer for plasmid pCMV-ABCA4-SV40 with a CMV promoter. Sucrose didn't affect the transfection efficiency, while sorbitol resulted in a fluctuation of the in vitro transfection efficiency. Subretinal gene therapy in Abca4-/- mice using ECO/pRHO-ABCA4 and ECO/pRHO-ABCA4-SV40 nanoparticles induced 36% and 29% reduction in A2E accumulation respectively. Therefore, the ECO/pABCA4 based nanoparticles are promising for non-viral gene therapy for Stargardt disease and can be expended for applications in a variety of visual dystrophies with mutated large genes.
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Affiliation(s)
- Da Sun
- Department of Biomedical Engineering, Case Western Reserve University, Cleveland, OH 44106, United States of America
| | - Wenyu Sun
- Department of Biomedical Engineering, Case Western Reserve University, Cleveland, OH 44106, United States of America
| | - Song-Qi Gao
- Department of Biomedical Engineering, Case Western Reserve University, Cleveland, OH 44106, United States of America
| | - Cheng Wei
- Department of Biomedical Engineering, Case Western Reserve University, Cleveland, OH 44106, United States of America
| | - Amirreza Naderi
- Department of Biomedical Engineering, Case Western Reserve University, Cleveland, OH 44106, United States of America
| | - Andrew L Schilb
- Department of Biomedical Engineering, Case Western Reserve University, Cleveland, OH 44106, United States of America
| | - Josef Scheidt
- Department of Biomedical Engineering, Case Western Reserve University, Cleveland, OH 44106, United States of America
| | - Sangjoon Lee
- Department of Biomedical Engineering, Case Western Reserve University, Cleveland, OH 44106, United States of America
| | - Timothy S Kern
- Department of Ophthalmology, Physiology & Biophysics, and Chemistry, University of California, Irvine, Irvine, CA 92697, United States of America; Veterans Administration Medical Center Research Service, Long Beach, CA, 90822, United States of America
| | - Krzysztof Palczewski
- Department of Ophthalmology, Physiology & Biophysics, and Chemistry, University of California, Irvine, Irvine, CA 92697, United States of America
| | - Zheng-Rong Lu
- Department of Biomedical Engineering, Case Western Reserve University, Cleveland, OH 44106, United States of America.
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27
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Agarwal S, Bonefas KM, Garay PM, Brookes E, Murata-Nakamura Y, Porter RS, Macfarlan TS, Ren B, Iwase S. KDM1A maintains genome-wide homeostasis of transcriptional enhancers. Genome Res 2021; 31:186-197. [PMID: 33414108 PMCID: PMC7849409 DOI: 10.1101/gr.234559.118] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2018] [Accepted: 12/07/2020] [Indexed: 12/27/2022]
Abstract
Transcriptional enhancers enable exquisite spatiotemporal control of gene expression in metazoans. Enrichment of monomethylation of histone H3 lysine 4 (H3K4me1) is a major chromatin signature of transcriptional enhancers. Lysine (K)-specific demethylase 1A (KDM1A, also known as LSD1), an H3K4me2/me1 demethylase, inactivates stem-cell enhancers during the differentiation of mouse embryonic stem cells (mESCs). However, its role in undifferentiated mESCs remains obscure. Here, we show that KDM1A actively maintains the optimal enhancer status in both undifferentiated and lineage-committed cells. KDM1A occupies a majority of enhancers in undifferentiated mESCs. KDM1A levels at enhancers exhibit clear positive correlations with its substrate H3K4me2, H3K27ac, and transcription at enhancers. In Kdm1a-deficient mESCs, a large fraction of these enhancers gains additional H3K4 methylation, which is accompanied by increases in H3K27 acetylation and increased expression of both enhancer RNAs (eRNAs) and target genes. In postmitotic neurons, loss of KDM1A leads to premature activation of neuronal activity-dependent enhancers and genes. Taken together, these results suggest that KDM1A is a versatile regulator of enhancers and acts as a rheostat to maintain optimal enhancer activity by counterbalancing H3K4 methylation at enhancers.
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Affiliation(s)
- Saurabh Agarwal
- Ludwig Institute for Cancer Research, Department of Cellular and Molecular Medicine, University of California, San Diego School of Medicine, La Jolla, California 92093-0653, USA
- Department of Human Genetics, University of Michigan, Ann Arbor, Michigan 48109, USA
| | - Katherine M Bonefas
- Neuroscience Graduate Program, The University of Michigan Medical School, Ann Arbor, Michigan 48109, USA
| | - Patricia M Garay
- Neuroscience Graduate Program, The University of Michigan Medical School, Ann Arbor, Michigan 48109, USA
| | - Emily Brookes
- Division of Newborn Medicine, Boston Children's Hospital, and Department of Cell Biology, Harvard Medical School, Boston, Massachusetts 02115, USA
| | - Yumie Murata-Nakamura
- Department of Human Genetics, University of Michigan, Ann Arbor, Michigan 48109, USA
| | - Robert S Porter
- Department of Human Genetics, University of Michigan, Ann Arbor, Michigan 48109, USA
| | - Todd S Macfarlan
- Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland 20892, USA
| | - Bing Ren
- Ludwig Institute for Cancer Research, Department of Cellular and Molecular Medicine, University of California, San Diego School of Medicine, La Jolla, California 92093-0653, USA
| | - Shigeki Iwase
- Department of Human Genetics, University of Michigan, Ann Arbor, Michigan 48109, USA
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28
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Kyrchanova O, Georgiev P. Mechanisms of Enhancer-Promoter Interactions in Higher Eukaryotes. Int J Mol Sci 2021; 22:ijms22020671. [PMID: 33445415 PMCID: PMC7828040 DOI: 10.3390/ijms22020671] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2020] [Revised: 12/28/2020] [Accepted: 01/09/2021] [Indexed: 12/13/2022] Open
Abstract
In higher eukaryotes, enhancers determine the activation of developmental gene transcription in specific cell types and stages of embryogenesis. Enhancers transform the signals produced by various transcription factors within a given cell, activating the transcription of the targeted genes. Often, developmental genes can be associated with dozens of enhancers, some of which are located at large distances from the promoters that they regulate. Currently, the mechanisms underlying specific distance interactions between enhancers and promoters remain poorly understood. This review briefly describes the properties of enhancers and discusses the mechanisms of distance interactions and potential proteins involved in this process.
