1
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Whitney PH, Lionnet T. The method in the madness: Transcriptional control from stochastic action at the single-molecule scale. Curr Opin Struct Biol 2024; 87:102873. [PMID: 38954990 DOI: 10.1016/j.sbi.2024.102873] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2024] [Revised: 05/07/2024] [Accepted: 06/05/2024] [Indexed: 07/04/2024]
Abstract
Cell states result from the ordered activation of gene expression by transcription factors. Transcription factors face opposing design constraints: they need to be dynamic to trigger rapid cell state transitions, but also stable enough to maintain terminal cell identities indefinitely. Recent progress in live-cell single-molecule microscopy has helped define the biophysical principles underlying this paradox. Beyond transcription factor activity, single-molecule experiments have revealed that at nearly every level of transcription regulation, control emerges from multiple short-lived stochastic interactions, rather than deterministic, stable interactions typical of other biochemical pathways. This architecture generates consistent outcomes that can be rapidly choreographed. Here, we highlight recent results that demonstrate how order in transcription regulation emerges from the apparent molecular-scale chaos and discuss remaining conceptual challenges.
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Affiliation(s)
- Peter H Whitney
- Institute for Systems Genetics, New York University School of Medicine, New York, NY 10016, USA; Department of Cell Biology, New York University School of Medicine, New York, NY 10016, USA
| | - Timothée Lionnet
- Institute for Systems Genetics, New York University School of Medicine, New York, NY 10016, USA; Department of Cell Biology, New York University School of Medicine, New York, NY 10016, USA; Department of Biomedical Engineering, NYU Tandon School of Engineering, Brooklyn, NY 11201, USA.
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2
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Yang JH, Hansen AS. Enhancer selectivity in space and time: from enhancer-promoter interactions to promoter activation. Nat Rev Mol Cell Biol 2024; 25:574-591. [PMID: 38413840 DOI: 10.1038/s41580-024-00710-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/30/2024] [Indexed: 02/29/2024]
Abstract
The primary regulators of metazoan gene expression are enhancers, originally functionally defined as DNA sequences that can activate transcription at promoters in an orientation-independent and distance-independent manner. Despite being crucial for gene regulation in animals, what mechanisms underlie enhancer selectivity for promoters, and more fundamentally, how enhancers interact with promoters and activate transcription, remain poorly understood. In this Review, we first discuss current models of enhancer-promoter interactions in space and time and how enhancers affect transcription activation. Next, we discuss different mechanisms that mediate enhancer selectivity, including repression, biochemical compatibility and regulation of 3D genome structure. Through 3D polymer simulations, we illustrate how the ability of 3D genome folding mechanisms to mediate enhancer selectivity strongly varies for different enhancer-promoter interaction mechanisms. Finally, we discuss how recent technical advances may provide new insights into mechanisms of enhancer-promoter interactions and how technical biases in methods such as Hi-C and Micro-C and imaging techniques may affect their interpretation.
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Affiliation(s)
- Jin H Yang
- Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, MA, USA
- Gene Regulation Observatory, Broad Institute of MIT and Harvard, Cambridge, MA, USA
- Koch Institute for Integrative Cancer Research, Cambridge, MA, USA
| | - Anders S Hansen
- Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, MA, USA.
- Gene Regulation Observatory, Broad Institute of MIT and Harvard, Cambridge, MA, USA.
- Koch Institute for Integrative Cancer Research, Cambridge, MA, USA.
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3
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Hwang DW, Maekiniemi A, Singer RH, Sato H. Real-time single-molecule imaging of transcriptional regulatory networks in living cells. Nat Rev Genet 2024; 25:272-285. [PMID: 38195868 DOI: 10.1038/s41576-023-00684-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/27/2023] [Indexed: 01/11/2024]
Abstract
Gene regulatory networks drive the specific transcriptional programmes responsible for the diversification of cell types during the development of multicellular organisms. Although our knowledge of the genes involved in these dynamic networks has expanded rapidly, our understanding of how transcription is spatiotemporally regulated at the molecular level over a wide range of timescales in the small volume of the nucleus remains limited. Over the past few decades, advances in the field of single-molecule fluorescence imaging have enabled real-time behaviours of individual transcriptional components to be measured in living cells and organisms. These efforts are now shedding light on the dynamic mechanisms of transcription, revealing not only the temporal rules but also the spatial coordination of underlying molecular interactions during various biological events.
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Affiliation(s)
- Dong-Woo Hwang
- Department of Cell Biology, Albert Einstein College of Medicine, New York, NY, USA
| | - Anna Maekiniemi
- Department of Cell Biology, Albert Einstein College of Medicine, New York, NY, USA
| | - Robert H Singer
- Department of Cell Biology, Albert Einstein College of Medicine, New York, NY, USA
| | - Hanae Sato
- Department of Cell Biology, Albert Einstein College of Medicine, New York, NY, USA.
- Nano Life Science Institute (WPI-Nano LSI), Kanazawa University, Kakuma-machi, Kanazawa, Japan.
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4
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Ryu K, Park G, Cho WK. Emerging insights into transcriptional condensates. Exp Mol Med 2024; 56:820-826. [PMID: 38658705 PMCID: PMC11059374 DOI: 10.1038/s12276-024-01228-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2023] [Revised: 02/26/2024] [Accepted: 03/05/2024] [Indexed: 04/26/2024] Open
Abstract
Eukaryotic transcription, a fundamental process that governs cell-specific gene expression, has long been the subject of extensive investigations in the fields of molecular biology, biochemistry, and structural biology. Recent advances in microscopy techniques have led to a fascinating concept known as "transcriptional condensates." These dynamic assemblies are the result of a phenomenon called liquid‒liquid phase separation, which is driven by multivalent interactions between the constituent proteins in cells. The essential proteins associated with transcription are concentrated in transcriptional condensates. Recent studies have shed light on the temporal dynamics of transcriptional condensates and their potential role in enhancing the efficiency of transcription. In this article, we explore the properties of transcriptional condensates, investigate how they evolve over time, and evaluate the significant impact they have on the process of transcription. Furthermore, we highlight innovative techniques that allow us to manipulate these condensates, thus demonstrating their responsiveness to cellular signals and their connection to transcriptional bursting. As our understanding of transcriptional condensates continues to grow, they are poised to revolutionize our understanding of eukaryotic gene regulation.
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Affiliation(s)
- Kwangmin Ryu
- Department of Biological Sciences, Korea Advanced Institute of Science and Technology (KAIST), 291 Deahak-ro, Yuseong-gu, Daejeon, 34141, Korea
| | - Gunhee Park
- Department of Biological Sciences, Korea Advanced Institute of Science and Technology (KAIST), 291 Deahak-ro, Yuseong-gu, Daejeon, 34141, Korea
| | - Won-Ki Cho
- Department of Biological Sciences, Korea Advanced Institute of Science and Technology (KAIST), 291 Deahak-ro, Yuseong-gu, Daejeon, 34141, Korea.
- KAIST Stem Cell Research Center, Korea Advanced Institute of Science and Technology (KAIST), 291 Deahak-ro, Yuseong-gu, Daejeon, 34141, Korea.
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5
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Valyaeva AA, Sheval EV. Nonspecific Interactions in Transcription Regulation and Organization of Transcriptional Condensates. BIOCHEMISTRY. BIOKHIMIIA 2024; 89:688-700. [PMID: 38831505 DOI: 10.1134/s0006297924040084] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/10/2023] [Revised: 11/19/2023] [Accepted: 11/20/2023] [Indexed: 06/05/2024]
Abstract
Eukaryotic cells are characterized by a high degree of compartmentalization of their internal contents, which ensures precise and controlled regulation of intracellular processes. During many processes, including different stages of transcription, dynamic membraneless compartments termed biomolecular condensates are formed. Transcription condensates contain various transcription factors and RNA polymerase and are formed by high- and low-specificity interactions between the proteins, DNA, and nearby RNA. This review discusses recent data demonstrating important role of nonspecific multivalent protein-protein and RNA-protein interactions in organization and regulation of transcription.
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Affiliation(s)
- Anna A Valyaeva
- Faculty of Bioengineering and Bioinformatics, Lomonosov Moscow State University, Moscow, 119991, Russia.
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, 119991, Russia
- Department of Cell Biology and Histology, Faculty of Biology, Lomonosov Moscow State University, Moscow, 119991, Russia
| | - Eugene V Sheval
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, 119991, Russia
- Department of Cell Biology and Histology, Faculty of Biology, Lomonosov Moscow State University, Moscow, 119991, Russia
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6
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Archuleta SR, Goodrich JA, Kugel JF. Mechanisms and Functions of the RNA Polymerase II General Transcription Machinery during the Transcription Cycle. Biomolecules 2024; 14:176. [PMID: 38397413 PMCID: PMC10886972 DOI: 10.3390/biom14020176] [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: 12/21/2023] [Revised: 01/29/2024] [Accepted: 01/30/2024] [Indexed: 02/25/2024] Open
Abstract
Central to the development and survival of all organisms is the regulation of gene expression, which begins with the process of transcription catalyzed by RNA polymerases. During transcription of protein-coding genes, the general transcription factors (GTFs) work alongside RNA polymerase II (Pol II) to assemble the preinitiation complex at the transcription start site, open the promoter DNA, initiate synthesis of the nascent messenger RNA, transition to productive elongation, and ultimately terminate transcription. Through these different stages of transcription, Pol II is dynamically phosphorylated at the C-terminal tail of its largest subunit, serving as a control mechanism for Pol II elongation and a signaling/binding platform for co-transcriptional factors. The large number of core protein factors participating in the fundamental steps of transcription add dense layers of regulation that contribute to the complexity of temporal and spatial control of gene expression within any given cell type. The Pol II transcription system is highly conserved across different levels of eukaryotes; however, most of the information here will focus on the human Pol II system. This review walks through various stages of transcription, from preinitiation complex assembly to termination, highlighting the functions and mechanisms of the core machinery that participates in each stage.
