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Mbonye U, Karn J. The cell biology of HIV-1 latency and rebound. Retrovirology 2024; 21:6. [PMID: 38580979 PMCID: PMC10996279 DOI: 10.1186/s12977-024-00639-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/07/2024] Open
Abstract
Transcriptionally latent forms of replication-competent proviruses, present primarily in a small subset of memory CD4+ T cells, pose the primary barrier to a cure for HIV-1 infection because they are the source of the viral rebound that almost inevitably follows the interruption of antiretroviral therapy. Over the last 30 years, many of the factors essential for initiating HIV-1 transcription have been identified in studies performed using transformed cell lines, such as the Jurkat T-cell model. However, as highlighted in this review, several poorly understood mechanisms still need to be elucidated, including the molecular basis for promoter-proximal pausing of the transcribing complex and the detailed mechanism of the delivery of P-TEFb from 7SK snRNP. Furthermore, the central paradox of HIV-1 transcription remains unsolved: how are the initial rounds of transcription achieved in the absence of Tat? A critical limitation of the transformed cell models is that they do not recapitulate the transitions between active effector cells and quiescent memory T cells. Therefore, investigation of the molecular mechanisms of HIV-1 latency reversal and LRA efficacy in a proper physiological context requires the utilization of primary cell models. Recent mechanistic studies of HIV-1 transcription using latently infected cells recovered from donors and ex vivo cellular models of viral latency have demonstrated that the primary blocks to HIV-1 transcription in memory CD4+ T cells are restrictive epigenetic features at the proviral promoter, the cytoplasmic sequestration of key transcription initiation factors such as NFAT and NF-κB, and the vanishingly low expression of the cellular transcription elongation factor P-TEFb. One of the foremost schemes to eliminate the residual reservoir is to deliberately reactivate latent HIV-1 proviruses to enable clearance of persisting latently infected cells-the "Shock and Kill" strategy. For "Shock and Kill" to become efficient, effective, non-toxic latency-reversing agents (LRAs) must be discovered. Since multiple restrictions limit viral reactivation in primary cells, understanding the T-cell signaling mechanisms that are essential for stimulating P-TEFb biogenesis, initiation factor activation, and reversing the proviral epigenetic restrictions have become a prerequisite for the development of more effective LRAs.
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Affiliation(s)
- Uri Mbonye
- Department of Molecular Biology and Microbiology, Case Western Reserve University School of Medicine, Cleveland, OH, 44106, USA.
| | - Jonathan Karn
- Department of Molecular Biology and Microbiology, Case Western Reserve University School of Medicine, Cleveland, OH, 44106, USA.
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2
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Mayer MP, Blair L, Blatch GL, Borges TJ, Chadli A, Chiosis G, de Thonel A, Dinkova-Kostova A, Ecroyd H, Edkins AL, Eguchi T, Fleshner M, Foley KP, Fragkostefanakis S, Gestwicki J, Goloubinoff P, Heritz JA, Heske CM, Hibshman JD, Joutsen J, Li W, Lynes M, Mendillo ML, Mivechi N, Mokoena F, Okusha Y, Prahlad V, Repasky E, Sannino S, Scalia F, Shalgi R, Sistonen L, Sontag E, van Oosten-Hawle P, Vihervaara A, Wickramaratne A, Wang SXY, Zininga T. Stress biology: Complexity and multifariousness in health and disease. Cell Stress Chaperones 2024; 29:143-157. [PMID: 38311120 PMCID: PMC10939078 DOI: 10.1016/j.cstres.2024.01.006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2024] Open
Abstract
Preserving and regulating cellular homeostasis in the light of changing environmental conditions or developmental processes is of pivotal importance for single cellular and multicellular organisms alike. To counteract an imbalance in cellular homeostasis transcriptional programs evolved, called the heat shock response, unfolded protein response, and integrated stress response, that act cell-autonomously in most cells but in multicellular organisms are subjected to cell-nonautonomous regulation. These transcriptional programs downregulate the expression of most genes but increase the expression of heat shock genes, including genes encoding molecular chaperones and proteases, proteins involved in the repair of stress-induced damage to macromolecules and cellular structures. Sixty-one years after the discovery of the heat shock response by Ferruccio Ritossa, many aspects of stress biology are still enigmatic. Recent progress in the understanding of stress responses and molecular chaperones was reported at the 12th International Symposium on Heat Shock Proteins in Biology, Medicine and the Environment in the Old Town Alexandria, VA, USA from 28th to 31st of October 2023.
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Affiliation(s)
- Matthias P Mayer
- Center for Molecular Biology of Heidelberg University (ZMBH), DKFZ-ZMBH Alliance, Heidelberg, Germany.
| | - Laura Blair
- Department of Molecular Medicine, Morsani College of Medicine, University of South Florida, Tampa, FL 33612, USA
| | - Gregory L Blatch
- Biomedical Research and Drug Discovery Research Group, Faculty of Health Sciences, Higher Colleges of Technology, Sharjah, United Arab Emirates; Biomedical Biotechnology Research Unit, Department of Biochemistry and Microbiology, Rhodes University, Grahamstown, South Africa
| | - Thiago J Borges
- Department of Surgery, Center for Transplantation Sciences, Massachusetts General Hospital, Harvard Medical School, Boston, MA 02129, USA
| | - Ahmed Chadli
- Georgia Cancer Center, Medical College of Georgia at Augusta University, Augusta, GA 30912, USA
| | - Gabriela Chiosis
- Department of Medicine, Division of Solid Tumors, Memorial Sloan Kettering Cancer Center, New York, NY 10065, USA; Chemical Biology Program, Memorial Sloan Kettering Cancer Center, New York, NY 10065, USA
| | - Aurélie de Thonel
- CNRS, UMR 7216, 75250 Paris Cedex 13, Paris, France; Univeristy of Paris Diderot, Sorbonne Paris Cité, Paris, France; Département Hospitalo-Universitaire DHU PROTECT, Paris, France
| | - Albena Dinkova-Kostova
- Division of Cellular and Systems Medicine, Jacqui Wood Cancer Centre, School of Medicine, University of Dundee, Dundee, UK
| | - Heath Ecroyd
- Molecular Horizons and School of Chemistry and Molecular Bioscience, University of Wollongong, Wollongong, New South Wales 2522, Australia
| | - Adrienne L Edkins
- Biomedical Biotechnology Research Unit (BioBRU), Department of Biochemistry and Microbiology, Rhodes University, Makhanda, South Africa
| | - Takanori Eguchi
- Department of Dental Pharmacology, Faculty of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University, Okayama 700-8525, Japan
| | - Monika Fleshner
- Department of Integrative Physiology, University of Colorado at Boulder, Boulder, CO 80309, USA
| | | | - Sotirios Fragkostefanakis
- Department of Biosciences, Molecular Cell Biology of Plants, Goethe University Frankfurt am Main, Frankfurt am Main 60438, Germany
| | - Jason Gestwicki
- Institute for Neurodegenerative Diseases, University of California, San Francisco, CA 94158, USA
| | - Pierre Goloubinoff
- Department of Plant Molecular Biology, Faculty of Biology and Medicine, University of Lausanne, Lausanne, Switzerland
| | - Jennifer A Heritz
- Department of Urology, SUNY Upstate Medical University, Syracuse, NY 13210, USA; Upstate Cancer Center, SUNY Upstate Medical University, Syracuse, NY 13210, USA; Department of Biochemistry and Molecular Biology, SUNY Upstate Medical University, Syracuse, NY 13210, USA
| | - Christine M Heske
- Pediatric Oncology Branch, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - Jonathan D Hibshman
- Biology Department, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Jenny Joutsen
- Department of Pathology, Lapland Central Hospital, Lapland Wellbeing Services County, Rovaniemi, Finland
| | - Wei Li
- Department of Dermatology and the Norris Comprehensive Cancer Center, University of Southern California Keck Medical Center, Los Angeles, CA 90033, USA
| | - Michael Lynes
- Department of Molecular and Cell Biology, University of Connecticut, Storrs, CT 06269, USA
| | - Marc L Mendillo
- Department of Biochemistry and Molecular Genetics, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, USA; Simpson Querrey Center for Epigenetics, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, USA
| | - Nahid Mivechi
- Molecular Chaperone Biology, Medical College of Georgia, Georgia Cancer Center, Augusta University, Augusta, GA 30912, USA
| | - Fortunate Mokoena
- Department of Biochemistry, North-West University, Mmabatho 2735, South Africa
| | - Yuka Okusha
- Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA 02215, USA
| | - Veena Prahlad
- Department of Cell Stress Biology, Roswell Park Comprehensive Cancer Center, Buffalo, NY 14203, USA
| | - Elizabeth Repasky
- Department of Hematology and Oncology, Roswell Park Comprehensive Cancer Center, Buffalo, NY 14263, USA
| | - Sara Sannino
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, PA 15260, USA
| | - Federica Scalia
- Department of Biomedicine, Neuroscience and Advanced Diagnostics (BIND), University of Palermo, Palermo, Italy; Euro-Mediterranean Institute of Science and Technology (IEMEST), Palermo, Italy
| | - Reut Shalgi
- Department of Biochemistry, Rappaport Faculty of Medicine, Technion-Israel Institute of Technology, Haifa 31096, Israel
| | - Lea Sistonen
- Faculty of Science and Engineering, Cell Biology, Åbo Akademi University, Turku, Finland; Turku Bioscience Centre, University of Turku and Åbo Akademi University, Turku, Finland
| | - Emily Sontag
- Department of Biological Sciences, Marquette University, Milwaukee, WI 53233, USA
| | | | - Anniina Vihervaara
- Department of Gene Technology, KTH Royal Institute of Technology, Science for Life Laboratory, Stockholm, Sweden
| | - Anushka Wickramaratne
- Laboratory of Molecular Biology, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - Shawn Xiang Yang Wang
- Developmental Therapeutics Program, VCU Comprehensive Massey Cancer Center, VCU Institute of Molecular Medicine, Virginia Commonwealth University, School of Medicine, Richmond, VA 23298, USA
| | - Tawanda Zininga
- Department of Biochemistry, Stellenbosch University, Stellenbosch 7602, South Africa
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3
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Bunch H, Kim D, Naganuma M, Nakagawa R, Cong A, Jeong J, Ehara H, Vu H, Chang JH, Schellenberg MJ, Sekine SI. ERK2-topoisomerase II regulatory axis is important for gene activation in immediate early genes. Nat Commun 2023; 14:8341. [PMID: 38097570 PMCID: PMC10721843 DOI: 10.1038/s41467-023-44089-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2022] [Accepted: 11/29/2023] [Indexed: 12/17/2023] Open
Abstract
The function of the mitogen-activated protein kinase signaling pathway is required for the activation of immediate early genes (IEGs), including EGR1 and FOS, for cell growth and proliferation. Recent studies have identified topoisomerase II (TOP2) as one of the important regulators of the transcriptional activation of IEGs. However, the mechanism underlying transcriptional regulation involving TOP2 in IEG activation has remained unknown. Here, we demonstrate that ERK2, but not ERK1, is important for IEG transcriptional activation and report a critical ELK1 binding sequence for ERK2 function at the EGR1 gene. Our data indicate that both ERK1 and ERK2 extensively phosphorylate the C-terminal domain of TOP2B at mutual and distinctive residues. Although both ERK1 and ERK2 enhance the catalytic rate of TOP2B required to relax positive DNA supercoiling, ERK2 delays TOP2B catalysis of negative DNA supercoiling. In addition, ERK1 may relax DNA supercoiling by itself. ERK2 catalytic inhibition or knock-down interferes with transcription and deregulates TOP2B in IEGs. Furthermore, we present the first cryo-EM structure of the human cell-purified TOP2B and etoposide together with the EGR1 transcriptional start site (-30 to +20) that has the strongest affinity to TOP2B within -423 to +332. The structure shows TOP2B-mediated breakage and dramatic bending of the DNA. Transcription is activated by etoposide, while it is inhibited by ICRF193 at EGR1 and FOS, suggesting that TOP2B-mediated DNA break to favor transcriptional activation. Taken together, this study suggests that activated ERK2 phosphorylates TOP2B to regulate TOP2-DNA interactions and favor transcriptional activation in IEGs. We propose that TOP2B association, catalysis, and dissociation on its substrate DNA are important processes for regulating transcription and that ERK2-mediated TOP2B phosphorylation may be key for the catalysis and dissociation steps.
