1
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Mindel V, Brodsky S, Yung H, Manadre W, Barkai N. Revisiting the model for coactivator recruitment: Med15 can select its target sites independent of promoter-bound transcription factors. Nucleic Acids Res 2024:gkae718. [PMID: 39187372 DOI: 10.1093/nar/gkae718] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2024] [Revised: 07/08/2024] [Accepted: 08/09/2024] [Indexed: 08/28/2024] Open
Abstract
Activation domains (ADs) within transcription factors (TFs) induce gene expression by recruiting coactivators such as the Mediator complex. Coactivators lack DNA binding domains (DBDs) and are assumed to passively follow their recruiting TFs. This is supported by direct AD-coactivator interactions seen in vitro but has not yet been tested in living cells. To examine that, we targeted two Med15-recruiting ADs to a range of budding yeast promoters through fusion with different DBDs. The DBD-AD fusions localized to hundreds of genomic sites but recruited Med15 and induced transcription in only a subset of bound promoters, characterized by a fuzzy-nucleosome architecture. Direct DBD-Med15 fusions shifted DBD localization towards fuzzy-nucleosome promoters, including promoters devoid of the endogenous Mediator. We propose that Med15, and perhaps other coactivators, possess inherent promoter preference and thus actively contribute to the selection of TF-induced genes.
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Affiliation(s)
- Vladimir Mindel
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Sagie Brodsky
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Hadas Yung
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Wajd Manadre
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Naama Barkai
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 76100, Israel
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2
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Malik S, Roeder RG. Regulation of the RNA polymerase II pre-initiation complex by its associated coactivators. Nat Rev Genet 2023; 24:767-782. [PMID: 37532915 PMCID: PMC11088444 DOI: 10.1038/s41576-023-00630-9] [Citation(s) in RCA: 15] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/15/2023] [Indexed: 08/04/2023]
Abstract
The RNA polymerase II (Pol II) pre-initiation complex (PIC) is a critical node in eukaryotic transcription regulation, and its formation is the major rate-limiting step in transcriptional activation. Diverse cellular signals borne by transcriptional activators converge on this large, multiprotein assembly and are transduced via intermediary factors termed coactivators. Cryogenic electron microscopy, multi-omics and single-molecule approaches have recently offered unprecedented insights into both the structure and cellular functions of the PIC and two key PIC-associated coactivators, Mediator and TFIID. Here, we review advances in our understanding of how Mediator and TFIID interact with activators and affect PIC formation and function. We also discuss how their functions are influenced by their chromatin environment and selected cofactors. We consider how, through its multifarious interactions and functionalities, a Mediator-containing and TFIID-containing PIC can yield an integrated signal processing system with the flexibility to determine the unique temporal and spatial expression pattern of a given gene.
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Affiliation(s)
- Sohail Malik
- Laboratory of Biochemistry & Molecular Biology, The Rockefeller University, New York, NY, USA.
| | - Robert G Roeder
- Laboratory of Biochemistry & Molecular Biology, The Rockefeller University, New York, NY, USA
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3
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Donovan MG, Galbraith MD, Espinosa JM. Multi-omics investigation reveals functional specialization of transcriptional cyclin dependent kinases in cancer biology. Sci Rep 2022; 12:22505. [PMID: 36577800 PMCID: PMC9797569 DOI: 10.1038/s41598-022-26860-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2022] [Accepted: 12/21/2022] [Indexed: 12/30/2022] Open
Abstract
Transcriptional addiction is recognized as a valid therapeutic target in cancer, whereby the dependency of cancer cells on oncogenic transcriptional regulators may be pharmacologically exploited. However, a comprehensive understanding of the key factors within the transcriptional machinery that might afford a useful therapeutic window remains elusive. Herein, we present a cross-omics investigation into the functional specialization of the transcriptional cyclin dependent kinases (tCDKs) through analysis of high-content genetic dependency, gene expression, patient survival, and drug response datasets. This analysis revealed specialization among tCDKs in terms of contributions to cancer cell fitness, clinical prognosis, and interaction with oncogenic signaling pathways. CDK7 and CDK9 stand out as the most relevant targets, albeit through distinct mechanisms of oncogenicity and context-dependent contributions to cancer survival and drug sensitivity. Genetic ablation of CDK9, but not CDK7, mimics the effect on cell viability the loss of key components of the transcriptional machinery. Pathway analysis of genetic co-dependency and drug sensitivity data show CDK7 and CDK9 have distinct relationships with major oncogenic signatures, including MYC and E2F targets, oxidative phosphorylation, and the unfolded protein response. Altogether, these results inform the improved design of therapeutic strategies targeting tCDKs in cancer.
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Affiliation(s)
- Micah G Donovan
- Department of Pharmacology, University of Colorado Anschutz Medical Campus, Aurora, CO, USA
- Linda Crnic Institute for Down Syndrome, University of Colorado Anschutz Medical Campus, Aurora, CO, USA
| | - Matthew D Galbraith
- Department of Pharmacology, University of Colorado Anschutz Medical Campus, Aurora, CO, USA
- Linda Crnic Institute for Down Syndrome, University of Colorado Anschutz Medical Campus, Aurora, CO, USA
| | - Joaquin M Espinosa
- Department of Pharmacology, University of Colorado Anschutz Medical Campus, Aurora, CO, USA.
- Linda Crnic Institute for Down Syndrome, University of Colorado Anschutz Medical Campus, Aurora, CO, USA.
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4
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Warfield L, Donczew R, Mahendrawada L, Hahn S. Yeast Mediator facilitates transcription initiation at most promoters via a Tail-independent mechanism. Mol Cell 2022; 82:4033-4048.e7. [PMID: 36208626 PMCID: PMC9637718 DOI: 10.1016/j.molcel.2022.09.016] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2021] [Revised: 05/12/2022] [Accepted: 09/13/2022] [Indexed: 11/06/2022]
Abstract
Mediator (MED) is a conserved factor with important roles in basal and activated transcription. Here, we investigate the genome-wide roles of yeast MED by rapid depletion of its activator-binding domain (Tail) and monitoring changes in nascent transcription. Rapid Tail depletion surprisingly reduces transcription from only a small subset of genes. At most of these Tail-dependent genes, in unperturbed conditions, MED is detected at both the UASs and promoters. In contrast, at most Tail-independent genes, we find MED primarily at promoters but not at the UASs. These results suggest that MED Tail and activator-mediated MED recruitment regulates only a small subset of genes. Furthermore, we define three classes of genes that differ in PIC assembly pathways and the requirements for MED Tail, SAGA, TFIID, and BET factors Bdf1/2. Our combined results have broad implications for the roles of MED, other coactivators, and mechanisms of transcriptional regulation at different gene classes.
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Affiliation(s)
- Linda Warfield
- Fred Hutchinson Cancer Center, 1100 Fairview Ave N, Mailstop A1-162, Seattle, WA 98109, USA
| | - Rafal Donczew
- Fred Hutchinson Cancer Center, 1100 Fairview Ave N, Mailstop A1-162, Seattle, WA 98109, USA
| | - Lakshmi Mahendrawada
- Fred Hutchinson Cancer Center, 1100 Fairview Ave N, Mailstop A1-162, Seattle, WA 98109, USA
| | - Steven Hahn
- Fred Hutchinson Cancer Center, 1100 Fairview Ave N, Mailstop A1-162, Seattle, WA 98109, USA.