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29
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Lambert JT, Su-Feher L, Cichewicz K, Warren TL, Zdilar I, Wang Y, Lim KJ, Haigh JL, Morse SJ, Canales CP, Stradleigh TW, Castillo Palacios E, Haghani V, Moss SD, Parolini H, Quintero D, Shrestha D, Vogt D, Byrne LC, Nord AS. Parallel functional testing identifies enhancers active in early postnatal mouse brain. eLife 2021; 10:69479. [PMID: 34605404 PMCID: PMC8577842 DOI: 10.7554/elife.69479] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2021] [Accepted: 10/02/2021] [Indexed: 01/07/2023] Open
Abstract
Enhancers are cis-regulatory elements that play critical regulatory roles in modulating developmental transcription programs and driving cell-type-specific and context-dependent gene expression in the brain. The development of massively parallel reporter assays (MPRAs) has enabled high-throughput functional screening of candidate DNA sequences for enhancer activity. Tissue-specific screening of in vivo enhancer function at scale has the potential to greatly expand our understanding of the role of non-coding sequences in development, evolution, and disease. Here, we adapted a self-transcribing regulatory element MPRA strategy for delivery to early postnatal mouse brain via recombinant adeno-associated virus (rAAV). We identified and validated putative enhancers capable of driving reporter gene expression in mouse forebrain, including regulatory elements within an intronic CACNA1C linkage disequilibrium block associated with risk in neuropsychiatric disorder genetic studies. Paired screening and single enhancer in vivo functional testing, as we show here, represents a powerful approach towards characterizing regulatory activity of enhancers and understanding how enhancer sequences organize gene expression in the brain.
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Affiliation(s)
- Jason T Lambert
- Department of Psychiatry and Behavioral Sciences, University of California, DavisDavisUnited States,Department of Neurobiology, Physiology and Behavior, University of California, DavisDavisUnited States
| | - Linda Su-Feher
- Department of Psychiatry and Behavioral Sciences, University of California, DavisDavisUnited States,Department of Neurobiology, Physiology and Behavior, University of California, DavisDavisUnited States
| | - Karol Cichewicz
- Department of Psychiatry and Behavioral Sciences, University of California, DavisDavisUnited States,Department of Neurobiology, Physiology and Behavior, University of California, DavisDavisUnited States
| | - Tracy L Warren
- Department of Psychiatry and Behavioral Sciences, University of California, DavisDavisUnited States,Department of Neurobiology, Physiology and Behavior, University of California, DavisDavisUnited States
| | - Iva Zdilar
- Department of Psychiatry and Behavioral Sciences, University of California, DavisDavisUnited States,Department of Neurobiology, Physiology and Behavior, University of California, DavisDavisUnited States
| | - Yurong Wang
- Department of Psychiatry and Behavioral Sciences, University of California, DavisDavisUnited States,Department of Neurobiology, Physiology and Behavior, University of California, DavisDavisUnited States
| | - Kenneth J Lim
- Department of Psychiatry and Behavioral Sciences, University of California, DavisDavisUnited States,Department of Neurobiology, Physiology and Behavior, University of California, DavisDavisUnited States
| | - Jessica L Haigh
- Department of Psychiatry and Behavioral Sciences, University of California, DavisDavisUnited States,Department of Neurobiology, Physiology and Behavior, University of California, DavisDavisUnited States
| | - Sarah J Morse
- Department of Psychiatry and Behavioral Sciences, University of California, DavisDavisUnited States,Department of Neurobiology, Physiology and Behavior, University of California, DavisDavisUnited States
| | - Cesar P Canales
- Department of Psychiatry and Behavioral Sciences, University of California, DavisDavisUnited States,Department of Neurobiology, Physiology and Behavior, University of California, DavisDavisUnited States
| | - Tyler W Stradleigh
- Department of Psychiatry and Behavioral Sciences, University of California, DavisDavisUnited States,Department of Neurobiology, Physiology and Behavior, University of California, DavisDavisUnited States
| | - Erika Castillo Palacios
- Department of Psychiatry and Behavioral Sciences, University of California, DavisDavisUnited States,Department of Neurobiology, Physiology and Behavior, University of California, DavisDavisUnited States
| | - Viktoria Haghani
- Department of Psychiatry and Behavioral Sciences, University of California, DavisDavisUnited States,Department of Neurobiology, Physiology and Behavior, University of California, DavisDavisUnited States
| | - Spencer D Moss
- Department of Psychiatry and Behavioral Sciences, University of California, DavisDavisUnited States,Department of Neurobiology, Physiology and Behavior, University of California, DavisDavisUnited States
| | - Hannah Parolini
- Department of Psychiatry and Behavioral Sciences, University of California, DavisDavisUnited States,Department of Neurobiology, Physiology and Behavior, University of California, DavisDavisUnited States
| | - Diana Quintero
- Department of Psychiatry and Behavioral Sciences, University of California, DavisDavisUnited States,Department of Neurobiology, Physiology and Behavior, University of California, DavisDavisUnited States
| | - Diwash Shrestha
- Department of Psychiatry and Behavioral Sciences, University of California, DavisDavisUnited States,Department of Neurobiology, Physiology and Behavior, University of California, DavisDavisUnited States
| | - Daniel Vogt
- Department of Pediatrics and Human Development, Grand Rapids Research Center, Michigan State UniversityGrand RapidsUnited States
| | - Leah C Byrne
- Helen Wills Neuroscience Institute, University of California, BerkeleyBerkeleyUnited States,Departments of Ophthalmology and Neurobiology, University of PittsburghPittsburghUnited States
| | - Alex S Nord
- Department of Psychiatry and Behavioral Sciences, University of California, DavisDavisUnited States,Department of Neurobiology, Physiology and Behavior, University of California, DavisDavisUnited States
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30
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Agrawal P, Blinka S, Pulakanti K, Reimer MH, Stelloh C, Meyer AE, Rao S. Genome editing demonstrates that the -5 kb Nanog enhancer regulates Nanog expression by modulating RNAPII initiation and/or recruitment. J Biol Chem 2020; 296:100189. [PMID: 33334884 PMCID: PMC7948488 DOI: 10.1074/jbc.ra120.015152] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2020] [Revised: 12/07/2020] [Accepted: 12/15/2020] [Indexed: 12/30/2022] Open
Abstract
Transcriptional enhancers have been defined by their ability to operate independent of distance and orientation in plasmid-based reporter assays of gene expression. At present, histone marks are used to identify and define enhancers but do not consider the endogenous role of an enhancer in the context of native chromatin. We employed a combination of genomic editing, single cell analyses, and sequencing approaches to investigate a Nanog-associated cis-regulatory element, which has been reported by others to be either an alternative promoter or a super-enhancer. We first demonstrate both distance and orientation independence in native chromatin, eliminating the issues raised with plasmid-based approaches. We next demonstrate that the dominant super-enhancer modulates Nanog globally and operates by recruiting and/or initiating RNA Polymerase II. Our studies have important implications to how transcriptional enhancers are defined and how they regulate gene expression.
