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Bell CC, Balic JJ, Talarmain L, Gillespie A, Scolamiero L, Lam EYN, Ang CS, Faulkner GJ, Gilan O, Dawson MA. Comparative cofactor screens show the influence of transactivation domains and core promoters on the mechanisms of transcription. Nat Genet 2024:10.1038/s41588-024-01749-z. [PMID: 38769457 DOI: 10.1038/s41588-024-01749-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2023] [Accepted: 04/09/2024] [Indexed: 05/22/2024]
Abstract
Eukaryotic transcription factors (TFs) activate gene expression by recruiting cofactors to promoters. However, the relationships between TFs, promoters and their associated cofactors remain poorly understood. Here we combine GAL4-transactivation assays with comparative CRISPR-Cas9 screens to identify the cofactors used by nine different TFs and core promoters in human cells. Using this dataset, we associate TFs with cofactors, classify cofactors as ubiquitous or specific and discover transcriptional co-dependencies. Through a reductionistic, comparative approach, we demonstrate that TFs do not display discrete mechanisms of activation. Instead, each TF depends on a unique combination of cofactors, which influences distinct steps in transcription. By contrast, the influence of core promoters appears relatively discrete. Different promoter classes are constrained by either initiation or pause-release, which influences their dynamic range and compatibility with cofactors. Overall, our comparative cofactor screens characterize the interplay between TFs, cofactors and core promoters, identifying general principles by which they influence transcription.
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Affiliation(s)
- Charles C Bell
- Cancer Research Division, Peter MacCallum Cancer Centre, Melbourne, Victoria, Australia.
- Sir Peter MacCallum Department of Oncology, University of Melbourne, Melbourne, Victoria, Australia.
- Mater Research Institute, University of Queensland, TRI Building, Woolloongabba, Queensland, Australia.
| | - Jesse J Balic
- Cancer Research Division, Peter MacCallum Cancer Centre, Melbourne, Victoria, Australia
- Sir Peter MacCallum Department of Oncology, University of Melbourne, Melbourne, Victoria, Australia
| | - Laure Talarmain
- Cancer Research Division, Peter MacCallum Cancer Centre, Melbourne, Victoria, Australia
- Sir Peter MacCallum Department of Oncology, University of Melbourne, Melbourne, Victoria, Australia
| | - Andrea Gillespie
- Cancer Research Division, Peter MacCallum Cancer Centre, Melbourne, Victoria, Australia
| | - Laura Scolamiero
- Cancer Research Division, Peter MacCallum Cancer Centre, Melbourne, Victoria, Australia
- Sir Peter MacCallum Department of Oncology, University of Melbourne, Melbourne, Victoria, Australia
| | - Enid Y N Lam
- Cancer Research Division, Peter MacCallum Cancer Centre, Melbourne, Victoria, Australia
| | - Ching-Seng Ang
- Bio21 Mass Spectrometry and Proteomics Facility, The University of Melbourne, Parkville, Victoria, Australia
| | - Geoffrey J Faulkner
- Mater Research Institute, University of Queensland, TRI Building, Woolloongabba, Queensland, Australia
- Queensland Brain Institute, University of Queensland, Brisbane, Queensland, Australia
| | - Omer Gilan
- Cancer Research Division, Peter MacCallum Cancer Centre, Melbourne, Victoria, Australia
- Australian Centre for Blood Diseases, Monash University, Melbourne, Victoria, Australia
| | - Mark A Dawson
- Cancer Research Division, Peter MacCallum Cancer Centre, Melbourne, Victoria, Australia.
- Sir Peter MacCallum Department of Oncology, University of Melbourne, Melbourne, Victoria, Australia.
- Department of Haematology, Peter MacCallum Cancer Centre, Melbourne, Victoria, Australia.
- Centre for Cancer Research, University of Melbourne, Melbourne, Victoria, Australia.
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2
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Martinez-Corral R, Park M, Biette KM, Friedrich D, Scholes C, Khalil AS, Gunawardena J, DePace AH. Transcriptional kinetic synergy: A complex landscape revealed by integrating modeling and synthetic biology. Cell Syst 2023; 14:324-339.e7. [PMID: 37080164 PMCID: PMC10472254 DOI: 10.1016/j.cels.2023.02.003] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2021] [Revised: 08/22/2022] [Accepted: 02/10/2023] [Indexed: 04/22/2023]
Abstract
Transcription factors (TFs) control gene expression, often acting synergistically. Classical thermodynamic models offer a biophysical explanation for synergy based on binding cooperativity and regulated recruitment of RNA polymerase. Because transcription requires polymerase to transition through multiple states, recent work suggests that "kinetic synergy" can arise through TFs acting on distinct steps of the transcription cycle. These types of synergy are not mutually exclusive and are difficult to disentangle conceptually and experimentally. Here, we model and build a synthetic circuit in which TFs bind to a single shared site on DNA, such that TFs cannot synergize by simultaneous binding. We model mRNA production as a function of both TF binding and regulation of the transcription cycle, revealing a complex landscape dependent on TF concentration, DNA binding affinity, and regulatory activity. We use synthetic TFs to confirm that the transcription cycle must be integrated with recruitment for a quantitative understanding of gene regulation.
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Affiliation(s)
| | - Minhee Park
- Biological Design Center, Boston University, Boston, MA 02215, USA; Department of Biomedical Engineering, Boston University, Boston, MA 02215, USA
| | - Kelly M Biette
- Department of Systems Biology, Harvard Medical School, Boston, MA 02115, USA
| | - Dhana Friedrich
- Department of Systems Biology, Harvard Medical School, Boston, MA 02115, USA
| | - Clarissa Scholes
- Department of Systems Biology, Harvard Medical School, Boston, MA 02115, USA
| | - Ahmad S Khalil
- Biological Design Center, Boston University, Boston, MA 02215, USA; Department of Biomedical Engineering, Boston University, Boston, MA 02215, USA; Wyss Institute for Biologically Inspired Engineering, Harvard University, Boston, MA 02115, USA
| | - Jeremy Gunawardena
- Department of Systems Biology, Harvard Medical School, Boston, MA 02115, USA
| | - Angela H DePace
- Department of Systems Biology, Harvard Medical School, Boston, MA 02115, USA.
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3
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Loell K, Wu Y, Staller MV, Cohen B. Activation domains can decouple the mean and noise of gene expression. Cell Rep 2022; 40:111118. [PMID: 35858548 PMCID: PMC9912357 DOI: 10.1016/j.celrep.2022.111118] [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: 09/08/2021] [Revised: 01/18/2022] [Accepted: 06/28/2022] [Indexed: 11/03/2022] Open
Abstract
Regulatory mechanisms set a gene's average level of expression, but a gene's expression constantly fluctuates around that average. These stochastic fluctuations, or expression noise, play a role in cell-fate transitions, bet hedging in microbes, and the development of chemotherapeutic resistance in cancer. An outstanding question is what regulatory mechanisms contribute to noise. Here, we demonstrate that, for a fixed mean level of expression, strong activation domains (ADs) at low abundance produce high expression noise, while weak ADs at high abundance generate lower expression noise. We conclude that differences in noise can be explained by the interplay between a TF's nuclear concentration and the strength of its AD's effect on mean expression, without invoking differences between classes of ADs. These results raise the possibility of engineering gene expression noise independently of mean levels in synthetic biology contexts and provide a potential mechanism for natural selection to tune the noisiness of gene expression.
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Affiliation(s)
- Kaiser Loell
- Department of Genetics, Washington University School of Medicine in St. Louis, St. Louis, MO 63108, USA,The Edison Family Center for Genome Sciences & Systems Biology, Washington University School of Medicine in St. Louis, St. Louis, MO 63108, USA
| | - Yawei Wu
- Department of Genetics, Washington University School of Medicine in St. Louis, St. Louis, MO 63108, USA,The Edison Family Center for Genome Sciences & Systems Biology, Washington University School of Medicine in St. Louis, St. Louis, MO 63108, USA
| | - Max V. Staller
- Center for Computational Biology, University of California, Berkeley, Berkeley, CA 94720, USA
| | - Barak Cohen
- Department of Genetics, Washington University School of Medicine in St. Louis, St. Louis, MO 63108, USA; The Edison Family Center for Genome Sciences & Systems Biology, Washington University School of Medicine in St. Louis, St. Louis, MO 63108, USA.
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4
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Target-binding behavior of IDPs via pre-structured motifs. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2021; 183:187-247. [PMID: 34656329 DOI: 10.1016/bs.pmbts.2021.07.031] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
Pre-Structured Motifs (PreSMos) are transient secondary structures observed in many intrinsically disordered proteins (IDPs) and serve as protein target-binding hot spots. The prefix "pre" highlights that PreSMos exist a priori in the target-unbound state of IDPs as the active pockets of globular proteins pre-exist before target binding. Therefore, a PreSMo is an "active site" of an IDP; it is not a spatial pocket, but rather a secondary structural motif. The classical and perhaps the most effective approach to understand the function of a protein has been to determine and investigate its structure. Ironically or by definition IDPs do not possess structure (here structure refers to tertiary structure only). Are IDPs then entirely structureless? The PreSMos provide us with an atomic-resolution answer to this question. For target binding, IDPs do not rely on the spatial pockets afforded by tertiary or higher structures. Instead, they utilize the PreSMos possessing particular conformations that highly presage the target-bound conformations. PreSMos are recognized or captured by targets via conformational selection (CS) before their conformations eventually become stabilized via structural induction into more ordered bound structures. Using PreSMos, a number of, if not all, IDPs can bind targets following a sequential pathway of CS followed by an induced fit (IF). This chapter presents several important PreSMos implicated in cancers, neurodegenerative diseases, and other diseases along with discussions on their conformational details that mediate target binding, a structural rationale for unstructured proteins.
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5
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Isa NF, Bensaude O, Aziz NC, Murphy S. HSV-1 ICP22 Is a Selective Viral Repressor of Cellular RNA Polymerase II-Mediated Transcription Elongation. Vaccines (Basel) 2021; 9:1054. [PMID: 34696162 PMCID: PMC8539892 DOI: 10.3390/vaccines9101054] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2021] [Revised: 09/09/2021] [Accepted: 09/13/2021] [Indexed: 11/16/2022] Open
Abstract
The Herpes Simplex Virus (HSV-1) immediate-early protein ICP22 interacts with cellular proteins to inhibit host cell gene expression and promote viral gene expression. ICP22 inhibits phosphorylation of Ser2 of the RNA polymerase II (pol II) carboxyl-terminal domain (CTD) and productive elongation of pol II. Here we show that ICP22 affects elongation of pol II through both the early-elongation checkpoint and the poly(A)-associated elongation checkpoint of a protein-coding gene model. Coimmunoprecipitation assays using tagged ICP22 expressed in human cells and pulldown assays with recombinant ICP22 in vitro coupled with mass spectrometry identify transcription elongation factors, including P-TEFb, additional CTD kinases and the FACT complex as interacting cellular factors. Using a photoreactive amino acid incorporated into ICP22, we found that L191, Y230 and C225 crosslink to both subunits of the FACT complex in cells. Our findings indicate that ICP22 interacts with critical elongation regulators to inhibit transcription elongation of cellular genes, which may be vital for HSV-1 pathogenesis. We also show that the HSV viral activator, VP16, has a region of structural similarity to the ICP22 region that interacts with elongation factors, suggesting a model where VP16 competes with ICP22 to deliver elongation factors to viral genes.
