251
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Wen H, Li Y, Xi Y, Jiang S, Stratton S, Peng D, Tanaka K, Ren Y, Xia Z, Wu J, Li B, Barton MC, Li W, Li H, Shi X. ZMYND11 links histone H3.3K36me3 to transcription elongation and tumour suppression. Nature 2014; 508:263-8. [PMID: 24590075 DOI: 10.1038/nature13045] [Citation(s) in RCA: 229] [Impact Index Per Article: 22.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2013] [Accepted: 01/20/2014] [Indexed: 12/31/2022]
Abstract
Recognition of modified histones by 'reader' proteins plays a critical role in the regulation of chromatin. H3K36 trimethylation (H3K36me3) is deposited onto the nucleosomes in the transcribed regions after RNA polymerase II elongation. In yeast, this mark in turn recruits epigenetic regulators to reset the chromatin to a relatively repressive state, thus suppressing cryptic transcription. However, much less is known about the role of H3K36me3 in transcription regulation in mammals. This is further complicated by the transcription-coupled incorporation of the histone variant H3.3 in gene bodies. Here we show that the candidate tumour suppressor ZMYND11 specifically recognizes H3K36me3 on H3.3 (H3.3K36me3) and regulates RNA polymerase II elongation. Structural studies show that in addition to the trimethyl-lysine binding by an aromatic cage within the PWWP domain, the H3.3-dependent recognition is mediated by the encapsulation of the H3.3-specific 'Ser 31' residue in a composite pocket formed by the tandem bromo-PWWP domains of ZMYND11. Chromatin immunoprecipitation followed by sequencing shows a genome-wide co-localization of ZMYND11 with H3K36me3 and H3.3 in gene bodies, and its occupancy requires the pre-deposition of H3.3K36me3. Although ZMYND11 is associated with highly expressed genes, it functions as an unconventional transcription co-repressor by modulating RNA polymerase II at the elongation stage. ZMYND11 is critical for the repression of a transcriptional program that is essential for tumour cell growth; low expression levels of ZMYND11 in breast cancer patients correlate with worse prognosis. Consistently, overexpression of ZMYND11 suppresses cancer cell growth in vitro and tumour formation in mice. Together, this study identifies ZMYND11 as an H3.3-specific reader of H3K36me3 that links the histone-variant-mediated transcription elongation control to tumour suppression.
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Affiliation(s)
- Hong Wen
- 1] Department of Biochemistry and Molecular Biology, The University of Texas MD Anderson Cancer Center, Houston, Texas 77030, USA [2] Center for Cancer Epigenetics, Center for Genetics and Genomics, and Center for Stem Cell and Developmental Biology, The University of Texas MD Anderson Cancer Center, Houston, Texas 77030, USA [3]
| | - Yuanyuan Li
- 1] MOE Key Laboratory of Protein Sciences, Center for Structural Biology, School of Life Sciences, Tsinghua University, Beijing 100084, China [2] Department of Basic Medical Sciences, School of Medicine, Tsinghua University, Beijing 100084, China [3]
| | - Yuanxin Xi
- 1] Dan L. Duncan Cancer Center, Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, Texas 77030, USA [2]
| | - Shiming Jiang
- Department of Biochemistry and Molecular Biology, The University of Texas MD Anderson Cancer Center, Houston, Texas 77030, USA
| | - Sabrina Stratton
- Department of Biochemistry and Molecular Biology, The University of Texas MD Anderson Cancer Center, Houston, Texas 77030, USA
| | - Danni Peng
- Department of Biochemistry and Molecular Biology, The University of Texas MD Anderson Cancer Center, Houston, Texas 77030, USA
| | - Kaori Tanaka
- Department of Biochemistry and Molecular Biology, The University of Texas MD Anderson Cancer Center, Houston, Texas 77030, USA
| | - Yongfeng Ren
- 1] MOE Key Laboratory of Protein Sciences, Center for Structural Biology, School of Life Sciences, Tsinghua University, Beijing 100084, China [2] Department of Basic Medical Sciences, School of Medicine, Tsinghua University, Beijing 100084, China
| | - Zheng Xia
- Dan L. Duncan Cancer Center, Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, Texas 77030, USA
| | - Jun Wu
- Department of Molecular Biology, The University of Texas Southwestern Medical Center, Dallas, Texas 75390, USA
| | - Bing Li
- Department of Molecular Biology, The University of Texas Southwestern Medical Center, Dallas, Texas 75390, USA
| | - Michelle C Barton
- 1] Department of Biochemistry and Molecular Biology, The University of Texas MD Anderson Cancer Center, Houston, Texas 77030, USA [2] Center for Cancer Epigenetics, Center for Genetics and Genomics, and Center for Stem Cell and Developmental Biology, The University of Texas MD Anderson Cancer Center, Houston, Texas 77030, USA [3] Genes and Development Graduate Program, The University of Texas Graduate School of Biomedical Sciences, Houston, Teaxs 77030, USA
| | - Wei Li
- Dan L. Duncan Cancer Center, Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, Texas 77030, USA
| | - Haitao Li
- 1] MOE Key Laboratory of Protein Sciences, Center for Structural Biology, School of Life Sciences, Tsinghua University, Beijing 100084, China [2] Department of Basic Medical Sciences, School of Medicine, Tsinghua University, Beijing 100084, China
| | - Xiaobing Shi
- 1] Department of Biochemistry and Molecular Biology, The University of Texas MD Anderson Cancer Center, Houston, Texas 77030, USA [2] Center for Cancer Epigenetics, Center for Genetics and Genomics, and Center for Stem Cell and Developmental Biology, The University of Texas MD Anderson Cancer Center, Houston, Texas 77030, USA [3] Genes and Development Graduate Program, The University of Texas Graduate School of Biomedical Sciences, Houston, Teaxs 77030, USA
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252
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Villicaña C, Cruz G, Zurita M. The basal transcription machinery as a target for cancer therapy. Cancer Cell Int 2014; 14:18. [PMID: 24576043 PMCID: PMC3942515 DOI: 10.1186/1475-2867-14-18] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2013] [Accepted: 02/21/2014] [Indexed: 01/11/2023] Open