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5
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Richter WF, Nayak S, Iwasa J, Taatjes DJ. The Mediator complex as a master regulator of transcription by RNA polymerase II. Nat Rev Mol Cell Biol 2022; 23:732-749. [PMID: 35725906 PMCID: PMC9207880 DOI: 10.1038/s41580-022-00498-3] [Citation(s) in RCA: 77] [Impact Index Per Article: 38.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/17/2022] [Indexed: 02/08/2023]
Abstract
The Mediator complex, which in humans is 1.4 MDa in size and includes 26 subunits, controls many aspects of RNA polymerase II (Pol II) function. Apart from its size, a defining feature of Mediator is its intrinsic disorder and conformational flexibility, which contributes to its ability to undergo phase separation and to interact with a myriad of regulatory factors. In this Review, we discuss Mediator structure and function, with emphasis on recent cryogenic electron microscopy data of the 4.0-MDa transcription preinitiation complex. We further discuss how Mediator and sequence-specific DNA-binding transcription factors enable enhancer-dependent regulation of Pol II function at distal gene promoters, through the formation of molecular condensates (or transcription hubs) and chromatin loops. Mediator regulation of Pol II reinitiation is also discussed, in the context of transcription bursting. We propose a working model for Mediator function that combines experimental results and theoretical considerations related to enhancer-promoter interactions, which reconciles contradictory data regarding whether enhancer-promoter communication is direct or indirect. We conclude with a discussion of Mediator's potential as a therapeutic target and of future research directions.
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Affiliation(s)
- William F Richter
- Department of Biochemistry, University of Colorado, Boulder, CO, USA
| | - Shraddha Nayak
- Department of Biochemistry, University of Utah, Salt Lake City, UT, USA
| | - Janet Iwasa
- Department of Biochemistry, University of Utah, Salt Lake City, UT, USA
| | - Dylan J Taatjes
- Department of Biochemistry, University of Colorado, Boulder, CO, USA.
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6
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Morse RH. Function and dynamics of the Mediator complex: novel insights and new frontiers. Transcription 2022; 13:39-52. [PMID: 35708525 PMCID: PMC9467533 DOI: 10.1080/21541264.2022.2085502] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022] Open
Abstract
The Mediator complex was discovered in the early 1990s as a biochemically fractionated factor from yeast extracts that was necessary for activator-stimulated transcriptional activation to be observed in in vitro transcription assays. The structure of this large, multi-protein complex is now understood in great detail, and novel genetic approaches have provided rich insights into its dynamics during transcriptional activation and the mechanism by which it facilitates activated transcription. Here I review recent findings and unanswered questions regarding Mediator dynamics, the roles of individual subunits, and differences between its function in yeast and metazoan cells.
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Affiliation(s)
- Randall H Morse
- Wadsworth Center, New York State Department of Health, Albany, NY, United States.,Department of Biomedical Sciences, University at Albany School of Public Health, Albany, NY, United States
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7
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Yang W, Gao K, Qian Y, Huang Y, Xiang Q, Chen C, Chen Q, Wang Y, Fang F, He Q, Chen S, Xiong J, Chen Y, Xie N, Zheng D, Zhai R. A novel tRNA-derived fragment AS-tDR-007333 promotes the malignancy of NSCLC via the HSPB1/MED29 and ELK4/MED29 axes. J Hematol Oncol 2022; 15:53. [PMID: 35526007 PMCID: PMC9077895 DOI: 10.1186/s13045-022-01270-y] [Citation(s) in RCA: 32] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2021] [Accepted: 04/21/2022] [Indexed: 12/25/2022] Open
Abstract
Background Transfer RNA-derived fragments (tRFs) are a new class of small non-coding RNAs. Recent studies suggest that tRFs participate in some pathological processes. However, the biological functions and mechanisms of tRFs in non-small cell lung cancer (NSCLC) are largely unknown.
Methods Differentially expressed tRFs were identified by tRF and tiRNA sequencing using 9 pairs of pre- and post-operation plasma from patients with NSCLC. Quantitative real-time PCR (qRT-PCR) and fluorescence in situ hybridization (FISH) were used to determine the levels of tRF in tissues, plasma, and cells. Gain- and loss-of-function experiments were implemented to investigate the oncogenic effects of tRF on NSCLC cells in vitro and in vivo. Chromatin immunoprecipitation (ChIP), luciferase reporter, RNA pulldown, mass spectrum, RNA immunoprecipitation (RIP), Western blot, co-immunoprecipitation (Co-IP) assays, and rescue experiments were performed to explore the regulatory mechanisms of tRF in NSCLC. Results AS-tDR-007333 was an uncharacterized tRF and significantly up-regulated in NSCLC tissues, plasma, and cells. Clinically, AS-tDR-007333 overexpression could distinguish NSCLC patients from healthy controls and associated with poorer prognosis of NSCLC patients. Functionally, overexpression of AS-tDR-007333 enhanced proliferation and migration of NSCLC cells, whereas knockdown of AS-tDR-007333 resulted in opposite effects. Mechanistically, AS-tDR-007333 promoted the malignancy of NSCLC cells by activating MED29 through two distinct mechanisms. First, AS-tDR-007333 bound to and interacted with HSPB1, which activated MED29 expression by enhancing H3K4me1 and H3K27ac in MED29 promoter. Second, AS-tDR-007333 stimulated the expression of transcription factor ELK4, which bound to MED29 promoter and increased its transcription. Therapeutically, inhibition of AS-tDR-007333 suppressed NSCLC cell growth in vivo. Conclusions Our study identifies a new oncogenic tRF and uncovers a novel mechanism that AS-tDR-007333 promotes NSCLC malignancy through the HSPB1-MED29 and ELK4-MED29 axes. AS-tDR-007333 is a potential diagnostic or prognostic marker and therapeutic target for NSCLC. Supplementary Information The online version contains supplementary material available at 10.1186/s13045-022-01270-y.
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Affiliation(s)
- Wenhan Yang
- School of Public Health, Shenzhen University Health Science Center, 1066 Xueyuan Ave., Shenzhen, 518055, China.,Guangdong Provincial Key Laboratory of Genome Stability and Disease Prevention, International Cancer Center, Shenzhen University Health Science Center, Shenzhen, China
| | - Kaiping Gao
- School of Public Health, Shenzhen University Health Science Center, 1066 Xueyuan Ave., Shenzhen, 518055, China.,Guangdong Provincial Key Laboratory of Genome Stability and Disease Prevention, International Cancer Center, Shenzhen University Health Science Center, Shenzhen, China
| | - Youhui Qian
- Department of Thoracic Surgery, The First Affiliated Hospital of Shenzhen University, 3002 West Shungang Road, Shenzhen, 518035, China
| | - Yongyi Huang
- School of Public Health, Shenzhen University Health Science Center, 1066 Xueyuan Ave., Shenzhen, 518055, China.,Guangdong Provincial Key Laboratory of Genome Stability and Disease Prevention, International Cancer Center, Shenzhen University Health Science Center, Shenzhen, China
| | - Qin Xiang
- Guangdong Provincial Key Laboratory of Genome Stability and Disease Prevention, International Cancer Center, Shenzhen University Health Science Center, Shenzhen, China
| | - Cheng Chen
- Guangdong Provincial Key Laboratory of Genome Stability and Disease Prevention, International Cancer Center, Shenzhen University Health Science Center, Shenzhen, China
| | - Qianqian Chen
- School of Public Health, Shenzhen University Health Science Center, 1066 Xueyuan Ave., Shenzhen, 518055, China.,Guangdong Provincial Key Laboratory of Genome Stability and Disease Prevention, International Cancer Center, Shenzhen University Health Science Center, Shenzhen, China
| | - Yiling Wang
- School of Public Health, Shenzhen University Health Science Center, 1066 Xueyuan Ave., Shenzhen, 518055, China.,Guangdong Provincial Key Laboratory of Genome Stability and Disease Prevention, International Cancer Center, Shenzhen University Health Science Center, Shenzhen, China
| | - Fuyuan Fang
- Department of Thoracic Surgery, The First Affiliated Hospital of Shenzhen University, 3002 West Shungang Road, Shenzhen, 518035, China
| | - Qihan He
- School of Public Health, Shenzhen University Health Science Center, 1066 Xueyuan Ave., Shenzhen, 518055, China.,Guangdong Provincial Key Laboratory of Genome Stability and Disease Prevention, International Cancer Center, Shenzhen University Health Science Center, Shenzhen, China
| | - Siqi Chen
- Department of Thoracic Surgery, The First Affiliated Hospital of Shenzhen University, 3002 West Shungang Road, Shenzhen, 518035, China
| | - Juan Xiong
- School of Public Health, Shenzhen University Health Science Center, 1066 Xueyuan Ave., Shenzhen, 518055, China.,Guangdong Provincial Key Laboratory of Genome Stability and Disease Prevention, International Cancer Center, Shenzhen University Health Science Center, Shenzhen, China
| | - Yangchao Chen
- Faculty of Medicine, The Chinese University of Hong Kong, Rm508A, Lo Kwee-Seong Integrated Biomedical Sciences Bldg, Shatin, NT, Hong Kong, China
| | - Ni Xie
- Department of Thoracic Surgery, The First Affiliated Hospital of Shenzhen University, 3002 West Shungang Road, Shenzhen, 518035, China.