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Affiliation(s)
- Nur Firdaus Isa
- Sir William Dunn School of Pathology, University of Oxford, Oxford OX1 3RE, UK
- Research Unit for Bioinformatics and Computational Biology, Department of Biotechnology, Kulliyyah of Science, International Islamic University Malaysia, Kuantan 25200, Pahang, Malaysia;
| | - Olivier Bensaude
- Ecole Normale Supérieure, Institut de Biologie de l’Ecole Normale Supérieure, PSL Research University, CNRS UMR 8197, INSERM U 1024, F-75005 Paris, France;
| | - Nadiah C. Aziz
- Research Unit for Bioinformatics and Computational Biology, Department of Biotechnology, Kulliyyah of Science, International Islamic University Malaysia, Kuantan 25200, Pahang, Malaysia;
| | - Shona Murphy
- Sir William Dunn School of Pathology, University of Oxford, Oxford OX1 3RE, UK
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6
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Sanford EM, Emert BL, Coté A, Raj A. Gene regulation gravitates toward either addition or multiplication when combining the effects of two signals. eLife 2020; 9:e59388. [PMID: 33284110 PMCID: PMC7771960 DOI: 10.7554/elife.59388] [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: 05/28/2020] [Accepted: 12/04/2020] [Indexed: 01/07/2023] Open
Abstract
Two different cell signals often affect transcription of the same gene. In such cases, it is natural to ask how the combined transcriptional response compares to the individual responses. The most commonly used mechanistic models predict additive or multiplicative combined responses, but a systematic genome-wide evaluation of these predictions is not available. Here, we analyzed the transcriptional response of human MCF-7 cells to retinoic acid and TGF-β, applied individually and in combination. The combined transcriptional responses of induced genes exhibited a range of behaviors, but clearly favored both additive and multiplicative outcomes. We performed paired chromatin accessibility measurements and found that increases in accessibility were largely additive. There was some association between super-additivity of accessibility and multiplicative or super-multiplicative combined transcriptional responses, while sub-additivity of accessibility associated with additive transcriptional responses. Our findings suggest that mechanistic models of combined transcriptional regulation must be able to reproduce a range of behaviors.
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Affiliation(s)
- Eric M Sanford
- Genomics and Computational Biology Graduate Group, Perelman School of Medicine, University of PennsylvaniaPhiladelphiaUnited States
| | - Benjamin L Emert
- Genomics and Computational Biology Graduate Group, Perelman School of Medicine, University of PennsylvaniaPhiladelphiaUnited States
| | - Allison Coté
- Department of Bioengineering, School of Engineering and Applied Sciences, University of PennsylvaniaPhiladelphiaUnited States
- Department of Genetics, Perelman School of Medicine, University of PennsylvaniaPhiladelphiaUnited States
| | - Arjun Raj
- Department of Bioengineering, School of Engineering and Applied Sciences, University of PennsylvaniaPhiladelphiaUnited States
- Department of Genetics, Perelman School of Medicine, University of PennsylvaniaPhiladelphiaUnited States
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7
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Kane M, Mele V, Liberatore RA, Bieniasz PD. Inhibition of spumavirus gene expression by PHF11. PLoS Pathog 2020; 16:e1008644. [PMID: 32678836 PMCID: PMC7390438 DOI: 10.1371/journal.ppat.1008644] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2020] [Revised: 07/29/2020] [Accepted: 05/19/2020] [Indexed: 01/05/2023] Open
Abstract
The foamy viruses (FV) or spumaviruses are an ancient subfamily of retroviruses that infect a variety of vertebrates. FVs are endemic, but apparently apathogenic, in modern non-human primates. Like other retroviruses, FV replication is inhibited by type-I interferon (IFN). In a previously described screen of IFN-stimulated genes (ISGs), we identified the macaque PHD finger domain protein-11 (PHF11) as an inhibitor of prototype foamy virus (PFV) replication. Here, we show that human and macaque PHF11 inhibit the replication of multiple spumaviruses, but are inactive against several orthoretroviruses. Analysis of other mammalian PHF11 proteins revealed that antiviral activity is host species dependent. Using multiple reporter viruses and cell lines, we determined that PHF11 specifically inhibits a step in the replication cycle that is unique to FVs, namely basal transcription from the FV internal promoter (IP). In so doing, PHF11 prevents expression of the viral transactivator Tas and subsequent activation of the viral LTR promoter. These studies reveal a previously unreported inhibitory mechanism in mammalian cells, that targets a family of ancient viruses and may promote viral latency.
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Affiliation(s)
- Melissa Kane
- Department of Pediatrics, Infectious Diseases Division, UPMC Children’s Hospital of Pittsburgh, Pittsburgh, Pennsylvania, United States of America
- Center for Microbial Pathogenesis, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, United States of America
| | - Vincent Mele
- Department of Pediatrics, Infectious Diseases Division, UPMC Children’s Hospital of Pittsburgh, Pittsburgh, Pennsylvania, United States of America
- Center for Microbial Pathogenesis, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, United States of America
| | - Rachel A. Liberatore
- Laboratory of Retrovirology, The Rockefeller University, New York, New York, United States of America
- Howard Hughes Medical Institute, The Rockefeller University, New York, New York, United States of America
| | - Paul D. Bieniasz
- Laboratory of Retrovirology, The Rockefeller University, New York, New York, United States of America
- Howard Hughes Medical Institute, The Rockefeller University, New York, New York, United States of America
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8
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Chen CH, Zheng R, Tokheim C, Dong X, Fan J, Wan C, Tang Q, Brown M, Liu JS, Meyer CA, Liu XS. Determinants of transcription factor regulatory range. Nat Commun 2020; 11:2472. [PMID: 32424124 PMCID: PMC7235260 DOI: 10.1038/s41467-020-16106-x] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2019] [Accepted: 04/14/2020] [Indexed: 01/03/2023] Open
Abstract
Characterization of the genomic distances over which transcription factor (TF) binding influences gene expression is important for inferring target genes from TF chromatin immunoprecipitation followed by sequencing (ChIP-seq) data. Here we systematically examine the relationship between thousands of TF and histone modification ChIP-seq data sets with thousands of gene expression profiles. We develop a model for integrating these data, which reveals two classes of TFs with distinct ranges of regulatory influence, chromatin-binding preferences, and auto-regulatory properties. We find that the regulatory range of the same TF bound within different topologically associating domains (TADs) depend on intrinsic TAD properties such as local gene density and G/C content, but also on the TAD chromatin states. Our results suggest that considering TF type, binding distance to gene locus, as well as chromatin context is important in identifying implicated TFs from GWAS SNPs.
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Affiliation(s)
- Chen-Hao Chen
- Department of Data Sciences, Dana-Farber Cancer Institute. Harvard T.H. Chan School of Public Health, Boston, MA, USA
- Biological and Biomedical Science Program, Harvard Medical School, Boston, MA, USA
- Center for Functional Cancer Epigenetics, Dana-Farber Cancer Institute, Boston, MA, USA
| | - Rongbin Zheng
- Clinical Translational Research Center, Shanghai Pulmonary Hospital, School of Life Sciences and Technology, Tongji University, Shanghai, 200092, China
| | - Collin Tokheim
- Department of Data Sciences, Dana-Farber Cancer Institute. Harvard T.H. Chan School of Public Health, Boston, MA, USA
- Center for Functional Cancer Epigenetics, Dana-Farber Cancer Institute, Boston, MA, USA
| | - Xin Dong
- Clinical Translational Research Center, Shanghai Pulmonary Hospital, School of Life Sciences and Technology, Tongji University, Shanghai, 200092, China
| | - Jingyu Fan
- Clinical Translational Research Center, Shanghai Pulmonary Hospital, School of Life Sciences and Technology, Tongji University, Shanghai, 200092, China
| | - Changxin Wan
- Clinical Translational Research Center, Shanghai Pulmonary Hospital, School of Life Sciences and Technology, Tongji University, Shanghai, 200092, China
| | - Qin Tang
- Center for Functional Cancer Epigenetics, Dana-Farber Cancer Institute, Boston, MA, USA
- Department of Medical Oncology, Dana-Farber Cancer Institute, Harvard Medical School, Boston, MA, USA
| | - Myles Brown
- Center for Functional Cancer Epigenetics, Dana-Farber Cancer Institute, Boston, MA, USA
- Department of Medical Oncology, Dana-Farber Cancer Institute, Harvard Medical School, Boston, MA, USA
| | - Jun S Liu
- Department of Statistics, Harvard University, Cambridge, MA, USA
| | - Clifford A Meyer
- Department of Data Sciences, Dana-Farber Cancer Institute. Harvard T.H. Chan School of Public Health, Boston, MA, USA.
- Center for Functional Cancer Epigenetics, Dana-Farber Cancer Institute, Boston, MA, USA.
| | - X Shirley Liu
- Department of Data Sciences, Dana-Farber Cancer Institute. Harvard T.H. Chan School of Public Health, Boston, MA, USA.
- Center for Functional Cancer Epigenetics, Dana-Farber Cancer Institute, Boston, MA, USA.
- Department of Statistics, Harvard University, Cambridge, MA, USA.
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9
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Park H, Do E, Kim M, Park HJ, Lee J, Han SW. A LysR-Type Transcriptional Regulator LcrX Is Involved in Virulence, Biofilm Formation, Swimming Motility, Siderophore Secretion, and Growth in Sugar Sources in Xanthomonas axonopodis Pv. glycines. FRONTIERS IN PLANT SCIENCE 2020; 10:1657. [PMID: 31998344 PMCID: PMC6965072 DOI: 10.3389/fpls.2019.01657] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/03/2019] [Accepted: 11/25/2019] [Indexed: 05/30/2023]
Abstract
Xanthomonas axonopodis pv. glycines (Xag) is a Gram-negative bacterium that causes bacterial pustule disease in soybean. To acclimate to new environments, the expression of genes in bacteria is controlled directly or indirectly by diverse transcriptional factors. Among them, LysR type transcriptional regulators are well-characterized and abundant in bacteria. In a previous study, comparative proteomic analysis revealed that LysR type carbohydrate-related transcriptional regulator in Xag (LcrX) was more abundant in XVM2, which is a minimal medium, compared with a rich medium. However, the functions of LcrX in Xag have not been characterized. In this study, we generated an LcrX-overexpressing strain, Xag(LcrX), and the knockout mutant strain, XagΔlcrX(EV), to elucidate the functions of LcrX. Bacterial multiplication of Xag(LcrX) in soybean was significantly impaired, indicating that LcrX is related to virulence. Comparative proteomic analysis revealed that LcrX is mainly involved in carbohydrate metabolism/transport and inorganic ion transport/metabolism. Based on the results of proteomics analysis, diverse phenotypic assays were carried out. A gel electrophoresis mobility shift assay demonstrated that LcrX specifically bound to the putative promoter regions of genes encoding putative fructose 1,6-bisphosphatase and protease. Through a 96-well plate assay under various conditions, we confirmed that the growth of Xag(LcrX) was dramatically affected in the presence of various carbon sources, while the growth of XagΔlcrX(EV) was only slightly changed. Biofilm formation activity was reduced in Xag(LcrX) but enhanced in XagΔlcrX(EV). The production of siderophores was also decreased in Xag(LcrX) but not altered in XagΔlcrX(EV). In contrast, LcrX was not associated with exopolysaccharide production, protease activity, or bacterial motility. These findings provide new insights into the functions of a carbohydrate-related transcriptional regulator in Xag.