Abstract
General transcription is required for the growth and survival of all living cells. However, tumor cells require extraordinary levels of transcription, including the transcription of ribosomal RNA genes by RNA polymerase I (RNPI) and mRNA by RNA polymerase II (RNPII). In fact, cancer cells have mutations that directly enhance transcription and are frequently required for cancer transformation. For example, the recent discovery that MYC enhances the transcription of the majority genes in the genome correlates with the fact that several transcription interfering drugs preferentially kill cancer cells. In recent years, advances in the mechanistic studies of the basal transcription machinery and the discovery of drugs that interfere with multiple components of transcription are being used to combat cancer. For example, drugs such as triptolide that targets the general transcription factors TFIIH and JQ1 to inhibit BRD4 are administered to target the high proliferative rate of cancer cells. Given the importance of finding new strategies to preferentially sensitize tumor cells, this review primarily focuses on several transcription inhibitory drugs to demonstrate that the basal transcription machinery constitutes a potential target for the design of novel cancer drugs. We highlight the drugs’ mechanisms for interfering with tumor cell survival, their importance in cancer treatment and the challenges of clinical application.
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Affiliation(s)
| | | | - Mario Zurita
- Departament of Developmental Genetics, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Mexico, Mexico.
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253
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Smale ST, Tarakhovsky A, Natoli G. Chromatin contributions to the regulation of innate immunity. Annu Rev Immunol 2014; 32:489-511. [PMID: 24555473 DOI: 10.1146/annurev-immunol-031210-101303] [Citation(s) in RCA: 127] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
A fundamental property of cells of the innate immune system is their ability to elicit a transcriptional response to a microbial stimulus or danger signal with a high degree of cell type and stimulus specificity. The selective response activates effector pathways to control the insult and plays a central role in regulating adaptive immunity through the differential regulation of cytokine genes. Selectivity is dictated by signaling pathways and their transcription factor targets. However, a growing body of evidence supports models in which different subsets of genes exhibit distinct chromatin features that play active roles in shaping the response. Chromatin also participates in innate memory mechanisms that can promote tolerance to a stimulus or prime cells for a more robust response. These findings have generated interest in the capacity to modulate chromatin regulators with small-molecule compounds for the treatment of diseases associated with innate or adaptive immunity.
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Affiliation(s)
- Stephen T Smale
- Department of Microbiology, Immunology, and Molecular Genetics, University of California, Los Angeles, California 90095;
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254
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Regulation of MYC expression and differential JQ1 sensitivity in cancer cells. PLoS One 2014; 9:e87003. [PMID: 24466310 PMCID: PMC3900694 DOI: 10.1371/journal.pone.0087003] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2013] [Accepted: 12/16/2013] [Indexed: 11/19/2022] Open
Abstract
High level MYC expression is associated with almost all human cancers. JQ1, a chemical compound that inhibits MYC expression is therapeutically effective in preclinical animal models in midline carcinoma, and Burkitt's lymphoma (BL). Here we show that JQ1 does not inhibit MYC expression to a similar extent in all tumor cells. The BL cells showed a ∼90% decrease in MYC transcription upon treatment with JQ1, however, no corresponding reduction was seen in several non-BL cells. Molecularly, these differences appear due to requirements of Brd4, the most active version of the Positive Transcription Elongation Factor B (P-TEFb) within the Super Elongation Complex (SEC), and transcription factors such as Gdown1, and MED26 and also other unknown cell specific factors. Our study demonstrates that the regulation of high levels of MYC expression in different cancer cells is driven by unique regulatory mechanisms and that such exclusive regulatory signatures in each cancer cells could be employed for targeted therapeutics.
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255
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ELL inhibits E2F1 transcriptional activity by enhancing E2F1 deacetylation via recruitment of histone deacetylase 1. Mol Cell Biol 2013; 34:765-75. [PMID: 24344198 DOI: 10.1128/mcb.00878-13] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
ELL (eleven-nineteen lysine-rich leukemia protein) was first identified as a translocation partner of MLL in acute myeloid leukemia; however, the exact mechanism of its action has remained elusive. In this study, we identified ELL as a direct downstream target gene of E2F1. Coimmunoprecipitation assays showed that ELL interacted with E2F1 in vitro and in vivo, leading to inhibition of E2F1 transcriptional activity. In addition, ELL enhanced E2F1 deacetylation via recruitment of histone deacetylase 1 (HDAC1). Notably, the MLL-ELL fusion protein lost the inhibitory role of ELL in E2F1 transcriptional activity. Furthermore, DNA damage induced ELL in an E2F1-dependent manner and ELL protected cells against E2F1-dependent apoptosis. Our findings not only connect ELL to E2F1 function and uncover a novel role of ELL in response to DNA damage but also provide an insight into the mechanism for MLL-ELL-associated leukemogenesis.