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Affiliation(s)
| | - James A. Goodrich
- Department of Biochemistry, University of Colorado Boulder, 596 UCB, Boulder, CO 80309, USA;
| | - Jennifer F. Kugel
- Department of Biochemistry, University of Colorado Boulder, 596 UCB, Boulder, CO 80309, USA;
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7
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Meeussen JVW, Lenstra TL. Time will tell: comparing timescales to gain insight into transcriptional bursting. Trends Genet 2024; 40:160-174. [PMID: 38216391 PMCID: PMC10860890 DOI: 10.1016/j.tig.2023.11.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2023] [Revised: 11/27/2023] [Accepted: 11/27/2023] [Indexed: 01/14/2024]
Abstract
Recent imaging studies have captured the dynamics of regulatory events of transcription inside living cells. These events include transcription factor (TF) DNA binding, chromatin remodeling and modification, enhancer-promoter (E-P) proximity, cluster formation, and preinitiation complex (PIC) assembly. Together, these molecular events culminate in stochastic bursts of RNA synthesis, but their kinetic relationship remains largely unclear. In this review, we compare the timescales of upstream regulatory steps (input) with the kinetics of transcriptional bursting (output) to generate mechanistic models of transcription dynamics in single cells. We highlight open questions and potential technical advances to guide future endeavors toward a quantitative and kinetic understanding of transcription regulation.
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Affiliation(s)
- Joseph V W Meeussen
- Division of Gene Regulation, The Netherlands Cancer Institute, Oncode Institute, Amsterdam 1066CX, The Netherlands
| | - Tineke L Lenstra
- Division of Gene Regulation, The Netherlands Cancer Institute, Oncode Institute, Amsterdam 1066CX, The Netherlands.
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8
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Martinez TC, McNerney ME. Haploinsufficient Transcription Factors in Myeloid Neoplasms. ANNUAL REVIEW OF PATHOLOGY 2024; 19:571-598. [PMID: 37906947 DOI: 10.1146/annurev-pathmechdis-051222-013421] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/02/2023]
Abstract
Many transcription factors (TFs) function as tumor suppressor genes with heterozygous phenotypes, yet haploinsufficiency generally has an underappreciated role in neoplasia. This is no less true in myeloid cells, which are normally regulated by a delicately balanced and interconnected transcriptional network. Detailed understanding of TF dose in this circuitry sheds light on the leukemic transcriptome. In this review, we discuss the emerging features of haploinsufficient transcription factors (HITFs). We posit that: (a) monoallelic and biallelic losses can have distinct cellular outcomes; (b) the activity of a TF exists in a greater range than the traditional Mendelian genetic doses; and (c) how a TF is deleted or mutated impacts the cellular phenotype. The net effect of a HITF is a myeloid differentiation block and increased intercellular heterogeneity in the course of myeloid neoplasia.
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Affiliation(s)
- Tanner C Martinez
- Department of Pathology, Department of Pediatrics, Section of Hematology/Oncology, The University of Chicago Medicine Comprehensive Cancer Center, The University of Chicago, Chicago, Illinois, USA;
- Medical Scientist Training Program, The University of Chicago, Chicago, Illinois, USA
| | - Megan E McNerney
- Department of Pathology, Department of Pediatrics, Section of Hematology/Oncology, The University of Chicago Medicine Comprehensive Cancer Center, The University of Chicago, Chicago, Illinois, USA;
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9
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Atsumi Y, Iwata R, Kimura H, Vanderhaeghen P, Yamamoto N, Sugo N. Repetitive CREB-DNA interactions at gene loci predetermined by CBP induce activity-dependent gene expression in human cortical neurons. Cell Rep 2024; 43:113576. [PMID: 38128530 DOI: 10.1016/j.celrep.2023.113576] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2023] [Revised: 11/10/2023] [Accepted: 11/27/2023] [Indexed: 12/23/2023] Open
Abstract
Neuronal activity-dependent transcription plays a key role in plasticity and pathology in the brain. An intriguing question is how neuronal activity controls gene expression via interactions of transcription factors with DNA and chromatin modifiers in the nucleus. By utilizing single-molecule imaging in human embryonic stem cell (ESC)-derived cortical neurons, we demonstrate that neuronal activity increases repetitive emergence of cAMP response element-binding protein (CREB) at histone acetylation sites in the nucleus, where RNA polymerase II (RNAPII) accumulation and FOS expression occur rapidly. Neuronal activity also enhances co-localization of CREB and CREB-binding protein (CBP). Increased binding of a constitutively active CREB to CBP efficiently induces CREB repetitive emergence. On the other hand, the formation of histone acetylation sites is dependent on CBP histone modification via acetyltransferase (HAT) activity but is not affected by neuronal activity. Taken together, our results suggest that neuronal activity promotes repetitive CREB-CRE and CREB-CBP interactions at predetermined histone acetylation sites, leading to rapid gene expression.
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Affiliation(s)
- Yuri Atsumi
- Graduate School of Frontier Biosciences, Osaka University, Suita, Osaka 565-0871, Japan
| | - Ryohei Iwata
- VIB-KU Leuven, Center for Brain & Disease Research and KU Leuven, Department of Neurosciences & Leuven Brain Institute, 3000 Leuven, Belgium
| | - Hiroshi Kimura
- Cell Biology Center, Institute of Innovative Research, Tokyo Institute of Technology, Yokohama, Kanagawa 226-8503, Japan
| | - Pierre Vanderhaeghen
- VIB-KU Leuven, Center for Brain & Disease Research and KU Leuven, Department of Neurosciences & Leuven Brain Institute, 3000 Leuven, Belgium
| | - Nobuhiko Yamamoto
- Graduate School of Frontier Biosciences, Osaka University, Suita, Osaka 565-0871, Japan; Institute of Neurological and Psychiatric Disorders, Shenzhen Bay Laboratory, Shenzhen, Guangdong 518132, China.
| | - Noriyuki Sugo
- Graduate School of Frontier Biosciences, Osaka University, Suita, Osaka 565-0871, Japan.
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10
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Du M, Stitzinger SH, Spille JH, Cho WK, Lee C, Hijaz M, Quintana A, Cissé II. Direct observation of a condensate effect on super-enhancer controlled gene bursting. Cell 2024; 187:331-344.e17. [PMID: 38194964 DOI: 10.1016/j.cell.2023.12.005] [Citation(s) in RCA: 14] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2023] [Revised: 10/29/2023] [Accepted: 12/04/2023] [Indexed: 01/11/2024]
Abstract
Enhancers are distal DNA elements believed to loop and contact promoters to control gene expression. Recently, we found diffraction-sized transcriptional condensates at genes controlled by clusters of enhancers (super-enhancers). However, a direct function of endogenous condensates in controlling gene expression remains elusive. Here, we develop live-cell super-resolution and multi-color 3D-imaging approaches to investigate putative roles of endogenous condensates in the regulation of super-enhancer controlled gene Sox2. In contrast to enhancer distance, we find instead that the condensate's positional dynamics are a better predictor of gene expression. A basal gene bursting occurs when the condensate is far (>1 μm), but burst size and frequency are enhanced when the condensate moves in proximity (<1 μm). Perturbations of cohesin and local DNA elements do not prevent basal bursting but affect the condensate and its burst enhancement. We propose a three-way kissing model whereby the condensate interacts transiently with gene locus and regulatory DNA elements to control gene bursting.
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Affiliation(s)
- Manyu Du
- Department of Biological Physics, Max Planck Institute for Immunobiology and Epigenetics, Freiburg im Breisgau, Baden-Württemberg 79108, Germany
| | - Simon Hendrik Stitzinger
- Department of Biological Physics, Max Planck Institute for Immunobiology and Epigenetics, Freiburg im Breisgau, Baden-Württemberg 79108, Germany
| | - Jan-Hendrik Spille
- Department of Biological Physics, Max Planck Institute for Immunobiology and Epigenetics, Freiburg im Breisgau, Baden-Württemberg 79108, Germany
| | - Won-Ki Cho
- Department of Biological Physics, Max Planck Institute for Immunobiology and Epigenetics, Freiburg im Breisgau, Baden-Württemberg 79108, Germany
| | - Choongman Lee
- Department of Biological Physics, Max Planck Institute for Immunobiology and Epigenetics, Freiburg im Breisgau, Baden-Württemberg 79108, Germany
| | - Mohammed Hijaz
- Department of Biological Physics, Max Planck Institute for Immunobiology and Epigenetics, Freiburg im Breisgau, Baden-Württemberg 79108, Germany
| | - Andrea Quintana
- Department of Biological Physics, Max Planck Institute for Immunobiology and Epigenetics, Freiburg im Breisgau, Baden-Württemberg 79108, Germany
| | - Ibrahim I Cissé
- Department of Biological Physics, Max Planck Institute for Immunobiology and Epigenetics, Freiburg im Breisgau, Baden-Württemberg 79108, Germany.