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Affiliation(s)
- Hanbi Park
- Department of Plant Science and Technology, Chung-Ang University, Anseong, South Korea
| | - Eunsoo Do
- Department of Systems Biotechnology, Chung-Ang University, Anseong, South Korea
| | - Minyoung Kim
- Department of Plant Science and Technology, Chung-Ang University, Anseong, South Korea
| | - Hye-Jee Park
- Department of Plant Science and Technology, Chung-Ang University, Anseong, South Korea
| | - Jongchan Lee
- Department of Plant Science and Technology, Chung-Ang University, Anseong, South Korea
| | - Sang-Wook Han
- Department of Plant Science and Technology, Chung-Ang University, Anseong, South Korea
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10
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Lis JT. A 50 year history of technologies that drove discovery in eukaryotic transcription regulation. Nat Struct Mol Biol 2019; 26:777-782. [PMID: 31439942 DOI: 10.1038/s41594-019-0288-9] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2019] [Accepted: 07/26/2019] [Indexed: 01/12/2023]
Abstract
Transcription regulation is critical to organism development and homeostasis. Control of expression of the 20,000 genes in human cells requires many hundreds of proteins acting through sophisticated multistep mechanisms. In this Historical Perspective, I highlight the progress that has been made in elucidating eukaryotic transcriptional mechanisms through an array of disciplines and approaches, and how this concerted effort has been driven by the development of new technologies.
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Affiliation(s)
- John T Lis
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY, USA.
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11
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Wan X, Marsafari M, Xu P. Engineering metabolite-responsive transcriptional factors to sense small molecules in eukaryotes: current state and perspectives. Microb Cell Fact 2019; 18:61. [PMID: 30914048 PMCID: PMC6434827 DOI: 10.1186/s12934-019-1111-3] [Citation(s) in RCA: 43] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2019] [Accepted: 03/20/2019] [Indexed: 11/18/2022] Open
Abstract
Nature has evolved exquisite sensing mechanisms to detect cellular and environmental signals surrounding living organisms. These biosensors have been widely used to sense small molecules, detect environmental cues and diagnose disease markers. Metabolic engineers and synthetic biologists have been able to exploit metabolites-responsive transcriptional factors (MRTFs) as basic tools to rewire cell metabolism, reprogram cellular activity as well as boost cell’s productivity. This is commonly achieved by integrating sensor-actuator systems with biocatalytic functions and dynamically allocating cellular resources to drive carbon flux toward the target pathway. Up to date, most of identified MRTFs are derived from bacteria. As an endeavor to advance intelligent biomanufacturing in yeast cell factory, we will summarize the opportunities and challenges to transfer the bacteria-derived MRTFs to expand the small-molecule sensing capability in eukaryotic cells. We will discuss the design principles underlying MRTF-based biosensors in eukaryotic cells, including the choice of reliable reporters and the characterization tools to minimize background noise, strategies to tune the sensor dynamic range, sensitivity and specificity, as well as the criteria to engineer activator and repressor-based biosensors. Due to the physical separation of transcription and protein expression in eukaryotes, we argue that nuclear import/export mechanism of MRTFs across the nuclear membrane plays a critical role in regulating the MRTF sensor dynamics. Precisely-controlled MRTF response will allow us to repurpose the vast majority of transcriptional factors as molecular switches to achieve temporal or spatial gene expression in eukaryotes. Uncovering this knowledge will inform us fundamental design principles to deliver robust cell factories and enable the design of reprogrammable and predictable biological systems for intelligent biomanufacturing, smart therapeutics or precision medicine in the foreseeable future.
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Affiliation(s)
- Xia Wan
- Department of Chemical Biochemical and Environmental Engineering, University of Maryland Baltimore County, Baltimore, MD, 21250, USA.,Oil Crops Research Institute of Chinese Academy of Agricultural Sciences, Wuhan, 430062, Hubei, China.,Key Laboratory of Biology and Genetic Improvement of Oil Crops, Ministry of Agriculture, Wuhan, 430062, Hubei, China
| | - Monireh Marsafari
- Department of Chemical Biochemical and Environmental Engineering, University of Maryland Baltimore County, Baltimore, MD, 21250, USA.,Department of Agronomy and Plant Breeding, University of Guilan, Rasht, Islamic Republic of Iran
| | - Peng Xu
- Department of Chemical Biochemical and Environmental Engineering, University of Maryland Baltimore County, Baltimore, MD, 21250, USA.
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12
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Geltinger C, Hörtnagel K, Polack A. TATA box and Sp1 sites mediate the activation of c-myc promoter P1 by immunoglobulin kappa enhancers. Gene Expr 2018; 6:113-27. [PMID: 8979089 PMCID: PMC6148303] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
In Burkitt's lymphoma (BL) cells the proto-oncogene c-myc is transcriptionally activated by chromosomal translocation to the immunoglobulin (Ig) gene loci. This activation is characterized by preferential transcription from the c-myc promoter P1 and accomplished by juxtaposed Ig enhancer elements. To identify promoter elements required for enhancer-activated P1 transcription, we studied the activation of c-myc reporter gene constructs by the Ig kappa intron and 3' enhancers. Deletion analysis defined the core promoter with a TATA box and two adjacent GC/GT boxes upstream sufficient for basal and enhancer-activated transcription. Gel retardation assays revealed Sp1's binding affinity to the GC/GT box proximal to the TATA box to be higher than to the distal one. This difference correlated well with the resulting levels of transcription mediated by Sp1 in contransfection experiments in BL and Sp1-deficient SL2 cells. Sp3 also bound to the core promoter in vitro, but failed to transactivate in vivo. Mutation of the distal Sp1 site moderately affected basal transcription concomitant with a modest decrease in enhancer stimulation. Mutation of the proximal Sp1 site almost entirely abolished basal as well as enhanced transcription. A considerable level of basal transcription was maintained upon mutation of the TATA box, whereas enhancer-activated transcription largely was abolished. Stable transfection of the BL cell line Raji with constructs containing core promoter mutations confirmed that the proximal Sp1 site and the TATA box are essential for the activation of promoter P1 by the Ig kappa enhancers.
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Affiliation(s)
- C Geltinger
- GSF-National Research Center for Environment and Health, Institute of Clinical Molecular Biology and Tumour Genetics, München, Germany
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13
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Zhu S, Khatun R, Lento C, Sheng Y, Wilson DJ. Enhanced Binding Affinity via Destabilization of the Unbound State: A Millisecond Hydrogen–Deuterium Exchange Study of the Interaction between p53 and a Pleckstrin Homology Domain. Biochemistry 2017; 56:4127-4133. [DOI: 10.1021/acs.biochem.7b00193] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Shaolong Zhu
- Department
of Chemistry, York University, Toronto, Ontario, Canada M3J 1P3
| | - Rahima Khatun
- Department
of Biology, York University, Toronto, Ontario, Canada M3J 1P3
| | - Cristina Lento
- Department
of Chemistry, York University, Toronto, Ontario, Canada M3J 1P3
| | - Yi Sheng
- Department
of Biology, York University, Toronto, Ontario, Canada M3J 1P3
| | - Derek J. Wilson
- Department
of Chemistry, York University, Toronto, Ontario, Canada M3J 1P3
- Centre
for Research in Mass Spectrometry, York University, Toronto, Ontario, Canada M3J 1P3
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14
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Wang D, Kon N, Tavana O, Gu W. The "readers" of unacetylated p53 represent a new class of acidic domain proteins. Nucleus 2017; 8:360-369. [PMID: 28406743 DOI: 10.1080/19491034.2017.1313939] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Acetylation of non-histone proteins plays important roles in regulating protein functions but the mechanisms of action are poorly understood. Our recent study uncovered a previously unknown mechanism by which C-terminal domain (CTD) acetylation of p53 serves as a "switch" to determine the interaction between a unique group of acidic domain-containing proteins and p53, as well as revealed that acidic domains may act as a novel class of "readers" for unacetylated p53. However, the properties of acidic domain "readers" are not well elucidated yet. Here, we identified that the charge effect between acidic domain "readers" and the p53 CTD is necessary for their interaction. Both the length and the amino acid composition of a given acidic domain contributed to its ability to recognize the p53 CTD. Finally, we summarized the characteristic features of our identified acidic domains, which would distinguish this kind of "readers" from other types of acidic amino acid-containing domains.
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Affiliation(s)
- Donglai Wang
- a Institute for Cancer Genetics, Department of Pathology and Cell Biology, Herbert Irving Comprehensive Cancer Center, College of Physicians & Surgeons , Columbia University , New York , NY , USA
| | - Ning Kon
- a Institute for Cancer Genetics, Department of Pathology and Cell Biology, Herbert Irving Comprehensive Cancer Center, College of Physicians & Surgeons , Columbia University , New York , NY , USA
| | - Omid Tavana
- a Institute for Cancer Genetics, Department of Pathology and Cell Biology, Herbert Irving Comprehensive Cancer Center, College of Physicians & Surgeons , Columbia University , New York , NY , USA
| | - Wei Gu
- a Institute for Cancer Genetics, Department of Pathology and Cell Biology, Herbert Irving Comprehensive Cancer Center, College of Physicians & Surgeons , Columbia University , New York , NY , USA
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15
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Chambers M, Turki-Judeh W, Kim MW, Chen K, Gallaher SD, Courey AJ. Mechanisms of Groucho-mediated repression revealed by genome-wide analysis of Groucho binding and activity. BMC Genomics 2017; 18:215. [PMID: 28245789 PMCID: PMC5331681 DOI: 10.1186/s12864-017-3589-6] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2016] [Accepted: 02/13/2017] [Indexed: 12/24/2022] Open
Abstract
Background The transcriptional corepressor Groucho (Gro) is required for the function of many developmentally regulated DNA binding repressors, thus helping to define the gene expression profile of each cell during development. The ability of Gro to repress transcription at a distance together with its ability to oligomerize and bind to histones has led to the suggestion that Gro may spread along chromatin. However, much is unknown about the mechanism of Gro-mediated repression and about the dynamics of Gro targeting. Results Our chromatin immunoprecipitation sequencing analysis of temporally staged Drosophila embryos shows that Gro binds in a highly dynamic manner primarily to clusters of discrete (<1 kb) segments. Consistent with the idea that Gro may facilitate communication between silencers and promoters, Gro binding is enriched at both cis-regulatory modules, as well as within the promotors of potential target genes. While this Gro-recruitment is required for repression, our data show that it is not sufficient for repression. Integration of Gro binding data with transcriptomic analysis suggests that, contrary to what has been observed for another Gro family member, Drosophila Gro is probably a dedicated repressor. This analysis also allows us to define a set of high confidence Gro repression targets. Using publically available data regarding the physical and genetic interactions between these targets, we are able to place them in the regulatory network controlling development. Through analysis of chromatin associated pre-mRNA levels at these targets, we find that genes regulated by Gro in the embryo are enriched for characteristics of promoter proximal paused RNA polymerase II. Conclusions Our findings are inconsistent with a one-dimensional spreading model for long-range repression and suggest that Gro-mediated repression must be regulated at a post-recruitment step. They also show that Gro is likely a dedicated repressor that sits at a prominent highly interconnected regulatory hub in the developmental network. Furthermore, our findings suggest a role for RNA polymerase II pausing in Gro-mediated repression. Electronic supplementary material The online version of this article (doi:10.1186/s12864-017-3589-6) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Michael Chambers
- Department of Chemistry and Biochemistry, University of California, Los Angeles, CA, 90095, USA
| | - Wiam Turki-Judeh
- Department of Chemistry and Biochemistry, University of California, Los Angeles, CA, 90095, USA.,Molecular Biology Institute, University of California, Los Angeles, CA, 90095, USA
| | - Min Woo Kim
- Department of Chemistry and Biochemistry, University of California, Los Angeles, CA, 90095, USA
| | - Kenny Chen
- Department of Chemistry and Biochemistry, University of California, Los Angeles, CA, 90095, USA
| | - Sean D Gallaher
- Department of Chemistry and Biochemistry, University of California, Los Angeles, CA, 90095, USA.,Department of Energy, Institute of Genomics and Proteomics, University of California, Los Angeles, CA, 90095, USA
| | - Albert J Courey
- Department of Chemistry and Biochemistry, University of California, Los Angeles, CA, 90095, USA. .,Molecular Biology Institute, University of California, Los Angeles, CA, 90095, USA.