| | - Duo Zheng
- Guangdong Provincial Key Laboratory of Genome Stability and Disease Prevention, International Cancer Center, Shenzhen University Health Science Center, Shenzhen, China.
| | - Rihong Zhai
- School of Public Health, Shenzhen University Health Science Center, 1066 Xueyuan Ave., Shenzhen, 518055, China. .,Guangdong Provincial Key Laboratory of Genome Stability and Disease Prevention, International Cancer Center, Shenzhen University Health Science Center, Shenzhen, China. .,Department of Thoracic Surgery, Shenzhen University General Hospital, 1098 Xueyuan Ave., Shenzhen, 518055, China.
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8
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Galouzis CC, Furlong EEM. Regulating specificity in enhancer-promoter communication. Curr Opin Cell Biol 2022; 75:102065. [PMID: 35240372 DOI: 10.1016/j.ceb.2022.01.010] [Citation(s) in RCA: 20] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2021] [Revised: 01/23/2022] [Accepted: 01/25/2022] [Indexed: 12/14/2022]
Abstract
Enhancers are cis-regulatory elements that can activate transcription remotely to regulate a specific pattern of a gene's expression. Genes typically have many enhancers that are often intermingled in the loci of other genes. To regulate expression, enhancers must therefore activate their correct promoter while ignoring others that may be in closer linear proximity. In this review, we discuss mechanisms by which enhancers engage with promoters, including recent findings on the role of cohesin and the Mediator complex, and how this specificity in enhancer-promoter communication is encoded. Genetic dissection of model loci, in addition to more recent findings using genome-wide approaches, highlight the core promoter sequence, its accessibility, cofactor-promoter preference, in addition to the surrounding genomic context, as key components.
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Affiliation(s)
| | - Eileen E M Furlong
- European Molecular Biology Laboratory (EMBL), Genome Biology Unit, D-69117, Heidelberg, Germany.
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9
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De S, Edwards DM, Dwivedi V, Wang J, Varsally W, Dixon HL, Singh AK, Owuamalam PO, Wright MT, Summers RP, Hossain MN, Price EM, Wojewodzic MW, Falciani F, Hodges NJ, Saponaro M, Tanaka K, Azzalin CM, Baumann P, Hebenstreit D, Brogna S. Genome-wide chromosomal association of Upf1 is linked to Pol II transcription in Schizosaccharomyces pombe. Nucleic Acids Res 2021; 50:350-367. [PMID: 34928380 PMCID: PMC8754637 DOI: 10.1093/nar/gkab1249] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2021] [Revised: 11/30/2021] [Accepted: 12/06/2021] [Indexed: 11/23/2022] Open
Abstract
Although the RNA helicase Upf1 has hitherto been examined mostly in relation to its cytoplasmic role in nonsense mediated mRNA decay (NMD), here we report high-throughput ChIP data indicating genome-wide association of Upf1 with active genes in Schizosaccharomyces pombe. This association is RNase sensitive, correlates with Pol II transcription and mRNA expression levels. Changes in Pol II occupancy were detected in a Upf1 deficient (upf1Δ) strain, prevalently at genes showing a high Upf1 relative to Pol II association in wild-type. Additionally, an increased Ser2 Pol II signal was detected at all highly transcribed genes examined by ChIP-qPCR. Furthermore, upf1Δ cells are hypersensitive to the transcription elongation inhibitor 6-azauracil. A significant proportion of the genes associated with Upf1 in wild-type conditions are also mis-regulated in upf1Δ. These data envisage that by operating on the nascent transcript, Upf1 might influence Pol II phosphorylation and transcription.
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Affiliation(s)
- Sandip De
- School of Biosciences and Birmingham Centre of Genome Biology (BCGB), University of Birmingham, UK.,Division of Cellular and Gene Therapies, Tumor Vaccines and Biotechnology Branch, Center for Biologics and Evaluation Research, US Food and Drug Administration, Silver Spring, MD, USA
| | - David M Edwards
- School of Life Sciences, University of Warwick, Coventry, UK
| | - Vibha Dwivedi
- School of Biosciences and Birmingham Centre of Genome Biology (BCGB), University of Birmingham, UK
| | - Jianming Wang
- School of Biosciences and Birmingham Centre of Genome Biology (BCGB), University of Birmingham, UK
| | - Wazeer Varsally
- School of Biosciences and Birmingham Centre of Genome Biology (BCGB), University of Birmingham, UK
| | - Hannah L Dixon
- School of Biosciences and Birmingham Centre of Genome Biology (BCGB), University of Birmingham, UK
| | - Anand K Singh
- School of Biosciences and Birmingham Centre of Genome Biology (BCGB), University of Birmingham, UK.,Interdisciplinary School of Life Sciences, Banaras Hindu University, Varanasi 221005, India
| | - Precious O Owuamalam
- School of Biosciences and Birmingham Centre of Genome Biology (BCGB), University of Birmingham, UK
| | - Matthew T Wright
- School of Biosciences and Birmingham Centre of Genome Biology (BCGB), University of Birmingham, UK
| | - Reece P Summers
- School of Biosciences and Birmingham Centre of Genome Biology (BCGB), University of Birmingham, UK
| | - Md Nazmul Hossain
- School of Biosciences and Birmingham Centre of Genome Biology (BCGB), University of Birmingham, UK.,Department of Microbial Biotechnology, Faculty of Biotechnology and Genetic Engineering, Sylhet Agricultural University, Sylhet 3100, Bangladesh
| | - Emily M Price
- School of Biosciences and Birmingham Centre of Genome Biology (BCGB), University of Birmingham, UK
| | - Marcin W Wojewodzic
- School of Biosciences and Birmingham Centre of Genome Biology (BCGB), University of Birmingham, UK.,Department of Environmental Health, Norwegian Institute of Public Health, Oslo, Norway & Department of Research, Cancer Registry of Norway, Oslo University Hospital, Oslo, Norway & Environmental Genomics, School of Biosciences, University of Birmingham, Birmingham, UK
| | - Francesco Falciani
- School of Biosciences and Birmingham Centre of Genome Biology (BCGB), University of Birmingham, UK
| | - Nikolas J Hodges
- School of Biosciences and Birmingham Centre of Genome Biology (BCGB), University of Birmingham, UK
| | - Marco Saponaro
- Institute of Cancer and Genomic Sciences, University of Birmingham, UK
| | - Kayoko Tanaka
- Department of Molecular and Cell Biology, University of Leicester, UK
| | - Claus M Azzalin
- Instituto de Medicina Molecular João Lobo Antunes (iMM), Faculdade de Medicina da Universidade de Lisboa, Lisbon, Portugal
| | | | | | - Saverio Brogna
- School of Biosciences and Birmingham Centre of Genome Biology (BCGB), University of Birmingham, UK
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10
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Mediator dynamics during heat shock in budding yeast. Genome Res 2021; 32:111-123. [PMID: 34785526 PMCID: PMC8744673 DOI: 10.1101/gr.275750.121] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2021] [Accepted: 11/13/2021] [Indexed: 11/25/2022]
Abstract
The Mediator complex is central to transcription by RNA polymerase II (Pol II) in eukaryotes. In budding yeast (Saccharomyces cerevisiae), Mediator is recruited by activators and associates with core promoter regions, where it facilitates preinitiation complex (PIC) assembly, only transiently before Pol II escape. Interruption of the transcription cycle by inactivation or depletion of Kin28 inhibits Pol II escape and stabilizes this association. However, Mediator occupancy and dynamics have not been examined on a genome-wide scale in yeast grown in nonstandard conditions. Here we investigate Mediator occupancy following heat shock or CdCl2 exposure, with and without depletion of Kin28. We find that Pol II occupancy shows similar dependence on Mediator under normal and heat shock conditions. However, although Mediator association increases at many genes upon Kin28 depletion under standard growth conditions, little or no increase is observed at most genes upon heat shock, indicating a more stable association of Mediator after heat shock. Unexpectedly, Mediator remains associated upstream of the core promoter at genes repressed by heat shock or CdCl2 exposure whether or not Kin28 is depleted, suggesting that Mediator is recruited by activators but is unable to engage PIC components at these repressed targets. This persistent association is strongest at promoters that bind the HMGB family member Hmo1, and is reduced but not eliminated in hmo1Δ yeast. Finally, we show a reduced dependence on PIC components for Mediator occupancy at promoters after heat shock, further supporting altered dynamics or stronger engagement with activators under these conditions.