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11
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Lu F, Park BJ, Fujiwara R, Wilusz JE, Gilmour DS, Lehmann R, Lionnet T. Integrator-mediated clustering of poised RNA polymerase II synchronizes histone transcription. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2023.10.07.561364. [PMID: 37873455 PMCID: PMC10592978 DOI: 10.1101/2023.10.07.561364] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/25/2023]
Abstract
Numerous components of the transcription machinery, including RNA polymerase II (Pol II), accumulate in regions of high local concentration known as clusters, which are thought to facilitate transcription. Using the histone locus of Drosophila nurse cells as a model, we find that Pol II forms long-lived, transcriptionally poised clusters distinct from liquid droplets, which contain unbound and paused Pol II. Depletion of the Integrator complex endonuclease module, but not its phosphatase module or Pol II pausing factors disperses these Pol II clusters. Consequently, histone transcription fails to reach peak levels during S-phase and aberrantly continues throughout the cell cycle. We propose that Pol II clustering is a regulatory step occurring near promoters that limits rapid gene activation to defined times. One Sentence Summary Using the Drosophila histone locus as a model, we show that clustered RNA polymerase II is poised for synchronous activation.
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12
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Malik S, Roeder RG. Regulation of the RNA polymerase II pre-initiation complex by its associated coactivators. Nat Rev Genet 2023; 24:767-782. [PMID: 37532915 PMCID: PMC11088444 DOI: 10.1038/s41576-023-00630-9] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/15/2023] [Indexed: 08/04/2023]
Abstract
The RNA polymerase II (Pol II) pre-initiation complex (PIC) is a critical node in eukaryotic transcription regulation, and its formation is the major rate-limiting step in transcriptional activation. Diverse cellular signals borne by transcriptional activators converge on this large, multiprotein assembly and are transduced via intermediary factors termed coactivators. Cryogenic electron microscopy, multi-omics and single-molecule approaches have recently offered unprecedented insights into both the structure and cellular functions of the PIC and two key PIC-associated coactivators, Mediator and TFIID. Here, we review advances in our understanding of how Mediator and TFIID interact with activators and affect PIC formation and function. We also discuss how their functions are influenced by their chromatin environment and selected cofactors. We consider how, through its multifarious interactions and functionalities, a Mediator-containing and TFIID-containing PIC can yield an integrated signal processing system with the flexibility to determine the unique temporal and spatial expression pattern of a given gene.
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Affiliation(s)
- Sohail Malik
- Laboratory of Biochemistry & Molecular Biology, The Rockefeller University, New York, NY, USA.
| | - Robert G Roeder
- Laboratory of Biochemistry & Molecular Biology, The Rockefeller University, New York, NY, USA
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13
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Eichenberger BT, Griesbach E, Mitchell J, Chao JA. Following the Birth, Life, and Death of mRNAs in Single Cells. Annu Rev Cell Dev Biol 2023; 39:253-275. [PMID: 37843928 DOI: 10.1146/annurev-cellbio-022723-024045] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2023]
Abstract
Recent advances in single-molecule imaging of mRNAs in fixed and living cells have enabled the lives of mRNAs to be studied with unprecedented spatial and temporal detail. These approaches have moved beyond simply being able to observe specific events and have begun to allow an understanding of how regulation is coupled between steps in the mRNA life cycle. Additionally, these methodologies are now being applied in multicellular systems and animals to provide more nuanced insights into the physiological regulation of RNA metabolism.
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Affiliation(s)
- Bastian T Eichenberger
- Friedrich Miescher Institute for Biomedical Research, Basel, Switzerland;
- University of Basel, Basel, Switzerland
| | - Esther Griesbach
- Friedrich Miescher Institute for Biomedical Research, Basel, Switzerland;
| | - Jessica Mitchell
- Friedrich Miescher Institute for Biomedical Research, Basel, Switzerland;
| | - Jeffrey A Chao
- Friedrich Miescher Institute for Biomedical Research, Basel, Switzerland;
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14
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Kassouf M, Ford S, Blayney J, Higgs D. Understanding fundamental principles of enhancer biology at a model locus: Analysing the structure and function of an enhancer cluster at the α-globin locus. Bioessays 2023; 45:e2300047. [PMID: 37404089 DOI: 10.1002/bies.202300047] [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: 03/08/2023] [Revised: 05/03/2023] [Accepted: 05/05/2023] [Indexed: 07/06/2023]
Abstract
Despite ever-increasing accumulation of genomic data, the fundamental question of how individual genes are switched on during development, lineage-specification and differentiation is not fully answered. It is widely accepted that this involves the interaction between at least three fundamental regulatory elements: enhancers, promoters and insulators. Enhancers contain transcription factor binding sites which are bound by transcription factors (TFs) and co-factors expressed during cell fate decisions and maintain imposed patterns of activation, at least in part, via their epigenetic modification. This information is transferred from enhancers to their cognate promoters often by coming into close physical proximity to form a 'transcriptional hub' containing a high concentration of TFs and co-factors. The mechanisms underlying these stages of transcriptional activation are not fully explained. This review focuses on how enhancers and promoters are activated during differentiation and how multiple enhancers work together to regulate gene expression. We illustrate the currently understood principles of how mammalian enhancers work and how they may be perturbed in enhanceropathies using expression of the α-globin gene cluster during erythropoiesis, as a model.
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Affiliation(s)
- Mira Kassouf
- Laboratory of Gene Regulation, MRC Weatherall Institute of Molecular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford, UK
| | - Seren Ford
- Laboratory of Gene Regulation, MRC Weatherall Institute of Molecular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford, UK
| | - Joseph Blayney
- Laboratory of Gene Regulation, MRC Weatherall Institute of Molecular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford, UK
| | - Doug Higgs
- Laboratory of Gene Regulation, MRC Weatherall Institute of Molecular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford, UK
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15
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Tschurikow X, Gadzekpo A, Tran MP, Chatterjee R, Sobucki M, Zaburdaev V, Göpfrich K, Hilbert L. Amphiphiles Formed from Synthetic DNA-Nanomotifs Mimic the Stepwise Dispersal of Transcriptional Clusters in the Cell Nucleus. NANO LETTERS 2023; 23:7815-7824. [PMID: 37586706 PMCID: PMC10510709 DOI: 10.1021/acs.nanolett.3c01301] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/06/2023] [Revised: 07/28/2023] [Indexed: 08/18/2023]
Abstract
Stem cells exhibit prominent clusters controlling the transcription of genes into RNA. These clusters form by a phase-separation mechanism, and their size and shape are controlled via an amphiphilic effect of transcribed genes. Here, we construct amphiphile-nanomotifs purely from DNA, and we achieve similar size and shape control for phase-separated droplets formed from fully synthetic, self-interacting DNA-nanomotifs. Increasing amphiphile concentrations induce rounding of droplets, prevent droplet fusion, and, at high concentrations, cause full dispersal of droplets. Super-resolution microscopy data obtained from zebrafish embryo stem cells reveal a comparable transition for transcriptional clusters with increasing transcription levels. Brownian dynamics and lattice simulations further confirm that the addition of amphiphilic particles is sufficient to explain the observed changes in shape and size. Our work reproduces key aspects of transcriptional cluster formation in biological cells using relatively simple DNA sequence-programmable nanostructures, opening novel ways to control the mesoscopic organization of synthetic nanomaterials.
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Affiliation(s)
- Xenia Tschurikow
- Institute
of Biological and Chemical Systems, Karlsruhe
Institute of Technology, Eggenstein-Leopoldshafen 76344, Germany
- Zoological
Institute, Karlsruhe Institute of Technology, Karlsruhe 76131, Germany
| | - Aaron Gadzekpo
- Institute
of Biological and Chemical Systems, Karlsruhe
Institute of Technology, Eggenstein-Leopoldshafen 76344, Germany
- Zoological
Institute, Karlsruhe Institute of Technology, Karlsruhe 76131, Germany
| | - Mai P. Tran
- Center
for Molecular Biology of Heidelberg University (ZMBH), Heidelberg 69120, Germany
- Max
Planck Institute for Medical Research, Heidelberg 69120, Germany
| | - Rakesh Chatterjee
- Max
Planck Zentrum für Physik und Medizin, Erlangen 91058, Germany
- Chair
of Mathematics in Life Sciences, Friedrich-Alexander
Universität Erlangen-Nürnberg, Erlangen 91058, Germany
| | - Marcel Sobucki
- Institute
of Biological and Chemical Systems, Karlsruhe
Institute of Technology, Eggenstein-Leopoldshafen 76344, Germany
| | - Vasily Zaburdaev
- Max
Planck Zentrum für Physik und Medizin, Erlangen 91058, Germany
- Chair
of Mathematics in Life Sciences, Friedrich-Alexander
Universität Erlangen-Nürnberg, Erlangen 91058, Germany
| | - Kerstin Göpfrich
- Center
for Molecular Biology of Heidelberg University (ZMBH), Heidelberg 69120, Germany
- Max
Planck Institute for Medical Research, Heidelberg 69120, Germany
| | - Lennart Hilbert
- Institute
of Biological and Chemical Systems, Karlsruhe
Institute of Technology, Eggenstein-Leopoldshafen 76344, Germany
- Zoological
Institute, Karlsruhe Institute of Technology, Karlsruhe 76131, Germany
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16
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Ochiai H, Ohishi H, Sato Y, Kimura H. Organization of transcription and 3D genome as revealed by live-cell imaging. Curr Opin Struct Biol 2023; 81:102615. [PMID: 37257205 DOI: 10.1016/j.sbi.2023.102615] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2023] [Revised: 04/03/2023] [Accepted: 05/01/2023] [Indexed: 06/02/2023]
Abstract
Higher-order genomic structures play a critical role in regulating gene expression by influencing the spatial proximity of promoters and enhancers. Live-cell imaging studies have demonstrated that three-dimensional genome structures undergo dynamic changes over time. Transcription is also dynamic, with genes frequently switching between active and inactive states. Recent observations suggest that the formation of condensates, composed of transcription-related factors, RNA, and RNA-binding proteins, around genes can regulate transcription. Advancements in technology have facilitated the visualization of the intricate spatiotemporal relationship between higher-order genomic structures, condensate formation, and transcriptional activity in living cells.