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16
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Grossman SR, Zhang X, Wang L, Engreitz J, Melnikov A, Rogov P, Tewhey R, Isakova A, Deplancke B, Bernstein BE, Mikkelsen TS, Lander ES. Systematic dissection of genomic features determining transcription factor binding and enhancer function. Proc Natl Acad Sci U S A 2017; 114:E1291-E1300. [PMID: 28137873 PMCID: PMC5321001 DOI: 10.1073/pnas.1621150114] [Citation(s) in RCA: 102] [Impact Index Per Article: 14.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Enhancers regulate gene expression through the binding of sequence-specific transcription factors (TFs) to cognate motifs. Various features influence TF binding and enhancer function-including the chromatin state of the genomic locus, the affinities of the binding site, the activity of the bound TFs, and interactions among TFs. However, the precise nature and relative contributions of these features remain unclear. Here, we used massively parallel reporter assays (MPRAs) involving 32,115 natural and synthetic enhancers, together with high-throughput in vivo binding assays, to systematically dissect the contribution of each of these features to the binding and activity of genomic regulatory elements that contain motifs for PPARγ, a TF that serves as a key regulator of adipogenesis. We show that distinct sets of features govern PPARγ binding vs. enhancer activity. PPARγ binding is largely governed by the affinity of the specific motif site and higher-order features of the larger genomic locus, such as chromatin accessibility. In contrast, the enhancer activity of PPARγ binding sites depends on varying contributions from dozens of TFs in the immediate vicinity, including interactions between combinations of these TFs. Different pairs of motifs follow different interaction rules, including subadditive, additive, and superadditive interactions among specific classes of TFs, with both spatially constrained and flexible grammars. Our results provide a paradigm for the systematic characterization of the genomic features underlying regulatory elements, applicable to the design of synthetic regulatory elements or the interpretation of human genetic variation.
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Affiliation(s)
- Sharon R Grossman
- Broad Institute, Cambridge, MA 02142
- Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02139
- Health Sciences and Technology, Harvard Medical School, Boston, MA 02215
| | | | - Li Wang
- Broad Institute, Cambridge, MA 02142
| | - Jesse Engreitz
- Broad Institute, Cambridge, MA 02142
- Division of Health Sciences and Technology, Massachusetts Institute of Technology, Cambridge, MA 02139
| | | | | | - Ryan Tewhey
- Broad Institute, Cambridge, MA 02142
- Faculty of Arts and Sciences Center for Systems Biology, Harvard University, Cambridge, MA 02138
- Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, MA 02138
| | - Alina Isakova
- Institute of Bioengineering, CH-1015 Lausanne, Switzerland
- Swiss Institute of Bioinformatics, CH-1015 Lausanne, Switzerland
| | - Bart Deplancke
- Institute of Bioengineering, CH-1015 Lausanne, Switzerland
- Swiss Institute of Bioinformatics, CH-1015 Lausanne, Switzerland
| | - Bradley E Bernstein
- Broad Institute, Cambridge, MA 02142
- Department of Pathology, Massachusetts General Hospital and Harvard Medical School, Boston, MA 02114
- Center for Cancer Research, Massachusetts General Hospital and Harvard Medical School, Boston, MA 02114
| | - Tarjei S Mikkelsen
- Broad Institute, Cambridge, MA 02142
- Harvard Stem Cell Institute, Harvard University, Cambridge, MA 02138
- Department of Stem Cell and Regenerative Biology, Harvard University, Cambridge, MA 02138
| | - Eric S Lander
- Broad Institute, Cambridge, MA 02142;
- Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02139
- Department of Systems Biology, Harvard Medical School, Boston, MA 02215
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17
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Scholes C, DePace AH, Sánchez Á. Combinatorial Gene Regulation through Kinetic Control of the Transcription Cycle. Cell Syst 2016; 4:97-108.e9. [PMID: 28041762 DOI: 10.1016/j.cels.2016.11.012] [Citation(s) in RCA: 50] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2016] [Revised: 08/09/2016] [Accepted: 11/23/2016] [Indexed: 11/20/2022]
Abstract
Cells decide when, where, and to what level to express their genes by "computing" information from transcription factors (TFs) binding to regulatory DNA. How is the information contained in multiple TF-binding sites integrated to dictate the rate of transcription? The dominant conceptual and quantitative model is that TFs combinatorially recruit one another and RNA polymerase to the promoter by direct physical interactions. Here, we develop a quantitative framework to explore kinetic control, an alternative model in which combinatorial gene regulation can result from TFs working on different kinetic steps of the transcription cycle. Kinetic control can generate a wide range of analog and Boolean computations without requiring the input TFs to be simultaneously bound to regulatory DNA. We propose experiments that will illuminate the role of kinetic control in transcription and discuss implications for deciphering the cis-regulatory "code."
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Affiliation(s)
- Clarissa Scholes
- Department of Systems Biology, Harvard Medical School, Boston, MA 02115, USA; Department of Molecular and Cellular Biology, Harvard University, Cambridge, MA 02138, USA
| | - Angela H DePace
- Department of Systems Biology, Harvard Medical School, Boston, MA 02115, USA.
| | - Álvaro Sánchez
- The Rowland Institute at Harvard, Harvard University, Cambridge, MA 02142, USA.
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18
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Pance A. Oct-1, to go or not to go? That is the PolII question. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2016; 1859:820-4. [PMID: 27063953 DOI: 10.1016/j.bbagrm.2016.04.003] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/01/2016] [Revised: 04/04/2016] [Accepted: 04/05/2016] [Indexed: 10/22/2022]
Abstract
The Oct transcription factors recognise an octamer DNA element from which they regulate transcription of specific target genes. Oct-1 is the only member of the subfamily that is ubiquitously expressed and has a wide role in transcriptional control. Through interaction with various partner proteins, Oct-1 can modulate accessibility to the chromatin to recruit the transcription machinery and form the pre-initiation complex. The recruited PolII is induced to initiate transcription and stalled until elongation is triggered on interaction with signalling transcription factors. In this way, Oct-1 can fulfil general roles in transcription by opening the chromatin as well as transduce extracellular signals by relaying activation through various interacting partners. The emerging picture of Oct-1 is that of a complex and versatile transcription factor with fundamental functions in cell homeostasis and signal response in general as well as cell specific contexts. This article is part of a Special Issue entitled: The Oct Transcription Factor Family, edited by Dr. Dean Tantin.
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Affiliation(s)
- Alena Pance
- The Wellcome Trust Sanger Institute, Hinxton CB10 1SA, Cambridgeshire, UK.
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19
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Vincent BJ, Estrada J, DePace AH. The appeasement of Doug: a synthetic approach to enhancer biology. Integr Biol (Camb) 2016; 8:475-84. [DOI: 10.1039/c5ib00321k] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Affiliation(s)
- Ben J. Vincent
- Department of Systems Biology, Harvard Medical School, 200 Longwood Avenue, Boston, MA 02115, USA
| | - Javier Estrada
- Department of Systems Biology, Harvard Medical School, 200 Longwood Avenue, Boston, MA 02115, USA
| | - Angela H. DePace
- Department of Systems Biology, Harvard Medical School, 200 Longwood Avenue, Boston, MA 02115, USA
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20
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Fimiani C, Goina E, Mallamaci A. Upregulating endogenous genes by an RNA-programmable artificial transactivator. Nucleic Acids Res 2015; 43:7850-64. [PMID: 26152305 PMCID: PMC4652751 DOI: 10.1093/nar/gkv682] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2014] [Accepted: 06/22/2015] [Indexed: 11/12/2022] Open
Abstract
To promote expression of endogenous genes ad libitum, we developed a novel, programmable transcription factor prototype. Kept together via an MS2 coat protein/RNA interface, it includes a fixed, polypeptidic transactivating domain and a variable RNA domain that recognizes the desired gene. Thanks to this device, we specifically upregulated five genes, in cell lines and primary cultures of murine pallial precursors. Gene upregulation was small, however sufficient to robustly inhibit neuronal differentiation. The transactivator interacted with target gene chromatin via its RNA cofactor. Its activity was restricted to cells in which the target gene is normally transcribed. Our device might be useful for specific applications. However for this purpose, it will require an improvement of its transactivation power as well as a better characterization of its target specificity and mechanism of action.