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11
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Petrenko N, Struhl K. Comparison of transcriptional initiation by RNA polymerase II across eukaryotic species. eLife 2021; 10:e67964. [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] [MESH Headings] [Grants] [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 SchoolBostonUnited States
| | - Kevin Struhl
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical SchoolBostonUnited States
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12
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Nguyen VQ, Ranjan A, Liu S, Tang X, Ling YH, Wisniewski J, Mizuguchi G, Li KY, Jou V, Zheng Q, Lavis LD, Lionnet T, Wu C. Spatiotemporal coordination of transcription preinitiation complex assembly in live cells. Mol Cell 2021; 81:3560-3575.e6. [PMID: 34375585 PMCID: PMC8420877 DOI: 10.1016/j.molcel.2021.07.022] [Citation(s) in RCA: 56] [Impact Index Per Article: 18.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2021] [Revised: 05/18/2021] [Accepted: 07/16/2021] [Indexed: 12/17/2022]
Abstract
Transcription initiation by RNA polymerase II (RNA Pol II) requires preinitiation complex (PIC) assembly at gene promoters. In the dynamic nucleus, where thousands of promoters are broadly distributed in chromatin, it is unclear how multiple individual components converge on any target to establish the PIC. Here we use live-cell, single-molecule tracking in S. cerevisiae to visualize constrained exploration of the nucleoplasm by PIC components and Mediator's key role in guiding this process. On chromatin, TFIID/TATA-binding protein (TBP), Mediator, and RNA Pol II instruct assembly of a short-lived PIC, which occurs infrequently but efficiently within a few seconds on average. Moreover, PIC exclusion by nucleosome encroachment underscores regulated promoter accessibility by chromatin remodeling. Thus, coordinated nuclear exploration and recruitment to accessible targets underlies dynamic PIC establishment in yeast. Our study provides a global spatiotemporal model for transcription initiation in live cells.
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Affiliation(s)
- Vu Q Nguyen
- Department of Biology, Johns Hopkins University, Baltimore, MD 21218, USA
| | - Anand Ranjan
- Department of Biology, Johns Hopkins University, Baltimore, MD 21218, USA
| | - Sheng Liu
- Department of Biology, Johns Hopkins University, Baltimore, MD 21218, USA
| | - Xiaona Tang
- Department of Biology, Johns Hopkins University, Baltimore, MD 21218, USA
| | - Yick Hin Ling
- Department of Biology, Johns Hopkins University, Baltimore, MD 21218, USA
| | - Jan Wisniewski
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA 20147, USA; Experimental Immunology Branch, National Cancer Institute, Bethesda, MD 20892, USA
| | - Gaku Mizuguchi
- Department of Biology, Johns Hopkins University, Baltimore, MD 21218, USA
| | - Kai Yu Li
- Department of Biology, Johns Hopkins University, Baltimore, MD 21218, USA
| | - Vivian Jou
- Department of Biology, Johns Hopkins University, Baltimore, MD 21218, USA
| | - Qinsi Zheng
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA 20147, USA
| | - Luke D Lavis
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA 20147, USA
| | - Timothée Lionnet
- Institute of Systems Genetics, Langone Medical Center, New York University, New York, NY 10016, USA
| | - Carl Wu
- Department of Biology, Johns Hopkins University, Baltimore, MD 21218, USA; Department of Molecular Biology and Genetics, Johns Hopkins School of Medicine, Baltimore, MD 21287, USA.
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13
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Connection of core and tail Mediator modules restrains transcription from TFIID-dependent promoters. PLoS Genet 2021; 17:e1009529. [PMID: 34383744 PMCID: PMC8384189 DOI: 10.1371/journal.pgen.1009529] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2021] [Revised: 08/24/2021] [Accepted: 07/30/2021] [Indexed: 11/19/2022] Open
Abstract
The Mediator coactivator complex is divided into four modules: head, middle, tail, and kinase. Deletion of the architectural subunit Med16 separates core Mediator (cMed), comprising the head, middle, and scaffold (Med14), from the tail. However, the direct global effects of tail/cMed disconnection are unclear. We find that rapid depletion of Med16 downregulates genes that require the SAGA complex for full expression, consistent with their reported tail dependence, but also moderately overactivates TFIID-dependent genes in a manner partly dependent on the separated tail, which remains associated with upstream activating sequences. Suppression of TBP dynamics via removal of the Mot1 ATPase partially restores normal transcriptional activity to Med16-depleted cells, suggesting that cMed/tail separation results in an imbalance in the levels of PIC formation at SAGA-requiring and TFIID-dependent genes. We propose that the preferential regulation of SAGA-requiring genes by tailed Mediator helps maintain a proper balance of transcription between these genes and those more dependent on TFIID. Composed of over two dozen subunits, the Mediator complex plays several roles in RNA polymerase II (RNAPII) transcription in eukaryotes. In yeast, deletion of Med16, which splits Mediator into two stable subcomplexes, both increases and decreases transcript levels, suggesting that Med16 might play a repressive role. However, the direct effects of Med16 removal on RNAPII transcription have not been assessed, owing to the use of deletion mutants and measurement of steady-state RNA levels in prior studies. Here, using a combination of inducible protein depletion and analysis of nascent RNA, we find that Med16 removal 1) downregulates a small group of genes reported to be highly dependent on the SAGA complex and 2) upregulates a larger set of genes reported to be more dependent on the TFIID complex in a manner dependent on another component of Mediator. We find that artificially altering the balance of transcription pre-initiation complex (PIC) formation toward SAGA-requiring promoters and away from TFIID-dependent promoters partially restores normal transcription, indicating a contribution of altered PIC formation to the transcriptional alterations observed with Med16 loss. Taken together, our results indicate that the structural integrity of Mediator is important for maintaining balanced transcription between different gene classes.