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Affiliation(s)
- Hiroshi Ochiai
- Medical Institute of Bioregulation, Kyushu University, Fukuoka, 812-0054, Japan.
| | - Hiroaki Ohishi
- Medical Institute of Bioregulation, Kyushu University, Fukuoka, 812-0054, Japan
| | - Yuko Sato
- School of Life Science and Technology, Tokyo Institute of Technology, Yokohama, 226-8501, Japan; Cell Biology Center, Institute of Innovative Research, Tokyo Institute of Technology, Yokohama, 226-8503, Japan
| | - Hiroshi Kimura
- School of Life Science and Technology, Tokyo Institute of Technology, Yokohama, 226-8501, Japan; Cell Biology Center, Institute of Innovative Research, Tokyo Institute of Technology, Yokohama, 226-8503, Japan.
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17
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Stasevich TJ, Kimura H. An expanded view of transcription. Science 2023; 381:26-27. [PMID: 37410830 DOI: 10.1126/science.adi8187] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/08/2023]
Abstract
A new method expands chromatin to provide detailed images of transcription sites.
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Affiliation(s)
- Timothy J Stasevich
- Department of Biochemistry and Molecular Biology, Colorado State University, Fort Collins, CO, USA
| | - Hiroshi Kimura
- Cell Biology Center, Institute of Innovative Research, Tokyo Institute of Technology, Yokohama, Japan
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18
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Mizutani A, Tan C, Sugita Y, Takada S. Micelle-like clusters in phase-separated Nanog condensates: A molecular simulation study. PLoS Comput Biol 2023; 19:e1011321. [PMID: 37486948 PMCID: PMC10399900 DOI: 10.1371/journal.pcbi.1011321] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2023] [Revised: 08/03/2023] [Accepted: 06/30/2023] [Indexed: 07/26/2023] Open
Abstract
The phase separation model for transcription suggests that transcription factors (TFs), coactivators, and RNA polymerases form biomolecular condensates around active gene loci and regulate transcription. However, the structural details of condensates remain elusive. In this study, for Nanog, a master TF in mammalian embryonic stem cells known to form protein condensates in vitro, we examined protein structures in the condensates using residue-level coarse-grained molecular simulations. Human Nanog formed micelle-like clusters in the condensate. In the micelle-like cluster, the C-terminal disordered domains, including the tryptophan repeat (WR) regions, interacted with each other near the cluster center primarily via hydrophobic interaction. In contrast, hydrophilic disordered N-terminal and DNA-binding domains were exposed on the surface of the clusters. Electrostatic attractions of these surface residues were responsible for bridging multiple micelle-like structures in the condensate. The micelle-like structure and condensate were dynamic and liquid-like. Mutation of tryptophan residues in the WR region which was implicated to be important for a Nanog function resulted in dissolution of the Nanog condensate. Finally, to examine the impact of Nanog cluster to DNA, we added DNA fragments to the Nanog condensate. Nanog DNA-binding domains exposed to the surface of the micelle-like cluster could recruit more than one DNA fragments, making DNA-DNA distance shorter.
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Affiliation(s)
- Azuki Mizutani
- Department of Biophysics, Graduate School of Science, Kyoto University, Kyoto, Japan
| | - Cheng Tan
- Computational Biophysics Research Team, RIKEN Center for Computational Science, Minatojima-Minamimachi, Chuo-ku, Kobe, Hyogo, Japan
| | - Yuji Sugita
- Computational Biophysics Research Team, RIKEN Center for Computational Science, Minatojima-Minamimachi, Chuo-ku, Kobe, Hyogo, Japan
- Theoretical Molecular Science Laboratory, RIKEN Cluster for Pioneering Research, Hirosawa, Wako, Saitama, Japan
- Laboratory for Biomolecular Function Simulation, RIKEN Center for Biosystems Dynamics Research, Minatojima-Minamimachi, Chuo-ku, Kobe, Hyogo, Japan
| | - Shoji Takada
- Department of Biophysics, Graduate School of Science, Kyoto University, Kyoto, Japan
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19
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Meeussen JVW, Pomp W, Brouwer I, de Jonge WJ, Patel HP, Lenstra TL. Transcription factor clusters enable target search but do not contribute to target gene activation. Nucleic Acids Res 2023; 51:5449-5468. [PMID: 36987884 PMCID: PMC10287935 DOI: 10.1093/nar/gkad227] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2022] [Revised: 03/06/2023] [Accepted: 03/16/2023] [Indexed: 03/30/2023] Open
Abstract
Many transcription factors (TFs) localize in nuclear clusters of locally increased concentrations, but how TF clustering is regulated and how it influences gene expression is not well understood. Here, we use quantitative microscopy in living cells to study the regulation and function of clustering of the budding yeast TF Gal4 in its endogenous context. Our results show that Gal4 forms clusters that overlap with the GAL loci. Cluster number, density and size are regulated in different growth conditions by the Gal4-inhibitor Gal80 and Gal4 concentration. Gal4 truncation mutants reveal that Gal4 clustering is facilitated by, but does not completely depend on DNA binding and intrinsically disordered regions. Moreover, we discover that clustering acts as a double-edged sword: self-interactions aid TF recruitment to target genes, but recruited Gal4 molecules that are not DNA-bound do not contribute to, and may even inhibit, transcription activation. We propose that cells need to balance the different effects of TF clustering on target search and transcription activation to facilitate proper gene expression.
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Affiliation(s)
- Joseph V W Meeussen
- Division of Gene Regulation, The Netherlands Cancer Institute, Oncode Institute, 1066CX Amsterdam, The Netherlands
| | - Wim Pomp
- Division of Gene Regulation, The Netherlands Cancer Institute, Oncode Institute, 1066CX Amsterdam, The Netherlands
| | - Ineke Brouwer
- Division of Gene Regulation, The Netherlands Cancer Institute, Oncode Institute, 1066CX Amsterdam, The Netherlands
| | - Wim J de Jonge
- Division of Gene Regulation, The Netherlands Cancer Institute, Oncode Institute, 1066CX Amsterdam, The Netherlands
| | - Heta P Patel
- Division of Gene Regulation, The Netherlands Cancer Institute, Oncode Institute, 1066CX Amsterdam, The Netherlands
| | - Tineke L Lenstra
- Division of Gene Regulation, The Netherlands Cancer Institute, Oncode Institute, 1066CX Amsterdam, The Netherlands
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20
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van Staalduinen J, van Staveren T, Grosveld F, Wendt KS. Live-cell imaging of chromatin contacts opens a new window into chromatin dynamics. Epigenetics Chromatin 2023; 16:27. [PMID: 37349773 PMCID: PMC10288748 DOI: 10.1186/s13072-023-00503-9] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2023] [Accepted: 06/15/2023] [Indexed: 06/24/2023] Open
Abstract
Our understanding of the organization of the chromatin fiber within the cell nucleus has made great progress in the last few years. High-resolution techniques based on next-generation sequencing as well as optical imaging that can investigate chromatin conformations down to the single cell level have revealed that chromatin structure is highly heterogeneous at the level of the individual allele. While TAD boundaries and enhancer-promoter pairs emerge as hotspots of 3D proximity, the spatiotemporal dynamics of these different types of chromatin contacts remain largely unexplored. Investigation of chromatin contacts in live single cells is necessary to close this knowledge gap and further enhance the current models of 3D genome organization and enhancer-promoter communication. In this review, we first discuss the potential of single locus labeling to study architectural and enhancer-promoter contacts and provide an overview of the available single locus labeling techniques such as FROS, TALE, CRISPR-dCas9 and ANCHOR, and discuss the latest developments and applications of these systems.
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Affiliation(s)
- Jente van Staalduinen
- Department of Cell Biology, Erasmus MC, Dr. Molewaterplein 50, 3015 GE, Rotterdam, The Netherlands
| | - Thomas van Staveren
- Department of Cell Biology, Erasmus MC, Dr. Molewaterplein 50, 3015 GE, Rotterdam, The Netherlands
| | - Frank Grosveld
- Department of Cell Biology, Erasmus MC, Dr. Molewaterplein 50, 3015 GE, Rotterdam, The Netherlands
| | - Kerstin S Wendt
- Department of Cell Biology, Erasmus MC, Dr. Molewaterplein 50, 3015 GE, Rotterdam, The Netherlands.