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256
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Dambacher S, de Almeida GP, Schotta G. Dynamic changes of the epigenetic landscape during cellular differentiation. Epigenomics 2013; 5:701-13. [DOI: 10.2217/epi.13.67] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
Epigenetic mechanisms are crucial to stabilize cell type-specific gene-expression programs. However, during differentiation, these programs need to be modified – a complex process that requires dynamic but tightly controlled rearrangements in the epigenetic landscape. During recent years, the major epigenetic machineries for gene activation and repression have been extensively characterized. Snapshots of the epigenetic landscape in pluripotent versus differentiated cells have further revealed how chromatin can change during cellular differentiation. Although transcription factors are the key drivers of developmental transitions, it became clear that their function is greatly influenced by the chromatin environment. Better insight into the tight interplay between transcription factor networks and the epigenetic landscape is therefore necessary to improve our understanding of cellular differentiation mechanisms. These systems can then be challenged and modified for the development of regenerative therapies.
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Affiliation(s)
- Silvia Dambacher
- Ludwig Maximilians University & Munich Center for Integrated Protein Science (CiPSM), Adolf-Butenandt-Institute, Schillerstrasse 44, 80336 Munich, Germany
| | - Gustavo Pereira de Almeida
- Ludwig Maximilians University & Munich Center for Integrated Protein Science (CiPSM), Adolf-Butenandt-Institute, Schillerstrasse 44, 80336 Munich, Germany
| | - Gunnar Schotta
- Ludwig Maximilians University & Munich Center for Integrated Protein Science (CiPSM), Adolf-Butenandt-Institute, Schillerstrasse 44, 80336 Munich, Germany
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257
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Affiliation(s)
- Jiannan Guo
- Biochemistry Department, University of Iowa , Iowa City, Iowa 52242, United States
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258
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Zhang C, Hong Z, Ma W, Ma D, Qian Y, Xie W, Tie F, Fang M. Drosophila UTX coordinates with p53 to regulate ku80 expression in response to DNA damage. PLoS One 2013; 8:e78652. [PMID: 24265704 PMCID: PMC3827076 DOI: 10.1371/journal.pone.0078652] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2013] [Accepted: 09/13/2013] [Indexed: 01/08/2023] Open
Abstract
UTX is known as a general factor that activates gene transcription during development. Here, we demonstrate an additional essential role of UTX in the DNA damage response, in which it upregulates the expression of ku80 in Drosophila, both in cultured cells and in third instar larvae. We further showed that UTX mediates the expression of ku80 by the demethylation of H3K27me3 at the ku80 promoter upon exposure to ionizing radiation (IR) in a p53-dependent manner. UTX interacts physically with p53, and both UTX and p53 are recruited to the ku80 promoter following IR exposure in an interdependent manner. In contrast, the loss of utx has little impact on the expression of ku70, mre11, hid and reaper, suggesting the specific regulation of ku80 expression by UTX. Thus, our findings further elucidate the molecular function of UTX.
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Affiliation(s)
- Chengwan Zhang
- Institute of Life Sciences, Southeast University, State Ministry of Education Key Laboratory of Developmental Genes and Human Diseases, Nanjing, China
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259
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Levens D. Cellular MYCro economics: Balancing MYC function with MYC expression. Cold Spring Harb Perspect Med 2013; 3:3/11/a014233. [PMID: 24186489 DOI: 10.1101/cshperspect.a014233] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
The expression levels of the MYC oncoprotein have long been recognized to be associated with the outputs of major cellular processes including proliferation, cell growth, apoptosis, differentiation, and metabolism. Therefore, to understand how MYC operates, it is important to define quantitatively the relationship between MYC input and expression output for its targets as well as the higher-order relationships between the expression levels of subnetwork components and the flow of information and materials through those networks. Two different views of MYC are considered, first as a molecular microeconomic manager orchestrating specific positive and negative responses at individual promoters in collaboration with other transcription and chromatin components, and second, as a macroeconomic czar imposing an overarching rule onto all active genes. In either case, c-myc promoter output requires multiple inputs and exploits diverse mechanisms to tune expression to the appropriate levels relative to the thresholds of expression that separate health and disease.