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14
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Donczew R, Hahn S. BET family members Bdf1/2 modulate global transcription initiation and elongation in Saccharomyces cerevisiae. eLife 2021; 10:e69619. [PMID: 34137374 PMCID: PMC8266393 DOI: 10.7554/elife.69619] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2021] [Accepted: 06/16/2021] [Indexed: 01/10/2023] Open
Abstract
Human bromodomain and extra-terminal domain (BET) family members are promising targets for therapy of cancer and immunoinflammatory diseases, but their mechanisms of action and functional redundancies are poorly understood. Bdf1/2, yeast homologues of the human BET factors, were previously proposed to target transcription factor TFIID to acetylated histone H4, analogous to bromodomains that are present within the largest subunit of metazoan TFIID. We investigated the genome-wide roles of Bdf1/2 and found that their important contributions to transcription extend beyond TFIID function as transcription of many genes is more sensitive to Bdf1/2 than to TFIID depletion. Bdf1/2 co-occupy the majority of yeast promoters and affect preinitiation complex formation through recruitment of TFIID, Mediator, and basal transcription factors to chromatin. Surprisingly, we discovered that hypersensitivity of genes to Bdf1/2 depletion results from combined defects in transcription initiation and early elongation, a striking functional similarity to human BET proteins, most notably Brd4. Our results establish Bdf1/2 as critical for yeast transcription and provide important mechanistic insights into the function of BET proteins in all eukaryotes.
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Affiliation(s)
- Rafal Donczew
- Fred Hutchinson Cancer Research Center, Division of Basic SciencesSeattleUnited States
| | - Steven Hahn
- Fred Hutchinson Cancer Research Center, Division of Basic SciencesSeattleUnited States
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15
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Sanborn AL, Yeh BT, Feigerle JT, Hao CV, Townshend RJ, Lieberman Aiden E, Dror RO, Kornberg RD. Simple biochemical features underlie transcriptional activation domain diversity and dynamic, fuzzy binding to Mediator. eLife 2021; 10:68068. [PMID: 33904398 PMCID: PMC8137143 DOI: 10.7554/elife.68068] [Citation(s) in RCA: 66] [Impact Index Per Article: 22.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2021] [Accepted: 04/25/2021] [Indexed: 01/07/2023] Open
Abstract
Gene activator proteins comprise distinct DNA-binding and transcriptional activation domains (ADs). Because few ADs have been described, we tested domains tiling all yeast transcription factors for activation in vivo and identified 150 ADs. By mRNA display, we showed that 73% of ADs bound the Med15 subunit of Mediator, and that binding strength was correlated with activation. AD-Mediator interaction in vitro was unaffected by a large excess of free activator protein, pointing to a dynamic mechanism of interaction. Structural modeling showed that ADs interact with Med15 without shape complementarity (‘fuzzy’ binding). ADs shared no sequence motifs, but mutagenesis revealed biochemical and structural constraints. Finally, a neural network trained on AD sequences accurately predicted ADs in human proteins and in other yeast proteins, including chromosomal proteins and chromatin remodeling complexes. These findings solve the longstanding enigma of AD structure and function and provide a rationale for their role in biology. Cells adapt and respond to changes by regulating the activity of their genes. To turn genes on or off, they use a family of proteins called transcription factors. Transcription factors influence specific but overlapping groups of genes, so that each gene is controlled by several transcription factors that act together like a dimmer switch to regulate gene activity. The presence of transcription factors attracts proteins such as the Mediator complex, which activates genes by gathering the protein machines that read the genes. The more transcription factors are found near a specific gene, the more strongly they attract Mediator and the more active the gene is. A specific region on the transcription factor called the activation domain is necessary for this process. The biochemical sequences of these domains vary greatly between species, yet activation domains from, for example, yeast and human proteins are often interchangeable. To understand why this is the case, Sanborn et al. analyzed the genome of baker’s yeast and identified 150 activation domains, each very different in sequence. Three-quarters of them bound to a subunit of the Mediator complex called Med15. Sanborn et al. then developed a machine learning algorithm to predict activation domains in both yeast and humans. This algorithm also showed that negatively charged and greasy regions on the activation domains were essential to be activated by the Mediator complex. Further analyses revealed that activation domains used different poses to bind multiple sites on Med15, a behavior known as ‘fuzzy’ binding. This creates a high overall affinity even though the binding strength at each individual site is low, enabling the protein complexes to remain dynamic. These weak interactions together permit fine control over the activity of several genes, allowing cells to respond quickly and precisely to many changes. The computer algorithm used here provides a new way to identify activation domains across species and could improve our understanding of how living things grow, adapt and evolve. It could also give new insights into mechanisms of disease, particularly cancer, where transcription factors are often faulty.
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Affiliation(s)
- Adrian L Sanborn
- Department of Structural Biology, Stanford University School of Medicine, Stanford, United States.,Department of Computer Science, Stanford University, Stanford, United States
| | - Benjamin T Yeh
- Department of Computer Science, Stanford University, Stanford, United States
| | - Jordan T Feigerle
- Department of Structural Biology, Stanford University School of Medicine, Stanford, United States
| | - Cynthia V Hao
- Department of Structural Biology, Stanford University School of Medicine, Stanford, United States
| | | | - Erez Lieberman Aiden
- The Center for Genome Architecture, Baylor College of Medicine, Houston, United States.,Center for Theoretical Biological Physics, Rice University, Houston, United States
| | - Ron O Dror
- Department of Computer Science, Stanford University, Stanford, United States
| | - Roger D Kornberg
- Department of Structural Biology, Stanford University School of Medicine, Stanford, United States
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16
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Jaeger MG, Winter GE. Fast-acting chemical tools to delineate causality in transcriptional control. Mol Cell 2021; 81:1617-1630. [PMID: 33689749 DOI: 10.1016/j.molcel.2021.02.015] [Citation(s) in RCA: 41] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2020] [Revised: 01/20/2021] [Accepted: 02/11/2021] [Indexed: 12/11/2022]
Abstract
Multi-dimensional omics profiling continues to illuminate the complexity of cellular processes. Because of difficult mechanistic interpretation of phenotypes induced by slow perturbation, fast experimental setups are increasingly used to dissect causal interactions directly in cells. Here we review a growing body of studies that leverage rapid pharmacological perturbation to delineate causality in gene control. When coupled with kinetically matched readouts, fast chemical genetic tools allow recording of primary phenotypes before confounding secondary effects manifest. The toolbox encompasses directly acting probes, such as active-site inhibitors and proteolysis-targeting chimeras, as well as strategies using genetic engineering to render target proteins chemically tractable, such as analog-sensitive and degron systems. We anticipate that extrapolation of these concepts to single-cell setups will further transform our mechanistic understanding of transcriptional control in the future. Importantly, the concept of leveraging speed to derive causality should be broadly applicable to many aspects of biological regulation.
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Affiliation(s)
- Martin G Jaeger
- CeMM Research Center for Molecular Medicine of the Austrian Academy of Sciences, Vienna, Austria
| | - Georg E Winter
- CeMM Research Center for Molecular Medicine of the Austrian Academy of Sciences, Vienna, Austria.