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21
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Leyes Porello EA, Trudeau RT, Lim B. Transcriptional bursting: stochasticity in deterministic development. Development 2023; 150:dev201546. [PMID: 37337971 PMCID: PMC10323239 DOI: 10.1242/dev.201546] [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: 06/21/2023]
Abstract
The transcription of DNA by RNA polymerase occurs as a discontinuous process described as transcriptional bursting. This bursting behavior is observed across species and has been quantified using various stochastic modeling approaches. There is a large body of evidence that suggests the bursts are actively modulated by transcriptional machinery and play a role in regulating developmental processes. Under a commonly used two-state model of transcription, various enhancer-, promoter- and chromatin microenvironment-associated features are found to differentially influence the size and frequency of bursting events - key parameters of the two-state model. Advancement of modeling and analysis tools has revealed that the simple two-state model and associated parameters may not sufficiently characterize the complex relationship between these features. The majority of experimental and modeling findings support the view of bursting as an evolutionarily conserved transcriptional control feature rather than an unintended byproduct of the transcription process. Stochastic transcriptional patterns contribute to enhanced cellular fitness and execution of proper development programs, which posit this mode of transcription as an important feature in developmental gene regulation. In this Review, we present compelling examples of the role of transcriptional bursting in development and explore the question of how stochastic transcription leads to deterministic organism development.
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Affiliation(s)
- Emilia A. Leyes Porello
- Department of Chemical and Biomolecular Engineering, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Robert T. Trudeau
- Department of Chemical and Biomolecular Engineering, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Bomyi Lim
- Department of Chemical and Biomolecular Engineering, University of Pennsylvania, Philadelphia, PA 19104, USA
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22
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Mach P, Giorgetti L. Integrative approaches to study enhancer-promoter communication. Curr Opin Genet Dev 2023; 80:102052. [PMID: 37257410 PMCID: PMC10293802 DOI: 10.1016/j.gde.2023.102052] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2023] [Revised: 04/21/2023] [Accepted: 04/22/2023] [Indexed: 06/02/2023]
Abstract
The spatiotemporal control of gene expression in complex multicellular organisms relies on noncoding regulatory sequences such as enhancers, which activate transcription of target genes often over large genomic distances. Despite the advances in the identification and characterization of enhancers, the principles and mechanisms by which enhancers select and control their target genes remain largely unknown. Here, we review recent interdisciplinary and quantitative approaches based on emerging techniques that aim to address open questions in the field, notably how regulatory information is encoded in the DNA sequence, how this information is transferred from enhancers to promoters, and how these processes are regulated in time.
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Affiliation(s)
- Pia Mach
- Friedrich Miescher Institute for Biomedical Research, Basel, Switzerland; University of Basel, Basel, Switzerland. https://twitter.com/@MachPia
| | - Luca Giorgetti
- Friedrich Miescher Institute for Biomedical Research, Basel, Switzerland.
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23
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Gerber A, van Otterdijk S, Bruggeman FJ, Tutucci E. Understanding spatiotemporal coupling of gene expression using single molecule RNA imaging technologies. Transcription 2023; 14:105-126. [PMID: 37050882 PMCID: PMC10807504 DOI: 10.1080/21541264.2023.2199669] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2022] [Revised: 03/30/2023] [Accepted: 04/01/2023] [Indexed: 04/14/2023] Open
Abstract
Across all kingdoms of life, gene regulatory mechanisms underlie cellular adaptation to ever-changing environments. Regulation of gene expression adjusts protein synthesis and, in turn, cellular growth. Messenger RNAs are key molecules in the process of gene expression. Our ability to quantitatively measure mRNA expression in single cells has improved tremendously over the past decades. This revealed an unexpected coordination between the steps that control the life of an mRNA, from transcription to degradation. Here, we provide an overview of the state-of-the-art imaging approaches for measurement and quantitative understanding of gene expression, starting from the early visualizations of single genes by electron microscopy to current fluorescence-based approaches in single cells, including live-cell RNA-imaging approaches to FISH-based spatial transcriptomics across model organisms. We also highlight how these methods have shaped our current understanding of the spatiotemporal coupling between transcriptional and post-transcriptional events in prokaryotes. We conclude by discussing future challenges of this multidisciplinary field.Abbreviations: mRNA: messenger RNA; rRNA: ribosomal rDNA; tRNA: transfer RNA; sRNA: small RNA; FISH: fluorescence in situ hybridization; RNP: ribonucleoprotein; smFISH: single RNA molecule FISH; smiFISH: single molecule inexpensive FISH; HCR-FISH: Hybridization Chain-Reaction-FISH; RCA: Rolling Circle Amplification; seqFISH: Sequential FISH; MERFISH: Multiplexed error robust FISH; UTR: Untranslated region; RBP: RNA binding protein; FP: fluorescent protein; eGFP: enhanced GFP, MCP: MS2 coat protein; PCP: PP7 coat protein; MB: Molecular beacons; sgRNA: single guide RNA.
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Affiliation(s)
- Alan Gerber
- Amsterdam UMC, Location Vrije Universiteit Amsterdam, Department of Neurosurgery, Amsterdam, The Netherlands
- Cancer Center Amsterdam, Brain Tumor Center Amsterdam, Amsterdam, The Netherlands
| | - Sander van Otterdijk
- Systems Biology Lab, A-LIFE department, Amsterdam Institute of Molecular and Life Sciences (AIMMS), Vrije Universiteit Amsterdam, Amsterdam, The Netherlands
| | - Frank J. Bruggeman
- Systems Biology Lab, A-LIFE department, Amsterdam Institute of Molecular and Life Sciences (AIMMS), Vrije Universiteit Amsterdam, Amsterdam, The Netherlands
| | - Evelina Tutucci
- Systems Biology Lab, A-LIFE department, Amsterdam Institute of Molecular and Life Sciences (AIMMS), Vrije Universiteit Amsterdam, Amsterdam, The Netherlands
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24
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Martinez-Corral R, Park M, Biette KM, Friedrich D, Scholes C, Khalil AS, Gunawardena J, DePace AH. Transcriptional kinetic synergy: A complex landscape revealed by integrating modeling and synthetic biology. Cell Syst 2023; 14:324-339.e7. [PMID: 37080164 PMCID: PMC10472254 DOI: 10.1016/j.cels.2023.02.003] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2021] [Revised: 08/22/2022] [Accepted: 02/10/2023] [Indexed: 04/22/2023]
Abstract
Transcription factors (TFs) control gene expression, often acting synergistically. Classical thermodynamic models offer a biophysical explanation for synergy based on binding cooperativity and regulated recruitment of RNA polymerase. Because transcription requires polymerase to transition through multiple states, recent work suggests that "kinetic synergy" can arise through TFs acting on distinct steps of the transcription cycle. These types of synergy are not mutually exclusive and are difficult to disentangle conceptually and experimentally. Here, we model and build a synthetic circuit in which TFs bind to a single shared site on DNA, such that TFs cannot synergize by simultaneous binding. We model mRNA production as a function of both TF binding and regulation of the transcription cycle, revealing a complex landscape dependent on TF concentration, DNA binding affinity, and regulatory activity. We use synthetic TFs to confirm that the transcription cycle must be integrated with recruitment for a quantitative understanding of gene regulation.
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Affiliation(s)
| | - Minhee Park
- Biological Design Center, Boston University, Boston, MA 02215, USA; Department of Biomedical Engineering, Boston University, Boston, MA 02215, USA
| | - Kelly M Biette
- Department of Systems Biology, Harvard Medical School, Boston, MA 02115, USA
| | - Dhana Friedrich
- Department of Systems Biology, Harvard Medical School, Boston, MA 02115, USA
| | - Clarissa Scholes
- Department of Systems Biology, Harvard Medical School, Boston, MA 02115, USA
| | - Ahmad S Khalil
- Biological Design Center, Boston University, Boston, MA 02215, USA; Department of Biomedical Engineering, Boston University, Boston, MA 02215, USA; Wyss Institute for Biologically Inspired Engineering, Harvard University, Boston, MA 02115, USA
| | - Jeremy Gunawardena
- Department of Systems Biology, Harvard Medical School, Boston, MA 02115, USA
| | - Angela H DePace
- Department of Systems Biology, Harvard Medical School, Boston, MA 02115, USA.
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25
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Li Y, Matsunaga S. Various Strategies for Improved Signal-to-Noise Ratio in CRISPR-Based Live Cell Imaging. CYTOLOGIA 2023. [DOI: 10.1508/cytologia.88.3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/28/2023]
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26
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Cheng L, De C, Li J, Pertsinidis A. Mechanisms of transcription control by distal enhancers from high-resolution single-gene imaging. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.03.19.533190. [PMID: 36993179 PMCID: PMC10055225 DOI: 10.1101/2023.03.19.533190] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/31/2023]
Abstract
How distal enhancers physically control promoters over large genomic distances, to enable cell-type specific gene expression, remains obscure. Using single-gene super-resolution imaging and acute targeted perturbations, we define physical parameters of enhancer-promoter communication and elucidate processes that underlie target gene activation. Productive enhancer-promoter encounters happen at 3D distances δ200 nm - a spatial scale corresponding to unexpected enhancer-associated clusters of general transcription factor (GTF) components of the Pol II machinery. Distal activation is achieved by increasing transcriptional bursting frequency, a process facilitated by embedding a promoter into such GTF clusters and by accelerating an underlying multi-step cascade comprising early phases in the Pol II transcription cycle. These findings help clarify molecular/biochemical signals involved in long-range activation and their means of transmission from enhancer to promoter.