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Affiliation(s)
- Heeyoun Bunch
- Department of Applied Biosciences, Kyungpook National University, Daegu, 41566, Republic of Korea.
- School of Applied Biosciences, College of Agriculture & Life Sciences, Kyungpook National University, Daegu, 41566, Republic of Korea.
| | - Deukyeong Kim
- School of Applied Biosciences, College of Agriculture & Life Sciences, Kyungpook National University, Daegu, 41566, Republic of Korea
- Department of Biological Sciences, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, 34141, Republic of Korea
| | - Masahiro Naganuma
- Laboratory for Transcription Structural Biology, RIKEN Center for Biosystems Dynamics Research, 1-7-22 Suehiro-cho, Tsurumi-ku, Yokohama, 230-0045, Japan
| | - Reiko Nakagawa
- RIKEN BDR Laboratory for Phyloinformatics, Hyogo, 650-0047, Japan
| | - Anh Cong
- Department of Biochemistry and Molecular Biology, Mayo Clinic, Rochester, MN, 55905, USA
| | - Jaehyeon Jeong
- Department of Applied Biosciences, Kyungpook National University, Daegu, 41566, Republic of Korea
| | - Haruhiko Ehara
- Laboratory for Transcription Structural Biology, RIKEN Center for Biosystems Dynamics Research, 1-7-22 Suehiro-cho, Tsurumi-ku, Yokohama, 230-0045, Japan
| | - Hongha Vu
- Department of Biology Education, Kyungpook National University, Daegu, 41566, Republic of Korea
| | - Jeong Ho Chang
- Department of Biology Education, Kyungpook National University, Daegu, 41566, Republic of Korea
| | - Matthew J Schellenberg
- Department of Biochemistry and Molecular Biology, Mayo Clinic, Rochester, MN, 55905, USA
| | - Shun-Ichi Sekine
- Laboratory for Transcription Structural Biology, RIKEN Center for Biosystems Dynamics Research, 1-7-22 Suehiro-cho, Tsurumi-ku, Yokohama, 230-0045, Japan
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4
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Martin BJE, Ablondi EF, Goglia C, Mimoso CA, Espinel-Cabrera PR, Adelman K. Global identification of SWI/SNF targets reveals compensation by EP400. Cell 2023; 186:5290-5307.e26. [PMID: 37922899 DOI: 10.1016/j.cell.2023.10.006] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2023] [Revised: 08/11/2023] [Accepted: 10/03/2023] [Indexed: 11/07/2023]
Abstract
Mammalian SWI/SNF chromatin remodeling complexes move and evict nucleosomes at gene promoters and enhancers to modulate DNA access. Although SWI/SNF subunits are commonly mutated in disease, therapeutic options are limited by our inability to predict SWI/SNF gene targets and conflicting studies on functional significance. Here, we leverage a fast-acting inhibitor of SWI/SNF remodeling to elucidate direct targets and effects of SWI/SNF. Blocking SWI/SNF activity causes a rapid and global loss of chromatin accessibility and transcription. Whereas repression persists at most enhancers, we uncover a compensatory role for the EP400/TIP60 remodeler, which reestablishes accessibility at most promoters during prolonged loss of SWI/SNF. Indeed, we observe synthetic lethality between EP400 and SWI/SNF in cancer cell lines and human cancer patient data. Our data define a set of molecular genomic features that accurately predict gene sensitivity to SWI/SNF inhibition in diverse cancer cell lines, thereby improving the therapeutic potential of SWI/SNF inhibitors.
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Affiliation(s)
- Benjamin J E Martin
- Department of Biological Chemistry and Molecular Pharmacology, Blavatnik Institute, Harvard Medical School, Boston, MA 02115, USA; Ludwig Center at Harvard, Boston, MA 02115, USA
| | - Eileen F Ablondi
- Department of Biological Chemistry and Molecular Pharmacology, Blavatnik Institute, Harvard Medical School, Boston, MA 02115, USA
| | - Christine Goglia
- Department of Biological Chemistry and Molecular Pharmacology, Blavatnik Institute, Harvard Medical School, Boston, MA 02115, USA
| | - Claudia A Mimoso
- Department of Biological Chemistry and Molecular Pharmacology, Blavatnik Institute, Harvard Medical School, Boston, MA 02115, USA
| | - Piero R Espinel-Cabrera
- Department of Biological Chemistry and Molecular Pharmacology, Blavatnik Institute, Harvard Medical School, Boston, MA 02115, USA
| | - Karen Adelman
- Department of Biological Chemistry and Molecular Pharmacology, Blavatnik Institute, Harvard Medical School, Boston, MA 02115, USA; Ludwig Center at Harvard, Boston, MA 02115, USA; Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA.
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5
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Schibler U, Dibner C, Ripperger J. Steve Brown. J Biol Rhythms 2023; 38:119-124. [PMID: 36762620 PMCID: PMC10037542 DOI: 10.1177/07487304231152275] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/11/2023]
Affiliation(s)
- Ueli Schibler
- Ueli Schibler, Department
of Molecular and Cellular Biology, University of Geneva, 30, Quai Ernest
Ansermet, Geneva, CH-1211, Switzerland; e-mail:
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6
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Bunch H. Studying RNA Polymerase II Promoter-Proximal Pausing by In Vitro Immobilized Template and Transcription Assays. Methods Mol Biol 2023; 2693:13-24. [PMID: 37540423 DOI: 10.1007/978-1-0716-3342-7_2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/05/2023]
Abstract
The immobilized template assay is a versatile biochemical method for studying protein-nucleic acid interactions. Using this method, immobilized nucleic acid-associated or specific proteins can be identified and quantified by techniques such as mass spectrometry and immunoblotting. Here, a modified immobilized template assay combined with in vitro transcription assay to study the function of transcription factors and transcriptional activities at the human heat shock protein 70 (HSP70) gene is described. Notably, this method can be applied to study other important genes and transcription factors in vitro.
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Affiliation(s)
- Heeyoun Bunch
- Department of Applied Biosciences, Kyungpook National University, Daegu, Republic of Korea
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7
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Abuhashem A, Garg V, Hadjantonakis AK. RNA polymerase II pausing in development: orchestrating transcription. Open Biol 2022; 12:210220. [PMID: 34982944 PMCID: PMC8727152 DOI: 10.1098/rsob.210220] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
The coordinated regulation of transcriptional networks underpins cellular identity and developmental progression. RNA polymerase II promoter-proximal pausing (Pol II pausing) is a prevalent mechanism by which cells can control and synchronize transcription. Pol II pausing regulates the productive elongation step of transcription at key genes downstream of a variety of signalling pathways, such as FGF and Nodal. Recent advances in our understanding of the Pol II pausing machinery and its role in transcription call for an assessment of these findings within the context of development. In this review, we discuss our current understanding of the molecular basis of Pol II pausing and its function during organismal development. By critically assessing the tools used to study this process we conclude that combining recently developed genomics approaches with refined perturbation systems has the potential to expand our understanding of Pol II pausing mechanistically and functionally in the context of development and beyond.
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Affiliation(s)
- Abderhman Abuhashem
- Developmental Biology Program, Sloan Kettering Institute, Memorial Sloan Kettering Cancer Center, New York, NY 10065, USA,Weill Cornell/Rockefeller/Sloan Kettering Tri-Institutional MD-PhD Program, New York, NY 10021, USA,Biochemistry, Cell and Molecular Biology Graduate Program, Weill Cornell Medical College, New York, NY 10021, USA
| | - Vidur Garg
- Developmental Biology Program, Sloan Kettering Institute, Memorial Sloan Kettering Cancer Center, New York, NY 10065, USA
| | - Anna-Katerina Hadjantonakis
- Developmental Biology Program, Sloan Kettering Institute, Memorial Sloan Kettering Cancer Center, New York, NY 10065, USA,Biochemistry, Cell and Molecular Biology Graduate Program, Weill Cornell Medical College, New York, NY 10021, USA
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8
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Aoi Y, Takahashi YH, Shah AP, Iwanaszko M, Rendleman EJ, Khan NH, Cho BK, Goo YA, Ganesan S, Kelleher NL, Shilatifard A. SPT5 stabilization of promoter-proximal RNA polymerase II. Mol Cell 2021; 81:4413-4424.e5. [PMID: 34480849 PMCID: PMC8687145 DOI: 10.1016/j.molcel.2021.08.006] [Citation(s) in RCA: 37] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2021] [Revised: 06/28/2021] [Accepted: 08/03/2021] [Indexed: 01/02/2023]
Abstract
Based on in vitro studies, it has been demonstrated that the DSIF complex, composed of SPT4 and SPT5, regulates the elongation stage of transcription catalyzed by RNA polymerase II (RNA Pol II). The precise cellular function of SPT5 is not clear, because conventional gene depletion strategies for SPT5 result in loss of cellular viability. Using an acute inducible protein depletion strategy to circumvent this issue, we report that SPT5 loss triggers the ubiquitination and proteasomal degradation of the core RNA Pol II subunit RPB1, a process that we show to be evolutionarily conserved from yeast to human cells. RPB1 degradation requires the E3 ligase Cullin 3, the unfoldase VCP/p97, and a novel form of CDK9 kinase complex. Our study demonstrates that SPT5 stabilizes RNA Pol II specifically at promoter-proximal regions, permitting RNA Pol II release from promoters into gene bodies and providing mechanistic insight into the cellular function of SPT5 in safeguarding accurate gene expression.
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Affiliation(s)
- Yuki Aoi
- Simpson Querrey Institute for Epigenetics, Department of Biochemistry and Molecular Genetics Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA
| | - Yoh-Hei Takahashi
- Simpson Querrey Institute for Epigenetics, Department of Biochemistry and Molecular Genetics Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA
| | - Avani P Shah
- Simpson Querrey Institute for Epigenetics, Department of Biochemistry and Molecular Genetics Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA
| | - Marta Iwanaszko
- Simpson Querrey Institute for Epigenetics, Department of Biochemistry and Molecular Genetics Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA
| | - Emily J Rendleman
- Simpson Querrey Institute for Epigenetics, Department of Biochemistry and Molecular Genetics Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA
| | - Nabiha H Khan
- Simpson Querrey Institute for Epigenetics, Department of Biochemistry and Molecular Genetics Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA
| | - Byoung-Kyu Cho
- Simpson Querrey Institute for Epigenetics, Department of Biochemistry and Molecular Genetics Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA; Proteomics Center of Excellence, Northwestern University, Evanston, IL 60611, USA
| | - Young Ah Goo
- Simpson Querrey Institute for Epigenetics, Department of Biochemistry and Molecular Genetics Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA; Proteomics Center of Excellence, Northwestern University, Evanston, IL 60611, USA
| | - Sheetal Ganesan
- Simpson Querrey Institute for Epigenetics, Department of Biochemistry and Molecular Genetics Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA
| | - Neil L Kelleher
- Simpson Querrey Institute for Epigenetics, Department of Biochemistry and Molecular Genetics Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA; Proteomics Center of Excellence, Northwestern University, Evanston, IL 60611, USA
| | - Ali Shilatifard
- Simpson Querrey Institute for Epigenetics, Department of Biochemistry and Molecular Genetics Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA.
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9
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Dollinger R, Gilmour DS. Regulation of Promoter Proximal Pausing of RNA Polymerase II in Metazoans. J Mol Biol 2021; 433:166897. [PMID: 33640324 DOI: 10.1016/j.jmb.2021.166897] [Citation(s) in RCA: 38] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2020] [Revised: 02/15/2021] [Accepted: 02/19/2021] [Indexed: 12/12/2022]
Abstract
Regulation of transcription is a tightly choreographed process. The establishment of RNA polymerase II promoter proximal pausing soon after transcription initiation and the release of Pol II into productive elongation are key regulatory processes that occur in early elongation. We describe the techniques and tools that have become available for the study of promoter proximal pausing and their utility for future experiments. We then provide an overview of the factors and interactions that govern a multipartite pausing process and address emerging questions surrounding the mechanism of RNA polymerase II's subsequent advancement into the gene body. Finally, we address remaining controversies and future areas of study.