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17
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Tourigny JP, Schumacher K, Saleh MM, Devys D, Zentner GE. Architectural Mediator subunits are differentially essential for global transcription in Saccharomyces cerevisiae. Genetics 2021; 217:iyaa042. [PMID: 33789343 PMCID: PMC8045717 DOI: 10.1093/genetics/iyaa042] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2020] [Accepted: 12/16/2020] [Indexed: 12/18/2022] Open
Abstract
Mediator is a modular coactivator complex involved in the transcription of the majority of RNA polymerase II-regulated genes. However, the degrees to which individual core subunits of Mediator contribute to its activity have been unclear. Here, we investigate the contribution of two essential architectural subunits of Mediator to transcription in Saccharomyces cerevisiae. We show that acute depletion of the main complex scaffold Med14 or the head module nucleator Med17 is lethal and results in global transcriptional downregulation, though Med17 removal has a markedly greater negative effect. Consistent with this, Med17 depletion impairs preinitiation complex (PIC) assembly to a greater extent than Med14 removal. Co-depletion of Med14 and Med17 reduced transcription and TFIIB promoter occupancy similarly to Med17 ablation alone, indicating that the contributions of Med14 and Med17 to Mediator function are not additive. We propose that, while the structural integrity of complete Mediator and the head module are both important for PIC assembly and transcription, the head module plays a greater role in this process and is thus the key functional module of Mediator in this regard.
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Affiliation(s)
- Jason P Tourigny
- Department of Biology, Indiana University, Bloomington, IN 47405, USA
| | - Kenny Schumacher
- Institut de Génétique et de Biologie Moléculaire et Cellulaire, 67404 Illkirch, France
- UMR7104, Centre National de la Recherche Scientifique, 67404 Illkirch, France
- U964, Institut National de la Santé et de la Recherche Médicale, 67404 Illkirch, France
- Université de Strasbourg, 67404 Illkirch, France
| | - Moustafa M Saleh
- Department of Biology, Indiana University, Bloomington, IN 47405, USA
| | - Didier Devys
- Institut de Génétique et de Biologie Moléculaire et Cellulaire, 67404 Illkirch, France
- UMR7104, Centre National de la Recherche Scientifique, 67404 Illkirch, France
- U964, Institut National de la Santé et de la Recherche Médicale, 67404 Illkirch, France
- Université de Strasbourg, 67404 Illkirch, France
| | - Gabriel E Zentner
- Department of Biology, Indiana University, Bloomington, IN 47405, USA
- Indiana University Melvin and Bren Simon Cancer Center, Indianapolis, IN 46202, USA
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18
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He C, Zhang HY, Zhang YX, Fu P, You LL, Xiao WB, Wang ZH, Song HY, Huang YJ, Liao JL. Cytosine methylations in the promoter regions of genes involved in the cellular oxidation equilibrium pathways affect rice heat tolerance. BMC Genomics 2020; 21:560. [PMID: 32799794 PMCID: PMC7430847 DOI: 10.1186/s12864-020-06975-3] [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: 01/04/2020] [Accepted: 08/06/2020] [Indexed: 11/15/2022] Open
Abstract
Background High temperatures, particularly at night, decrease rice yield and quality. As high nighttime temperatures (HNTs) become increasingly frequent due to climate change, it is imperative to develop rice crops that tolerate HNTs. DNA methylation may represent a potential avenue for HNT-tolerant rice strain development, as this mechanism regulates gene activity and cellular phenotype in response to adverse environmental conditions without changing the nucleotide sequence. Results After HNT exposure, the methylation patterns of cytosines in the CHH context differed noticeably between two coisogenic rice strains with significantly different levels in heat tolerance. Methylation differences between strains were primarily observed on successive cytosines in the promoter or downstream regions of transcription factors and transposon elements. In contrast to the heat-sensitive rice strain, the regions 358–359 bp and 2–60 bp downstream of two basal transcriptional factors (TFIID subunit 11 and mediator of RNA polymerase II transcription subunit 31, respectively) were fully demethylated in the heat-tolerant strain after HNT exposure. In the heat-tolerant strain, HNTs reversed the methylation patterns of successive cytosines in the promoter regions of various genes involved in abscisic acid (ABA)-related reactive oxygen species (ROS) equilibrium pathways, including the pentatricopeptide repeat domain gene PPR (LOC_Os07g28900) and the homeobox domain gene homeobox (LOC_Os01g19694). Indeed, PRR expression was inhibited in heat-sensitive rice strains, and the methylation rates of the cytosines in the promoter region of PRR were greater in heat-sensitive strains as compared to heat-tolerant strains. Conclusions After HNT exposure, cytosines in the CHH context were more likely than cytosines in other contexts to be methylated differently between the heat-sensitive and heat-tolerant rice strains. Methylation in the promoter regions of the genes associated with ABA-related oxidation and ROS scavenging improved heat tolerance in rice. Our results help to clarify the molecular mechanisms underlying rice heat tolerance.
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Affiliation(s)
- Chao He
- Key Laboratory of Crop Physiology, Ecology and Genetic Breeding (Jiangxi Agricultural University), Ministry of Education of China, Nanchang, 330045, China
| | - Hong-Yu Zhang
- Key Laboratory of Crop Physiology, Ecology and Genetic Breeding (Jiangxi Agricultural University), Ministry of Education of China, Nanchang, 330045, China
| | - Yong-Xin Zhang
- South Zhejiang Key Laboratory of Crop Breeding, Institute of Crop Research, Wenzhou Academy of Agricultural Sciences, Wenzhou, 325006, China
| | - Pei Fu
- Key Laboratory of Crop Physiology, Ecology and Genetic Breeding (Jiangxi Agricultural University), Ministry of Education of China, Nanchang, 330045, China
| | - Li-Li You
- Key Laboratory of Crop Physiology, Ecology and Genetic Breeding (Jiangxi Agricultural University), Ministry of Education of China, Nanchang, 330045, China
| | - Wen-Bo Xiao
- Key Laboratory of Crop Physiology, Ecology and Genetic Breeding (Jiangxi Agricultural University), Ministry of Education of China, Nanchang, 330045, China
| | - Zhao-Hai Wang
- Key Laboratory of Crop Physiology, Ecology and Genetic Breeding (Jiangxi Agricultural University), Ministry of Education of China, Nanchang, 330045, China
| | - Hai-Yan Song
- Key Laboratory of Crop Physiology, Ecology and Genetic Breeding (Jiangxi Agricultural University), Ministry of Education of China, Nanchang, 330045, China
| | - Ying-Jin Huang
- Key Laboratory of Crop Physiology, Ecology and Genetic Breeding (Jiangxi Agricultural University), Ministry of Education of China, Nanchang, 330045, China. .,Southern Regional Collaborative Innovation Center for Grain and Oil Crops in China, Changsha, 410128, China.
| | - Jiang-Lin Liao
- Key Laboratory of Crop Physiology, Ecology and Genetic Breeding (Jiangxi Agricultural University), Ministry of Education of China, Nanchang, 330045, China. .,Southern Regional Collaborative Innovation Center for Grain and Oil Crops in China, Changsha, 410128, China.