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Affiliation(s)
- Cristina Fimiani
- Laboratory of Cerebral Cortex Development, SISSA, Trieste, 34136, Italy
| | - Elisa Goina
- Laboratory of Cerebral Cortex Development, SISSA, Trieste, 34136, Italy
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21
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Fuda NJ, Guertin MJ, Sharma S, Danko CG, Martins AL, Siepel A, Lis JT. GAGA factor maintains nucleosome-free regions and has a role in RNA polymerase II recruitment to promoters. PLoS Genet 2015; 11:e1005108. [PMID: 25815464 PMCID: PMC4376892 DOI: 10.1371/journal.pgen.1005108] [Citation(s) in RCA: 68] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2014] [Accepted: 02/26/2015] [Indexed: 11/28/2022] Open
Abstract
Previous studies have shown that GAGA Factor (GAF) is enriched on promoters with paused RNA Polymerase II (Pol II), but its genome-wide function and mechanism of action remain largely uncharacterized. We assayed the levels of transcriptionally-engaged polymerase using global run-on sequencing (GRO-seq) in control and GAF-RNAi Drosophila S2 cells and found promoter-proximal polymerase was significantly reduced on a large subset of paused promoters where GAF occupancy was reduced by knock down. These promoters show a dramatic increase in nucleosome occupancy upon GAF depletion. These results, in conjunction with previous studies showing that GAF directly interacts with nucleosome remodelers, strongly support a model where GAF directs nucleosome displacement at the promoter and thereby allows the entry Pol II to the promoter and pause sites. This action of GAF on nucleosomes is at least partially independent of paused Pol II because intergenic GAF binding sites with little or no Pol II also show GAF-dependent nucleosome displacement. In addition, the insulator factor BEAF, the BEAF-interacting protein Chriz, and the transcription factor M1BP are strikingly enriched on those GAF-associated genes where pausing is unaffected by knock down, suggesting insulators or the alternative promoter-associated factor M1BP protect a subset of GAF-bound paused genes from GAF knock-down effects. Thus, GAF binding at promoters can lead to the local displacement of nucleosomes, but this activity can be restricted or compensated for when insulator protein or M1BP complexes also reside at GAF bound promoters. Transcriptional regulation is critical for proper gene expression in response to environmental changes and developmental programs. Eukaryotes have evolved multiple mechanisms by which transcription factors regulate transcription. One mechanism is the reorganization of chromatin to allow Pol II recruitment. Another is the release of promoter-proximal paused Pol II, where Pol II transcription that is halted 20–60 bases downstream of the transcription start site (TSS) is allowed to enter into productive elongation through the gene body. The Drosophila transcription factor GAF binds to genes that undergo pausing and interacts with nucleosome remodelers and the pausing factor NELF. Thus, GAF can regulate multiple points necessary for transcription, but its mechanistic role is not fully understood genome-wide. We depleted GAF from cells and examined the genome-wide changes in Pol II and nucleosome distributions across genes. We found that GAF depletion reduces polymerase density at genes where GAF binds just upstream of the TSS, and results in nucleosomes moving into the promoter region. Our results show that GAF is important for maintaining the promoter accessibility, allowing Pol II to be recruited to promoters and enter the pause sites downstream of the TSS. Thus, GAF is critical for providing the chromatin environment necessary for the proper control of gene expression.
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Affiliation(s)
- Nicholas J. Fuda
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, New York, United States of America
| | - Michael J. Guertin
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, New York, United States of America
| | - Sumeet Sharma
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, New York, United States of America
| | - Charles G. Danko
- Department of Biological Statistics and Computational Biology, Cornell University, Ithaca, New York, United States of America
| | - André L. Martins
- Department of Biological Statistics and Computational Biology, Cornell University, Ithaca, New York, United States of America
| | - Adam Siepel
- Department of Biological Statistics and Computational Biology, Cornell University, Ithaca, New York, United States of America
| | - John T. Lis
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, New York, United States of America
- * E-mail:
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22
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Getting up to speed with transcription elongation by RNA polymerase II. Nat Rev Mol Cell Biol 2015; 16:167-77. [PMID: 25693130 DOI: 10.1038/nrm3953] [Citation(s) in RCA: 565] [Impact Index Per Article: 62.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Recent advances in sequencing techniques that measure nascent transcripts and that reveal the positioning of RNA polymerase II (Pol II) have shown that the pausing of Pol II in promoter-proximal regions and its release to initiate a phase of productive elongation are key steps in transcription regulation. Moreover, after the release of Pol II from the promoter-proximal region, elongation rates are highly dynamic throughout the transcription of a gene, and vary on a gene-by-gene basis. Interestingly, Pol II elongation rates affect co-transcriptional processes such as splicing, termination and genome stability. Increasing numbers of factors and regulatory mechanisms have been associated with the steps of transcription elongation by Pol II, revealing that elongation is a highly complex process. Elongation is thus now recognized as a key phase in the regulation of transcription by Pol II.
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23
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How slow RNA polymerase II elongation favors alternative exon skipping. Mol Cell 2014; 54:683-90. [PMID: 24793692 DOI: 10.1016/j.molcel.2014.03.044] [Citation(s) in RCA: 154] [Impact Index Per Article: 15.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2013] [Revised: 01/23/2014] [Accepted: 03/01/2014] [Indexed: 11/20/2022]
Abstract
Splicing is functionally coupled to transcription, linking the rate of RNA polymerase II (Pol II) elongation and the ability of splicing factors to recognize splice sites (ss) of various strengths. In most cases, slow Pol II elongation allows weak splice sites to be recognized, leading to higher inclusion of alternative exons. Using CFTR alternative exon 9 (E9) as a model, we show here that slowing down elongation can also cause exon skipping by promoting the recruitment of the negative factor ETR-3 onto the UG-repeat at E9 3' splice site, which displaces the constitutive splicing factor U2AF65 from the overlapping polypyrimidine tract. Weakening of E9 5' ss increases ETR-3 binding at the 3' ss and subsequent E9 skipping, whereas strengthening of the 5' ss usage has the opposite effect. This indicates that a delay in the cotranscriptional emergence of the 5' ss promotes ETR-3 recruitment and subsequent inhibition of E9 inclusion.
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24
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Abstract
The rapid expansion of genomics methods has enabled developmental biologists to address fundamental questions of developmental gene regulation on a genome-wide scale. These efforts have demonstrated that transcription of developmental control genes by RNA polymerase II (Pol II) is commonly regulated at the transition to productive elongation, resulting in the promoter-proximal accumulation of transcriptionally engaged but paused Pol II prior to gene induction. Here we review the mechanisms and possible functions of Pol II pausing and their implications for development.
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Affiliation(s)
- Bjoern Gaertner
- Stowers Institute for Medical Research, Kansas City, 64110 MO, USA
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25
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Jonkers I, Kwak H, Lis JT. Genome-wide dynamics of Pol II elongation and its interplay with promoter proximal pausing, chromatin, and exons. eLife 2014; 3:e02407. [PMID: 24843027 PMCID: PMC4001325 DOI: 10.7554/elife.02407] [Citation(s) in RCA: 389] [Impact Index Per Article: 38.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
Production of mRNA depends critically on the rate of RNA polymerase II (Pol II) elongation. To dissect Pol II dynamics in mouse ES cells, we inhibited Pol II transcription at either initiation or promoter-proximal pause escape with Triptolide or Flavopiridol, and tracked Pol II kinetically using GRO-seq. Both inhibitors block transcription of more than 95% of genes, showing that pause escape, like initiation, is a ubiquitous and crucial step within the transcription cycle. Moreover, paused Pol II is relatively stable, as evidenced from half-life measurements at ∼3200 genes. Finally, tracking the progression of Pol II after drug treatment establishes Pol II elongation rates at over 1000 genes. Notably, Pol II accelerates dramatically while transcribing through genes, but slows at exons. Furthermore, intergenic variance in elongation rates is substantial, and is influenced by a positive effect of H3K79me2 and negative effects of exon density and CG content within genes.DOI: http://dx.doi.org/10.7554/eLife.02407.001.
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Affiliation(s)
- Iris Jonkers
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, United States
| | - Hojoong Kwak
- Howard Hughes Medical Institute, University of Michigan, Ann Harbor, United States
| | - John T Lis
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, United States
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26
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Sena JA, Wang L, Pawlus MR, Hu CJ. HIFs enhance the transcriptional activation and splicing of adrenomedullin. Mol Cancer Res 2014; 12:728-41. [PMID: 24523299 DOI: 10.1158/1541-7786.mcr-13-0607] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
UNLABELLED Adrenomedullin (ADM) is important for tumor angiogenesis, tumor cell growth, and survival. Under normoxic conditions, the ADM gene was found to produce two alternative transcripts, a fully spliced transcript that produces AM and PAMP peptides and intron-3-retaining transcript that produces a less functionally significant PAMP peptide only. ADM is a well-established hypoxia inducible gene; however, it is not clear which ADM isoform is induced by hypoxia. In this study, it was determined that various cancer and normal cells express two predominant types of ADM transcripts, a AM/PAMP peptide producing full-length transcript in which all introns are removed, and a nonprotein producing I1-3 transcript in which all introns are retained. Interestingly, hypoxia preferentially induced the full-length isoform. Moreover, hypoxia-inducible factors (HIF), but not hypoxia per se, are necessary and sufficient to increase splicing of ADM pre-mRNA. ADM splicing reporters confirmed that transcriptional activation by HIF or other transcription factors is sufficient to enhance splicing. However, HIFs are more potent in enhancing ADM pre-mRNA splicing than other transcriptional activators. Thus, ADM intron retention is not a consequence of abnormal splicing, but is an important mechanism to regulate ADM expression. These results demonstrate a novel function of HIFs in regulating ADM expression by enhancing its pre-mRNA splicing. Importantly, using endogenous and cloned ADM gene, further evidence is provided for the coupling of transcription and RNA splicing. IMPLICATIONS Here, a novel function of HIFs in regulating ADM gene expression is identified by enhancing ADM pre-mRNA splicing.
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Affiliation(s)
- Johnny A Sena
- Authors' Affiliations: Molecular Biology Graduate Program, 2Department of Craniofacial Biology School of Dental Medicine, University of Colorado Anschutz Medical Campus, Aurora, Colorado
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27
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Stable pausing by RNA polymerase II provides an opportunity to target and integrate regulatory signals. Mol Cell 2013; 52:517-28. [PMID: 24184211 DOI: 10.1016/j.molcel.2013.10.001] [Citation(s) in RCA: 167] [Impact Index Per Article: 15.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2013] [Revised: 09/03/2013] [Accepted: 09/26/2013] [Indexed: 01/17/2023]
Abstract
Metazoan gene expression is often regulated after the recruitment of RNA polymerase II (Pol II) to promoters, through the controlled release of promoter-proximally paused Pol II into productive RNA synthesis. Despite the prevalence of paused Pol II, very little is known about the dynamics of these early elongation complexes or the fate of the short transcription start site-associated (tss) RNAs they produce. Here, we demonstrate that paused elongation complexes can be remarkably stable, with half-lives exceeding 15 min at genes with inefficient pause release. Promoter-proximal termination by Pol II is infrequent, and released tssRNAs are targeted for rapid degradation. Further, we provide evidence that the predominant tssRNA species observed are nascent RNAs held within early elongation complexes. We propose that stable pausing of polymerase provides a temporal window of opportunity for recruitment of factors to modulate gene expression and that the nascent tssRNA represents an appealing target for these interactions.
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28
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Salces-Ortiz J, González C, Moreno-Sánchez N, Calvo JH, Pérez-Guzmán MD, Serrano MM. Ovine HSP90AA1 expression rate is affected by several SNPs at the promoter under both basal and heat stress conditions. PLoS One 2013; 8:e66641. [PMID: 23826107 PMCID: PMC3691178 DOI: 10.1371/journal.pone.0066641] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2013] [Accepted: 05/08/2013] [Indexed: 11/30/2022] Open
Abstract
The aim of this work was to investigate the association between polymorphisms located at the HSP90AA1 ovine gene promoter and gene expression rate under different environmental conditions, using a mixed model approach. Blood samples from 120 unrelated rams of the Manchega sheep breed were collected at three time points differing in environmental conditions. Rams were selected on the basis of their genotype for the transversion G/C located 660 base pairs upstream the gene transcription initiation site. Animals were also genotyped for another set of 6 SNPs located at the gene promoter. Two SNPs, G/C−660 and A/G−444, were associated with gene overexpression resulting from heat stress. The composed genotype CC−660-AG−444 was the genotype having the highest expression rates with fold changes ranging from 2.2 to 3.0. The genotype AG−522 showed the highest expression levels under control conditions with a fold change of 1.4. Under these conditions, the composed genotype CC−601-TT−524-AG−522-TT−468 is expected to be correlated with higher basal expression of the gene according to genotype frequencies and linkage disequilibrium values. Some putative transcription factors were predicted for binding sites where the SNPs considered are located. Since the expression rate of the gene under alternative environmental conditions seems to depend on the composed genotype of several SNPs located at its promoter, a cooperative regulation of the transcription of the HSP90AA1 gene could be hypothesized. Nevertheless epigenetic regulation mechanisms cannot be discarded.