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Affiliation(s)
- David Levens
- Laboratory of Pathology, Center for Cancer Research, National Cancer Institute, Bethesda, Maryland 20892-1500
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260
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Physical and functional interaction of Rnf2 with Af9 regulates basal and aldosterone-stimulated transcription of the α-ENaC gene in a renal collecting duct cell line. Biosci Rep 2013; 33:BSR20130086. [PMID: 24070375 PMCID: PMC3979232 DOI: 10.1042/bsr20130086] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
The physical and functional interaction of Rnf2 (RING finger protein 2), a central component of the PRC (Polycomb repressive complex) 1 and Af9 (ALL1-fused gene from chromosome 9 protein), an aldosterone-sensitive transcription factor, in regulating basal and aldosterone-stimulated transcription of the α-ENaC (epithelial Na+ channel α-subunit) gene was explored in mIMCD3 CD (collecting duct) cells. Since Rnf2 lacks DNA-specific binding activity, other factors must mediate its site-specific chromatin recruitment. Rnf2 and Af9 co-localized in the nucleus and co-immunoprecipitated. A GST (glutathione transferase)-Af9 carboxy-terminal fusion protein directly interacted with in vitro translated Rnf2 in GST pull-down assays. Rnf2 knock down enhanced basal and aldosterone-stimulated α-ENaC mRNA levels and α-ENaC promoter activity. ChIP/QPCR (chromatin immunoprecipitation/quantitative PCR) assays demonstrated enrichment of Rnf2, H2AK119 (mono-ubiquitinated histone H2A lysine 119), and H3K27me3 (histone H3 lysine 27 trimethylated), a PRC2 chromatin mark, at multiple α-ENaC promoter subregions corresponding to regions of known Af9 enrichment, under basal conditions. Sequential ChIP confirmed Rnf2-Af9 co-occupancy of the α-ENaC promoter. Aldosterone provoked early and sustained depletion of Rnf2, ubiquitinated H2AK119, and trimethylated H3K27 associated with the subregions of the α-ENaC promoter. Thus, Af9 mediates site-selective physical and functional recruitment of Rnf2 to the α-ENaC promoter to constrain basal α-ENaC transcription in collecting duct cells, and aldosterone reverses this process.
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261
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Abstract
The Mediator complex is a multi-subunit assembly that appears to be required for regulating expression of most RNA polymerase II (pol II) transcripts, which include protein-coding and most non-coding RNA genes. Mediator and pol II function within the pre-initiation complex (PIC), which consists of Mediator, pol II, TFIIA, TFIIB, TFIID, TFIIE, TFIIF and TFIIH and is approximately 4.0 MDa in size. Mediator serves as a central scaffold within the PIC and helps regulate pol II activity in ways that remain poorly understood. Mediator is also generally targeted by sequence-specific, DNA-binding transcription factors (TFs) that work to control gene expression programs in response to developmental or environmental cues. At a basic level, Mediator functions by relaying signals from TFs directly to the pol II enzyme, thereby facilitating TF-dependent regulation of gene expression. Thus, Mediator is essential for converting biological inputs (communicated by TFs) to physiological responses (via changes in gene expression). In this review, we summarize an expansive body of research on the Mediator complex, with an emphasis on yeast and mammalian complexes. We focus on the basics that underlie Mediator function, such as its structure and subunit composition, and describe its broad regulatory influence on gene expression, ranging from chromatin architecture to transcription initiation and elongation, to mRNA processing. We also describe factors that influence Mediator structure and activity, including TFs, non-coding RNAs and the CDK8 module.
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Affiliation(s)
- Zachary C Poss
- Department of Chemistry and Biochemistry, University of Colorado , Boulder, CO , USA
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262
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Abstract
Elongation is becoming increasingly recognized as a critical step in eukaryotic transcriptional regulation. Although traditional genetic and biochemical studies have identified major players of transcriptional elongation, our understanding of the importance and roles of these factors is evolving rapidly through the recent advances in genome-wide and single-molecule technologies. Here, we focus on how elongation can modulate the transcriptional outcome through the rate-liming step of RNA polymerase II (Pol II) pausing near promoters and how the participating factors were identified. Among the factors we describe are the pausing factors--NELF (negative elongation factor) and DSIF (DRB sensitivity-inducing factor)--and P-TEFb (positive elongation factor b), which is the key player in pause release. We also describe the high-resolution view of Pol II pausing and propose nonexclusive models for how pausing is achieved. We then discuss Pol II elongation through the bodies of genes and the roles of FACT and SPT6, factors that allow Pol II to move through nucleosomes.
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Affiliation(s)
- Hojoong Kwak
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, New York 14853-2703; ,
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263
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Akiyama T, Shinzawa M, Qin J, Akiyama N. Regulations of gene expression in medullary thymic epithelial cells required for preventing the onset of autoimmune diseases. Front Immunol 2013; 4:249. [PMID: 23986760 PMCID: PMC3752772 DOI: 10.3389/fimmu.2013.00249] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2013] [Accepted: 08/09/2013] [Indexed: 11/13/2022] Open
Abstract
Elimination of potential self-reactive T cells in the thymus is crucial for preventing the onset of autoimmune diseases. Epithelial cell subsets localized in thymic medulla [medullary thymic epithelial cells (mTECs)] contribute to this process by supplying a wide range of self-antigens that are otherwise expressed in a tissue-specific manner (TSAs). Expression of some TSAs in mTECs is controlled by the autoimmune regulator (AIRE) protein, of which dysfunctional mutations are the causative factor of autoimmune polyendocrinopathy-candidiasis-ectodermal dystrophy (APECED). In addition to the elimination of self-reactive T cells, recent studies indicated roles of mTECs in the development of Foxp3-positive regulatory T cells, which suppress autoimmunity and excess immune reactions in peripheral tissues. The TNF family cytokines, RANK ligand, CD40 ligand, and lymphotoxin were found to promote the differentiation of AIRE- and TSA-expressing mTECs. Furthermore, activation of NF-κB is essential for mTEC differentiation. In this mini-review, we focus on molecular mechanisms that regulate induction of AIRE and TSA expression and discuss possible contributions of these mechanisms to prevent the onset of autoimmune diseases.