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Affiliation(s)
- Roberta Dollinger
- Center for Eukaryotic Gene Regulation, Department of Biochemistry and Molecular Biology, The Pennsylvania State University, 462 North Frear, University Park, PA 16802, USA.
| | - David S Gilmour
- Center for Eukaryotic Gene Regulation, Department of Biochemistry and Molecular Biology, The Pennsylvania State University, 465A North Frear, University Park, PA 16802, USA.
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10
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Darracq A, Pak H, Bourgoin V, Zmiri F, Dellaire G, Affar EB, Milot E. NPM and NPM-MLF1 interact with chromatin remodeling complexes and influence their recruitment to specific genes. PLoS Genet 2019; 15:e1008463. [PMID: 31675375 PMCID: PMC6853375 DOI: 10.1371/journal.pgen.1008463] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2019] [Revised: 11/13/2019] [Accepted: 10/04/2019] [Indexed: 11/18/2022] Open
Abstract
Nucleophosmin (NPM1) is frequently mutated or subjected to chromosomal translocation in acute myeloid leukemia (AML). NPM protein is primarily located in the nucleus, but the recurrent NPMc+ mutation, which creates a nuclear export signal, is characterized by cytoplasmic localization and leukemogenic properties. Similarly, the NPM-MLF1 translocation product favors the partial cytoplasmic retention of NPM. Regardless of their common cellular distribution, NPM-MLF1 malignancies engender different effects on hematopoiesis compared to NPMc+ counterparts, highlighting possible aberrant nuclear function(s) of NPM in NPMc+ and NPM-MLF1 AML. We performed a proteomic analysis and found that NPM and NPM-MLF1 interact with various nuclear proteins including subunits of the chromatin remodeling complexes ISWI, NuRD and P/BAF. Accordingly, NPM and NPM-MLF1 are recruited to transcriptionally active or repressed genes along with NuRD subunits. Although the overall gene expression program in NPM knockdown cells is similar to that resulting from NPMc+, NPM-MLF1 expression differentially altered gene transcription regulated by NPM. The abnormal gene regulation imposed by NPM-MLF1 can be characterized by the enhanced recruitment of NuRD to gene regulatory regions. Thus, different mechanisms would orchestrate the dysregulation of NPM function in NPMc+- versus NPM1-MLF1-associated leukemia. NPMc+ mutation is the most common mutation in acute myeloid leukemia (AML) with prevalence in one third of all AML cases. NPM can also be involved in leukemogenic translocation including the t(3;5)(q25;q34) NPM-MLF1 translocation, which is associated to bad clinical course but remains poorly defined. We are reporting that NPM and the leukemogenic NPM-MLF1 play central role in chromatin organization and gene regulation in hematopoietic cells. A proteomic analysis provided the evidence that NPM and NPM-MLF1 are interacting with the chromatin remodeling complexes NuRD, P/BAF and ISWI in hematopoietic cells. The NPM nuclear depletion, such as imposed by the leukemogenic NPMc+ mutation, or the expression of NPM-MLF1 favors the uncontrolled recruitment of the CHD4/NuRD to chromatin and the abnormal regulation of NPM-target genes. Our results suggest that the abnormal gene regulation forced by NPM-MLF1 is different than the loss of nuclear function imposed by NPMc+, and it can be characterized by the enhanced recruitment of CHD4/NuRD to genes. Thus, NPM-MLF1 is likely to promote hematopoietic malignancies by disruption of gene regulation imposed by the NuRD activity.
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Affiliation(s)
- Anaïs Darracq
- Maisonneuve Rosemont Hospital Research Center, CIUSSS Est de l’Île de Montréal, boulevard l’Assomption, Montreal, Quebec, Canada
- Molecular Biology Program, University of Montreal, Montreal, Quebec, Canada
| | - Helen Pak
- Maisonneuve Rosemont Hospital Research Center, CIUSSS Est de l’Île de Montréal, boulevard l’Assomption, Montreal, Quebec, Canada
| | - Vincent Bourgoin
- Maisonneuve Rosemont Hospital Research Center, CIUSSS Est de l’Île de Montréal, boulevard l’Assomption, Montreal, Quebec, Canada
| | - Farah Zmiri
- Maisonneuve Rosemont Hospital Research Center, CIUSSS Est de l’Île de Montréal, boulevard l’Assomption, Montreal, Quebec, Canada
| | - Graham Dellaire
- Departments of Pathology and Biochemistry & Molecular Biology, Dalhousie University, Halifax, Nova Scotia, Canada
| | - El Bachir Affar
- Maisonneuve Rosemont Hospital Research Center, CIUSSS Est de l’Île de Montréal, boulevard l’Assomption, Montreal, Quebec, Canada
- Department of Medicine, University of Montreal, Boulevard Edouard-Montpetit, Montreal, Quebec, Canada
| | - Eric Milot
- Maisonneuve Rosemont Hospital Research Center, CIUSSS Est de l’Île de Montréal, boulevard l’Assomption, Montreal, Quebec, Canada
- Department of Medicine, University of Montreal, Boulevard Edouard-Montpetit, Montreal, Quebec, Canada
- * E-mail:
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11
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Abstract
In this review, Core et al. discuss the recent advances in our understanding of the early steps in Pol II transcription, highlighting the events and factors involved in the establishment and release of paused Pol II. They also discuss a number of unanswered questions about the regulation and function of Pol II pausing. Precise spatio–temporal control of gene activity is essential for organismal development, growth, and survival in a changing environment. Decisive steps in gene regulation involve the pausing of RNA polymerase II (Pol II) in early elongation, and the controlled release of paused polymerase into productive RNA synthesis. Here we describe the factors that enable pausing and the events that trigger Pol II release into the gene. We also discuss open questions in the field concerning the stability of paused Pol II, nucleosomes as obstacles to elongation, and potential roles of pausing in defining the precision and dynamics of gene expression.
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Affiliation(s)
- Leighton Core
- Department of Molecular and Cell Biology, Institute of Systems Genomics, University of Connecticut, Storrs, Connecticut 06269, USA
| | - Karen Adelman
- Department of Biological Chemistry and Molecular Pharmacology, Blavatnik Institute, Harvard Medical School, Boston, Massachusetts 02115, USA
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12
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Shao W, Alcantara SGM, Zeitlinger J. Reporter-ChIP-nexus reveals strong contribution of the Drosophila initiator sequence to RNA polymerase pausing. eLife 2019; 8:41461. [PMID: 31021316 PMCID: PMC6483594 DOI: 10.7554/elife.41461] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2018] [Accepted: 04/04/2019] [Indexed: 12/11/2022] Open
Abstract
RNA polymerase II (Pol II) pausing is a general regulatory step in transcription, yet the stability of paused Pol II varies widely between genes. Although paused Pol II stability correlates with core promoter elements, the contribution of individual sequences remains unclear, in part because no rapid assay is available for measuring the changes in Pol II pausing as a result of altered promoter sequences. Here, we overcome this hurdle by showing that ChIP-nexus captures the endogenous Pol II pausing on transfected plasmids. Using this reporter-ChIP-nexus assay in Drosophila cells, we show that the pausing stability is influenced by downstream promoter sequences, but that the strongest contribution to Pol II pausing comes from the initiator sequence, in which a single nucleotide, a G at the +2 position, is critical for stable Pol II pausing. These results establish reporter-ChIP-nexus as a valuable tool to analyze Pol II pausing.
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Affiliation(s)
- Wanqing Shao
- Stowers Institute for Medical Research, Kansas City, United States
| | | | - Julia Zeitlinger
- Stowers Institute for Medical Research, Kansas City, United States.,Department of Pathology and Laboratory Medicine, University of Kansas Medical Center, Kansas City, United States
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13
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Bunch H, Choe H, Kim J, Jo DS, Jeon S, Lee S, Cho DH, Kang K. P-TEFb Regulates Transcriptional Activation in Non-coding RNA Genes. Front Genet 2019; 10:342. [PMID: 31068966 PMCID: PMC6491683 DOI: 10.3389/fgene.2019.00342] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2019] [Accepted: 03/29/2019] [Indexed: 01/16/2023] Open
Abstract
Many non-coding RNAs (ncRNAs) serve as regulatory molecules in various physiological pathways, including gene expression in mammalian cells. Distinct from protein-coding RNA expression, ncRNA expression is regulated solely by transcription and RNA processing/stability. It is thus important to understand transcriptional regulation in ncRNA genes but is yet to be known completely. Previously, we identified that a subset of mammalian ncRNA genes is transcriptionally regulated by RNA polymerase II (Pol II) promoter-proximal pausing and in a tissue-specific manner. In this study, human ncRNA genes that are expressed in the early G1 phase, termed immediate early ncRNA genes, were monitored to assess the function of positive transcription elongation factor b (P-TEFb), a master Pol II pausing regulator for protein-coding genes, in ncRNA transcription. Our findings indicate that the expression of many ncRNA genes is induced in the G0–G1 transition and regulated by P-TEFb. Interestingly, a biphasic characteristic of P-TEFb-dependent transcription of serum responsive ncRNA genes was observed: Pol II carboxyl-terminal domain phosphorylated at serine 2 (S2) was largely increased in the transcription start site (TSS, -300 to +300) whereas overall, it was decreased in the gene body (GB, > +350) upon chemical inhibition of P-TEFb. In addition, the three representative, immediate early ncRNAs, whose expression is dependent on P-TEFb, metastasis-associated lung adenocarcinoma transcript 1 (MALAT1), nuclear enriched abundant transcript 1 (NEAT1), and X-inactive specific transcript (XIST), were further analyzed for determining P-TEFb association. Taken together, our data suggest that transcriptional activation of many human ncRNAs utilizes the pausing and releasing of Pol II, and that the regulatory mechanism of transcriptional elongation in these genes requires the function of P-TEFb. Furthermore, we propose that ncRNA and mRNA transcription are regulated by similar mechanisms while P-TEFb inhibition unexpectedly increases S2 Pol II phosphorylation in the TSSs in many ncRNA genes. One Sentence Summary: P-TEFb regulates Pol II phosphorylation for transcriptional activation in many stimulus-inducible ncRNA genes.
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Affiliation(s)
- Heeyoun Bunch
- Department of Applied Biosciences, College of Agriculture and Life Sciences, Kyungpook National University, Daegu, South Korea
| | - Hyeseung Choe
- Department of Applied Biosciences, College of Agriculture and Life Sciences, Kyungpook National University, Daegu, South Korea
| | - Jongbum Kim
- Department of Transcriptome & Epigenome, Macrogen Incorporated, Seoul, South Korea
| | - Doo Sin Jo
- Institute of Life Science and Biotechnology, College of Natural Science, Kyungpook National University, Daegu, South Korea
| | - Soyeon Jeon
- Department of Applied Biosciences, College of Agriculture and Life Sciences, Kyungpook National University, Daegu, South Korea
| | - Sanghwa Lee
- Department of Applied Biosciences, College of Agriculture and Life Sciences, Kyungpook National University, Daegu, South Korea
| | - Dong-Hyung Cho
- Department of Life Science, College of Natural Science, Kyungpook National University, Daegu, South Korea
| | - Keunsoo Kang
- Department of Microbiology, College of Natural Sciences, Dankook University, Cheonan, South Korea
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14
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Pfammatter S, Bonneil E, McManus FP, Prasad S, Bailey DJ, Belford M, Dunyach JJ, Thibault P. A Novel Differential Ion Mobility Device Expands the Depth of Proteome Coverage and the Sensitivity of Multiplex Proteomic Measurements. Mol Cell Proteomics 2018; 17:2051-2067. [PMID: 30007914 DOI: 10.1074/mcp.tir118.000862] [Citation(s) in RCA: 86] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2018] [Revised: 07/11/2018] [Indexed: 01/17/2023] Open
Abstract
The depth of proteomic analyses is often limited by the overwhelming proportion of confounding background ions that compromise the identification and quantification of low abundance peptides. To alleviate these limitations, we present a new high field asymmetric waveform ion mobility spectrometry (FAIMS) interface that can be coupled to the Orbitrap Tribrid mass spectrometers. The interface provides several advantages over previous generations of FAIMS devices, including ease of operation, robustness, and high ion transmission. Replicate LC-FAIMS-MS/MS analyses (n = 100) of HEK293 protein digests showed stable ion current over extended time periods with uniform peptide identification on more than 10,000 distinct peptides. For complex tryptic digest analyses, the coupling of FAIMS to LC-MS/MS enabled a 30% gain in unique peptide identification compared with non-FAIMS experiments. Improvement in sensitivity facilitated the identification of low abundance peptides, and extended the limit of detection by almost an order of magnitude. The reduction in chimeric MS/MS spectra using FAIMS also improved the precision and the number of quantifiable peptides when using isobaric labeling with tandem mass tag (TMT) 10-plex reagent. We compared quantitative proteomic measurements for LC-MS/MS analyses performed using synchronous precursor selection (SPS) and LC-FAIMS-MS/MS to profile the temporal changes in protein abundance of HEK293 cells following heat shock for periods up to 9 h. FAIMS provided 2.5-fold increase in the number of quantifiable peptides compared with non-FAIMS experiments (30,848 peptides from 2,646 proteins for FAIMS versus 12,400 peptides from 1,229 proteins with SPS). Altogether, the enhancement in ion transmission and duty cycle of the new FAIMS interface extended the depth and comprehensiveness of proteomic analyses and improved the precision of quantitative measurements.