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Affiliation(s)
- Judit Salces-Ortiz
- Dpto. Mejora Genética animal. Inst. Nac. Invest. Agrarias y Alimentarias, Madrid, Spain.
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Valin A, Gill G. Enforcing the pause: transcription factor Sp3 limits productive elongation by RNA polymerase II. Cell Cycle 2013; 12:1828-34. [PMID: 23676218 DOI: 10.4161/cc.24992] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
The transition of paused RNA polymerase II into productive elongation is a highly dynamic process that serves to fine-tune gene expression in response to changing cellular environments. We have recently reported that the transcription factor Sp3 inhibits the transition of paused RNA Pol II to productive elongation at the promoter of the cyclin-dependent kinase inhibitor p21(CIP1) and other Sp3-repressed genes. Our studies support the view that Sp3 has three modes of action: activation, SUMO-Sp3-mediated heterochromatin silencing and SUMO-independent inhibition of elongation. At the p21(CIP1) promoter, binding of the positive elongation factor P-TEFb kinase was not affected by Sp3. In contrast, Sp3 promoted binding of the protein phosphatase PP1 to the p21(CIP1) promoter, suggesting that Sp3-dependent regulation of the local balance between kinase and phosphatase activities may contribute to gene expression. Our findings show that the transition of paused RNA Pol II to productive elongation is an important step regulated by both promoter-specific activators and repressors to finely modulate mRNA expression levels.
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Affiliation(s)
- Alvaro Valin
- Department of Anatomy and Cellular Biology, Tufts University School of Medicine, Boston, MA, USA
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Promoter-proximal pausing of RNA polymerase II: emerging roles in metazoans. Nat Rev Genet 2012; 13:720-31. [PMID: 22986266 DOI: 10.1038/nrg3293] [Citation(s) in RCA: 850] [Impact Index Per Article: 70.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Recent years have witnessed a sea change in our understanding of transcription regulation: whereas traditional models focused solely on the events that brought RNA polymerase II (Pol II) to a gene promoter to initiate RNA synthesis, emerging evidence points to the pausing of Pol II during early elongation as a widespread regulatory mechanism in higher eukaryotes. Current data indicate that pausing is particularly enriched at genes in signal-responsive pathways. Here the evidence for pausing of Pol II from recent high-throughput studies will be discussed, as well as the potential interconnected functions of promoter-proximally paused Pol II.
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Core LJ, Waterfall JJ, Gilchrist DA, Fargo DC, Kwak H, Adelman K, Lis JT. Defining the status of RNA polymerase at promoters. Cell Rep 2012; 2:1025-35. [PMID: 23062713 DOI: 10.1016/j.celrep.2012.08.034] [Citation(s) in RCA: 183] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2012] [Revised: 08/24/2012] [Accepted: 08/30/2012] [Indexed: 10/27/2022] Open
Abstract
Recent genome-wide studies in metazoans have shown that RNA polymerase II (Pol II) accumulates to high densities on many promoters at a rate-limited step in transcription. However, the status of this Pol II remains an area of debate. Here, we compare quantitative outputs of a global run-on sequencing assay and chromatin immunoprecipitation sequencing assays and demonstrate that the majority of the Pol II on Drosophila promoters is transcriptionally engaged; very little exists in a preinitiation or arrested complex. These promoter-proximal polymerases are inhibited from further elongation by detergent-sensitive factors, and knockdown of negative elongation factor, NELF, reduces their levels. These results not only solidify the notion that pausing occurs at most promoters, but demonstrate that it is the major rate-limiting step in early transcription at these promoters. Finally, the divergent elongation complexes seen at mammalian promoters are far less prevalent in Drosophila, and this specificity in orientation correlates with directional core promoter elements, which are abundant in Drosophila.
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Affiliation(s)
- Leighton J Core
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY 14853, USA
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Transition step during assembly of HIV Tat:P-TEFb transcription complexes and transfer to TAR RNA. Mol Cell Biol 2012; 32:4780-93. [PMID: 23007159 DOI: 10.1128/mcb.00206-12] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
Transcription factors regulate eukaryotic RNA polymerase II (Pol II) activity by assembling and remodeling complexes at multiple steps in the transcription cycle. In HIV, we previously proposed a two-step model where the viral Tat protein first preassembles at the promoter with an inactive P-TEFb:7SK snRNP complex and later transfers P-TEFb to TAR on the nascent transcript, displacing the inhibitory snRNP and resulting in Pol II phosphorylation and stimulation of elongation. It is unknown how the Tat:P-TEFb complex transitions to TAR to activate the P-TEFb kinase. Here, we show that P-TEFb artificially recruited to the nascent transcript is not competent for transcription but rather remains inactive due to its assembly with the 7SK snRNP. Tat supplied in trans is able to displace the kinase inhibitor Hexim1 from the snRNP and activate P-TEFb, thereby uncoupling Tat requirements for kinase activation and TAR binding. By combining comprehensive mutagenesis of Tat with multiple cell-based reporter assays that probe the activity of Tat in different arrangements, we genetically defined a transition step in which preassembled Tat:P-TEFb complexes switch to TAR. We propose that a conserved network of residues in Tat has evolved to control this transition and thereby switch the host elongation machinery to viral transcription.
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Jenkins LMM, Durell SR, Mazur SJ, Appella E. p53 N-terminal phosphorylation: a defining layer of complex regulation. Carcinogenesis 2012; 33:1441-9. [PMID: 22505655 DOI: 10.1093/carcin/bgs145] [Citation(s) in RCA: 83] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
The p53 tumor suppressor is a critical component of the cellular response to stress. As it can inhibit cell growth, p53 is mutated or functionally inactivated in most tumors. A multitude of protein-protein interactions with transcriptional cofactors are central to p53-dependent responses. In its activated state, p53 is extensively modified in both the N- and C-terminal regions of the protein. These modifications, especially phosphorylation of serine and threonine residues in the N-terminal transactivation domain, affect p53 stability and activity by modulating the affinity of protein-protein interactions. Here, we review recent findings from in vitro and in vivo studies on the role of p53 N-terminal phosphorylation. These modifications can either positively or negatively affect p53 and add a second layer of complex regulation to the divergent interactions of the p53 transactivation domain.
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Affiliation(s)
- Lisa M Miller Jenkins
- Laboratory of Cell Biology, National Cancer Institute, NIH, 37 Convent Drive, Room 2140, Bethesda, MD 20892, USA
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Control of Transcriptional Elongation by RNA Polymerase II: A Retrospective. GENETICS RESEARCH INTERNATIONAL 2012; 2012:170173. [PMID: 22567377 PMCID: PMC3335475 DOI: 10.1155/2012/170173] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/12/2011] [Accepted: 10/11/2011] [Indexed: 11/17/2022]
Abstract
The origins of our current understanding of control of transcription elongation lie in pioneering experiments that mapped RNA polymerase II on viral and cellular genes. These studies first uncovered the surprising excess of polymerase molecules that we now know to be situated at the at the 5' ends of most genes in multicellular organisms. The pileup of pol II near transcription start sites reflects a ubiquitous bottle-neck that limits elongation right at the start of the transcription elongation. Subsequent seminal work identified conserved protein factors that positively and negatively control the flux of polymerase through this bottle-neck, and make a major contribution to control of gene expression.
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Langlois C, Del Gatto A, Arseneault G, Lafrance-Vanasse J, De Simone M, Morse T, de Paola I, Lussier-Price M, Legault P, Pedone C, Zaccaro L, Omichinski JG. Structure-based design of a potent artificial transactivation domain based on p53. J Am Chem Soc 2012; 134:1715-23. [PMID: 22191432 DOI: 10.1021/ja208999e] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Malfunctions in transcriptional regulation are associated with a number of critical human diseases. As a result, there is considerable interest in designing artificial transcription activators (ATAs) that specifically control genes linked to human diseases. Like native transcriptional activator proteins, an ATA must minimally contain a DNA-binding domain (DBD) and a transactivation domain (TAD) and, although there are several reliable methods for designing artificial DBDs, designing artificial TADs has proven difficult. In this manuscript, we present a structure-based strategy for designing short peptides containing natural amino acids that function as artificial TADs. Using a segment of the TAD of p53 as the scaffolding, modifications are introduced to increase the helical propensity of the peptides. The most active artificial TAD, termed E-Cap-(LL), is a 13-mer peptide that contains four key residues from p53, an N-capping motif and a dileucine hydrophobic bridge. In vitro analysis demonstrates that E-Cap-(LL) interacts with several known p53 target proteins, while in vivo studies in a yeast model system show that it is a 20-fold more potent transcriptional activator than the native p53-13 peptide. These results demonstrate that structure-based design represents a promising approach for developing artificial TADs that can be combined with artificial DBDs to create potent and specific ATAs.
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Affiliation(s)
- Chantal Langlois
- Département de Biochimie, Université de Montréal, C.P. 6128 Succursale, Centre-Ville, Montréal, Quebec H3C 3J7, Canada
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Transcriptional activators and activation mechanisms. Protein Cell 2011; 2:879-88. [PMID: 22180087 DOI: 10.1007/s13238-011-1101-7] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2011] [Accepted: 08/22/2011] [Indexed: 10/14/2022] Open
Abstract
Transcriptional activators are required to turn on the expression of genes in a eukaryotic cell. Activators bound to the enhancer can facilitate either the recruitment of RNA polymerase II to the promoter or its elongation. This article examines a few selected issues in understanding activator functions and activation mechanisms.
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Liu PY, Hsieh TY, Liu ST, Chang YL, Lin WS, Wang WM, Huang SM. Zac1, an Sp1-like protein, regulates human p21WAF1/Cip1 gene expression in HeLa cells. Exp Cell Res 2011; 317:2925-37. [DOI: 10.1016/j.yexcr.2011.09.018] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2011] [Revised: 09/26/2011] [Accepted: 09/30/2011] [Indexed: 11/26/2022]
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Hirai H, Tani T, Kikyo N. Structure and functions of powerful transactivators: VP16, MyoD and FoxA. THE INTERNATIONAL JOURNAL OF DEVELOPMENTAL BIOLOGY 2011; 54:1589-96. [PMID: 21404180 DOI: 10.1387/ijdb.103194hh] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
Induced pluripotent stem cell (iPSC) technology is a promising approach for converting one type of a differentiated cell into another type of differentiated cell through a pluripotent state as an intermediate step. Recent studies, however, indicate the possibility of directly converting one cell type to another without going through a pluripotent state. This direct reprogramming approach is dependent on a combination of highly potent transcription factors for cell-type conversion, presumably skipping more physiological and multi-step differentiation processes. A trial-and-error strategy is commonly used to screen many candidate transcription factors to identify the correct combination of factors. We speculate, however, that a better understanding of the functional mechanisms of exemplary transcriptional activators will facilitate the identification of novel factor combinations capable of direct reprogramming. The purpose of this review is to critically examine the literature on three highly potent transcriptional activators: the herpes virus protein, VP16; the master regulator of skeletal muscle differentiation, MyoD and the "pioneer" factor for hepatogenesis, FoxA. We discuss the roles of their functional protein domains, interacting partners and chromatin remodeling mechanisms during gene activation to understand how these factors open the chromatin of inactive genes and reset the transcriptional pattern during cell type conversion.