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Affiliation(s)
- Puja Agrawal
- Department of Cell Biology, Neurobiology, and Anatomy, Medical College of Wisconsin, Milwaukee, Wisconsin, USA; Blood Research Institute, Versiti, Milwaukee, Wisconsin, USA
| | - Steven Blinka
- Department of Cell Biology, Neurobiology, and Anatomy, Medical College of Wisconsin, Milwaukee, Wisconsin, USA; Blood Research Institute, Versiti, Milwaukee, Wisconsin, USA
| | | | | | - Cary Stelloh
- Blood Research Institute, Versiti, Milwaukee, Wisconsin, USA
| | - Alison E Meyer
- Blood Research Institute, Versiti, Milwaukee, Wisconsin, USA
| | - Sridhar Rao
- Department of Cell Biology, Neurobiology, and Anatomy, Medical College of Wisconsin, Milwaukee, Wisconsin, USA; Blood Research Institute, Versiti, Milwaukee, Wisconsin, USA; Department of Pediatrics, Medical College of Wisconsin, Milwaukee, Wisconsin, USA.
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31
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Klein JC, Agarwal V, Inoue F, Keith A, Martin B, Kircher M, Ahituv N, Shendure J. A systematic evaluation of the design and context dependencies of massively parallel reporter assays. Nat Methods 2020; 17:1083-1091. [PMID: 33046894 PMCID: PMC7727316 DOI: 10.1038/s41592-020-0965-y] [Citation(s) in RCA: 73] [Impact Index Per Article: 18.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2020] [Accepted: 08/27/2020] [Indexed: 01/02/2023]
Abstract
Massively parallel reporter assays (MPRAs) functionally screen thousands of sequences for regulatory activity in parallel. To date, there are limited studies that systematically compare differences in MPRA design. Here, we screen a library of 2,440 candidate liver enhancers and controls for regulatory activity in HepG2 cells using nine different MPRA designs. We identify subtle but significant differences that correlate with epigenetic and sequence-level features, as well as differences in dynamic range and reproducibility. We also validate that enhancer activity is largely independent of orientation, at least for our library and designs. Finally, we assemble and test the same enhancers as 192-mers, 354-mers and 678-mers and observe sizable differences. This work provides a framework for the experimental design of high-throughput reporter assays, suggesting that the extended sequence context of tested elements and to a lesser degree the precise assay, influence MPRA results.
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Affiliation(s)
- Jason C Klein
- Department of Genome Sciences, University of Washington, Seattle, WA, USA
- Memorial Sloan Kettering Cancer Center, New York, NY, USA
| | - Vikram Agarwal
- Department of Genome Sciences, University of Washington, Seattle, WA, USA
- Calico Life Sciences LLC, South San Francisco, CA, USA
| | - Fumitaka Inoue
- Department of Bioengineering and Therapeutic Sciences, University of California San Francisco, San Francisco, CA, USA
- Institute for Human Genetics, University of California San Francisco, San Francisco, CA, USA
- Institute for the Advanced Study of Human Biology (WPI-ASHBi), Kyoto University, Kyoto, Japan
| | - Aidan Keith
- Department of Genome Sciences, University of Washington, Seattle, WA, USA
| | - Beth Martin
- Department of Genome Sciences, University of Washington, Seattle, WA, USA
| | - Martin Kircher
- Department of Genome Sciences, University of Washington, Seattle, WA, USA
- Berlin Institute of Health (BIH), Berlin, Germany
- Charité - Universitätsmedizin Berlin, Berlin, Germany
| | - Nadav Ahituv
- Department of Bioengineering and Therapeutic Sciences, University of California San Francisco, San Francisco, CA, USA.
- Institute for Human Genetics, University of California San Francisco, San Francisco, CA, USA.
| | - Jay Shendure
- Department of Genome Sciences, University of Washington, Seattle, WA, USA.
- Howard Hughes Medical Institute, Seattle, WA, USA.
- Brotman Baty Institute for Precision Medicine, University of Washington, Seattle, WA, USA.
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32
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Hou TY, Kraus WL. Spirits in the Material World: Enhancer RNAs in Transcriptional Regulation. Trends Biochem Sci 2020; 46:138-153. [PMID: 32888773 DOI: 10.1016/j.tibs.2020.08.007] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2020] [Revised: 08/04/2020] [Accepted: 08/07/2020] [Indexed: 12/15/2022]
Abstract
Responses to developmental and environmental cues depend on precise spatiotemporal control of gene transcription. Enhancers, which comprise DNA elements bound by regulatory proteins, can activate target genes in response to these external signals. Recent studies have shown that enhancers are transcribed to produce enhancer RNAs (eRNAs). Do eRNAs play a functional role in activating gene expression or are they non-functional byproducts of nearby transcription machinery? The unstable nature of eRNAs and over-reliance on knockdown approaches have made elucidating the possible functions of eRNAs challenging. We focus here on studies using cloned eRNAs to study their function as transcripts, revealing roles for eRNAs in enhancer-promoter looping, recruiting transcriptional machinery, and facilitating RNA polymerase pause-release to regulate gene expression.
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Affiliation(s)
- Tim Y Hou
- Laboratory of Signaling and Gene Regulation, Cecil H. and Ida Green Center for Reproductive Biology Sciences, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA; Division of Basic Research, Department of Obstetrics and Gynecology, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - W Lee Kraus
- Laboratory of Signaling and Gene Regulation, Cecil H. and Ida Green Center for Reproductive Biology Sciences, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA; Division of Basic Research, Department of Obstetrics and Gynecology, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA.
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33
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Abstract
Key discoveries in Drosophila have shaped our understanding of cellular "enhancers." With a special focus on the fly, this chapter surveys properties of these adaptable cis-regulatory elements, whose actions are critical for the complex spatial/temporal transcriptional regulation of gene expression in metazoa. The powerful combination of genetics, molecular biology, and genomics available in Drosophila has provided an arena in which the developmental role of enhancers can be explored. Enhancers are characterized by diverse low- or high-throughput assays, which are challenging to interpret, as not all of these methods of identifying enhancers produce concordant results. As a model metazoan, the fly offers important advantages to comprehensive analysis of the central functions that enhancers play in gene expression, and their critical role in mediating the production of phenotypes from genotype and environmental inputs. A major challenge moving forward will be obtaining a quantitative understanding of how these cis-regulatory elements operate in development and disease.