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Affiliation(s)
- Taishin Akiyama
- Division of Cellular and Molecular Biology, Institute of Medical Science, University of Tokyo , Tokyo , Japan
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264
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Saunders A, Core LJ, Sutcliffe C, Lis JT, Ashe HL. Extensive polymerase pausing during Drosophila axis patterning enables high-level and pliable transcription. Genes Dev 2013; 27:1146-58. [PMID: 23699410 DOI: 10.1101/gad.215459.113] [Citation(s) in RCA: 67] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
Cascades of zygotic gene expression pattern the anterior-posterior (AP) and dorsal-ventral (DV) axes of the early Drosophila embryo. Here, we used the global run-on sequencing assay (GRO-seq) to map the genome-wide RNA polymerase distribution during early Drosophila embryogenesis, thus providing insights into how genes are regulated. We identify widespread promoter-proximal pausing yet show that the presence of paused polymerase does not necessarily equate to direct regulation through pause release to productive elongation. Our data reveal that a subset of early Zelda-activated genes is regulated at the level of polymerase recruitment, whereas other Zelda target and axis patterning genes are predominantly regulated through pause release. In contrast to other signaling pathways, we found that bone morphogenetic protein (BMP) target genes are collectively more highly paused than BMP pathway components and show that BMP target gene expression requires the pause-inducing negative elongation factor (NELF) complex. Our data also suggest that polymerase pausing allows plasticity in gene activation throughout embryogenesis, as transiently repressed and transcriptionally silenced genes maintain and lose promoter polymerases, respectively. Finally, we provide evidence that the major effect of pausing is on the levels, rather than timing, of transcription. These data are discussed in terms of the efficiency of transcriptional activation required across cell populations during developmental time constraints.
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Affiliation(s)
- Abbie Saunders
- Faculty of Life Sciences, University of Manchester, Manchester M13 9PT, United Kingdom
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265
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Smith E, Shilatifard A. Transcriptional elongation checkpoint control in development and disease. Genes Dev 2013; 27:1079-88. [PMID: 23699407 DOI: 10.1101/gad.215137.113] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Transcriptional elongation control by RNA polymerase II and its associated factors has taken center stage as a process essential for the regulation of gene expression throughout development. In this review, we analyze recent findings on the identification of factors functioning in the regulation of the transcriptional elongation checkpoint control (TECC) stage of gene expression and how the factors' misregulation is associated with disease pathogenesis, including cancer.
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Affiliation(s)
- Edwin Smith
- Stowers Institute for Medical Research, Kansas City, Missouri 64110, USA
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266
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Tian B, Zhao Y, Kalita M, Edeh CB, Paessler S, Casola A, Teng MN, Garofalo RP, Brasier AR. CDK9-dependent transcriptional elongation in the innate interferon-stimulated gene response to respiratory syncytial virus infection in airway epithelial cells. J Virol 2013; 87:7075-92. [PMID: 23596302 PMCID: PMC3676079 DOI: 10.1128/jvi.03399-12] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2012] [Accepted: 04/08/2013] [Indexed: 12/20/2022] Open
Abstract
Respiratory syncytial virus (RSV) is a negative-sense single-stranded RNA virus responsible for lower respiratory tract infections. During infection, the presence of double-stranded RNA (dsRNA) activates the interferon (IFN) regulatory factor 3 (IRF3) transcription factor, an event triggering expression of immediate early, IFN-stimulated genes (ISGs). We examine the role of transcriptional elongation in control of IRF3-dependent ISG expression. RSV infection induces ISG54, ISG56, and CIG5 gene expression in an IRF3-dependent manner demonstrated by IRF3 small interfering RNA (siRNA) silencing in both A549 epithelial cells and IRF3(-/-) MEFs. ISG expression was mediated by the recruitment of IRF3, CDK9, polymerase II (Pol II), and phospho-Ser(2) carboxy-terminal domain (CTD) Pol II to the IFN-stimulated response element (ISRE) binding sites of the IRF3-dependent ISG promoters in native chromatin. We find that RSV infection enhances the activated fraction of cyclin-dependent kinase 9 (CDK9) by promoting its association with bromodomain 4 (BRD4) and disrupting its association with the inhibitory 7SK small nuclear RNA. The requirement of CDK9 activity for ISG expression was shown by siRNA-mediated silencing of CDK9 and by a selective CDK9 inhibitor in A549 cells. In contrast, RSV-induced beta interferon (IFN-β) expression is not influenced by CDK9 inhibition. Using transcript-selective quantitative real-time reverse transcription-PCR (Q-RT-PCR) assays for the ISG54 gene, we observed that RSV induces transition from short to fully spliced mRNA transcripts and that this transition is blocked by CDK9 inhibition in both A549 and primary human small airway epithelial cells. These data indicate that transcription elongation plays a major role in RSV-induced ISG expression and is mediated by IRF3-dependent recruitment of activated CDK9. CDK9 activity may be a target for immunomodulation in RSV-induced lung disease.