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Haddad D, Puget N, Laviolette-Malirat N, Conte C, Khamlichi AA. Seeking sense of antisense switch transcripts. Transcription 2011; 2:183-188. [PMID: 21922061 DOI: 10.4161/trns.2.4.16784] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2011] [Revised: 06/03/2011] [Accepted: 06/03/2011] [Indexed: 11/19/2022] Open
Abstract
In B lymphocytes, class switch recombination (CSR) machinery targets highly repetitive sequences, called switch (S) sequences, in the constant domain of the immunoglobulin heavy chain (IgH) locus. Cotranscriptional generation of R loops at S sequences provides the substrate for the mutagenic enzyme AID (Activation-Induced cytidine Deaminase), which initiates the DNA breaks at the transcribed sequences. Both sense and antisense transcripts across the S regions have been reported. Our recent work shows that, unlike its sense counterpart, antisense transcription of S sequences is dispensable for CSR in vivo.
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Affiliation(s)
- Dania Haddad
- CNRS UMR 5089-IPBS (Institut de Pharmacologie et de Biologie Structurale) and Université Paul Sabatier III; Equipe "Instabilité Génétique et Régulation Transcriptionnelle"; Université de Toulouse; Toulouse, France
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40
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Hichri I, Deluc L, Barrieu F, Bogs J, Mahjoub A, Regad F, Gallois B, Granier T, Trossat-Magnin C, Gomès E, Lauvergeat V. A single amino acid change within the R2 domain of the VvMYB5b transcription factor modulates affinity for protein partners and target promoters selectivity. BMC PLANT BIOLOGY 2011; 11:117. [PMID: 21861899 PMCID: PMC3240579 DOI: 10.1186/1471-2229-11-117] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/30/2011] [Accepted: 08/23/2011] [Indexed: 05/20/2023]
Abstract
BACKGROUND Flavonoid pathway is spatially and temporally controlled during plant development and the transcriptional regulation of the structural genes is mostly orchestrated by a ternary protein complex that involves three classes of transcription factors (R2-R3-MYB, bHLH and WDR). In grapevine (Vitis vinifera L.), several MYB transcription factors have been identified but the interactions with their putative bHLH partners to regulate specific branches of the flavonoid pathway are still poorly understood. RESULTS In this work, we describe the effects of a single amino acid substitution (R69L) located in the R2 domain of VvMYB5b and predicted to affect the formation of a salt bridge within the protein. The activity of the mutated protein (name VvMYB5b(L), the native protein being referred as VvMYB5b(R)) was assessed in different in vivo systems: yeast, grape cell suspensions, and tobacco. In the first two systems, VvMYB5b(L) exhibited a modified trans-activation capability. Moreover, using yeast two-hybrid assay, we demonstrated that modification of VvMYB5b transcriptional properties impaired its ability to correctly interact with VvMYC1, a grape bHLH protein. These results were further substantiated by overexpression of VvMYB5b(R) and VvMYB5b(L) genes in tobacco. Flowers from 35S::VvMYB5b(L) transgenic plants showed a distinct phenotype in comparison with 35S::VvMYB5b(R) and the control plants. Finally, significant differences in transcript abundance of flavonoid metabolism genes were observed along with variations in pigments accumulation. CONCLUSIONS Taken together, our findings indicate that VvMYB5b(L) is still able to bind DNA but the structural consequences linked to the mutation affect the capacity of the protein to activate the transcription of some flavonoid genes by modifying the interaction with its co-partner(s). In addition, this study underlines the importance of an internal salt bridge for protein conformation and thus for the establishment of protein-protein interactions between MYB and bHLH transcription factors. Mechanisms underlying these interactions are discussed and a model is proposed to explain the transcriptional activity of VvMYB5(L) observed in the tobacco model.
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Affiliation(s)
- Imène Hichri
- Univ. de Bordeaux, Institut des Sciences de la Vigne et du Vin (ISVV), UMR 1287 Ecophysiologie et Génomique Fonctionnelle de la Vigne (EGFV), 210 Chemin de Leysotte, 33882 Villenave d'Ornon, France
- INRA, ISVV, UMR 1287 EGFV, 33882 Villenave d'Ornon, France
- ENITAB, ISVV, UMR 1287 EGFV, 33882 Villenave d'Ornon, France
| | - Laurent Deluc
- Department of Horticulture, Oregon State University, Corvallis, Oregon 97331, USA
| | - François Barrieu
- Univ. de Bordeaux, Institut des Sciences de la Vigne et du Vin (ISVV), UMR 1287 Ecophysiologie et Génomique Fonctionnelle de la Vigne (EGFV), 210 Chemin de Leysotte, 33882 Villenave d'Ornon, France
- INRA, ISVV, UMR 1287 EGFV, 33882 Villenave d'Ornon, France
- ENITAB, ISVV, UMR 1287 EGFV, 33882 Villenave d'Ornon, France
| | - Jochen Bogs
- Dienstleistungszentrum Landlicher Raum (DLR) Rheinpfalz, Breitenweg 71, Viticulture and Enology group, D-67435 Neustadt/W, Germany
- Fachhochschule Bingen, Berlinstr. 109, 55411 Bingen am Rhein, Germany
| | - Ali Mahjoub
- Univ. de Bordeaux, Institut des Sciences de la Vigne et du Vin (ISVV), UMR 1287 Ecophysiologie et Génomique Fonctionnelle de la Vigne (EGFV), 210 Chemin de Leysotte, 33882 Villenave d'Ornon, France
- INRA, ISVV, UMR 1287 EGFV, 33882 Villenave d'Ornon, France
- ENITAB, ISVV, UMR 1287 EGFV, 33882 Villenave d'Ornon, France
| | - Farid Regad
- Université de Toulouse, INP-ENSAT Toulouse, Génomique et Biotechnologie des Fruits, Avenue de l'Agrobiopole BP 32607, 31326 Castanet-Tolosan, France
| | - Bernard Gallois
- Chimie et Biologie des Membranes et des Nanoobjets, UMR CNRS 5248, Bâtiment B14bis, Allée Geoffroy de Saint Hilaire, Université Bordeaux, 33600 Pessac, France
| | - Thierry Granier
- Chimie et Biologie des Membranes et des Nanoobjets, UMR CNRS 5248, Bâtiment B14bis, Allée Geoffroy de Saint Hilaire, Université Bordeaux, 33600 Pessac, France
| | - Claudine Trossat-Magnin
- Univ. de Bordeaux, Institut des Sciences de la Vigne et du Vin (ISVV), UMR 1287 Ecophysiologie et Génomique Fonctionnelle de la Vigne (EGFV), 210 Chemin de Leysotte, 33882 Villenave d'Ornon, France
- INRA, ISVV, UMR 1287 EGFV, 33882 Villenave d'Ornon, France
- ENITAB, ISVV, UMR 1287 EGFV, 33882 Villenave d'Ornon, France
| | - Eric Gomès
- Univ. de Bordeaux, Institut des Sciences de la Vigne et du Vin (ISVV), UMR 1287 Ecophysiologie et Génomique Fonctionnelle de la Vigne (EGFV), 210 Chemin de Leysotte, 33882 Villenave d'Ornon, France
- INRA, ISVV, UMR 1287 EGFV, 33882 Villenave d'Ornon, France
- ENITAB, ISVV, UMR 1287 EGFV, 33882 Villenave d'Ornon, France
| | - Virginie Lauvergeat
- Univ. de Bordeaux, Institut des Sciences de la Vigne et du Vin (ISVV), UMR 1287 Ecophysiologie et Génomique Fonctionnelle de la Vigne (EGFV), 210 Chemin de Leysotte, 33882 Villenave d'Ornon, France
- INRA, ISVV, UMR 1287 EGFV, 33882 Villenave d'Ornon, France
- ENITAB, ISVV, UMR 1287 EGFV, 33882 Villenave d'Ornon, France
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Haddad D, Oruc Z, Puget N, Laviolette-Malirat N, Philippe M, Carrion C, Le Bert M, Khamlichi AA. Sense transcription through the S region is essential for immunoglobulin class switch recombination. EMBO J 2011; 30:1608-20. [PMID: 21378751 DOI: 10.1038/emboj.2011.56] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2010] [Accepted: 02/07/2011] [Indexed: 11/10/2022] Open
Abstract
Class switch recombination (CSR) occurs between highly repetitive sequences called switch (S) regions and is initiated by activation-induced cytidine deaminase (AID). CSR is preceded by a bidirectional transcription of S regions but the relative importance of sense and antisense transcription for CSR in vivo is unknown. We generated three mouse lines in which we attempted a premature termination of transcriptional elongation by inserting bidirectional transcription terminators upstream of Sμ, upstream of Sγ3 or downstream of Sγ3 sequences. The data show, at least for Sγ3, that sense transcriptional elongation across S region is absolutely required for CSR whereas its antisense counterpart is largely dispensable, strongly suggesting that sense transcription is sufficient for AID targeting to both DNA strands.
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Affiliation(s)
- Dania Haddad
- CNRS UMR 5089-IPBS (Institut de Pharmacologie et de Biologie Structurale) and Université Paul Sabatier III, Equipe 'Instabilité génétique et régulation transcriptionnelle', Toulouse Cedex, France
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Abstract
The last decade has seen an incredible breakthrough in technologies that allow histones, transcription factors (TFs), and RNA polymerases to be precisely mapped throughout the genome. From this research, it is clear that there is a complex interaction between the chromatin landscape and the general transcriptional machinery and that the dynamic control of this interface is central to gene regulation. However, the chromatin remodeling enzymes and general TFs cannot, on their own, recognize and stably bind to promoter or enhancer regions. Rather, they are recruited to cis regulatory regions through interaction with site-specific DNA binding TFs and/or proteins that recognize epigenetic marks such as methylated cytosines or specifically modified amino acids in histones. These "recruitment" factors are modular in structure, reflecting their ability to interact with the genome via one region of the protein and to simultaneously bind to other regulatory proteins via "effector" domains. In this chapter, we provide examples of common effector domains that can function in transcriptional regulation via their ability to (a) interact with the basal transcriptional machinery and general co-activators, (b) interact with other TFs to allow cooperative binding, and (c) directly or indirectly recruit histone and chromatin modifying enzymes.