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Affiliation(s)
- Stephen Small
- Department of Biology, Developmental Systems Training Program, New York University, 10003 and
| | - David N Arnosti
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, Michigan 48824
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34
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Osmala M, Lähdesmäki H. Enhancer prediction in the human genome by probabilistic modelling of the chromatin feature patterns. BMC Bioinformatics 2020; 21:317. [PMID: 32689977 PMCID: PMC7370432 DOI: 10.1186/s12859-020-03621-3] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2019] [Accepted: 06/19/2020] [Indexed: 12/11/2022] Open
Abstract
Background The binding sites of transcription factors (TFs) and the localisation of histone modifications in the human genome can be quantified by the chromatin immunoprecipitation assay coupled with next-generation sequencing (ChIP-seq). The resulting chromatin feature data has been successfully adopted for genome-wide enhancer identification by several unsupervised and supervised machine learning methods. However, the current methods predict different numbers and different sets of enhancers for the same cell type and do not utilise the pattern of the ChIP-seq coverage profiles efficiently. Results In this work, we propose a PRobabilistic Enhancer PRedictIoN Tool (PREPRINT) that assumes characteristic coverage patterns of chromatin features at enhancers and employs a statistical model to account for their variability. PREPRINT defines probabilistic distance measures to quantify the similarity of the genomic query regions and the characteristic coverage patterns. The probabilistic scores of the enhancer and non-enhancer samples are utilised to train a kernel-based classifier. The performance of the method is demonstrated on ENCODE data for two cell lines. The predicted enhancers are computationally validated based on the transcriptional regulatory protein binding sites and compared to the predictions obtained by state-of-the-art methods. Conclusion PREPRINT performs favorably to the state-of-the-art methods, especially when requiring the methods to predict a larger set of enhancers. PREPRINT generalises successfully to data from cell type not utilised for training, and often the PREPRINT performs better than the previous methods. The PREPRINT enhancers are less sensitive to the choice of prediction threshold. PREPRINT identifies biologically validated enhancers not predicted by the competing methods. The enhancers predicted by PREPRINT can aid the genome interpretation in functional genomics and clinical studies.
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Affiliation(s)
- Maria Osmala
- Department of Computer Science, Aalto University, Konemiehentie 2, Espoo, 02150, Finland.
| | - Harri Lähdesmäki
- Department of Computer Science, Aalto University, Konemiehentie 2, Espoo, 02150, Finland
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35
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Gasperini M, Tome JM, Shendure J. Towards a comprehensive catalogue of validated and target-linked human enhancers. Nat Rev Genet 2020; 21:292-310. [PMID: 31988385 PMCID: PMC7845138 DOI: 10.1038/s41576-019-0209-0] [Citation(s) in RCA: 148] [Impact Index Per Article: 37.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/13/2019] [Indexed: 12/14/2022]
Abstract
The human gene catalogue is essentially complete, but we lack an equivalently vetted inventory of bona fide human enhancers. Hundreds of thousands of candidate enhancers have been nominated via biochemical annotations; however, only a handful of these have been validated and confidently linked to their target genes. Here we review emerging technologies for discovering, characterizing and validating human enhancers at scale. We furthermore propose a new framework for operationally defining enhancers that accommodates the heterogeneous and complementary results that are emerging from reporter assays, biochemical measurements and CRISPR screens.
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Affiliation(s)
- Molly Gasperini
- Department of Genome Sciences, University of Washington, Seattle, WA, USA
| | - Jacob M Tome
- Department of Genome Sciences, University of Washington, Seattle, WA, USA
| | - Jay Shendure
- Department of Genome Sciences, University of Washington, Seattle, WA, USA.
- Brotman Baty Institute for Precision Medicine, Seattle, WA, USA.
- Allen Discovery Center for Cell Lineage, Seattle, WA, USA.
- Howard Hughes Medical Institute, University of Washington, Seattle, WA, USA.
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36
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Pomella S, Rota R. The CRISP(Y) Future of Pediatric Soft Tissue Sarcomas. Front Chem 2020; 8:178. [PMID: 32232030 PMCID: PMC7083251 DOI: 10.3389/fchem.2020.00178] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2020] [Accepted: 02/26/2020] [Indexed: 12/14/2022] Open
Abstract
The RNA-guided clustered regularly interspaced palindromic repeats (CRISPR)/associated nuclease 9 (Cas9)-based genome editing technology has increasingly become a recognized method for translational research. In oncology, the ease and versatility of CRISPR/Cas9 has made it possible to obtain many results in the identification of new target genes and in unravel mechanisms of resistance to therapy. The majority of the studies have been made on adult tumors so far. In this mini review we present an overview on the major aspects of CRISPR/Cas9 technology with a focus on a group of rare pediatric malignancies, soft tissue sarcomas, on which this approach is having promising results.
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Affiliation(s)
| | - Rossella Rota
- Department of Oncohematology, Bambino Gesù Children's Hospital, IRCCS, Rome, Italy
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37
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Ryan GE, Farley EK. Functional genomic approaches to elucidate the role of enhancers during development. WILEY INTERDISCIPLINARY REVIEWS. SYSTEMS BIOLOGY AND MEDICINE 2020; 12:e1467. [PMID: 31808313 PMCID: PMC7027484 DOI: 10.1002/wsbm.1467] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/07/2019] [Revised: 10/02/2019] [Accepted: 10/11/2019] [Indexed: 12/22/2022]
Abstract
Successful development depends on the precise tissue-specific regulation of genes by enhancers, genetic elements that act as switches to control when and where genes are expressed. Because enhancers are critical for development, and the majority of disease-associated mutations reside within enhancers, it is essential to understand which sequences within enhancers are important for function. Advances in sequencing technology have enabled the rapid generation of genomic data that predict putative active enhancers, but functionally validating these sequences at scale remains a fundamental challenge. Herein, we discuss the power of genome-wide strategies used to identify candidate enhancers, and also highlight limitations and misconceptions that have arisen from these data. We discuss the use of massively parallel reporter assays to test enhancers for function at scale. We also review recent advances in our ability to study gene regulation during development, including CRISPR-based tools to manipulate genomes and single-cell transcriptomics to finely map gene expression. Finally, we look ahead to a synthesis of complementary genomic approaches that will advance our understanding of enhancer function during development. This article is categorized under: Physiology > Mammalian Physiology in Health and Disease Developmental Biology > Developmental Processes in Health and Disease Laboratory Methods and Technologies > Genetic/Genomic Methods.