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Affiliation(s)
- Lingling Cheng
- Structural Biology Program, Memorial Sloan Kettering Cancer Center; New York, NY 10065, USA
| | - Chayan De
- Structural Biology Program, Memorial Sloan Kettering Cancer Center; New York, NY 10065, USA
| | - Jieru Li
- Structural Biology Program, Memorial Sloan Kettering Cancer Center; New York, NY 10065, USA
| | - Alexandros Pertsinidis
- Structural Biology Program, Memorial Sloan Kettering Cancer Center; New York, NY 10065, USA
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27
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Guo C, Zhang Y, Shuai S, Sigbessia A, Hao S, Xie P, Jiang X, Luo Z, Lin C. The super elongation complex (SEC) mediates phase transition of SPT5 during transcriptional pause release. EMBO Rep 2023; 24:e55699. [PMID: 36629390 PMCID: PMC9986819 DOI: 10.15252/embr.202255699] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2022] [Revised: 12/12/2022] [Accepted: 12/14/2022] [Indexed: 01/12/2023] Open
Abstract
Release of promoter-proximally paused RNA Pol II into elongation is a tightly regulated and rate-limiting step in metazoan gene transcription. However, the biophysical mechanism underlying pause release remains unclear. Here, we demonstrate that the pausing and elongation regulator SPT5 undergoes phase transition during transcriptional pause release. SPT5 per se is prone to form clusters. The disordered domain in SPT5 is required for pause release and gene activation. During early elongation, the super elongation complex (SEC) induces SPT5 transition into elongation droplets. Depletion of SEC increases SPT5 pausing clusters. Furthermore, disease-associated SEC mutations impair phase properties of elongation droplets and transcription. Our study suggests that SEC-mediated SPT5 phase transition might be essential for pause release and early elongation and that aberrant phase properties could contribute to transcription abnormality in diseases.
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Affiliation(s)
- Chenghao Guo
- Key Laboratory of Developmental Genes and Human Disease, School of Life Science and TechnologySoutheast UniversityNanjingChina
- Co‐innovation Center of NeuroregenerationNantong UniversityNantongChina
| | - Yadi Zhang
- Key Laboratory of Developmental Genes and Human Disease, School of Life Science and TechnologySoutheast UniversityNanjingChina
| | - Shimin Shuai
- Key Laboratory of Developmental Genes and Human Disease, School of Life Science and TechnologySoutheast UniversityNanjingChina
| | - Abire Sigbessia
- Key Laboratory of Developmental Genes and Human Disease, School of Life Science and TechnologySoutheast UniversityNanjingChina
| | - Shaohua Hao
- Key Laboratory of Developmental Genes and Human Disease, School of Life Science and TechnologySoutheast UniversityNanjingChina
| | - Peng Xie
- Southeast University‐Allen Institute Joint Center, Institute for Brain and IntelligenceSoutheast UniversityNanjingChina
| | - Xu Jiang
- Key Laboratory of Developmental Genes and Human Disease, School of Life Science and TechnologySoutheast UniversityNanjingChina
| | - Zhuojuan Luo
- Key Laboratory of Developmental Genes and Human Disease, School of Life Science and TechnologySoutheast UniversityNanjingChina
- Co‐innovation Center of NeuroregenerationNantong UniversityNantongChina
- Shenzhen Research InstituteSoutheast UniversityShenzhenChina
- Jiangsu Provincial Key Laboratory of Critical Care Medicine, School of Life Science and TechnologySoutheast UniversityNanjingChina
| | - Chengqi Lin
- Key Laboratory of Developmental Genes and Human Disease, School of Life Science and TechnologySoutheast UniversityNanjingChina
- Co‐innovation Center of NeuroregenerationNantong UniversityNantongChina
- Shenzhen Research InstituteSoutheast UniversityShenzhenChina
- Jiangsu Provincial Key Laboratory of Critical Care Medicine, School of Life Science and TechnologySoutheast UniversityNanjingChina
- Key Laboratory of Technical Evaluation of Fertility Regulation of Non‐human primate, Fujian Provincial Maternity and Children's HospitalAffiliated Hospital of Fujian Medical UniversityFuzhouChina
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28
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Ohishi H, Ochiai H. STREAMING-Tag System: Technology to Enable Visualization of Transcriptional Activity and Subnuclear Localization of Specific Endogenous Genes. Methods Mol Biol 2023; 2577:103-122. [PMID: 36173569 DOI: 10.1007/978-1-0716-2724-2_8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
The Spliced TetO REpeAt, MS2 repeat, and INtein sandwiched reporter Gene tag (STREAMING-tag) system enables imaging of nuclear localization as well as the transcription activity of a specific endogenous gene at sub-100-nm resolution in living cells. The use of this system combined with imaging of epigenome states enables a detailed analysis of the impact of epigenome status on transcriptional dynamics. In this chapter, we describe a method for quantifying distances between Nanog gene and clusters of cofactor BRD4 using the STREAMING-tag system in mouse embryonic stem cells.
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Affiliation(s)
- Hiroaki Ohishi
- Graduate School of Integrated Sciences for Life, Hiroshima University, Higashi-Hiroshima, Japan
| | - Hiroshi Ochiai
- Graduate School of Integrated Sciences for Life, Hiroshima University, Higashi-Hiroshima, Japan.
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29
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Wang X, Fan Y, Wu Q. The regulation of transcription elongation in embryonic stem cells. Front Cell Dev Biol 2023; 11:1145611. [PMID: 36875763 PMCID: PMC9978399 DOI: 10.3389/fcell.2023.1145611] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2023] [Accepted: 02/08/2023] [Indexed: 02/18/2023] Open
Abstract
Transcription elongation is a fundamental molecular process which is accurately regulated to ensure proper gene expression in cellular activities whereas its malfunction is associated with impaired cellular functions. Embryonic stem cells (ESCs) have significant value in regenerative medicine due to their self-renewal ability and their potential to differentiate to almost all types of cells. Therefore, dissection of the exact regulatory mechanism of transcription elongation in ESCs is crucial for both basic research and their clinical applications. In this review, we discuss the current understanding on the regulatory mechanisms of transcription elongation mediated by transcription factors and epigenetic modifications in ESCs.
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Affiliation(s)
- Xuepeng Wang
- The State Key Laboratory of Quality Research in Chinese Medicine, Macau University of Science and Technology, Taipa, Macao SAR, China
| | - Yudan Fan
- The State Key Laboratory of Quality Research in Chinese Medicine, Macau University of Science and Technology, Taipa, Macao SAR, China
| | - Qiang Wu
- The State Key Laboratory of Quality Research in Chinese Medicine, Macau University of Science and Technology, Taipa, Macao SAR, China
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30
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Ohishi H, Shimada S, Uchino S, Li J, Sato Y, Shintani M, Owada H, Ohkawa Y, Pertsinidis A, Yamamoto T, Kimura H, Ochiai H. STREAMING-tag system reveals spatiotemporal relationships between transcriptional regulatory factors and transcriptional activity. Nat Commun 2022; 13:7672. [PMID: 36539402 PMCID: PMC9768169 DOI: 10.1038/s41467-022-35286-2] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2022] [Accepted: 11/25/2022] [Indexed: 12/24/2022] Open
Abstract
Transcription is a dynamic process. To detect the dynamic relationship among protein clusters of RNA polymerase II and coactivators, gene loci, and transcriptional activity, we insert an MS2 repeat, a TetO repeat, and inteins with a selection marker just downstream of the transcription start site. By optimizing the individual elements, we develop the Spliced TetO REpeAt, MS2 repeat, and INtein sandwiched reporter Gene tag (STREAMING-tag) system. Clusters of RNA polymerase II and BRD4 are observed proximal to the transcription start site of Nanog when the gene is transcribed in mouse embryonic stem cells. In contrast, clusters of MED19 and MED22 tend to be located near the transcription start site, even without transcription activity. Thus, the STREAMING-tag system reveals the spatiotemporal relationships between transcriptional activity and protein clusters near the gene. This powerful tool is useful for quantitatively understanding transcriptional regulation in living cells.