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19
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Knoll ER, Zhu ZI, Sarkar D, Landsman D, Morse RH. Kin28 depletion increases association of TFIID subunits Taf1 and Taf4 with promoters in Saccharomyces cerevisiae. Nucleic Acids Res 2020; 48:4244-4255. [PMID: 32182349 DOI: 10.1093/nar/gkaa165] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2019] [Revised: 02/07/2020] [Accepted: 03/04/2020] [Indexed: 01/31/2023] Open
Abstract
Transcription of eukaryotic mRNA-encoding genes by RNA polymerase II (Pol II) begins with assembly of the pre-initiation complex (PIC), comprising Pol II and the general transcription factors. Although the pathway of PIC assembly is well established, the mechanism of assembly and the dynamics of PIC components are not fully understood. For example, only recently has it been shown that in yeast, the Mediator complex normally occupies promoters only transiently, but shows increased association when Pol II promoter escape is inhibited. Here we show that two subunits of TFIID, Taf1 and Taf4, similarly show increased occupancy as measured by ChIP upon depletion or inactivation of Kin28. In contrast, TBP occupancy is unaffected by depletion of Kin28, thus revealing an uncoupling of Taf and TBP occupancy during the transcription cycle. Increased Taf1 occupancy upon Kin28 depletion is suppressed by depletion of TBP, while depletion of TBP in the presence of Kin28 has little effect on Taf1 occupancy. The increase in Taf occupancy upon depletion of Kin28 is more pronounced at TFIID-dominated promoters compared to SAGA-dominated promoters. Our results support the suggestion, based on recent structural studies, that TFIID may not remain bound to gene promoters through the transcription initiation cycle.
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Affiliation(s)
- Elisabeth R Knoll
- Department of Biomedical Sciences, University at Albany School of Public Health, Albany, NY 12201-0509, USA
| | - Z Iris Zhu
- Computational Biology Branch, National Center for Biotechnology Information, National Library of Medicine, NIH, Bethesda, MD 20814, USA
| | - Debasish Sarkar
- Wadsworth Center, New York State Department of Health, Albany, NY 12201-0509, USA
| | - David Landsman
- Computational Biology Branch, National Center for Biotechnology Information, National Library of Medicine, NIH, Bethesda, MD 20814, USA
| | - Randall H Morse
- Department of Biomedical Sciences, University at Albany School of Public Health, Albany, NY 12201-0509, USA.,Wadsworth Center, New York State Department of Health, Albany, NY 12201-0509, USA
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20
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Yarrington RM, Yu Y, Yan C, Bai L, Stillman DJ. A Role for Mediator Core in Limiting Coactivator Recruitment in Saccharomyces cerevisiae. Genetics 2020; 215:407-420. [PMID: 32327563 PMCID: PMC7268993 DOI: 10.1534/genetics.120.303254] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2019] [Accepted: 04/21/2020] [Indexed: 01/12/2023] Open
Abstract
Mediator is an essential, multisubunit complex that functions as a transcriptional coactivator in yeast and other eukaryotic organisms. Mediator has four conserved modules, Head, Middle, Tail, and Kinase, and has been implicated in nearly all aspects of gene regulation. The Tail module has been shown to recruit the Mediator complex to the enhancer or upstream activating sequence (UAS) regions of genes via interactions with transcription factors, and the Kinase module facilitates the transition of Mediator from the UAS/enhancer to the preinitiation complex via protein phosphorylation. Here, we analyze expression of the Saccharomyces cerevisiaeHO gene using a sin4 Mediator Tail mutation that separates the Tail module from the rest of the complex; the sin4 mutation permits independent recruitment of the Tail module to promoters without the rest of Mediator. Significant increases in recruitment of the SWI/SNF and SAGA coactivators to the HO promoter UAS were observed in a sin4 mutant, along with increased gene activation. These results are consistent with recent studies that have suggested that the Kinase module functions negatively to inhibit activation by the Tail. However, we found that Kinase module mutations did not mimic the effect of a sin4 mutation on HO expression. This suggests that at HO the core Mediator complex (Middle and Head modules) must play a role in limiting Tail binding to the promoter UAS and gene activation. We propose that the core Mediator complex helps modulate Mediator binding to the UAS regions of genes to limit coactivator recruitment and ensure proper regulation of gene transcription.
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Affiliation(s)
- Robert M Yarrington
- Department of Pathology, University of Utah Health Sciences Center, Salt Lake City, Utah 84112
| | - Yaxin Yu
- Department of Pathology, University of Utah Health Sciences Center, Salt Lake City, Utah 84112
| | - Chao Yan
- Center for Eukaryotic Gene Regulation, The Pennsylvania State University, University Park, Pennsylvania 16802
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, Pennsylvania 16802
- Department of Physics, The Pennsylvania State University, University Park, Pennsylvania 16802
| | - Lu Bai
- Center for Eukaryotic Gene Regulation, The Pennsylvania State University, University Park, Pennsylvania 16802
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, Pennsylvania 16802
- Department of Physics, The Pennsylvania State University, University Park, Pennsylvania 16802
| | - David J Stillman
- Department of Pathology, University of Utah Health Sciences Center, Salt Lake City, Utah 84112
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21
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Nath VS, Shrestha A, Awasthi P, Mishra AK, Kocábek T, Matoušek J, Sečnik A, Jakše J, Radišek S, Hallan V. Mapping the Gene Expression Spectrum of Mediator Subunits in Response to Viroid Infection in Plants. Int J Mol Sci 2020; 21:E2498. [PMID: 32260277 PMCID: PMC7177877 DOI: 10.3390/ijms21072498] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2020] [Revised: 03/31/2020] [Accepted: 04/01/2020] [Indexed: 12/25/2022] Open
Abstract
The mediator (MED) represents a large, conserved, multi-subunit protein complex that regulates gene expression through interactions with RNA polymerase II and enhancer-bound transcription factors. Expanding research accomplishments suggest the predominant role of plant MED subunits in the regulation of various physiological and developmental processes, including the biotic stress response against bacterial and fungal pathogens. However, the involvement of MED subunits in virus/viroid pathogenesis remains elusive. In this study, we investigated for the first time the gene expression modulation of selected MED subunits in response to five viroid species (Apple fruit crinkle viroid (AFCVd), Citrus bark cracking viroid (CBCVd), Hop latent viroid (HLVd), Hop stunt viroid (HSVd), and Potato spindle tuber viroid (PSTVd)) in two model plant species (Nicotiana tabacum and N. benthamiana) and a commercially important hop (Humulus lupulus) cultivar. Our results showed a differential expression pattern of MED subunits in response to a viroid infection. The individual plant MED subunits displayed a differential and tailored expression pattern in response to different viroid species, suggesting that the MED expression is viroid- and plant species-dependent. The explicit evidence obtained from our results warrants further investigation into the association of the MED subunit with symptom development. Together, we provide a comprehensive portrait of MED subunit expression in response to viroid infection and a plausible involvement of MED subunits in fine-tuning transcriptional reprogramming in response to viroid infection, suggesting them as a potential candidate for rewiring the defense response network in plants against pathogens.
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Affiliation(s)
- Vishnu Sukumari Nath
- Department of Molecular Genetics, Biology Centre of the Czech Academy of Sciences, Institute of Plant Molecular Biology, Branišovská 31, 370 05 Ceske Budejovice, Czech Republic; (V.S.N.); (A.S.); (P.A.); (T.K.); (J.M.)
| | - Ankita Shrestha
- Department of Molecular Genetics, Biology Centre of the Czech Academy of Sciences, Institute of Plant Molecular Biology, Branišovská 31, 370 05 Ceske Budejovice, Czech Republic; (V.S.N.); (A.S.); (P.A.); (T.K.); (J.M.)
| | - Praveen Awasthi
- Department of Molecular Genetics, Biology Centre of the Czech Academy of Sciences, Institute of Plant Molecular Biology, Branišovská 31, 370 05 Ceske Budejovice, Czech Republic; (V.S.N.); (A.S.); (P.A.); (T.K.); (J.M.)
| | - Ajay Kumar Mishra
- Department of Molecular Genetics, Biology Centre of the Czech Academy of Sciences, Institute of Plant Molecular Biology, Branišovská 31, 370 05 Ceske Budejovice, Czech Republic; (V.S.N.); (A.S.); (P.A.); (T.K.); (J.M.)