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Affiliation(s)
- Genevieve E. Ryan
- Department of MedicineUniversity of CaliforniaSan DiegoCalifornia
- Division of Biological Sciences, Department of MedicineUniversity of CaliforniaSan DiegoCalifornia
| | - Emma K. Farley
- Department of MedicineUniversity of CaliforniaSan DiegoCalifornia
- Division of Biological Sciences, Department of MedicineUniversity of CaliforniaSan DiegoCalifornia
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38
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Tan JY, Biasini A, Young RS, Marques AC. Splicing of enhancer-associated lincRNAs contributes to enhancer activity. Life Sci Alliance 2020; 3:3/4/e202000663. [PMID: 32086317 PMCID: PMC7035876 DOI: 10.26508/lsa.202000663] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2020] [Revised: 02/12/2020] [Accepted: 02/13/2020] [Indexed: 12/19/2022] Open
Abstract
Transcription is common at active mammalian enhancers sometimes giving rise to stable enhancer-associated long intergenic noncoding RNAs (elincRNAs). Expression of elincRNA is associated with changes in neighboring gene product abundance and local chromosomal topology, suggesting that transcription at these loci contributes to gene expression regulation in cis Despite the lack of evidence supporting sequence-dependent functions for most elincRNAs, splicing of these transcripts is unexpectedly common. Whether elincRNA splicing is a mere consequence of cognate enhancer activity or if it directly impacts enhancer function remains unresolved. Here, we investigate the association between elincRNA splicing and enhancer activity in mouse embryonic stem cells. We show that multi-exonic elincRNAs are enriched at conserved enhancers, and the efficient processing of elincRNAs is strongly associated with their cognate enhancer activity. This association is supported by their enrichment in enhancer-specific chromatin signatures; elevated binding of co-transcriptional regulators; increased local intra-chromosomal DNA contacts; and strengthened cis-regulation on target gene expression. Our results support the role of efficient RNA processing of enhancer-associated transcripts to cognate enhancer activity.
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Affiliation(s)
- Jennifer Y Tan
- Department of Computational Biology, University of Lausanne, Lausanne, Switzerland
| | - Adriano Biasini
- Department of Computational Biology, University of Lausanne, Lausanne, Switzerland
| | - Robert S Young
- Medical Research Council Human Genetics Unit, Medical Research Council Institute of Genetics & Molecular Medicine, University of Edinburgh, Edinburgh, UK
| | - Ana C Marques
- Department of Computational Biology, University of Lausanne, Lausanne, Switzerland
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39
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Fleming AM, Zhu J, Ding Y, Burrows CJ. Location dependence of the transcriptional response of a potential G-quadruplex in gene promoters under oxidative stress. Nucleic Acids Res 2019; 47:5049-5060. [PMID: 30916339 PMCID: PMC6547423 DOI: 10.1093/nar/gkz207] [Citation(s) in RCA: 37] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2018] [Revised: 02/09/2019] [Accepted: 03/18/2019] [Indexed: 12/25/2022] Open
Abstract
Oxidation of the guanine (G) heterocycle to 8-oxo-7,8-dihydroguanine (OG) in mammalian gene promoters was demonstrated to induce transcription. Potential G-quadruplex forming sequences (PQSs) in promoters have a high density of G nucleotides rendering them highly susceptible to oxidation and possible gene activation. The VEGF PQS with OG or an abasic site were synthesized at key locations in the SV40 or HSV-TK model promoters to determine the location dependency in the gene expression profile in human cells. The PQS location with respect to the transcription start site (TSS) and strand of occupancy (coding versus non-coding strand) are key parameters that determine the magnitude and direction in which gene expression changes with the chemically modified VEGF PQS. The greatest impact observed for OG or F in the PQS context in these promoters was within ∼200 bp of the TSS. Established PQSs found to occur naturally in a similar location relative to the TSS for possible oxidation-induced gene activation include c-MYC, KRAS, c-KIT, HIF-1α, PDGF-A and hTERT. The studies provide experimental constraints that were used to probe bioinformatic data regarding PQSs in the human genome for those that have the possibility to be redox switches for gene regulation.
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Affiliation(s)
- Aaron M Fleming
- 315 South 1400 East, Dept. of Chemistry, University of Utah, Salt Lake City, UT 84112-0850, USA
| | - Judy Zhu
- 315 South 1400 East, Dept. of Chemistry, University of Utah, Salt Lake City, UT 84112-0850, USA
| | - Yun Ding
- 315 South 1400 East, Dept. of Chemistry, University of Utah, Salt Lake City, UT 84112-0850, USA
| | - Cynthia J Burrows
- 315 South 1400 East, Dept. of Chemistry, University of Utah, Salt Lake City, UT 84112-0850, USA
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40
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Nardini L, Holm I, Pain A, Bischoff E, Gohl DM, Zongo S, Guelbeogo WM, Sagnon N, Vernick KD, Riehle MM. Influence of genetic polymorphism on transcriptional enhancer activity in the malaria vector Anopheles coluzzii. Sci Rep 2019; 9:15275. [PMID: 31649293 PMCID: PMC6813320 DOI: 10.1038/s41598-019-51730-8] [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: 05/19/2019] [Accepted: 10/07/2019] [Indexed: 01/17/2023] Open
Abstract
Enhancers are cis-regulatory elements that control most of the developmental and spatial gene expression in eukaryotes. Genetic variation of enhancer sequences is known to influence phenotypes, but the effect of enhancer variation upon enhancer functional activity and downstream phenotypes has barely been examined in any species. In the African malaria vector, Anopheles coluzzii, we identified candidate enhancers in the proximity of genes relevant for immunity, insecticide resistance, and development. The candidate enhancers were functionally validated using luciferase reporter assays, and their activity was found to be essentially independent of their physical orientation, a typical property of enhancers. All of the enhancers segregated genetically polymorphic alleles, which displayed significantly different levels of functional activity. Deletion mutagenesis and functional testing revealed a fine structure of positive and negative regulatory elements that modulate activity of the enhancer core. Enhancer polymorphisms segregate in wild A. coluzzii populations in West Africa. Thus, enhancer variants that modify target gene expression leading to likely phenotypic consequences are frequent in nature. These results demonstrate the existence of naturally polymorphic A. coluzzii enhancers, which may help explain important differences between individuals or populations for malaria transmission efficiency and vector adaptation to the environment.