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Affiliation(s)
- Seth Frietze
- Department of Biochemistry and Molecular Biology, University of Southern California, Los Angeles, CA, 90033, USA,
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Kitchen NS, Schoenherr CJ. Sumoylation modulates a domain in CTCF that activates transcription and decondenses chromatin. J Cell Biochem 2010; 111:665-75. [DOI: 10.1002/jcb.22751] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
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Molvaersmyr AK, Saether T, Gilfillan S, Lorenzo PI, Kvaløy H, Matre V, Gabrielsen OS. A SUMO-regulated activation function controls synergy of c-Myb through a repressor-activator switch leading to differential p300 recruitment. Nucleic Acids Res 2010; 38:4970-84. [PMID: 20385574 PMCID: PMC2926607 DOI: 10.1093/nar/gkq245] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Synergy between transcription factors operating together on complex promoters is a key aspect of gene activation. The ability of specific factors to synergize is restricted by sumoylation (synergy control, SC). Focusing on the haematopoietic transcription factor c-Myb, we found evidence for a strong SC linked to SUMO-conjugation in its negative regulatory domain (NRD), while AMV v-Myb has escaped this control. Mechanistic studies revealed a SUMO-dependent switch in the function of NRD. When NRD is sumoylated, the activity of c-Myb is reduced. When sumoylation is abolished, NRD switches into being activating, providing the factor with a second activation function (AF). Thus, c-Myb harbours two AFs, one that is constitutively active and one in the NRD being SUMO-regulated (SRAF). This double AF augments c-Myb synergy at compound natural promoters. A similar SUMO-dependent switch was observed in the regulatory domains of Sp3 and p53. We show that the change in synergy behaviour correlates with a SUMO-dependent differential recruitment of p300 and a corresponding local change in histone H3 and H4 acetylation. We therefore propose a general model for SUMO-mediated SC, where SUMO controls synergy by determining the number and strength of AFs associated with a promoter leading to differential chromatin signatures.
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Arabidopsis IWS1 interacts with transcription factor BES1 and is involved in plant steroid hormone brassinosteroid regulated gene expression. Proc Natl Acad Sci U S A 2010; 107:3918-23. [PMID: 20139304 DOI: 10.1073/pnas.0909198107] [Citation(s) in RCA: 113] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Plant steroid hormones, brassinosteroids (BRs), regulate essential growth and developmental processes. BRs signal through membrane-localized receptor BRI1 and several other signaling components to regulate the BES1 and BZR1 family transcription factors, which in turn control the expression of hundreds of target genes. However, knowledge about the transcriptional mechanisms by which BES1/BZR1 regulate gene expression is limited. By a forward genetic approach, we have discovered that Arabidopsis thaliana Interact-With-Spt6 (AtIWS1), an evolutionarily conserved protein implicated in RNA polymerase II (RNAPII) postrecruitment and transcriptional elongation processes, is required for BR-induced gene expression. Loss-of-function mutations in AtIWS1 lead to overall dwarfism in Arabidopsis, reduced BR response, genome-wide decrease in BR-induced gene expression, and hypersensitivity to a transcription elongation inhibitor. Moreover, AtIWS1 interacts with BES1 both in vitro and in vivo. Chromatin immunoprecipitation experiments demonstrated that the presence of AtIWS1 is enriched in transcribed as well as promoter regions of the target genes under BR-induced conditions. Our results suggest that AtIWS1 is recruited to target genes by BES1 to promote gene expression during transcription elongation process. Recent genomic studies have indicated that a large number of genes could be regulated at steps after RNAPII recruitment; however, the mechanisms for such regulation have not been well established. The study therefore not only establishes an important role for AtIWS1 in plant steroid-induced gene expression but also suggests an exciting possibility that IWS1 protein can function as a target for pathway-specific activators, thereby providing a unique mechanism for the control of gene expression.
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Elena C, Banchio C. Specific interaction between E2F1 and Sp1 regulates the expression of murine CTP:phosphocholine cytidylyltransferase alpha during the S phase. Biochim Biophys Acta Mol Cell Biol Lipids 2010; 1801:537-46. [PMID: 20096375 DOI: 10.1016/j.bbalip.2010.01.005] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2009] [Revised: 01/06/2010] [Accepted: 01/13/2010] [Indexed: 11/16/2022]
Abstract
CTP:phosphocholine cytidylyltransferase alpha (CCTalpha) is a key enzyme for phosphatidylcholine biosynthesis in mammalian cells. This enzyme plays an essential role in all processes that require membrane biosynthesis such as cell proliferation and viability. Thus, CCTalpha activity and expression fluctuate during the cell cycle to achieve PtdCho requirements. We demonstrated, for the first time, that CCTalpha is localized in the nucleus in cells transiting the S phase, whereas it is localized in the cytoplasm of G(0)-arrested cells, suggesting a specific role of nuclear CCTalpha during the S phase. We also investigated how E2F1 influences the regulation of the CCTalpha-promoter during the S phase; we demonstrated that E2F1 is necessary, but not sufficient, to activate CCTalpha expression when this factor is over-expressed. However, when E2F1 and Sp1 were over-expressed, the transcription from the CCTalpha-promoter reporter construct was super-activated. Transient transfection studies demonstrated that E2F1 could super-activate Sp1-dependent transcription in a promoter containing only the Sp1 binding sites "B" or "C", and that Sp1 could activate Sp1-dependent transcription in a promoter containing the E2F site, thus, further demonstrating a functional interaction of these factors. In conclusion, the present results allowed us to portray the clearest picture of the CCTalpha-gene expression in proliferating cells, and understand the mechanism by which cells coordinate cell cycle progression with the requirement for phosphatidylcholine.
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Affiliation(s)
- Claudia Elena
- IBR (Instituto de Biología Molecular y Celular de Rosario), Consejo Nacional de Investigaciones Científicas y Técnicas, Area Biología, Departamento de Ciencias Biológicas, Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Suipacha 531, Rosario, Argentina
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Abstract
In the eukaryotic genome, the thousands of genes that encode messenger RNA are transcribed by a molecular machine called RNA polymerase II. Analysing the distribution and status of RNA polymerase II across a genome has provided crucial insights into the long-standing mysteries of transcription and its regulation. These studies identify points in the transcription cycle where RNA polymerase II accumulates after encountering a rate-limiting step. When coupled with genome-wide mapping of transcription factors, these approaches identify key regulatory steps and factors and, importantly, provide an understanding of the mechanistic generalities, as well as the rich diversities, of gene regulation.
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Lim PS, Hardy K, Bunting KL, Ma L, Peng K, Chen X, Shannon MF. Defining the chromatin signature of inducible genes in T cells. Genome Biol 2009; 10:R107. [PMID: 19807913 PMCID: PMC2784322 DOI: 10.1186/gb-2009-10-10-r107] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2009] [Revised: 07/27/2009] [Accepted: 10/06/2009] [Indexed: 12/18/2022] Open
Abstract
Inducible genes in T cells show the chromatin characteristics of active genes, suggesting they are primed for transcription. Background Specific chromatin characteristics, especially the modification status of the core histone proteins, are associated with active and inactive genes. There is growing evidence that genes that respond to environmental or developmental signals may possess distinct chromatin marks. Using a T cell model and both genome-wide and gene-focused approaches, we examined the chromatin characteristics of genes that respond to T cell activation. Results To facilitate comparison of genes with similar basal expression levels, we used expression-profiling data to bin genes according to their basal expression levels. We found that inducible genes in the lower basal expression bins, especially rapidly induced primary response genes, were more likely than their non-responsive counterparts to display the histone modifications of active genes, have RNA polymerase II (Pol II) at their promoters and show evidence of ongoing basal elongation. There was little or no evidence for the presence of active chromatin marks in the absence of promoter Pol II on these inducible genes. In addition, we identified a subgroup of genes with active promoter chromatin marks and promoter Pol II but no evidence of elongation. Following T cell activation, we find little evidence for a major shift in the active chromatin signature around inducible gene promoters but many genes recruit more Pol II and show increased evidence of elongation. Conclusions These results suggest that the majority of inducible genes are primed for activation by having an active chromatin signature and promoter Pol II with or without ongoing elongation.
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Affiliation(s)
- Pek S Lim
- Genome Biology Program and ACRF Biomolecular Resource Facility, John Curtin School of Medical Research, The Australian National University, Garran Road, Acton, ACT 0200, Australia.
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Alló M, Buggiano V, Fededa JP, Petrillo E, Schor I, de la Mata M, Agirre E, Plass M, Eyras E, Elela SA, Klinck R, Chabot B, Kornblihtt AR. Control of alternative splicing through siRNA-mediated transcriptional gene silencing. Nat Struct Mol Biol 2009; 16:717-24. [PMID: 19543290 DOI: 10.1038/nsmb.1620] [Citation(s) in RCA: 257] [Impact Index Per Article: 17.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2008] [Accepted: 05/15/2009] [Indexed: 02/07/2023]
Abstract
When targeting promoter regions, small interfering RNAs (siRNAs) trigger a previously proposed pathway known as transcriptional gene silencing by promoting heterochromatin formation. Here we show that siRNAs targeting intronic or exonic sequences close to an alternative exon regulate the splicing of that exon. The effect occurred in hepatoma and HeLa cells with siRNA antisense strands designed to enter the silencing pathway, suggesting hybridization with nascent pre-mRNA. Unexpectedly, in HeLa cells the sense strands were also effective, suggesting that an endogenous antisense transcript, detectable in HeLa but not in hepatoma cells, acts as a target. The effect depends on Argonaute-1 and is counterbalanced by factors favoring chromatin opening or transcriptional elongation. The increase in heterochromatin marks (dimethylation at Lys9 and trimethylation at Lys27 of histone H3) at the target site, the need for the heterochromatin-associated protein HP1alpha and the reduction in RNA polymerase II processivity suggest a mechanism involving the kinetic coupling of transcription and alternative splicing.
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Affiliation(s)
- Mariano Alló
- Laboratorio de Fisiología y Biología Molecular, Departamento de Fisiología, Biología Molecular y Celular, IFIBYNE-CONICET, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Ciudad Universitaria, Buenos Aires, Argentina
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Rossi M, Demidov ON, Anderson CW, Appella E, Mazur SJ. Induction of PPM1D following DNA-damaging treatments through a conserved p53 response element coincides with a shift in the use of transcription initiation sites. Nucleic Acids Res 2008; 36:7168-80. [PMID: 19015127 PMCID: PMC2602757 DOI: 10.1093/nar/gkn888] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
PPM1D (Wip1), a type PP2C phosphatase, is expressed at low levels in most normal tissues but is overexpressed in several types of cancers. In cells containing wild-type p53, the levels of PPM1D mRNA and protein increase following exposure to genotoxic stress, but the mechanism of regulation by p53 was unknown. PPM1D also has been identified as a CREB-regulated gene due to the presence of a cyclic AMP response element (CRE) in the promoter. Transient transfection and chromatin immunoprecipitation experiments in HCT116 cells were used to characterize a conserved p53 response element located in the 5' untranslated region (UTR) of the PPM1D gene that is required for the p53-dependent induction of transcription from the human PPM1D promoter. CREB binding to the CRE contributes to the regulation of basal expression of PPM1D and directs transcription initiation at upstream sites. Following exposure to ultraviolet (UV) or ionizing radiation, the abundance of transcripts with short 5' UTRs increased in cells containing wild-type p53, indicating increased utilization of downstream transcription initiation sites. In cells containing wild-type p53, exposure to UV resulted in increased PPM1D protein levels even when PPM1D mRNA levels remained constant, indicating post-transcriptional regulation of PPM1D protein levels.
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Affiliation(s)
- Matteo Rossi
- Laboratory of Cell Biology, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA
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