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Affiliation(s)
| | - Yingxin Zhao
- Department of Internal Medicine,
- Institute for Translational Sciences,
- Sealy Center for Molecular Medicine,
| | | | | | | | - Antonella Casola
- Institute for Translational Sciences,
- Sealy Center for Molecular Medicine,
- Pediatrics, University of Texas Medical Branch, Galveston, Texas, USA
| | - Michael N. Teng
- Joy McCann Culverhouse Airway Disease Research Center, Department of Internal Medicine, University of South Florida Morsani College of Medicine, Tampa, Florida, USA
| | - Roberto P. Garofalo
- Institute for Translational Sciences,
- Pediatrics, University of Texas Medical Branch, Galveston, Texas, USA
| | - Allan R. Brasier
- Department of Internal Medicine,
- Institute for Translational Sciences,
- Sealy Center for Molecular Medicine,
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267
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Faure G, Callebaut I. Identification of hidden relationships from the coupling of hydrophobic cluster analysis and domain architecture information. ACTA ACUST UNITED AC 2013; 29:1726-33. [PMID: 23677940 DOI: 10.1093/bioinformatics/btt271] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Abstract
MOTIVATION Describing domain architecture is a critical step in the functional characterization of proteins. However, some orphan domains do not match any profile stored in dedicated domain databases and are thereby difficult to analyze. RESULTS We present here an original novel approach, called TREMOLO-HCA, for the analysis of orphan domain sequences and inspired from our experience in the use of Hydrophobic Cluster Analysis (HCA). Hidden relationships between protein sequences can be more easily identified from the PSI-BLAST results, using information on domain architecture, HCA plots and the conservation degree of amino acids that may participate in the protein core. This can lead to reveal remote relationships with known families of domains, as illustrated here with the identification of a hidden Tudor tandem in the human BAHCC1 protein and a hidden ET domain in the Saccharomyces cerevisiae Taf14p and human AF9 proteins. The results obtained in such a way are consistent with those provided by HHPRED, based on pairwise comparisons of HHMs. Our approach can, however, be applied even in absence of domain profiles or known 3D structures for the identification of novel families of domains. It can also be used in a reverse way for refining domain profiles, by starting from known protein domain families and identifying highly divergent members, hitherto considered as orphan. AVAILABILITY We provide a possible integration of this approach in an open TREMOLO-HCA package, which is fully implemented in python v2.7 and is available on request. Instructions are available at http://www.impmc.upmc.fr/∼callebau/tremolohca.html. CONTACT isabelle.callebaut@impmc.upmc.fr SUPPLEMENTARY INFORMATION Supplementary Data are available at Bioinformatics online.
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Affiliation(s)
- Guilhem Faure
- IMPMC, UMR7590, CNRS, Université Pierre et Marie Curie-Paris6, Paris Cedex 05, France
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268
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Bywater MJ, Pearson RB, McArthur GA, Hannan RD. Dysregulation of the basal RNA polymerase transcription apparatus in cancer. Nat Rev Cancer 2013; 13:299-314. [PMID: 23612459 DOI: 10.1038/nrc3496] [Citation(s) in RCA: 166] [Impact Index Per Article: 15.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Mutations that directly affect transcription by RNA polymerases rank among the most central mediators of malignant transformation, but the frequency of new anticancer drugs that selectively target defective transcription apparatus entering the clinic has been limited. This is because targeting the large protein-protein and protein-DNA interfaces that control both generic and selective aspects of RNA polymerase transcription has proved extremely difficult. However, recent technological advances have led to a 'quantum leap' in our comprehension of the structure and function of the core RNA polymerase components, how they are dysregulated in a broad range of cancers and how they may be targeted for 'transcription therapy'.
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Affiliation(s)
- Megan J Bywater
- Division of Cancer Research, Peter MacCallum Cancer Centre, Melbourne 8006, Victoria, Australia
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269
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Jennings BH. Pausing for thought: disrupting the early transcription elongation checkpoint leads to developmental defects and tumourigenesis. Bioessays 2013; 35:553-60. [PMID: 23575664 PMCID: PMC3698693 DOI: 10.1002/bies.201200179] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2012] [Accepted: 03/04/2013] [Indexed: 12/30/2022]
Abstract
Factors affecting transcriptional elongation have been characterized extensively in in vitro, single cell (yeast) and cell culture systems; however, data from the context of multicellular organisms has been relatively scarce. While studies in homogeneous cell populations have been highly informative about the underlying molecular mechanisms and prevalence of polymerase pausing, they do not reveal the biological impact of perturbing this regulation in an animal. The core components regulating pausing are expressed in all animal cells and are recruited to the majority of genes, however, disrupting their function often results in discrete phenotypic effects. Mutations in genes encoding key regulators of transcriptional pausing have been recovered from several genetic screens for specific phenotypes or interactions with specific factors in mice, zebrafish and flies. Analysis of these mutations has revealed that control of transcriptional pausing is critical for a diverse range of biological pathways essential for animal development and survival.