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Affiliation(s)
- Luisa Nardini
- Unit of Insect Vector Genetics and Genomics, Department of Parasites and Insect Vectors, Institut Pasteur, Paris, France.,CNRS Unit of Evolutionary Genomics, Modeling, and Health (UMR2000), Institut Pasteur, Paris, France
| | - Inge Holm
- Unit of Insect Vector Genetics and Genomics, Department of Parasites and Insect Vectors, Institut Pasteur, Paris, France.,CNRS Unit of Evolutionary Genomics, Modeling, and Health (UMR2000), Institut Pasteur, Paris, France
| | - Adrien Pain
- Unit of Insect Vector Genetics and Genomics, Department of Parasites and Insect Vectors, Institut Pasteur, Paris, France.,CNRS Unit of Evolutionary Genomics, Modeling, and Health (UMR2000), Institut Pasteur, Paris, France.,Institut Pasteur Bioinformatics and Biostatistics Hub (C3BI), CNRS USR 3756, Institut Pasteur, Paris, France
| | - Emmanuel Bischoff
- Unit of Insect Vector Genetics and Genomics, Department of Parasites and Insect Vectors, Institut Pasteur, Paris, France.,CNRS Unit of Evolutionary Genomics, Modeling, and Health (UMR2000), Institut Pasteur, Paris, France
| | - Daryl M Gohl
- University of Minnesota Genomics Center, Minneapolis, MN, USA.,Department of Genetics, Cell Biology, and Development, University of Minnesota, Minneapolis, MN, USA
| | - Soumanaba Zongo
- Centre National de Recherche et de Formation sur le Paludisme (CNRFP), Ouagadougou, Burkina Faso
| | - Wamdaogo M Guelbeogo
- Centre National de Recherche et de Formation sur le Paludisme (CNRFP), Ouagadougou, Burkina Faso
| | - N'Fale Sagnon
- Centre National de Recherche et de Formation sur le Paludisme (CNRFP), Ouagadougou, Burkina Faso
| | - Kenneth D Vernick
- Unit of Insect Vector Genetics and Genomics, Department of Parasites and Insect Vectors, Institut Pasteur, Paris, France. .,CNRS Unit of Evolutionary Genomics, Modeling, and Health (UMR2000), Institut Pasteur, Paris, France.
| | - Michelle M Riehle
- Department of Microbiology and Immunology, Medical College of Wisconsin, Milwaukee, WI, USA.
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41
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Ghavi-Helm Y. Functional Consequences of Chromosomal Rearrangements on Gene Expression: Not So Deleterious After All? J Mol Biol 2019; 432:665-675. [PMID: 31626801 DOI: 10.1016/j.jmb.2019.09.010] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2019] [Revised: 09/04/2019] [Accepted: 09/12/2019] [Indexed: 12/14/2022]
Abstract
Chromosomes are folded and organized into topologically associating domains (TADs) which provide a framework for the interaction of enhancers with the promoter of their target gene(s). Structural rearrangements observed during evolution or in disease contexts suggest that changes in genome organization strongly affect gene expression and can have drastic phenotypic effects. In this review, I will discuss how recent genomic engineering experiments reveal a more contrasted picture, suggesting that TADs are important but not always essential for gene expression regulation.
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Affiliation(s)
- Yad Ghavi-Helm
- Institut de Génomique Fonctionnelle de Lyon, Univ Lyon, CNRS UMR 5242, Ecole Normale Supérieure de Lyon, Université Claude Bernard Lyon 1, 46 Allée D'Italie, F-69364 Lyon, France.
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42
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Determinants of enhancer and promoter activities of regulatory elements. Nat Rev Genet 2019; 21:71-87. [DOI: 10.1038/s41576-019-0173-8] [Citation(s) in RCA: 284] [Impact Index Per Article: 56.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/04/2019] [Indexed: 12/13/2022]
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43
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Lewis MW, Li S, Franco HL. Transcriptional control by enhancers and enhancer RNAs. Transcription 2019; 10:171-186. [PMID: 31791217 PMCID: PMC6948965 DOI: 10.1080/21541264.2019.1695492] [Citation(s) in RCA: 42] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2019] [Revised: 11/14/2019] [Accepted: 11/15/2019] [Indexed: 11/02/2022] Open
Abstract
The regulation of gene expression is a fundamental cellular process and its misregulation is a key component of disease. Enhancers are one of the most salient regulatory elements in the genome and help orchestrate proper spatiotemporal gene expression during development, in homeostasis, and in response to signaling. Notably, molecular aberrations at enhancers, such as translocations and single nucleotide polymorphisms, are emerging as an important source of human variation and susceptibility to disease. Herein we discuss emerging paradigms addressing how genes are regulated by enhancers, common features of active enhancers, and how non-coding enhancer RNAs (eRNAs) can direct gene expression programs that underlie cellular phenotypes. We survey the current evidence, which suggests that eRNAs can bind to transcription factors, mediate enhancer-promoter interactions, influence RNA Pol II elongation, and act as decoys for repressive cofactors. Furthermore, we discuss current methodologies for the identification of eRNAs and novel approaches to elucidate their functions.