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Affiliation(s)
- Sibylle Pfammatter
- From the ‡Institute for Research in Immunology and Cancer, H3T 1J4, Québec, Canada.,§University of Montréal, Department of Chemistry, H3T 1J4, Québec, Canada
| | - Eric Bonneil
- From the ‡Institute for Research in Immunology and Cancer, H3T 1J4, Québec, Canada
| | - Francis P McManus
- From the ‡Institute for Research in Immunology and Cancer, H3T 1J4, Québec, Canada
| | - Satendra Prasad
- ¶Thermo Fisher Scientific, San Jose, California 95134, United States
| | - Derek J Bailey
- ¶Thermo Fisher Scientific, San Jose, California 95134, United States
| | - Michael Belford
- ¶Thermo Fisher Scientific, San Jose, California 95134, United States
| | | | - Pierre Thibault
- From the ‡Institute for Research in Immunology and Cancer, H3T 1J4, Québec, Canada; .,§University of Montréal, Department of Chemistry, H3T 1J4, Québec, Canada
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15
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RNA polymerase II pausing and transcriptional regulation of the HSP70 expression. Eur J Cell Biol 2017; 96:739-745. [DOI: 10.1016/j.ejcb.2017.09.003] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2017] [Revised: 08/16/2017] [Accepted: 09/25/2017] [Indexed: 12/20/2022] Open
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16
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Bunch H. Gene regulation of mammalian long non-coding RNA. Mol Genet Genomics 2017; 293:1-15. [PMID: 28894972 DOI: 10.1007/s00438-017-1370-9] [Citation(s) in RCA: 97] [Impact Index Per Article: 13.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2017] [Accepted: 09/07/2017] [Indexed: 12/14/2022]
Abstract
RNA polymerase II (Pol II) transcribes two classes of RNAs, protein-coding and non-protein-coding (ncRNA) genes. ncRNAs are also synthesized by RNA polymerases I and III (Pol I and III). In humans, the number of ncRNA genes exceeds more than twice that of protein-coding genes. However, the history of studying Pol II-synthesized ncRNA is relatively short. Since early 2000s, important biological and pathological functions of these ncRNA genes have begun to be discovered and intensively studied. And transcription mechanisms of long non-coding RNA (lncRNA) have been recently reported. Transcription of lncRNAs utilizes some transcription factors and mechanisms shared in that of protein-coding genes. In addition, tissue specificity in lncRNA gene expression has been shown. LncRNAs play essential roles in regulating the expression of neighboring or distal genes through different mechanisms. This leads to the implication of lncRNAs in a wide variety of biological pathways and pathological development. In this review, the newly discovered transcription mechanisms, characteristics, and functions of lncRNA are discussed.
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Affiliation(s)
- Heeyoun Bunch
- School of Applied Biosciences, College of Agriculture and Life Sciences, Kyungpook National University, Agriculture & Life Sciences Building 1, Room 207, 80 Dae-Hak Ro, Daegu, Republic of Korea.
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17
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Zovoilis A, Cifuentes-Rojas C, Chu HP, Hernandez AJ, Lee JT. Destabilization of B2 RNA by EZH2 Activates the Stress Response. Cell 2017; 167:1788-1802.e13. [PMID: 27984727 DOI: 10.1016/j.cell.2016.11.041] [Citation(s) in RCA: 51] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2016] [Revised: 10/03/2016] [Accepted: 11/22/2016] [Indexed: 12/12/2022]
Abstract
More than 98% of the mammalian genome is noncoding, and interspersed transposable elements account for ∼50% of noncoding space. Here, we demonstrate that a specific interaction between the polycomb protein EZH2 and RNA made from B2 SINE retrotransposons controls stress-responsive genes in mouse cells. In the heat-shock model, B2 RNA binds stress genes and suppresses their transcription. Upon stress, EZH2 is recruited and triggers cleavage of B2 RNA. B2 degradation in turn upregulates stress genes. Evidence indicates that B2 RNA operates as a "speed bump" against advancement of RNA polymerase II, and temperature stress releases the brakes on transcriptional elongation. These data attribute a new function to EZH2 that is independent of its histone methyltransferase activity and reconcile how EZH2 can be associated with both gene repression and activation. Our study reveals that EZH2 and B2 together control activation of a large network of genes involved in thermal stress.
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Affiliation(s)
- Athanasios Zovoilis
- Howard Hughes Medical Institute; Department of Molecular Biology, Massachusetts General Hospital, Boston, MA 02114, USA; Department of Genetics, Harvard Medical School, Boston, MA 02114, USA
| | - Catherine Cifuentes-Rojas
- Howard Hughes Medical Institute; Department of Molecular Biology, Massachusetts General Hospital, Boston, MA 02114, USA; Department of Genetics, Harvard Medical School, Boston, MA 02114, USA
| | - Hsueh-Ping Chu
- Howard Hughes Medical Institute; Department of Molecular Biology, Massachusetts General Hospital, Boston, MA 02114, USA; Department of Genetics, Harvard Medical School, Boston, MA 02114, USA
| | - Alfredo J Hernandez
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02115, USA
| | - Jeannie T Lee
- Howard Hughes Medical Institute; Department of Molecular Biology, Massachusetts General Hospital, Boston, MA 02114, USA; Department of Genetics, Harvard Medical School, Boston, MA 02114, USA.
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18
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Lee J, Choi ES, Seo HD, Kang K, Gilmore JM, Florens L, Washburn MP, Choe J, Workman JL, Lee D. Chromatin remodeller Fun30 Fft3 induces nucleosome disassembly to facilitate RNA polymerase II elongation. Nat Commun 2017; 8:14527. [PMID: 28218250 PMCID: PMC5321744 DOI: 10.1038/ncomms14527] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2016] [Accepted: 01/09/2017] [Indexed: 01/30/2023] Open
Abstract
Previous studies have revealed that nucleosomes impede elongation of RNA polymerase II (RNAPII). Recent observations suggest a role for ATP-dependent chromatin remodellers in modulating this process, but direct in vivo evidence for this is unknown. Here using fission yeast, we identify Fun30Fft3 as a chromatin remodeller, which localizes at transcribing regions to promote RNAPII transcription. Fun30Fft3 associates with RNAPII and collaborates with the histone chaperone, FACT, which facilitates RNAPII elongation through chromatin, to induce nucleosome disassembly at transcribing regions during RNAPII transcription. Mutants, resulting in reduced nucleosome-barrier, such as deletion mutants of histones H3/H4 themselves and the genes encoding components of histone deacetylase Clr6 complex II suppress the defects in growth and RNAPII occupancy of cells lacking Fun30Fft3. These data suggest that RNAPII utilizes the chromatin remodeller, Fun30Fft3, to overcome the nucleosome barrier to transcription elongation. Nucleosomes have been shown to impede the elongation of RNA polymerase II during transcription. Here, the authors provide evidence that in fission yeast chromatin remodeller Fun30Fft3 localizes to transcribing regions to promote transcription by nucleosome disassembly in vivo.
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Affiliation(s)
- Junwoo Lee
- Department of Biological Sciences, Korea Advanced Institute of Science and Technology, Daejeon 34141, South Korea
| | - Eun Shik Choi
- Department of Biological Sciences, Korea Advanced Institute of Science and Technology, Daejeon 34141, South Korea
| | - Hogyu David Seo
- Department of Biological Sciences, Korea Advanced Institute of Science and Technology, Daejeon 34141, South Korea
| | - Keunsoo Kang
- Department of Microbiology, Dankook University, Cheonan, Chungnam 31116, South Korea
| | - Joshua M Gilmore
- Stowers Institute for Medical Research, Kansas City, Kansas City, Missouri 64110, USA
| | - Laurence Florens
- Stowers Institute for Medical Research, Kansas City, Kansas City, Missouri 64110, USA
| | - Michael P Washburn
- Stowers Institute for Medical Research, Kansas City, Kansas City, Missouri 64110, USA.,Department of Anatomy and Cell Biology, University of Kansas Medical Center, 3901 Rainbow Boulevard, Kansas City, Kansas 66160, USA
| | - Joonho Choe
- Department of Biological Sciences, Korea Advanced Institute of Science and Technology, Daejeon 34141, South Korea
| | - Jerry L Workman
- Stowers Institute for Medical Research, Kansas City, Kansas City, Missouri 64110, USA
| | - Daeyoup Lee
- Department of Biological Sciences, Korea Advanced Institute of Science and Technology, Daejeon 34141, South Korea
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19
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Vaňková Hausnerová V, Lanctôt C. Chromatin decondensation is accompanied by a transient increase in transcriptional output. Biol Cell 2016; 109:65-79. [PMID: 27633335 DOI: 10.1111/boc.201600032] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2016] [Revised: 09/12/2016] [Accepted: 09/13/2016] [Indexed: 12/26/2022]
Abstract
BACKGROUND INFORMATION The levels of chromatin condensation usually correlate inversely with the levels of transcription. The mechanistic links between chromatin condensation and RNA polymerase II activity remain to be elucidated. In the present work, we sought to experimentally determine whether manipulation of chromatin condensation levels can have a direct effect on transcriptional activity. RESULTS We generated a U-2-OS cell line in which the nascent transcription of a reporter gene could be imaged alongside chromatin compaction levels in living cells. The transcripts were tagged at their 5' end with PP7 stem loops, which can be detected upon expression of a PP7 capsid protein fused to green fluorescent protein. Cycles of global chromatin hypercondensation and decondensation were performed by perfusing culture media of different osmolarities during imaging. We used the fluorescence recovery after photobleaching technique to analyse the transcriptional dynamics in both conditions. Surprisingly, we found that, despite a drop in signal intensity, nascent transcription appeared to continue at the same rate in hypercondensed chromatin. Furthermore, quantification of transcriptional profiles revealed that chromatin decondensation was accompanied by a brief and transient spike in transcriptional output. CONCLUSIONS We propose a model whereby the initiation of transcription is not impaired in condensed chromatin, but inefficient elongation in these conditions leads to the accumulation of RNA polymerase II at the transcription site. Upon chromatin decondensation, release of the RNA polymerase II halt triggers a wave of transcription, which we detect as a transient spike in activity. SIGNIFICANCE The results presented here shed light on the activity of RNA polymerase II during chromatin condensation and decondensation. As such, they point to a new level of transcriptional regulation.