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270
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Bartholomeeusen K, Fujinaga K, Xiang Y, Peterlin BM. Histone deacetylase inhibitors (HDACis) that release the positive transcription elongation factor b (P-TEFb) from its inhibitory complex also activate HIV transcription. J Biol Chem 2013; 288:14400-14407. [PMID: 23539624 DOI: 10.1074/jbc.m113.464834] [Citation(s) in RCA: 66] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Numerous studies have looked at the effects of histone deacetylase inhibitors (HDACis) on HIV reactivation in established transformed cell lines and primary CD4(+) T cells. However, their findings remain confusing, and differences between effects of class I- and class II-specific HDACis persist. Because no clear picture emerged, we decided to determine how HDACis reactivate HIV in transformed cell lines and primary cells. We found that neither histone H3 nor tubulin acetylation correlated with HIV reactivation in Jurkat and HeLa cells. Rather, HDACis that could reactivate HIV in chromatin or on episomal plasmids also released free positive transcription elongation factor b (P-TEFb) from its inhibitory 7SK snRNP. In resting primary CD4(+) T cells, where levels of P-TEFb are vanishingly low, the most potent HDACi, suberoylanilide hydroxyamic acid (SAHA), had minimal effects. In contrast, when these cells were treated with a PKC agonist, bryostatin 1, which increased levels of P-TEFb, then SAHA once again reactivated HIV. We conclude that HDACis, which can reactivate HIV, work via the release of free P-TEFb from the 7SK snRNP.
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Affiliation(s)
- Koen Bartholomeeusen
- Departments of Medicine, Microbiology, and Immunology, Rosalind Russell Medical Research Center, University of California, San Francisco, California 94143-0703
| | - Koh Fujinaga
- Departments of Medicine, Microbiology, and Immunology, Rosalind Russell Medical Research Center, University of California, San Francisco, California 94143-0703
| | - Yanhui Xiang
- Departments of Medicine, Microbiology, and Immunology, Rosalind Russell Medical Research Center, University of California, San Francisco, California 94143-0703; State Key Laboratory of Molecular and Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China
| | - B Matija Peterlin
- Departments of Medicine, Microbiology, and Immunology, Rosalind Russell Medical Research Center, University of California, San Francisco, California 94143-0703.
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271
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Taube R, Peterlin BM. Lost in transcription: molecular mechanisms that control HIV latency. Viruses 2013; 5:902-27. [PMID: 23518577 PMCID: PMC3705304 DOI: 10.3390/v5030902] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2013] [Revised: 03/15/2013] [Accepted: 03/18/2013] [Indexed: 02/06/2023] Open
Abstract
Highly active antiretroviral therapy (HAART) has limited the replication and spread of the human immunodeficiency virus (HIV). However, despite treatment, HIV infection persists in latently infected reservoirs, and once therapy is interrupted, viral replication rebounds quickly. Extensive efforts are being directed at eliminating these cell reservoirs. This feat can be achieved by reactivating latent HIV while administering drugs that prevent new rounds of infection and allow the immune system to clear the virus. However, current approaches to HIV eradication have not been effective. Moreover, as HIV latency is multifactorial, the significance of each of its molecular mechanisms is still under debate. Among these, transcriptional repression as a result of reduced levels and activity of the positive transcription elongation factor b (P-TEFb: CDK9/cyclin T) plays a significant role. Therefore, increasing levels of P-TEFb expression and activity is an excellent strategy to stimulate viral gene expression. This review summarizes the multiple steps that cause HIV to enter into latency. It positions the interplay between transcriptionally active and inactive host transcriptional activators and their viral partner Tat as valid targets for the development of new strategies to reactivate latent viral gene expression and eradicate HIV.
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Affiliation(s)
- Ran Taube
- The Shraga Segal Department of Microbiology Immunology and Genetics, Faculty of Health Sciences, Ben-Gurion University of the Negev, P.O. Box 653, Beer-Sheva, 84105, Israel
- Author to whom correspondence should be addressed; E-Mail: ; Tel.: +972-8-6479858; Fax: +972-8-6479953
| | - Boris Matija Peterlin
- Department of Medicine, Microbiology and Immunology, Rosalind Russell Medical Research Center, University of California at San Francisco, San Francisco, CA 94143, USA; E-Mail:
- Department of Virology, Haartman Institute, University of Helsinki, 00014 Helsinki, Finland
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272
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Abstract
The gene expression programs that establish and maintain specific cell states in humans are controlled by thousands of transcription factors, cofactors, and chromatin regulators. Misregulation of these gene expression programs can cause a broad range of diseases. Here, we review recent advances in our understanding of transcriptional regulation and discuss how these have provided new insights into transcriptional misregulation in disease.
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Affiliation(s)
- Tong Ihn Lee
- Whitehead Institute for Biomedical Research, Cambridge, MA 02142, USA
| | - Richard A. Young
- Whitehead Institute for Biomedical Research, Cambridge, MA 02142, USA
- Department of Biology, Massachusetts
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273
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Abstract
A better understanding of the host cell protein complex that helps HIV replicate inside cells offers the possibility of new therapeutic targets.