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Affiliation(s)
- Michael W. Lewis
- The Lineberger Comprehensive Cancer Center, Department of Genetics, University of North Carolina, Chapel Hill, NC, USA
| | - Shen Li
- The Lineberger Comprehensive Cancer Center, Department of Genetics, University of North Carolina, Chapel Hill, NC, USA
| | - Hector L. Franco
- The Lineberger Comprehensive Cancer Center, Department of Genetics, University of North Carolina, Chapel Hill, NC, USA
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44
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Perenthaler E, Yousefi S, Niggl E, Barakat TS. Beyond the Exome: The Non-coding Genome and Enhancers in Neurodevelopmental Disorders and Malformations of Cortical Development. Front Cell Neurosci 2019; 13:352. [PMID: 31417368 PMCID: PMC6685065 DOI: 10.3389/fncel.2019.00352] [Citation(s) in RCA: 41] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2019] [Accepted: 07/16/2019] [Indexed: 12/22/2022] Open
Abstract
The development of the human cerebral cortex is a complex and dynamic process, in which neural stem cell proliferation, neuronal migration, and post-migratory neuronal organization need to occur in a well-organized fashion. Alterations at any of these crucial stages can result in malformations of cortical development (MCDs), a group of genetically heterogeneous neurodevelopmental disorders that present with developmental delay, intellectual disability and epilepsy. Recent progress in genetic technologies, such as next generation sequencing, most often focusing on all protein-coding exons (e.g., whole exome sequencing), allowed the discovery of more than a 100 genes associated with various types of MCDs. Although this has considerably increased the diagnostic yield, most MCD cases remain unexplained. As Whole Exome Sequencing investigates only a minor part of the human genome (1–2%), it is likely that patients, in which no disease-causing mutation has been identified, could harbor mutations in genomic regions beyond the exome. Even though functional annotation of non-coding regions is still lagging behind that of protein-coding genes, tremendous progress has been made in the field of gene regulation. One group of non-coding regulatory regions are enhancers, which can be distantly located upstream or downstream of genes and which can mediate temporal and tissue-specific transcriptional control via long-distance interactions with promoter regions. Although some examples exist in literature that link alterations of enhancers to genetic disorders, a widespread appreciation of the putative roles of these sequences in MCDs is still lacking. Here, we summarize the current state of knowledge on cis-regulatory regions and discuss novel technologies such as massively-parallel reporter assay systems, CRISPR-Cas9-based screens and computational approaches that help to further elucidate the emerging role of the non-coding genome in disease. Moreover, we discuss existing literature on mutations or copy number alterations of regulatory regions involved in brain development. We foresee that the future implementation of the knowledge obtained through ongoing gene regulation studies will benefit patients and will provide an explanation to part of the missing heritability of MCDs and other genetic disorders.
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Affiliation(s)
- Elena Perenthaler
- Department of Clinical Genetics, Erasmus MC - University Medical Center, Rotterdam, Netherlands
| | - Soheil Yousefi
- Department of Clinical Genetics, Erasmus MC - University Medical Center, Rotterdam, Netherlands
| | - Eva Niggl
- Department of Clinical Genetics, Erasmus MC - University Medical Center, Rotterdam, Netherlands
| | - Tahsin Stefan Barakat
- Department of Clinical Genetics, Erasmus MC - University Medical Center, Rotterdam, Netherlands
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45
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46
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Ho EYK, Cao Q, Gu M, Chan RWL, Wu Q, Gerstein M, Yip KY. Shaping the nebulous enhancer in the era of high-throughput assays and genome editing. Brief Bioinform 2019; 21:836-850. [PMID: 30895290 DOI: 10.1093/bib/bbz030] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2018] [Revised: 02/15/2019] [Accepted: 02/26/2019] [Indexed: 01/22/2023] Open
Abstract
Since the 1st discovery of transcriptional enhancers in 1981, their textbook definition has remained largely unchanged in the past 37 years. With the emergence of high-throughput assays and genome editing, which are switching the paradigm from bottom-up discovery and testing of individual enhancers to top-down profiling of enhancer activities genome-wide, it has become increasingly evidenced that this classical definition has left substantial gray areas in different aspects. Here we survey a representative set of recent research articles and report the definitions of enhancers they have adopted. The results reveal that a wide spectrum of definitions is used usually without the definition stated explicitly, which could lead to difficulties in data interpretation and downstream analyses. Based on these findings, we discuss the practical implications and suggestions for future studies.
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Affiliation(s)
| | - Qin Cao
- Department of Computer Science and Engineering, The Chinese University of Hong Kong, Hong Kong
| | - Mengting Gu
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, Connecticut, USA
| | - Ricky Wai-Lun Chan
- Department of Computer Science and Engineering, The Chinese University of Hong Kong, Hong Kong
| | - Qiong Wu
- Department of Computer Science and Engineering, The Chinese University of Hong Kong, Hong Kong.,School of Biomedical Sciences, The Chinese University of Hong Kong, Hong Kong
| | - Mark Gerstein
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, Connecticut, USA.,Program in Computational Biology and Bioinformatics.,Department of Computer Science, Yale University, New Haven, Connecticut, USA
| | - Kevin Y Yip
- Department of Biomedical Engineering.,Department of Computer Science and Engineering, The Chinese University of Hong Kong, Hong Kong.,Hong Kong Bioinformatics Centre.,CUHK-BGI Innovation Institute of Trans-omics.,Hong Kong Institute of Diabetes and Obesity, The Chinese University of Hong Kong, Hong Kong
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47
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Carullo NVN, Day JJ. Genomic Enhancers in Brain Health and Disease. Genes (Basel) 2019; 10:E43. [PMID: 30646598 PMCID: PMC6357130 DOI: 10.3390/genes10010043] [Citation(s) in RCA: 34] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2018] [Revised: 01/08/2019] [Accepted: 01/08/2019] [Indexed: 01/18/2023] Open
Abstract
Enhancers are non-coding DNA elements that function in cis to regulate transcription from nearby genes. Through direct interactions with gene promoters, enhancers give rise to spatially and temporally precise gene expression profiles in distinct cell or tissue types. In the brain, the accurate regulation of these intricate expression programs across different neuronal classes gives rise to an incredible cellular and functional diversity. Newly developed technologies have recently allowed more accurate enhancer mapping and more sophisticated enhancer manipulation, producing rapid progress in our understanding of enhancer biology. Furthermore, identification of disease-linked genetic variation in enhancer regions has highlighted the potential influence of enhancers in brain health and disease. This review outlines the key role of enhancers as transcriptional regulators, reviews the current understanding of enhancer regulation in neuronal development, function and dysfunction and provides our thoughts on how enhancers can be targeted for technological and therapeutic goals.
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Affiliation(s)
- Nancy V N Carullo
- Department of Neurobiology, University of Alabama at Birmingham, Birmingham, AL 35294, USA.
| | - Jeremy J Day
- Department of Neurobiology, University of Alabama at Birmingham, Birmingham, AL 35294, USA.