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Affiliation(s)
- Viola Vaňková Hausnerová
- Institute of Cellular Biology and Pathology, First Faculty of Medicine, Charles University, Prague, Czech Republic.,BIOCEV and Department of Cell Biology, Faculty of Science, Charles University, Vestec u Prahy, 252 50, Czech Republic
| | - Christian Lanctôt
- Institute of Cellular Biology and Pathology, First Faculty of Medicine, Charles University, Prague, Czech Republic.,BIOCEV and Department of Cell Biology, Faculty of Science, Charles University, Vestec u Prahy, 252 50, Czech Republic
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20
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Abstract
Thousands of human and Drosophila genes are regulated at the level of transcript elongation and nucleosomes are likely targets for this regulation. However, the molecular mechanisms of formation of the nucleosomal barrier to transcribing RNA polymerase II (Pol II) and nucleosome survival during/after transcription remain unknown. Here we show that both DNA-histone interactions and Pol II backtracking contribute to formation of the barrier and that nucleosome survival during transcription likely occurs through allosterically stabilized histone-histone interactions. Structural analysis indicates that after Pol II encounters the barrier, the enzyme backtracks and nucleosomal DNA recoils on the octamer, locking Pol II in the arrested state. DNA is displaced from one of the H2A/H2B dimers that remains associated with the octamer. The data reveal the importance of intranucleosomal DNA-protein and protein-protein interactions during conformational changes in the nucleosome structure on transcription. Mechanisms of nucleosomal barrier formation and nucleosome survival during transcription are proposed.
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21
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Scheidegger A, Nechaev S. RNA polymerase II pausing as a context-dependent reader of the genome. Biochem Cell Biol 2015; 94:82-92. [PMID: 26555214 DOI: 10.1139/bcb-2015-0045] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
The RNA polymerase II (Pol II) transcribes all mRNA genes in eukaryotes and is among the most highly regulated enzymes in the cell. The classic model of mRNA gene regulation involves recruitment of the RNA polymerase to gene promoters in response to environmental signals. Higher eukaryotes have an additional ability to generate multiple cell types. This extra level of regulation enables each cell to interpret the same genome by committing to one of the many possible transcription programs and executing it in a precise and robust manner. Whereas multiple mechanisms are implicated in cell type-specific transcriptional regulation, how one genome can give rise to distinct transcriptional programs and what mechanisms activate and maintain the appropriate program in each cell remains unclear. This review focuses on the process of promoter-proximal Pol II pausing during early transcription elongation as a key step in context-dependent interpretation of the metazoan genome. We highlight aspects of promoter-proximal Pol II pausing, including its interplay with epigenetic mechanisms, that may enable cell type-specific regulation, and emphasize some of the pertinent questions that remain unanswered and open for investigation.
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Affiliation(s)
- Adam Scheidegger
- Department of Basic Sciences, University of North Dakota School of Medicine, Grand Forks, ND 58201, USA.,Department of Basic Sciences, University of North Dakota School of Medicine, Grand Forks, ND 58201, USA
| | - Sergei Nechaev
- Department of Basic Sciences, University of North Dakota School of Medicine, Grand Forks, ND 58201, USA.,Department of Basic Sciences, University of North Dakota School of Medicine, Grand Forks, ND 58201, USA
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22
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GC skew defines distinct RNA polymerase pause sites in CpG island promoters. Genome Res 2015; 25:1600-9. [PMID: 26275623 PMCID: PMC4617957 DOI: 10.1101/gr.189068.114] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2014] [Accepted: 08/14/2015] [Indexed: 12/15/2022]
Abstract
CpG islands (CGIs) are associated with over half of human gene promoters and are characterized by a unique chromatin environment and high levels of bidirectional transcriptional activity relative to surrounding genomic regions, suggesting that RNA polymerase (Pol II) progression past the CGI boundaries is restricted. Here we describe a novel transcriptional regulatory step wherein Pol II encounters an additional barrier to elongation distinct from the promoter-proximal pause and occurring at the downstream boundary of the CGI domain. For most CGI-associated promoters, Pol II exhibits a dominant pause at either the promoter-proximal or this distal site that correlates, both in position and in intensity, with local regions of high GC skew, a sequence feature known to form unique secondary structures. Upon signal-induced gene activation, long-range enhancer contacts at the dominant pause site are selectively enhanced, suggesting a new role for enhancers at the downstream pause. These data point to an additional level of control over transcriptional output at a subset of CGI-associated genes that is linked to DNA sequence and the integrity of the CGI domain.
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23
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Samarakkody A, Abbas A, Scheidegger A, Warns J, Nnoli O, Jokinen B, Zarns K, Kubat B, Dhasarathy A, Nechaev S. RNA polymerase II pausing can be retained or acquired during activation of genes involved in the epithelial to mesenchymal transition. Nucleic Acids Res 2015; 43:3938-49. [PMID: 25820424 PMCID: PMC4417172 DOI: 10.1093/nar/gkv263] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2015] [Accepted: 03/17/2015] [Indexed: 12/26/2022] Open
Abstract
Promoter-proximal RNA polymerase II (Pol II) pausing is implicated in the regulation of gene transcription. However, the mechanisms of pausing including its dynamics during transcriptional responses remain to be fully understood. We performed global analysis of short capped RNAs and Pol II Chromatin Immunoprecipitation sequencing in MCF-7 breast cancer cells to map Pol II pausing across the genome, and used permanganate footprinting to specifically follow pausing during transcriptional activation of several genes involved in the epithelial to mesenchymal transition (EMT). We find that the gene for EMT master regulator Snail (SNAI1), but not Slug (SNAI2), shows evidence of Pol II pausing before activation. Transcriptional activation of the paused SNAI1 gene is accompanied by a further increase in Pol II pausing signal, whereas activation of non-paused SNAI2 gene results in the acquisition of a typical pausing signature. The increase in pausing signal reflects increased transcription initiation without changes in Pol II pausing. Activation of the heat shock HSP70 gene involves pausing release that speeds up Pol II turnover, but does not change pausing location. We suggest that Pol II pausing is retained during transcriptional activation and can further undergo regulated release in a signal-specific manner.
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Affiliation(s)
- Ann Samarakkody
- Department of Basic Sciences, University of North Dakota School of Medicine, Grand Forks, ND 58202, USA
| | - Ata Abbas
- Department of Basic Sciences, University of North Dakota School of Medicine, Grand Forks, ND 58202, USA
| | - Adam Scheidegger
- Department of Basic Sciences, University of North Dakota School of Medicine, Grand Forks, ND 58202, USA
| | - Jessica Warns
- Department of Basic Sciences, University of North Dakota School of Medicine, Grand Forks, ND 58202, USA
| | - Oscar Nnoli
- Department of Basic Sciences, University of North Dakota School of Medicine, Grand Forks, ND 58202, USA
| | - Bradley Jokinen
- Department of Computer Sciences, University of North Dakota, Grand Forks, ND 58202, USA
| | - Kris Zarns
- Department of Computer Sciences, University of North Dakota, Grand Forks, ND 58202, USA
| | - Brooke Kubat
- Department of Basic Sciences, University of North Dakota School of Medicine, Grand Forks, ND 58202, USA
| | - Archana Dhasarathy
- Department of Basic Sciences, University of North Dakota School of Medicine, Grand Forks, ND 58202, USA
| | - Sergei Nechaev
- Department of Basic Sciences, University of North Dakota School of Medicine, Grand Forks, ND 58202, USA
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24
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Jimeno-González S, Ceballos-Chávez M, Reyes JC. A positioned +1 nucleosome enhances promoter-proximal pausing. Nucleic Acids Res 2015; 43:3068-78. [PMID: 25735750 PMCID: PMC4381062 DOI: 10.1093/nar/gkv149] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2014] [Accepted: 02/13/2015] [Indexed: 02/07/2023] Open
Abstract
Chromatin distribution is not uniform along the human genome. In most genes there is a promoter-associated nucleosome free region (NFR) followed by an array of nucleosomes towards the gene body in which the first (+1) nucleosome is strongly positioned. The function of this characteristic chromatin distribution in transcription is not fully understood. Here we show in vivo that the +1 nucleosome plays a role in modulating RNA polymerase II (RNAPII) promoter-proximal pausing. When a +1 nucleosome is strongly positioned, elongating RNAPII has a tendency to stall at the promoter-proximal region, recruits more negative elongation factor (NELF) and produces less mRNA. The nucleosome-induced pause favors pre-mRNA quality control by promoting the addition of the cap to the nascent RNA. Moreover, the uncapped RNAs produced in the absence of a positioned nucleosome are degraded by the 5′-3′ exonuclease XRN2. Interestingly, reducing the levels of the chromatin remodeler ISWI factor SNF2H decreases +1 nucleosome positioning and increases RNAPII pause release. This work demonstrates a function for +1 nucleosome in regulation of transcription elongation, pre-mRNA processing and gene expression.
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Affiliation(s)
- Silvia Jimeno-González
- Centro Andaluz de Biología Molecular y Medicina Regenerativa (CABIMER), Consejo Superior de Investigaciones Científicas (CSIC), E-41012, Seville, Spain
| | - María Ceballos-Chávez
- Centro Andaluz de Biología Molecular y Medicina Regenerativa (CABIMER), Consejo Superior de Investigaciones Científicas (CSIC), E-41012, Seville, Spain
| | - José C Reyes
- Centro Andaluz de Biología Molecular y Medicina Regenerativa (CABIMER), Consejo Superior de Investigaciones Científicas (CSIC), E-41012, Seville, Spain
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25
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Ortner V, Ludwig A, Riegel E, Dunzinger S, Czerny T. An artificial HSE promoter for efficient and selective detection of heat shock pathway activity. Cell Stress Chaperones 2015; 20:277-88. [PMID: 25168173 PMCID: PMC4326385 DOI: 10.1007/s12192-014-0540-5] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2014] [Revised: 08/14/2014] [Accepted: 08/15/2014] [Indexed: 11/26/2022] Open
Abstract
Detection of cellular stress is of major importance for the survival of cells. During evolution, a network of stress pathways developed, with the heat shock (HS) response playing a major role. The key transcription factor mediating HS signalling activity in mammalian cells is the HS factor HSF1. When activated it binds to the heat shock elements (HSE) in the promoters of target genes like heat shock protein (HSP) genes. They are induced by HSF1 but in addition they integrate multiple signals from different stress pathways. Here, we developed an artificial promoter consisting only of HSEs and therefore selectively reacting to HSF-mediated pathway activation. The promoter is highly inducible but has an extreme low basal level. Direct comparison with the HSPA1A promoter activity indicates that heat-dependent expression can be fully recapitulated by isolated HSEs in human cells. Using this sensitive reporter, we measured the HS response for different temperatures and exposure times. In particular, long heat induction times of 1 or 2 h were compared with short heat durations down to 1 min, conditions typical for burn injuries. We found similar responses to both long and short heat durations but at completely different temperatures. Exposure times of 2 h result in pathway activation at 41 to 44 °C, whereas heat pulses of 1 min lead to a maximum HS response between 47 and 50 °C. The results suggest that the HS response is initiated by a combination of temperature and exposure time but not by a certain threshold temperature.
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Affiliation(s)
- Viktoria Ortner
- Department of Applied Life Sciences, University of Applied Sciences, FH Campus Wien, Helmut-Qualtinger-Gasse 2, A-1030, Vienna, Austria
| | - Alfred Ludwig
- Department of Agrarian Production, Genetics and Microbiology Research Group Public, University of Navarre, Pamplona, Navarre Spain
| | - Elisabeth Riegel
- Department of Applied Life Sciences, University of Applied Sciences, FH Campus Wien, Helmut-Qualtinger-Gasse 2, A-1030, Vienna, Austria
| | - Sarah Dunzinger
- Department of Applied Life Sciences, University of Applied Sciences, FH Campus Wien, Helmut-Qualtinger-Gasse 2, A-1030, Vienna, Austria
| | - Thomas Czerny
- Department of Applied Life Sciences, University of Applied Sciences, FH Campus Wien, Helmut-Qualtinger-Gasse 2, A-1030, Vienna, Austria
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26
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Abstract
Heat shock factor 1 (HSF1) is an evolutionarily highly conserved transcription factor that coordinates stress-induced transcription and directs versatile physiological processes in eukaryotes. The central position of HSF1 in cellular homeostasis has been well demonstrated, mainly through its strong effect in transactivating genes that encode heat shock proteins (HSPs). However, recent genome-wide studies have revealed that HSF1 is capable of reprogramming transcription more extensively than previously assumed; it is also involved in a multitude of processes in stressed and non-stressed cells. Consequently, the importance of HSF1 in fundamental physiological events, including metabolism, gametogenesis and aging, has become apparent and its significance in pathologies, such as cancer progression, is now evident. In this Cell Science at a Glance article, we highlight recent advances in the HSF1 field, discuss the organismal control over HSF1, and present the processes that are mediated by HSF1 in the context of cell type, cell-cycle phase, physiological condition and received stimuli.