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Affiliation(s)
- Christopher P Hill
- is at the Department of Biochemistry , University of Utah School of Medicine , Salt Lake City , United States
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274
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Schulze-Gahmen U, Upton H, Birnberg A, Bao K, Chou S, Krogan NJ, Zhou Q, Alber T. The AFF4 scaffold binds human P-TEFb adjacent to HIV Tat. eLife 2013; 2:e00327. [PMID: 23471103 PMCID: PMC3589825 DOI: 10.7554/elife.00327] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2012] [Accepted: 01/16/2013] [Indexed: 02/05/2023] Open
Abstract
Human positive transcription elongation factor b (P-TEFb) phosphorylates RNA polymerase II and regulatory proteins to trigger elongation of many gene transcripts. The HIV-1 Tat protein selectively recruits P-TEFb as part of a super elongation complex (SEC) organized on a flexible AFF1 or AFF4 scaffold. To understand this specificity and determine if scaffold binding alters P-TEFb conformation, we determined the structure of a tripartite complex containing the recognition regions of P-TEFb and AFF4. AFF4 meanders over the surface of the P-TEFb cyclin T1 (CycT1) subunit but makes no stable contacts with the CDK9 kinase subunit. Interface mutations reduced CycT1 binding and AFF4-dependent transcription. AFF4 is positioned to make unexpected direct contacts with HIV Tat, and Tat enhances P-TEFb affinity for AFF4. These studies define the mechanism of scaffold recognition by P-TEFb and reveal an unanticipated intersubunit pocket on the AFF4 SEC that potentially represents a target for therapeutic intervention against HIV/AIDS. DOI:http://dx.doi.org/10.7554/eLife.00327.001.
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Affiliation(s)
- Ursula Schulze-Gahmen
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, United States
| | - Heather Upton
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, United States
| | - Andrew Birnberg
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, United States
| | - Katherine Bao
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, United States
| | - Seemay Chou
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, United States
| | - Nevan J Krogan
- Department of Cellular and Molecular Pharmacology, University of California, San Francisco, San Francisco, United States
- California Institute for Quantitative Biosciences, QB3, Berkeley, United States
- J David Gladstone Institutes, San Francisco, United States
| | - Qiang Zhou
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, United States
| | - Tom Alber
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, United States
- California Institute for Quantitative Biosciences, QB3, Berkeley, United States
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275
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Abstract
Immune response to pathogens depends on coordinated regulation of numerous genes that contribute collectively to pathogen elimination and restoration of the integrity of the affected tissue. The pathogen-induced gene expression is governed largely by the signal-induced posttranslational histone modifications that facilitate assembly of the functionally distinct chromatin complexes. In this review, we describe the principles of chromatin-based gene regulation during innate immune responses. We discuss the ability of pathogens to hijack the host response by interfering with various arms of transcriptional machinery involved in the responses. In particular, we discuss the phenomenon of the histone mimicry where interaction between histones and transcriptional regulators is targeted by pathogens that carry the histone-like sequences (histone mimics). We show how the principle of isotone mimicry as an efficient way to control host gene expression has been sued for the development of novel anti-inflammatory pharmacological approaches.
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276
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Lin C, Garruss AS, Luo Z, Guo F, Shilatifard A. The RNA Pol II elongation factor Ell3 marks enhancers in ES cells and primes future gene activation. Cell 2012; 152:144-56. [PMID: 23273992 DOI: 10.1016/j.cell.2012.12.015] [Citation(s) in RCA: 78] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2012] [Revised: 09/10/2012] [Accepted: 12/04/2012] [Indexed: 01/27/2023]
Abstract
Enhancers play a central role in precisely regulating the expression of developmentally regulated genes. However, the machineries required for enhancer-promoter communication have remained largely unknown. We have found that Ell3, a member of the Ell (eleven-nineteen lysine-rich leukemia gene) family of RNA Pol II elongation factors, occupies enhancers in embryonic stem cells. Ell3's association with enhancers is required for setting up proper Pol II occupancy at the promoter-proximal regions of developmentally regulated genes and for the recruitment of the super elongation complex (SEC) to these loci following differentiation signals. Furthermore, Ell3 binding to inactive or poised enhancers is essential for stem cell specification. We have also detected the presence of Pol II and Ell3 in germ cell nuclei. These findings raise the possibility that transcription factors could prime gene expression by marking enhancers in ES cells or even as early as in the germ cell state.
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Affiliation(s)
- Chengqi Lin
- Stowers Institute for Medical Research, 1000 East 50th Street, Kansas City, MO 64110, USA
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277
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HIV-1 Tat recruits transcription elongation factors dispersed along a flexible AFF4 scaffold. Proc Natl Acad Sci U S A 2012; 110:E123-31. [PMID: 23251033 DOI: 10.1073/pnas.1216971110] [Citation(s) in RCA: 62] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
The HIV-1 Tat protein stimulates viral gene expression by recruiting human transcription elongation complexes containing P-TEFb, AFF4, ELL2, and ENL or AF9 to the viral promoter, but the molecular organization of these complexes remains unknown. To establish the overall architecture of the HIV-1 Tat elongation complex, we mapped the binding sites that mediate complex assembly in vitro and in vivo. The AFF4 protein emerges as the central scaffold that recruits other factors through direct interactions with short hydrophobic regions along its structurally disordered axis. Direct binding partners CycT1, ELL2, and ENL or AF9 act as bridging components that link this complex to two major elongation factors, P-TEFb and the PAF complex. The unique scaffolding properties of AFF4 allow dynamic and flexible assembly of multiple elongation factors and connect the components not only to each other but also to a larger network of transcriptional regulators.
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