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Affiliation(s)
- Hiroaki Ohishi
- grid.257022.00000 0000 8711 3200Graduate School of Integrated Sciences for Life, Hiroshima University, Higashi-Hiroshima, 739-0046 Japan
| | - Seiru Shimada
- grid.257022.00000 0000 8711 3200Graduate School of Integrated Sciences for Life, Hiroshima University, Higashi-Hiroshima, 739-0046 Japan
| | - Satoshi Uchino
- grid.32197.3e0000 0001 2179 2105School of Life Science and Technology, Tokyo Institute of Technology, Yokohama, 226-8501 Japan
| | - Jieru Li
- grid.51462.340000 0001 2171 9952Structural Biology Program, Memorial Sloan Kettering Cancer Center, New York, NY 10065 USA
| | - Yuko Sato
- grid.32197.3e0000 0001 2179 2105School of Life Science and Technology, Tokyo Institute of Technology, Yokohama, 226-8501 Japan ,grid.32197.3e0000 0001 2179 2105Cell Biology Center, Institute of Innovative Research, Tokyo Institute of Technology, Yokohama, 226-8503 Japan
| | - Manabu Shintani
- grid.257022.00000 0000 8711 3200Graduate School of Integrated Sciences for Life, Hiroshima University, Higashi-Hiroshima, 739-0046 Japan
| | - Hitoshi Owada
- grid.257022.00000 0000 8711 3200Graduate School of Integrated Sciences for Life, Hiroshima University, Higashi-Hiroshima, 739-0046 Japan
| | - Yasuyuki Ohkawa
- grid.177174.30000 0001 2242 4849Division of Transcriptomics, Medical Institute of Bioregulation, Kyushu University, Fukuoka, 812-8582 Japan
| | - Alexandros Pertsinidis
- grid.51462.340000 0001 2171 9952Structural Biology Program, Memorial Sloan Kettering Cancer Center, New York, NY 10065 USA
| | - Takashi Yamamoto
- grid.257022.00000 0000 8711 3200Graduate School of Integrated Sciences for Life, Hiroshima University, Higashi-Hiroshima, 739-0046 Japan
| | - Hiroshi Kimura
- grid.32197.3e0000 0001 2179 2105School of Life Science and Technology, Tokyo Institute of Technology, Yokohama, 226-8501 Japan ,grid.32197.3e0000 0001 2179 2105Cell Biology Center, Institute of Innovative Research, Tokyo Institute of Technology, Yokohama, 226-8503 Japan
| | - Hiroshi Ochiai
- grid.257022.00000 0000 8711 3200Graduate School of Integrated Sciences for Life, Hiroshima University, Higashi-Hiroshima, 739-0046 Japan
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31
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Ibrahim Z, Wang T, Destaing O, Salvi N, Hoghoughi N, Chabert C, Rusu A, Gao J, Feletto L, Reynoird N, Schalch T, Zhao Y, Blackledge M, Khochbin S, Panne D. Structural insights into p300 regulation and acetylation-dependent genome organisation. Nat Commun 2022; 13:7759. [PMID: 36522330 PMCID: PMC9755262 DOI: 10.1038/s41467-022-35375-2] [Citation(s) in RCA: 20] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2022] [Accepted: 11/29/2022] [Indexed: 12/23/2022] Open
Abstract
Histone modifications are deposited by chromatin modifying enzymes and read out by proteins that recognize the modified state. BRD4-NUT is an oncogenic fusion protein of the acetyl lysine reader BRD4 that binds to the acetylase p300 and enables formation of long-range intra- and interchromosomal interactions. We here examine how acetylation reading and writing enable formation of such interactions. We show that NUT contains an acidic transcriptional activation domain that binds to the TAZ2 domain of p300. We use NMR to investigate the structure of the complex and found that the TAZ2 domain has an autoinhibitory role for p300. NUT-TAZ2 interaction or mutations found in cancer that interfere with autoinhibition by TAZ2 allosterically activate p300. p300 activation results in a self-organizing, acetylation-dependent feed-forward reaction that enables long-range interactions by bromodomain multivalent acetyl-lysine binding. We discuss the implications for chromatin organisation, gene regulation and dysregulation in disease.
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Affiliation(s)
- Ziad Ibrahim
- Leicester Institute of Structural and Chemical Biology, Department of Molecular and Cell Biology, University of Leicester, Leicester, UK
- Department of Structural Biology, St. Jude Children's Research Hospital, Memphis, United States
| | - Tao Wang
- CNRS UMR 5309, INSERM U1209, Université Grenoble Alpes, Institute for Advanced Biosciences, Grenoble, France
| | - Olivier Destaing
- CNRS UMR 5309, INSERM U1209, Université Grenoble Alpes, Institute for Advanced Biosciences, Grenoble, France
| | - Nicola Salvi
- Institut de Biologie Structurale, CNRS, CEA, UGA, Grenoble, France
| | - Naghmeh Hoghoughi
- CNRS UMR 5309, INSERM U1209, Université Grenoble Alpes, Institute for Advanced Biosciences, Grenoble, France
| | - Clovis Chabert
- CNRS UMR 5309, INSERM U1209, Université Grenoble Alpes, Institute for Advanced Biosciences, Grenoble, France
| | - Alexandra Rusu
- Leicester Institute of Structural and Chemical Biology, Department of Molecular and Cell Biology, University of Leicester, Leicester, UK
| | - Jinjun Gao
- Ben May Department of Cancer Research, The University of Chicago, Chicago, IL, 60637, USA
| | - Leonardo Feletto
- Leicester Institute of Structural and Chemical Biology, Department of Molecular and Cell Biology, University of Leicester, Leicester, UK
| | - Nicolas Reynoird
- CNRS UMR 5309, INSERM U1209, Université Grenoble Alpes, Institute for Advanced Biosciences, Grenoble, France
| | - Thomas Schalch
- Leicester Institute of Structural and Chemical Biology, Department of Molecular and Cell Biology, University of Leicester, Leicester, UK
| | - Yingming Zhao
- Ben May Department of Cancer Research, The University of Chicago, Chicago, IL, 60637, USA
| | | | - Saadi Khochbin
- CNRS UMR 5309, INSERM U1209, Université Grenoble Alpes, Institute for Advanced Biosciences, Grenoble, France
| | - Daniel Panne
- Leicester Institute of Structural and Chemical Biology, Department of Molecular and Cell Biology, University of Leicester, Leicester, UK.
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32
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Ball DA, Jalloh B, Karpova TS. Impact of Saccharomyces cerevisiae on the Field of Single-Molecule Biophysics. Int J Mol Sci 2022; 23:ijms232415895. [PMID: 36555532 PMCID: PMC9781480 DOI: 10.3390/ijms232415895] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2022] [Revised: 12/10/2022] [Accepted: 12/11/2022] [Indexed: 12/15/2022] Open
Abstract
Cellular functions depend on the dynamic assembly of protein regulator complexes at specific cellular locations. Single Molecule Tracking (SMT) is a method of choice for the biochemical characterization of protein dynamics in vitro and in vivo. SMT follows individual molecules in live cells and provides direct information about their behavior. SMT was successfully applied to mammalian models. However, mammalian cells provide a complex environment where protein mobility depends on numerous factors that are difficult to control experimentally. Therefore, yeast cells, which are unicellular and well-studied with a small and completely sequenced genome, provide an attractive alternative for SMT. The simplicity of organization, ease of genetic manipulation, and tolerance to gene fusions all make yeast a great model for quantifying the kinetics of major enzymes, membrane proteins, and nuclear and cellular bodies. However, very few researchers apply SMT techniques to yeast. Our goal is to promote SMT in yeast to a wider research community. Our review serves a dual purpose. We explain how SMT is conducted in yeast cells, and we discuss the latest insights from yeast SMT while putting them in perspective with SMT of higher eukaryotes.
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33
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Richter WF, Nayak S, Iwasa J, Taatjes DJ. The Mediator complex as a master regulator of transcription by RNA polymerase II. Nat Rev Mol Cell Biol 2022; 23:732-749. [PMID: 35725906 PMCID: PMC9207880 DOI: 10.1038/s41580-022-00498-3] [Citation(s) in RCA: 57] [Impact Index Per Article: 28.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/17/2022] [Indexed: 02/08/2023]
Abstract
The Mediator complex, which in humans is 1.4 MDa in size and includes 26 subunits, controls many aspects of RNA polymerase II (Pol II) function. Apart from its size, a defining feature of Mediator is its intrinsic disorder and conformational flexibility, which contributes to its ability to undergo phase separation and to interact with a myriad of regulatory factors. In this Review, we discuss Mediator structure and function, with emphasis on recent cryogenic electron microscopy data of the 4.0-MDa transcription preinitiation complex. We further discuss how Mediator and sequence-specific DNA-binding transcription factors enable enhancer-dependent regulation of Pol II function at distal gene promoters, through the formation of molecular condensates (or transcription hubs) and chromatin loops. Mediator regulation of Pol II reinitiation is also discussed, in the context of transcription bursting. We propose a working model for Mediator function that combines experimental results and theoretical considerations related to enhancer-promoter interactions, which reconciles contradictory data regarding whether enhancer-promoter communication is direct or indirect. We conclude with a discussion of Mediator's potential as a therapeutic target and of future research directions.
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Affiliation(s)
- William F Richter
- Department of Biochemistry, University of Colorado, Boulder, CO, USA
| | - Shraddha Nayak
- Department of Biochemistry, University of Utah, Salt Lake City, UT, USA
| | - Janet Iwasa
- Department of Biochemistry, University of Utah, Salt Lake City, UT, USA
| | - Dylan J Taatjes
- Department of Biochemistry, University of Colorado, Boulder, CO, USA.
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34
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Li J, Pertsinidis A. Nanoscale nuclear environments, fine-scale 3D genome organization and transcription regulation. CURRENT OPINION IN SYSTEMS BIOLOGY 2022; 31:100436. [PMID: 37091742 PMCID: PMC10118054 DOI: 10.1016/j.coisb.2022.100436] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/25/2023]
Abstract
Decades of in vitro biochemical reconstitution, genetics and structural biology studies have established a vast knowledge base on the molecular mechanisms of chromatin regulation and transcription. A remaining challenge is to understand how these intricate biochemical systems operate in the context of the 3D genome organization and in the crowded and compartmentalized nuclear milieu. Here we review recent progress in this area based on high-resolution imaging approaches.