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Elsing AN, Aspelin C, Björk JK, Bergman HA, Himanen SV, Kallio MJ, Roos-Mattjus P, Sistonen L. Expression of HSF2 decreases in mitosis to enable stress-inducible transcription and cell survival. ACTA ACUST UNITED AC 2014; 206:735-49. [PMID: 25202032 PMCID: PMC4164949 DOI: 10.1083/jcb.201402002] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
In spite of global transcriptional inhibition, a decrease in HSF2 expression during mitosis allows for heat shock protein expression and protects cells against proteotoxicity. Unless mitigated, external and physiological stresses are detrimental for cells, especially in mitosis, resulting in chromosomal missegregation, aneuploidy, or apoptosis. Heat shock proteins (Hsps) maintain protein homeostasis and promote cell survival. Hsps are transcriptionally regulated by heat shock factors (HSFs). Of these, HSF1 is the master regulator and HSF2 modulates Hsp expression by interacting with HSF1. Due to global inhibition of transcription in mitosis, including HSF1-mediated expression of Hsps, mitotic cells are highly vulnerable to stress. Here, we show that cells can counteract transcriptional silencing and protect themselves against proteotoxicity in mitosis. We found that the condensed chromatin of HSF2-deficient cells is accessible for HSF1 and RNA polymerase II, allowing stress-inducible Hsp expression. Consequently, HSF2-deficient cells exposed to acute stress display diminished mitotic errors and have a survival advantage. We also show that HSF2 expression declines during mitosis in several but not all human cell lines, which corresponds to the Hsp70 induction and protection against stress-induced mitotic abnormalities and apoptosis.
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Affiliation(s)
- Alexandra N Elsing
- Department of Biosciences, Åbo Akademi University, 20520 Turku, Finland Turku Centre for Biotechnology, University of Turku and Åbo Akademi University, 20520 Turku, Finland
| | - Camilla Aspelin
- Department of Biosciences, Åbo Akademi University, 20520 Turku, Finland
| | - Johanna K Björk
- Department of Biosciences, Åbo Akademi University, 20520 Turku, Finland Turku Centre for Biotechnology, University of Turku and Åbo Akademi University, 20520 Turku, Finland
| | - Heidi A Bergman
- Department of Biosciences, Åbo Akademi University, 20520 Turku, Finland Turku Centre for Biotechnology, University of Turku and Åbo Akademi University, 20520 Turku, Finland
| | - Samu V Himanen
- Department of Biosciences, Åbo Akademi University, 20520 Turku, Finland Turku Centre for Biotechnology, University of Turku and Åbo Akademi University, 20520 Turku, Finland
| | - Marko J Kallio
- Turku Centre for Biotechnology, University of Turku and Åbo Akademi University, 20520 Turku, Finland VTT Health, VTT Technical Research Centre of Finland, 20520 Turku, Finland
| | - Pia Roos-Mattjus
- Department of Biosciences, Åbo Akademi University, 20520 Turku, Finland
| | - Lea Sistonen
- Department of Biosciences, Åbo Akademi University, 20520 Turku, Finland Turku Centre for Biotechnology, University of Turku and Åbo Akademi University, 20520 Turku, Finland
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28
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Wei D, Goldfarb D, Song S, Cannon C, Yan F, Sakellariou-Thompson D, Emanuele M, Major MB, Weissman BE, Kuwahara Y. SNF5/INI1 deficiency redefines chromatin remodeling complex composition during tumor development. Mol Cancer Res 2014; 12:1574-85. [PMID: 25009291 DOI: 10.1158/1541-7786.mcr-14-0005] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
UNLABELLED Malignant rhabdoid tumors (MRT), a pediatric cancer that most frequently appears in the kidney and brain, generally lack SNF5 (SMARCB1/INI1), a subunit of the SWI/SNF chromatin-remodeling complex. Recent studies have established that multiple SWI/SNF complexes exist due to the presence or absence of different complex members. Therefore, the effect of SNF5 loss upon SWI/SNF complex formation was investigated in human MRT cells. MRT cells and primary human tumors exhibited reduced levels of many complex proteins. Furthermore, reexpression of SNF5 increased SWI/SNF complex protein levels without concomitant increases in mRNA. Proteomic analysis, using mass spectrometry, of MRT cells before and after SNF5 reexpression indicated the recruitment of different components into the complex along with the expulsion of others. IP-Western blotting confirmed these results and demonstrated similar changes in other MRT cell lines. Finally, reduced expression of SNF5 in normal human fibroblasts led to altered levels of these same complex members. These data establish that SNF5 loss during MRT development alters the repertoire of available SWI/SNF complexes, generally disrupting those associated with cellular differentiation. These findings support a model where SNF5 inactivation blocks the conversion of growth-promoting SWI/SNF complexes to differentiation-inducing ones. Therefore, restoration of these complexes in tumors cells provides an attractive approach for the treatment of MRTs. IMPLICATIONS SNF5 loss dramatically alters SWI/SNF complex composition and prevents formation of complexes required for cellular differentiation.
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Affiliation(s)
- Darmood Wei
- Curriculum in Toxicology, University of North Carolina, Chapel Hill, North Carolina
| | - Dennis Goldfarb
- Department of Computer Science, University of North Carolina at Chapel Hill, North Carolina
| | - Shujie Song
- Oncology Center, ZhuJiang Hospital, Southern Medical University, Guangzhou, Guangdong, China. Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, North Carolina
| | - Courtney Cannon
- Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, North Carolina. Department of Pharmacology, University of North Carolina, Chapel Hill, North Carolina
| | - Feng Yan
- Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, North Carolina
| | | | - Michael Emanuele
- Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, North Carolina. Department of Pharmacology, University of North Carolina, Chapel Hill, North Carolina
| | - Michael B Major
- Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, North Carolina. Department of Cell Biology and Physiology, University of North Carolina, Chapel Hill, North Carolina
| | - Bernard E Weissman
- Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, North Carolina. Department of Pathology and Laboratory Medicine, University of North Carolina, Chapel Hill, North Carolina.
| | - Yasumichi Kuwahara
- Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, North Carolina. Department of Pediatrics, Kyoto Prefectural University of Medicine, Kyoto, Japan.
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29
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Li J, Liu Y, Rhee HS, Ghosh SKB, Bai L, Pugh BF, Gilmour DS. Kinetic competition between elongation rate and binding of NELF controls promoter-proximal pausing. Mol Cell 2013; 50:711-22. [PMID: 23746353 DOI: 10.1016/j.molcel.2013.05.016] [Citation(s) in RCA: 88] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2012] [Revised: 04/03/2013] [Accepted: 05/10/2013] [Indexed: 11/29/2022]
Abstract
Pausing of RNA polymerase II (Pol II) 20-60 bp downstream of transcription start sites is a major checkpoint during transcription in animal cells. Mechanisms that control pausing are largely unknown. We developed permanganate-ChIP-seq to evaluate the state of Pol II at promoters throughout the Drosophila genome, and a biochemical system that reconstitutes promoter-proximal pausing to define pausing mechanisms. Stable open complexes of Pol II are largely absent from the transcription start sites of most mRNA genes but are present at snRNA genes and the highly transcribed heat shock genes following their induction. The location of the pause is influenced by the timing between when NELF loads onto Pol II and how fast Pol II escapes the promoter region. Our biochemical analysis reveals that the sequence-specific transcription factor, GAF, orchestrates efficient pausing by recruiting NELF to promoters before transcription initiation and by assisting in loading NELF onto Pol II after initiation.
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Affiliation(s)
- Jian Li
- Center for Eukaryotic Gene Regulation, Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, PA 16802, USA
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30
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Distinct mechanisms of transcriptional pausing orchestrated by GAGA factor and M1BP, a novel transcription factor. EMBO J 2013; 32:1829-41. [PMID: 23708796 DOI: 10.1038/emboj.2013.111] [Citation(s) in RCA: 94] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2012] [Accepted: 04/24/2013] [Indexed: 01/14/2023] Open
Abstract
Thousands of genes in Drosophila have Pol II paused in the promoter proximal region. Almost half of these genes are associated with either GAGA factor (GAF) or a newly discovered factor we call M1BP. Although both factors dictate the association of Pol II at their target promoters, they are nearly mutually exclusive on the genome and mediate different mechanisms of regulation. High-resolution mapping of Pol II using permanganate-ChIP-seq indicates that pausing on M1BP genes is transient and could involve the +1 nucleosome. In contrast, pausing on GAF genes is much stronger and largely independent of nucleosomes. Distinct regulatory mechanisms are reflected by transcriptional plasticity: M1BP genes are constitutively expressed throughout development while GAF genes exhibit much greater developmental specificity. M1BP binds a core promoter element called Motif 1. Motif 1 potentially directs a distinct transcriptional mechanism from the canonical TATA box, which does not correlate with paused Pol II on the genomic scale. In contrast to M1BP and GAF genes, a significant portion of TATA box genes appear to be controlled at preinitiation complex formation.
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31
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Nock A, Ascano JM, Barrero MJ, Malik S. Mediator-regulated transcription through the +1 nucleosome. Mol Cell 2012; 48:837-48. [PMID: 23159738 DOI: 10.1016/j.molcel.2012.10.009] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2011] [Revised: 06/21/2012] [Accepted: 10/09/2012] [Indexed: 10/27/2022]
Abstract
Many genes are regulated at the level of a Pol II that is recruited to a nucleosome-free region upstream of the +1 nucleosome. How the Mediator coactivator complex, which functions at multiple steps, affects transcription through the promoter proximal region, including this nucleosome, remains largely unaddressed. We have established a fully defined in vitro assay system to delineate mechanisms for Pol II transit across the +1 nucleosome. Our results reveal cooperative functions of multiple cofactors, particularly of Mediator and elongation factor SII, in transcribing into this nucleosome. This is achieved, in part, through an unusual activity of SII that alters the intrinsic catalytic properties of promoter-proximal Pol II and, in concert with the Mediator, leads to enhancement in transcription of nucleosomal DNA. Our data provide additional mechanistic bases for Mediator function after recruitment of Pol II and, potentially, for regulation of genes controlled via nucleosome-mediated promoter-proximal pausing.
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Affiliation(s)
- Adam Nock
- Laboratory of Biochemistry and Molecular Biology, Rockefeller University, 1230 York Avenue, New York, NY, 10065, USA
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32
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Abstract
Every known SWI/SNF chromatin-remodeling complex incorporates an ARID DNA binding domain-containing subunit. Despite being a ubiquitous component of the complex, physiological roles for this domain remain undefined. Here, we show that disruption of ARID1a-DNA binding in mice results in embryonic lethality, with mutant embryos manifesting prominent defects in the heart and extraembryonic vasculature. The DNA binding-defective mutant ARID1a subunit is stably expressed and capable of assembling into a SWI/SNF complex with core catalytic properties, but nucleosome substrate binding and promoter occupancy by ARID1a-containing SWI/SNF complexes (BAF-A) are impaired. Depletion of ARID domain-dependent, BAF-A associations at THROMBOSPONDIN 1 (THBS1) led to the concomitant upregulation of this SWI/SNF target gene. Using a THBS1 promoter-reporter gene, we further show that BAF-A directly regulates THBS1 promoter activity in an ARID domain-dependent manner. Our data not only demonstrate that ARID1a-DNA interactions are physiologically relevant in higher eukaryotes but also indicate that these interactions facilitate SWI/SNF binding to target sites in vivo. These findings support the model wherein cooperative interactions among intrinsic subunit-chromatin interaction domains and sequence-specific transcription factors drive SWI/SNF recruitment.