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48
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Tarnita RM, Wilkie AR, DeCaprio JA. Contribution of DNA Replication to the FAM111A-Mediated Simian Virus 40 Host Range Phenotype. J Virol 2019; 93:e01330-18. [PMID: 30333173 PMCID: PMC6288344 DOI: 10.1128/jvi.01330-18] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2018] [Accepted: 10/11/2018] [Indexed: 01/12/2023] Open
Abstract
Host range (HR) mutants of simian virus 40 (SV40) containing mutations in the C terminus of large T antigen fail to replicate efficiently or form plaques in restrictive cell types. HR mutant viruses exhibit impairments at several stages of the viral life cycle, including early and late gene and protein expression, DNA replication, and virion assembly, although the underlying mechanism for these defects is unknown. Host protein FAM111A, whose depletion rescues early and late gene expression and plaque formation for SV40 HR viruses, has been shown to play a role in cellular DNA replication. SV40 viral DNA replication occurs in the nucleus of infected cells in viral replication centers where viral proteins and cellular replication factors localize. Here, we examined the role of viral replication center formation and DNA replication in the FAM111A-mediated HR phenotype. We found that SV40 HR virus rarely formed viral replication centers in restrictive cells, a phenotype that could be rescued by FAM111A depletion. Furthermore, while FAM111A localized to nucleoli in uninfected cells in a cell cycle-dependent manner, FAM111A relocalized to viral replication centers after infection with SV40 wild-type or HR viruses. We also found that inhibition of viral DNA replication through aphidicolin treatment or through the use of replication-defective SV40 mutants diminished the effects of FAM111A depletion on viral gene expression. These results indicate that FAM111A restricts SV40 HR viral replication center formation and that viral DNA replication contributes to the FAM111A-mediated effect on early gene expression.IMPORTANCE SV40 has served as a powerful tool for understanding fundamental viral and cellular processes; however, despite extensive study, the SV40 HR mutant phenotype remains poorly understood. Mutations in the C terminus of large T antigen that disrupt binding to the host protein FAM111A render SV40 HR viruses unable to replicate in restrictive cell types. Our work reveals a defect of HR mutant viruses in the formation of viral replication centers that can be rescued by depletion of FAM111A. Furthermore, inhibition of viral DNA replication reduces the effects of FAM111A restriction on viral gene expression. Additionally, FAM111A is a poorly characterized cellular protein whose mutation leads to two severe human syndromes, Kenny-Caffey syndrome and osteocraniostenosis. Our findings regarding the role of FAM111A in restricting viral replication and its localization to nucleoli and viral replication centers provide further insight into FAM111A function that could help reveal the underlying disease-associated mechanisms.
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Affiliation(s)
- Roxana M Tarnita
- Program in Virology, Division of Medical Sciences, Harvard Medical School, Boston, Massachusetts, USA
- Department of Medical Oncology, Dana-Farber Cancer Institute, Boston, Massachusetts, USA
| | - Adrian R Wilkie
- Program in Virology, Division of Medical Sciences, Harvard Medical School, Boston, Massachusetts, USA
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, Massachusetts, USA
| | - James A DeCaprio
- Program in Virology, Division of Medical Sciences, Harvard Medical School, Boston, Massachusetts, USA
- Department of Medical Oncology, Dana-Farber Cancer Institute, Boston, Massachusetts, USA
- Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts, USA
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49
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Agrawal P, Heimbruch KE, Rao S. Genome-Wide Maps of Transcription Regulatory Elements and Transcription Enhancers in Development and Disease. Compr Physiol 2018; 9:439-455. [PMID: 30549021 DOI: 10.1002/cphy.c180028] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Gene expression is regulated by numerous elements including enhancers, insulators, transcription factors, and architectural proteins. Regions of DNA distal to the transcriptional start site, called enhancers, play a central role in the temporal and tissue-specific regulation of gene expression through RNA polymerase II. The identification of enhancers and other cis regulatory elements has largely been possible due to advances in next generation sequencing technologies. Enhancers regulate gene expression through chromatin loops mediated by architectural proteins such as YY1, CTCF, the cohesin complex, and LDB1. Additionally, enhancers can be transcribed to produce noncoding RNAs termed enhancer RNAs that likely participate in transcriptional regulation. The central role of enhancers in regulating gene expression implicates them in both normal physiology but also many disease states. The importance of enhancers is evident by the suggested role of SNPs, duplications, and other alterations of enhancer function in many diseases, ranging from cancer to atherosclerosis to chronic kidney disease. Although much progress has been made in recent years, the field of enhancer biology and our knowledge of the cis regulome remains a work in progress. This review will highlight recent seminal studies which demonstrate the role of enhancers in normal physiology and disease pathogenesis. © 2019 American Physiological Society. Compr Physiol 9:439-455, 2019.
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Affiliation(s)
- Puja Agrawal
- Blood Research Institute, BloodCenter of Wisconsin, a part of Versiti, Milwaukee, Wisconsin, USA.,Department of Cell Biology, Neurobiology, and Anatomy, Medical College of Wisconsin, Milwaukee, Wisconsin, USA
| | - Katelyn E Heimbruch
- Blood Research Institute, BloodCenter of Wisconsin, a part of Versiti, Milwaukee, Wisconsin, USA.,Department of Cell Biology, Neurobiology, and Anatomy, Medical College of Wisconsin, Milwaukee, Wisconsin, USA
| | - Sridhar Rao
- Blood Research Institute, BloodCenter of Wisconsin, a part of Versiti, Milwaukee, Wisconsin, USA.,Department of Cell Biology, Neurobiology, and Anatomy, Medical College of Wisconsin, Milwaukee, Wisconsin, USA.,Department of Pediatrics, Division of Hematology, Oncology, and Bone Marrow Transplantation, Medical College of Wisconsin, Milwaukee, Wisconsin, USA
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50
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Vermunt MW, Zhang D, Blobel GA. The interdependence of gene-regulatory elements and the 3D genome. J Cell Biol 2018; 218:12-26. [PMID: 30442643 PMCID: PMC6314554 DOI: 10.1083/jcb.201809040] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2018] [Revised: 10/29/2018] [Accepted: 10/29/2018] [Indexed: 01/12/2023] Open
Abstract
Vermunt et al. discuss the relationship between gene-regulatory elements and nuclear architectural features in transcription. Imaging studies, high-resolution chromatin conformation maps, and genome-wide occupancy data of architectural proteins have revealed that genome topology is tightly intertwined with gene expression. Cross-talk between gene-regulatory elements is often organized within insulated neighborhoods, and regulatory cues that induce transcriptional changes can reshape chromatin folding patterns and gene positioning within the nucleus. The cause–consequence relationship of genome architecture and gene expression is intricate, and its molecular mechanisms are under intense investigation. Here, we review the interdependency of transcription and genome organization with emphasis on enhancer–promoter contacts in gene regulation.
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Affiliation(s)
- Marit W Vermunt
- Division of Hematology, The Children's Hospital of Philadelphia, Philadelphia, PA
| | - Di Zhang
- Division of Hematology, The Children's Hospital of Philadelphia, Philadelphia, PA.,Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA
| | - Gerd A Blobel
- Division of Hematology, The Children's Hospital of Philadelphia, Philadelphia, PA .,Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA
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