| | - Tomáš Kocábek
- Department of Molecular Genetics, Biology Centre of the Czech Academy of Sciences, Institute of Plant Molecular Biology, Branišovská 31, 370 05 Ceske Budejovice, Czech Republic; (V.S.N.); (A.S.); (P.A.); (T.K.); (J.M.)
| | - Jaroslav Matoušek
- Department of Molecular Genetics, Biology Centre of the Czech Academy of Sciences, Institute of Plant Molecular Biology, Branišovská 31, 370 05 Ceske Budejovice, Czech Republic; (V.S.N.); (A.S.); (P.A.); (T.K.); (J.M.)
| | - Andrej Sečnik
- Department of Agronomy, Biotechnical Faculty, University of Ljubljana, Jamnikarjeva 101, SI-1000 Ljubljana, Slovenia; (A.S.); (J.J.)
| | - Jernej Jakše
- Department of Agronomy, Biotechnical Faculty, University of Ljubljana, Jamnikarjeva 101, SI-1000 Ljubljana, Slovenia; (A.S.); (J.J.)
| | - Sebastjan Radišek
- Plant Protection Department, Slovenian Institute of Hop Research and Brewing, Cesta Žalskega Tabora 2, SI-3310 Žalec, Slovenia;
| | - Vipin Hallan
- CSIR-Institute of Himalayan Bioresource Technology, Palampur 176061, India;
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22
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Flores G, Everett JH, Boguslawski EA, Oswald BM, Madaj ZB, Beddows I, Dikalov S, Adams M, Klumpp-Thomas CA, Kitchen-Goosen SM, Martin SE, Caplen NJ, Helman LJ, Grohar PJ. CDK9 Blockade Exploits Context-dependent Transcriptional Changes to Improve Activity and Limit Toxicity of Mithramycin for Ewing Sarcoma. Mol Cancer Ther 2020; 19:1183-1196. [PMID: 32127464 DOI: 10.1158/1535-7163.mct-19-0775] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2019] [Revised: 12/17/2019] [Accepted: 02/19/2020] [Indexed: 11/16/2022]
Abstract
There is a need to develop novel approaches to improve the balance between efficacy and toxicity for transcription factor-targeted therapies. In this study, we exploit context-dependent differences in RNA polymerase II processivity as an approach to improve the activity and limit the toxicity of the EWS-FLI1-targeted small molecule, mithramycin, for Ewing sarcoma. The clinical activity of mithramycin for Ewing sarcoma is limited by off-target liver toxicity that restricts the serum concentration to levels insufficient to inhibit EWS-FLI1. In this study, we perform an siRNA screen of the druggable genome followed by a matrix drug screen to identify mithramycin potentiators and a synergistic "class" effect with cyclin-dependent kinase 9 (CDK9) inhibitors. These CDK9 inhibitors enhanced the mithramycin-mediated suppression of the EWS-FLI1 transcriptional program leading to a shift in the IC50 and striking regressions of Ewing sarcoma xenografts. To determine whether these compounds may also be liver protective, we performed a qPCR screen of all known liver toxicity genes in HepG2 cells to identify mithramycin-driven transcriptional changes that contribute to the liver toxicity. Mithramycin induces expression of the BTG2 gene in HepG2 but not Ewing sarcoma cells, which leads to a liver-specific accumulation of reactive oxygen species (ROS). siRNA silencing of BTG2 rescues the induction of ROS and the cytotoxicity of mithramycin in these cells. Furthermore, CDK9 inhibition blocked the induction of BTG2 to limit cytotoxicity in HepG2, but not Ewing sarcoma cells. These studies provide the basis for a synergistic and less toxic EWS-FLI1-targeted combination therapy for Ewing sarcoma.
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Affiliation(s)
- Guillermo Flores
- Center for Cancer and Cell Biology, Van Andel Research Institute, Grand Rapids, Michigan.,College of Human Medicine, Michigan State University, Grand Rapids, Michigan
| | - Joel H Everett
- Department of Pharmacology, Vanderbilt University, Nashville, Tennessee
| | - Elissa A Boguslawski
- Center for Cancer and Cell Biology, Van Andel Research Institute, Grand Rapids, Michigan
| | - Brandon M Oswald
- Center for Cancer and Cell Biology, Van Andel Research Institute, Grand Rapids, Michigan
| | - Zachary B Madaj
- Bioinformatics and Biostatistics Core, Van Andel Research Institute, Grand Rapids, Michigan
| | - Ian Beddows
- Bioinformatics and Biostatistics Core, Van Andel Research Institute, Grand Rapids, Michigan
| | - Sergey Dikalov
- The Free Radicals in Medicine Core, Division of Clinical Pharmacology Vanderbilt University Medical Center, Nashville, Tennessee
| | - Marie Adams
- Bioinformatics and Biostatistics Core, Van Andel Research Institute, Grand Rapids, Michigan
| | - Carleen A Klumpp-Thomas
- Trans-NIH RNAi Screening Facility, Division of Preclinical Innovation, National Center for Advancing Translational Sciences, NIH, Rockville, Maryland
| | - Susan M Kitchen-Goosen
- Center for Cancer and Cell Biology, Van Andel Research Institute, Grand Rapids, Michigan
| | - Scott E Martin
- Trans-NIH RNAi Screening Facility, Division of Preclinical Innovation, National Center for Advancing Translational Sciences, NIH, Rockville, Maryland
| | - Natasha J Caplen
- Genetics Branch, Center for Cancer Research, NCI, Bethesda, Maryland
| | - Lee J Helman
- Pediatric Oncology Branch, Center for Cancer Research, NCI, Bethesda, Maryland
| | - Patrick J Grohar
- Center for Cancer and Cell Biology, Van Andel Research Institute, Grand Rapids, Michigan. .,Pediatric Oncology Branch, Center for Cancer Research, NCI, Bethesda, Maryland.,Department of Pediatrics, Vanderbilt University, Nashville, Tennessee.,Department of Pediatrics and Human Development, Michigan State University, Grand Rapids, Michigan.,Division of Pediatric Hematology-Oncology, Helen DeVos Children's Hospital, Grand Rapids, Michigan.,Division of Oncology, Children's Hospital of Philadelphia, Philadelphia, PA
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23
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Cardiello JF, Sanchez GJ, Allen MA, Dowell RD. Lessons from eRNAs: understanding transcriptional regulation through the lens of nascent RNAs. Transcription 2019; 11:3-18. [PMID: 31856658 DOI: 10.1080/21541264.2019.1704128] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Nascent transcription assays, such as global run-on sequencing (GRO-seq) and precision run-on sequencing (PRO-seq), have uncovered a myriad of unstable RNAs being actively produced from numerous sites genome-wide. These transcripts provide a more complete and immediate picture of the impact of regulatory events. Transcription factors recruit RNA polymerase II, effectively initiating the process of transcription; repressors inhibit polymerase recruitment. Efficiency of recruitment is dictated by sequence elements in and around the RNA polymerase loading zone. A combination of sequence elements and RNA binding proteins subsequently influence the ultimate stability of the resulting transcript. Some of these transcripts are capable of providing feedback on the process, influencing subsequent transcription. By monitoring RNA polymerase activity, nascent assays provide insights into every step of the regulated process of transcription.
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Affiliation(s)
| | - Gilson J Sanchez
- BioFrontiers Institute, University of Colorado, Boulder, CO, USA
| | - Mary A Allen
- BioFrontiers Institute, University of Colorado, Boulder, CO, USA
| | - Robin D Dowell
- BioFrontiers Institute, University of Colorado, Boulder, CO, USA.,Molecular, Cellular, and Developmental Biology, University of Colorado, Boulder, CO, USA
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