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33
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Brannan K, Kim H, Erickson B, Glover-Cutter K, Kim S, Fong N, Kiemele L, Hansen K, Davis R, Lykke-Andersen J, Bentley DL. mRNA decapping factors and the exonuclease Xrn2 function in widespread premature termination of RNA polymerase II transcription. Mol Cell 2012; 46:311-24. [PMID: 22483619 DOI: 10.1016/j.molcel.2012.03.006] [Citation(s) in RCA: 167] [Impact Index Per Article: 13.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2011] [Revised: 12/27/2011] [Accepted: 03/08/2012] [Indexed: 02/07/2023]
Abstract
We report a function of human mRNA decapping factors in control of transcription by RNA polymerase II. Decapping proteins Edc3, Dcp1a, and Dcp2 and the termination factor TTF2 coimmunoprecipitate with Xrn2, the nuclear 5'-3' exonuclease "torpedo" that facilitates transcription termination at the 3' ends of genes. Dcp1a, Xrn2, and TTF2 localize near transcription start sites (TSSs) by ChIP-seq. At genes with 5' peaks of paused pol II, knockdown of decapping or termination factors Xrn2 and TTF2 shifted polymerase away from the TSS toward upstream and downstream distal positions. This redistribution of pol II is similar in magnitude to that caused by depletion of the elongation factor Spt5. We propose that coupled decapping of nascent transcripts and premature termination by the "torpedo" mechanism is a widespread mechanism that limits bidirectional pol II elongation. Regulated cotranscriptional decapping near promoter-proximal pause sites followed by premature termination could control productive pol II elongation.
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Affiliation(s)
- Kris Brannan
- Department of Biochemistry and Molecular Genetics, University of Colorado School of Medicine, Aurora, CO 80045, USA
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34
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Petesch SJ, Lis JT. Overcoming the nucleosome barrier during transcript elongation. Trends Genet 2012; 28:285-94. [PMID: 22465610 DOI: 10.1016/j.tig.2012.02.005] [Citation(s) in RCA: 123] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2012] [Revised: 02/22/2012] [Accepted: 02/23/2012] [Indexed: 12/21/2022]
Abstract
RNA polymerase II (Pol II) must break the nucleosomal barrier to gain access to DNA and transcribe genes efficiently. New single-molecule techniques have elucidated many molecular details of nucleosome disassembly and what happens once Pol II encounters a nucleosome. Our review highlights mechanisms that Pol II utilizes to transcribe through nucleosomes, including the roles of chromatin remodelers, histone chaperones, post-translational modifications of histones, incorporation of histone variants into nucleosomes, and activation of the poly(ADP-ribose) polymerase (PARP) enzyme. Future studies need to assess the molecular details and the contribution of each of these mechanisms, individually and in combination, to transcription across the genome to understand how cells are able to regulate transcription in response to developmental, environmental and nutritional cues.
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Affiliation(s)
- Steven J Petesch
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY 14853, USA
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35
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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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36
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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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37
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Anckar J, Sistonen L. Regulation of HSF1 function in the heat stress response: implications in aging and disease. Annu Rev Biochem 2011; 80:1089-115. [PMID: 21417720 DOI: 10.1146/annurev-biochem-060809-095203] [Citation(s) in RCA: 524] [Impact Index Per Article: 40.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
To dampen proteotoxic stresses and maintain protein homeostasis, organisms possess a stress-responsive molecular machinery that detects and neutralizes protein damage. A prominent feature of stressed cells is the increased synthesis of heat shock proteins (Hsps) that aid in the refolding of misfolded peptides and restrain protein aggregation. Transcriptional activation of the heat shock response is orchestrated by heat shock factor 1 (HSF1), which rapidly translocates to hsp genes and induces their expression. Although the role of HSF1 in protecting cells and organisms against severe stress insults is well established, many aspects of how HSF1 senses qualitatively and quantitatively different forms of stresses have remained poorly understood. Moreover, recent discoveries that HSF1 controls life span have prompted new ways of thinking about an old transcription factor. Here, we review the established role of HSF1 in counteracting cell stress and prospect the role of HSF1 as a regulator of disease states and aging.
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Affiliation(s)
- Julius Anckar
- Department of Biosciences, Åbo Akademi University, BioCity, 20520 Turku, Finland.
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38
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Zhang Z, Pugh BF. Genomic organization of H2Av containing nucleosomes in Drosophila heterochromatin. PLoS One 2011; 6:e20511. [PMID: 21738578 PMCID: PMC3124471 DOI: 10.1371/journal.pone.0020511] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2011] [Accepted: 04/28/2011] [Indexed: 12/23/2022] Open
Abstract
H2Av is a versatile histone variant that plays both positive and negative roles in transcription, DNA repair, and chromatin structure in Drosophila. H2Av, and its broader homolog H2A.Z, tend to be enriched toward 5′ ends of genes, and exist in both euchromatin and heterochromatin. Its organization around euchromatin genes and other features have been described in many eukaryotic model organisms. However, less is known about H2Av nucleosome organization in heterochromatin. Here we report the properties and organization of individual H2Av nucleosomes around genes and transposable elements located in Drosophila heterochromatic regions. We compare the similarity and differences with that found in euchromatic regions. Our analyses suggest that nucleosomes are intrinsically positioned on inverted repeats of DNA transposable elements such as those related to the “1360” element, but are not intrinsically positioned on retrotransposon-related elements.
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Affiliation(s)
- Zhenhai Zhang
- Center for Comparative Genomics and Bioinformatics, Center for Eukaryotic Gene Regulation, Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, Pennsylvania, United States of America
| | - B. Franklin Pugh
- Center for Comparative Genomics and Bioinformatics, Center for Eukaryotic Gene Regulation, Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, Pennsylvania, United States of America
- * E-mail:
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39
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Gaykalova DA, Nagarajavel V, Bondarenko VA, Bartholomew B, Clark DJ, Studitsky VM. A polar barrier to transcription can be circumvented by remodeler-induced nucleosome translocation. Nucleic Acids Res 2011; 39:3520-8. [PMID: 21245049 PMCID: PMC3089449 DOI: 10.1093/nar/gkq1273] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Many eukaryotic genes are regulated at the level of transcript elongation. Nucleosomes are likely targets for this regulation. Previously, we have shown that nucleosomes formed on very strong positioning sequences (601 and 603), present a high, orientation-dependent barrier to transcription by RNA polymerase II in vitro. The existence of this polar barrier correlates with the interaction of a 16-bp polar barrier signal (PBS) with the promoter-distal histone H3-H4 dimer. Here, we show that the polar barrier is relieved by ISW2, an ATP-dependent chromatin remodeler, which translocates the nucleosome over a short distance, such that the PBS no longer interacts with the distal H3-H4 dimer, although it remains within the nucleosome. In vivo, insertion of the 603 positioning sequence into the yeast CUP1 gene results in a modest reduction in transcription, but this reduction is orientation-independent, indicating that the polar barrier can be circumvented. However, the 603-nucleosome is present at the expected position in only a small fraction of cells. Thus, the polar barrier is probably non-functional in vivo because the nucleosome is not positioned appropriately, presumably due to nucleosome sliding activities. We suggest that interactions between PBSs and chromatin remodelers might have significant regulatory potential.
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Affiliation(s)
- Daria A Gaykalova
- Department of Pharmacology, UMDNJ-Robert Wood Johnson Medical School, Piscataway, NJ 08854, USA
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40
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Yoon YJ, Kim JA, Shin KD, Shin DS, Han YM, Lee YJ, Lee JS, Kwon BM, Han DC. KRIBB11 inhibits HSP70 synthesis through inhibition of heat shock factor 1 function by impairing the recruitment of positive transcription elongation factor b to the hsp70 promoter. J Biol Chem 2010; 286:1737-47. [PMID: 21078672 DOI: 10.1074/jbc.m110.179440] [Citation(s) in RCA: 119] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Heat shock factor 1 (HSF1) is the master switch for heat shock protein (HSP) expression in eukaryotes. A synthetic chemical library was screened to identify inhibitors of HSF1 using a luciferase reporter under the control of a heat shock element. A compound named KRIBB11 (N(2)-(1H-indazole-5-yl)-N(6)-methyl-3-nitropyridine-2,6-diamine) was identified for its activity in abolishing the heat shock-induced luciferase activity with an IC(50) of 1.2 μmol/liter. When the cells were exposed to heat shock in the presence of KRIBB11, the induction of HSF1 downstream target proteins such as HSP27 and HSP70 was blocked. In addition, treatment of HCT-116 cells with KRIBB11 induced growth arrest and apoptosis. Markers of apoptosis, such as cleaved poly(ADP-ribose) polymerase, were detected after KRIBB11 treatment. Biotinyl-KRIBB11 was synthesized as an affinity probe for the identification of KRIBB11 target proteins. Using affinity chromatography and competition assays, KRIBB11 was shown to associate with HSF1 in vitro. Chromatin immunoprecipitation analysis showed that KRIBB11 inhibited HSF1-dependent recruitment of p-TEFb (positive transcription elongation factor b) to the hsp70 promoter. Finally, intraperitoneal treatment of nude mice with KRIBB11 at 50 mg/kg resulted in a 47.4% (p < 0.05) inhibition of tumor growth without body weight loss. Immunoblotting assays showed that the expression of HSP70 was lower in KRIBB11-treated tumor tissue than in control tissues. Because HSPs are expressed at high levels in a wide range of tumors, these results strengthen the rationale for targeting HSF1 in cancer therapy.
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Affiliation(s)
- Young Ju Yoon
- Medical Genomics Research Center, Korea Research Institute of Bioscience and Biotechnology, Daejeon 305-806, Korea
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41
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Bakshi R, Hassan MQ, Pratap J, Lian JB, Montecino MA, van Wijnen AJ, Stein JL, Imbalzano AN, Stein GS. The human SWI/SNF complex associates with RUNX1 to control transcription of hematopoietic target genes. J Cell Physiol 2010; 225:569-76. [PMID: 20506188 DOI: 10.1002/jcp.22240] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
The acute myeloid leukemia 1 (AML1, RUNX1) transcription factor is a key regulator of hematopoietic differentiation that forms multi-protein complexes with co-regulatory proteins. These complexes are assembled at target gene promoters in nuclear microenvironments to mediate phenotypic gene expression and chromatin-related epigenetic modifications. Here, immunofluorescence microscopy and biochemical assays are used to show that RUNX1 associates with the human ATP-dependent SWI/SNF chromatin remodeling complex. The SWI/SNF subunits BRG1 and INI1 bind in vivo to RUNX1 target gene promoters (e.g., GMCSF, IL3, MCSF-R, MIP, and p21). These interactions correlate with histone modifications characteristic of active chromatin, including acetylated H4 and dimethylated H3 lysine 4. Downregulation of RUNX1 by RNA interference diminishes the binding of BRG1 and INI1 at selected target genes. Taken together, our findings indicate that RUNX1 interacts with the human SWI/SNF complex to control hematopoietic-specific gene expression.
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Affiliation(s)
- Rachit Bakshi
- Department of Cell Biology and Cancer Center, University of Massachusetts Medical School, Worcester, Massachusetts 01655, USA
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BRG1 helps RNA polymerase II to overcome a nucleosomal barrier during elongation, in vivo. EMBO Rep 2010; 11:751-7. [PMID: 20829883 DOI: 10.1038/embor.2010.131] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2010] [Revised: 07/06/2010] [Accepted: 07/27/2010] [Indexed: 11/08/2022] Open
Abstract
RNA polymerase II (RNAPII) transcribes genes in a chromatin context. We have designed a system to investigate the role of chromatin remodelling during elongation in vivo, which involves inserting a strong nucleosome-positioning sequence between a promoter and a reporter gene. Our data indicate that a nucleosome positioned in the body of a transcription unit impairs RNAPII progression, provokes RNAPII accumulation upstream to the positioned nucleosome and reduces transcription. By using this system, we show that BRG1, the enzymatic motor of the SWI-SNF chromatin-remodelling complex, is recruited to the positioned nucleosome in a transcription elongation-dependent manner and facilitates traversal of the nucleosome by RNAPII.
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43
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Akerfelt M, Morimoto RI, Sistonen L. Heat shock factors: integrators of cell stress, development and lifespan. Nat Rev Mol Cell Biol 2010; 11:545-55. [PMID: 20628411 DOI: 10.1038/nrm2938] [Citation(s) in RCA: 969] [Impact Index Per Article: 69.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Heat shock factors (HSFs) are essential for all organisms to survive exposures to acute stress. They are best known as inducible transcriptional regulators of genes encoding molecular chaperones and other stress proteins. Four members of the HSF family are also important for normal development and lifespan-enhancing pathways, and the repertoire of HSF targets has thus expanded well beyond the heat shock genes. These unexpected observations have uncovered complex layers of post-translational regulation of HSFs that integrate the metabolic state of the cell with stress biology, and in doing so control fundamental aspects of the health of the proteome and ageing.
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Affiliation(s)
- Malin Akerfelt
- Department of Biosciences, Abo Akademi University, BioCity, 20520 Turku, Finland
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44
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Interactions between DSIF (DRB sensitivity inducing factor), NELF (negative elongation factor), and the Drosophila RNA polymerase II transcription elongation complex. Proc Natl Acad Sci U S A 2010; 107:11301-6. [PMID: 20534440 DOI: 10.1073/pnas.1000681107] [Citation(s) in RCA: 123] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Negative elongation factor (NELF) and 5,6-dichloro-1-beta-D-ribofuranosylbenzimidazole sensitivity-inducing factor (DSIF) are involved in pausing RNA Polymerase II (Pol II) in the promoter-proximal region of the hsp70 gene in Drosophila, before heat shock induction. Such blocks in elongation are widespread in the Drosophila genome. However, the mechanism by which DSIF and NELF participate in setting up the paused Pol II remains unclear. We analyzed the interactions among DSIF, NELF, and a reconstituted Drosophila Pol II elongation complex to gain insight into the mechanism of pausing. Our results show that DSIF and NELF require a nascent transcript longer than 18 nt to stably associate with the Pol II elongation complex. Protein-RNA cross-linking reveals that Spt5, the largest subunit of DSIF, contacts the nascent RNA as the RNA emerges from the elongation complex. Taken together, these results provide a possible model by which DSIF binds the elongation complex via association with the nascent transcript and subsequently recruits NELF. Although DSIF and NELF were both required for inhibition of transcription, we did not detect a NELF-RNA contact when the nascent transcript was between 22 and 31 nt long, which encompasses the region where promoter-proximal pausing occurs on many genes in Drosophila. This raises the possibility that RNA binding by NELF is not necessary in promoter-proximal pausing.
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45
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Hodges C, Bintu L, Lubkowska L, Kashlev M, Bustamante C. Nucleosomal fluctuations govern the transcription dynamics of RNA polymerase II. Science 2009; 325:626-8. [PMID: 19644123 DOI: 10.1126/science.1172926] [Citation(s) in RCA: 275] [Impact Index Per Article: 18.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
RNA polymerase II (Pol II) must overcome the barriers imposed by nucleosomes during transcription elongation. We have developed an optical tweezers assay to follow individual Pol II complexes as they transcribe nucleosomal DNA. Our results indicate that the nucleosome behaves as a fluctuating barrier that locally increases pause density, slows pause recovery, and reduces the apparent pause-free velocity of Pol II. The polymerase, rather than actively separating DNA from histones, functions instead as a ratchet that rectifies nucleosomal fluctuations. We also obtained direct evidence that transcription through a nucleosome involves transfer of the core histones behind the transcribing polymerase via a transient DNA loop. The interplay between polymerase dynamics and nucleosome fluctuations provides a physical basis for the regulation of eukaryotic transcription.
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Affiliation(s)
- Courtney Hodges
- Jason L. Choy Laboratory of Single-Molecule Biophysics and Biophysics Graduate Group, University of California, Berkeley, CA 94720, USA
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46
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Abstract
The packaging of chromosomal DNA by nucleosomes condenses and organizes the genome, but occludes many regulatory DNA elements. However, this constraint also allows nucleosomes and other chromatin components to actively participate in the regulation of transcription, chromosome segregation, DNA replication, and DNA repair. To enable dynamic access to packaged DNA and to tailor nucleosome composition in chromosomal regions, cells have evolved a set of specialized chromatin remodeling complexes (remodelers). Remodelers use the energy of ATP hydrolysis to move, destabilize, eject, or restructure nucleosomes. Here, we address many aspects of remodeler biology: their targeting, mechanism, regulation, shared and unique properties, and specialization for particular biological processes. We also address roles for remodelers in development, cancer, and human syndromes.
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Affiliation(s)
- Cedric R Clapier
- Howard Hughes Medical Institute, Department of Oncological Sciences, Huntsman Cancer Institute, University of Utah School of Medicine, Salt Lake City, UT 84112, USA.
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47
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Chromatin structure is implicated in "late" elongation checkpoints on the U2 snRNA and beta-actin genes. Mol Cell Biol 2009; 29:4002-13. [PMID: 19451231 PMCID: PMC2704739 DOI: 10.1128/mcb.00189-09] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
The negative elongation factor NELF is a key component of an early elongation checkpoint generally located within 100 bp of the transcription start site of protein-coding genes. Negotiation of this checkpoint and conversion to productive elongation require phosphorylation of the carboxy-terminal domain of RNA polymerase II (pol II), NELF, and DRB sensitivity-inducing factor (DSIF) by positive transcription elongation factor b (P-TEFb). P-TEFb is dispensable for transcription of the noncoding U2 snRNA genes, suggesting that a NELF-dependent checkpoint is absent. However, we find that NELF at the end of the 800-bp U2 gene transcription unit and RNA interference-mediated knockdown of NELF causes a termination defect. NELF is also associated 800 bp downstream of the transcription start site of the beta-actin gene, where a "late" P-TEFb-dependent checkpoint occurs. Interestingly, both genes have an extended nucleosome-depleted region up to the NELF-dependent control point. In both cases, transcription through this region is P-TEFb independent, implicating chromatin in the formation of the terminator/checkpoint. Furthermore, CTCF colocalizes with NELF on the U2 and beta-actin genes, raising the possibility that it helps the positioning and/or function of the NELF-dependent control point on these genes.
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48
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Rodríguez-Paredes M, Ceballos-Chávez M, Esteller M, García-Domínguez M, Reyes JC. The chromatin remodeling factor CHD8 interacts with elongating RNA polymerase II and controls expression of the cyclin E2 gene. Nucleic Acids Res 2009; 37:2449-60. [PMID: 19255092 PMCID: PMC2677868 DOI: 10.1093/nar/gkp101] [Citation(s) in RCA: 71] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
CHD8 is a chromatin remodeling ATPase of the SNF2 family. We found that depletion of CHD8 impairs cell proliferation. In order to identify CHD8 target genes, we performed a transcriptomic analysis of CHD8-depleted cells, finding out that CHD8 controls the expression of cyclin E2 (CCNE2) and thymidylate synthetase (TYMS), two genes expressed in the G1/S transition of the cell cycle. CHD8 was also able to co-activate the CCNE2 promoter in transient transfection experiments. Chromatin immunoprecipitation experiments demonstrated that CHD8 binds directly to the 5' region of both CCNE2 and TYMS genes. Interestingly, both RNA polymerase II (RNAPII) and CHD8 bind constitutively to the 5' promoter-proximal region of CCNE2, regardless of the cell-cycle phase and, therefore, of the expression of CCNE2. The tandem chromodomains of CHD8 bind in vitro specifically to histone H3 di-methylated at lysine 4. However, CHD8 depletion does not affect the methylation levels of this residue. We also show that CHD8 associates with the elongating form of RNAPII, which is phosphorylated in its carboxy-terminal domain (CTD). Furthermore, CHD8-depleted cells are hypersensitive to drugs that inhibit RNAPII phosphorylation at serine 2, suggesting that CHD8 is required for an early step of the RNAPII transcription cycle.
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Affiliation(s)
- M Rodríguez-Paredes
- Centro Andaluz de Biología Molecular y Medicina Regenerativa (CABIMER), CSIC, Américo Vespucio s/n, E-41092 Sevilla, Spain
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49
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Vanti M, Gallastegui E, Respaldiza I, Rodríguez-Gil A, Gómez-Herreros F, Jimeno-González S, Jordan A, Chávez S. Yeast genetic analysis reveals the involvement of chromatin reassembly factors in repressing HIV-1 basal transcription. PLoS Genet 2009; 5:e1000339. [PMID: 19148280 PMCID: PMC2613532 DOI: 10.1371/journal.pgen.1000339] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2008] [Accepted: 12/12/2008] [Indexed: 12/22/2022] Open
Abstract
Rebound of HIV viremia after interruption of anti-retroviral therapy is due to the small population of CD4+ T cells that remain latently infected. HIV-1 transcription is the main process controlling post-integration latency. Regulation of HIV-1 transcription takes place at both initiation and elongation levels. Pausing of RNA polymerase II at the 5' end of HIV-1 transcribed region (5'HIV-TR), which is immediately downstream of the transcription start site, plays an important role in the regulation of viral expression. The activation of HIV-1 transcription correlates with the rearrangement of a positioned nucleosome located at this region. These two facts suggest that the 5'HIV-TR contributes to inhibit basal transcription of those HIV-1 proviruses that remain latently inactive. However, little is known about the cell elements mediating the repressive role of the 5'HIV-TR. We performed a genetic analysis of this phenomenon in Saccharomyces cerevisiae after reconstructing a minimal HIV-1 transcriptional system in this yeast. Unexpectedly, we found that the critical role played by the 5'HIV-TR in maintaining low levels of basal transcription in yeast is mediated by FACT, Spt6, and Chd1, proteins so far associated with chromatin assembly and disassembly during ongoing transcription. We confirmed that this group of factors plays a role in HIV-1 postintegration latency in human cells by depleting the corresponding human orthologs with shRNAs, both in HIV latently infected cell populations and in particular single-integration clones, including a latent clone with a provirus integrated in a highly transcribed gene. Our results indicate that chromatin reassembly factors participate in the establishment of the equilibrium between activation and repression of HIV-1 when it integrates into the human genome, and they open the possibility of considering these factors as therapeutic targets of HIV-1 latency.
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Affiliation(s)
- Manuela Vanti
- Departamento de Genética, Universidad de Sevilla, Seville, Spain
| | - Edurne Gallastegui
- Centre de Regulació Genòmica, Universitat Pompeu Fabra, Barcelona, Spain
| | - Iñaki Respaldiza
- Departamento de Genética, Universidad de Sevilla, Seville, Spain
| | | | | | | | - Albert Jordan
- Centre de Regulació Genòmica, Universitat Pompeu Fabra, Barcelona, Spain
| | - Sebastián Chávez
- Departamento de Genética, Universidad de Sevilla, Seville, Spain
- * E-mail:
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50
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Gilmour DS. Promoter proximal pausing on genes in metazoans. Chromosoma 2008; 118:1-10. [PMID: 18830703 DOI: 10.1007/s00412-008-0182-4] [Citation(s) in RCA: 81] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2008] [Revised: 09/14/2008] [Accepted: 09/14/2008] [Indexed: 10/21/2022]
Abstract
The past two decades of research into transcriptional control of protein-encoding genes in eukaryotes have focused on regulatory mechanisms that act by controlling the recruitment of Pol II to a gene's promoter. Recent genome-wide analyses of the distribution of Pol II indicates that Pol II is concentrated in the promoter regions of thousands of genes in human and Drosophila cells. In many cases, Pol II may have initiated transcription but paused in the promoter proximal region. Hence, release of Pol II from the promoter region into the body of a gene is now recognized as a common rate-limiting step in the control of gene expression. Notably, most genes with paused Pol II are expressed indicating that the pause can be transient. What causes Pol II to concentrate in the promoter region and how it is released to transcribe a gene are the focus of this review.
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Affiliation(s)
- David S Gilmour
- Center for Gene Regulation, Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, PA 16802, USA.
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