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Affiliation(s)
- Jieru Li
- Structural Biology Program, Memorial Sloan Kettering Cancer Center, NY 10065, USA
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35
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Zoller B, Gregor T, Tkačik G. Eukaryotic gene regulation at equilibrium, or non? CURRENT OPINION IN SYSTEMS BIOLOGY 2022; 31:100435. [PMID: 36590072 PMCID: PMC9802646 DOI: 10.1016/j.coisb.2022.100435] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Indexed: 06/17/2023]
Abstract
Models of transcriptional regulation that assume equilibrium binding of transcription factors have been less successful at predicting gene expression from sequence in eukaryotes than in bacteria. This could be due to the non-equilibrium nature of eukaryotic regulation. Unfortunately, the space of possible non-equilibrium mechanisms is vast and predominantly uninteresting. The key question is therefore how this space can be navigated efficiently, to focus on mechanisms and models that are biologically relevant. In this review, we advocate for the normative role of theory-theory that prescribes rather than just describes-in providing such a focus. Theory should expand its remit beyond inferring mechanistic models from data, towards identifying non-equilibrium gene regulatory schemes that may have been evolutionarily selected, despite their energy consumption, because they are precise, reliable, fast, or otherwise outperform regulation at equilibrium. We illustrate our reasoning by toy examples for which we provide simulation code.
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Affiliation(s)
- Benjamin Zoller
- Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton, NJ, USA
- Joseph Henry Laboratories of Physics, Princeton University, Princeton, NJ, USA
- Department of Developmental and Stem Cell Biology UMR3738, Institut Pasteur, Paris, France
| | - Thomas Gregor
- Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton, NJ, USA
- Joseph Henry Laboratories of Physics, Princeton University, Princeton, NJ, USA
- Department of Developmental and Stem Cell Biology UMR3738, Institut Pasteur, Paris, France
| | - Gašper Tkačik
- Institute of Science and Technology Austria, Klosterneuburg, Austria
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36
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Forero-Quintero LS, Raymond W, Munsky B, Stasevich TJ. Visualization, Quantification, and Modeling of Endogenous RNA Polymerase II Phosphorylation at a Single-copy Gene in Living Cells. Bio Protoc 2022; 12:e4482. [PMID: 36082371 PMCID: PMC9411018 DOI: 10.21769/bioprotoc.4482] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2022] [Revised: 06/12/2022] [Accepted: 06/14/2022] [Indexed: 01/05/2023] Open
Abstract
In eukaryotic cells, RNA Polymerase II (RNAP2) is the enzyme in charge of transcribing mRNA from DNA. RNAP2 possesses an extended carboxy-terminal domain (CTD) that gets dynamically phosphorylated as RNAP2 progresses through the transcription cycle, therefore regulating each step of transcription from recruitment to termination. Although RNAP2 residue-specific phosphorylation has been characterized in fixed cells by immunoprecipitation-based assays, or in live cells by using tandem gene arrays, these assays can mask heterogeneity and limit temporal and spatial resolution. Our protocol employs multi-colored complementary fluorescent antibody-based (Fab) probes to specifically detect the CTD of the RNAP2 (CTD-RNAP2), and its phosphorylated form at the serine 5 residue (Ser5ph-RNAP2) at a single-copy HIV-1 reporter gene. Together with high-resolution fluorescence microscopy, single-molecule tracking analysis, and rigorous computational modeling, our system allows us to visualize, quantify, and predict endogenous RNAP2 phosphorylation dynamics and mRNA synthesis at a single-copy gene, in living cells, and throughout the transcription cycle. Graphical abstract: Schematic of the steps for visualizing, quantifying, and predicting RNAP2 phosphorylation at a single-copy gene.
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Affiliation(s)
- Linda S. Forero-Quintero
- Department of Chemical and Biological Engineering, Colorado State University, Fort Collins, CO 80523, USA
,
*For correspondence:
| | - William Raymond
- School of Biomedical Engineering, Colorado State University, Fort Collins, CO 80523, USA
| | - Brian Munsky
- Department of Chemical and Biological Engineering, Colorado State University, Fort Collins, CO 80523, USA
,
School of Biomedical Engineering, Colorado State University, Fort Collins, CO 80523, USA
| | - Timothy J. Stasevich
- Department of Biochemistry and Molecular Biology, Colorado State University, Fort Collins, CO 80523, USA
,
Cell Biology Center and World Research Hub Initiative, Tokyo Institute of Technology, Yokohama, Kanagawa 226-8503, Japan
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37
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Keizer VIP, Grosse-Holz S, Woringer M, Zambon L, Aizel K, Bongaerts M, Delille F, Kolar-Znika L, Scolari VF, Hoffmann S, Banigan EJ, Mirny LA, Dahan M, Fachinetti D, Coulon A. Live-cell micromanipulation of a genomic locus reveals interphase chromatin mechanics. Science 2022; 377:489-495. [PMID: 35901134 DOI: 10.1126/science.abi9810] [Citation(s) in RCA: 40] [Impact Index Per Article: 20.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Our understanding of the physical principles organizing the genome in the nucleus is limited by the lack of tools to directly exert and measure forces on interphase chromosomes in vivo and probe their material nature. Here, we introduce an approach to actively manipulate a genomic locus using controlled magnetic forces inside the nucleus of a living human cell. We observed viscoelastic displacements over micrometers within minutes in response to near-piconewton forces, which are consistent with a Rouse polymer model. Our results highlight the fluidity of chromatin, with a moderate contribution of the surrounding material, revealing minor roles for cross-links and topological effects and challenging the view that interphase chromatin is a gel-like material. Our technology opens avenues for future research in areas from chromosome mechanics to genome functions.
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Affiliation(s)
- Veer I P Keizer
- Institut Curie, PSL Research University, Sorbonne Université, CNRS UMR3664, Laboratoire Dynamique du Noyau, 75005 Paris, France.,Institut Curie, PSL Research University, Sorbonne Université, CNRS UMR168, Laboratoire Physico Chimie Curie, 75005 Paris, France.,Institut Curie, PSL Research University, CNRS UMR144, Laboratoire Biologie Cellulaire et Cancer, 75005 Paris, France
| | - Simon Grosse-Holz
- Institut Curie, PSL Research University, Sorbonne Université, CNRS UMR3664, Laboratoire Dynamique du Noyau, 75005 Paris, France.,Institut Curie, PSL Research University, Sorbonne Université, CNRS UMR168, Laboratoire Physico Chimie Curie, 75005 Paris, France.,Department of Physics and Institute for Medical Engineering and Science, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Maxime Woringer
- Institut Curie, PSL Research University, Sorbonne Université, CNRS UMR3664, Laboratoire Dynamique du Noyau, 75005 Paris, France.,Institut Curie, PSL Research University, Sorbonne Université, CNRS UMR168, Laboratoire Physico Chimie Curie, 75005 Paris, France
| | - Laura Zambon
- Institut Curie, PSL Research University, Sorbonne Université, CNRS UMR3664, Laboratoire Dynamique du Noyau, 75005 Paris, France.,Institut Curie, PSL Research University, Sorbonne Université, CNRS UMR168, Laboratoire Physico Chimie Curie, 75005 Paris, France.,Institut Curie, PSL Research University, CNRS UMR144, Laboratoire Biologie Cellulaire et Cancer, 75005 Paris, France
| | - Koceila Aizel
- Institut Curie, PSL Research University, Sorbonne Université, CNRS UMR168, Laboratoire Physico Chimie Curie, 75005 Paris, France
| | - Maud Bongaerts
- Institut Curie, PSL Research University, Sorbonne Université, CNRS UMR168, Laboratoire Physico Chimie Curie, 75005 Paris, France
| | - Fanny Delille
- ESPCI Paris, PSL Research University, Sorbonne Université, CNRS UMR8213, Laboratoire de Physique et d'Étude des Matériaux, 75005 Paris, France
| | - Lorena Kolar-Znika
- Institut Curie, PSL Research University, Sorbonne Université, CNRS UMR3664, Laboratoire Dynamique du Noyau, 75005 Paris, France.,Institut Curie, PSL Research University, Sorbonne Université, CNRS UMR168, Laboratoire Physico Chimie Curie, 75005 Paris, France
| | - Vittore F Scolari
- Institut Curie, PSL Research University, Sorbonne Université, CNRS UMR3664, Laboratoire Dynamique du Noyau, 75005 Paris, France.,Institut Curie, PSL Research University, Sorbonne Université, CNRS UMR168, Laboratoire Physico Chimie Curie, 75005 Paris, France
| | - Sebastian Hoffmann
- Institut Curie, PSL Research University, CNRS UMR144, Laboratoire Biologie Cellulaire et Cancer, 75005 Paris, France
| | - Edward J Banigan
- Department of Physics and Institute for Medical Engineering and Science, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Leonid A Mirny
- Institut Curie, PSL Research University, Sorbonne Université, CNRS UMR3664, Laboratoire Dynamique du Noyau, 75005 Paris, France.,Department of Physics and Institute for Medical Engineering and Science, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Maxime Dahan
- Institut Curie, PSL Research University, Sorbonne Université, CNRS UMR168, Laboratoire Physico Chimie Curie, 75005 Paris, France
| | - Daniele Fachinetti
- Institut Curie, PSL Research University, CNRS UMR144, Laboratoire Biologie Cellulaire et Cancer, 75005 Paris, France
| | - Antoine Coulon
- Institut Curie, PSL Research University, Sorbonne Université, CNRS UMR3664, Laboratoire Dynamique du Noyau, 75005 Paris, France.,Institut Curie, PSL Research University, Sorbonne Université, CNRS UMR168, Laboratoire Physico Chimie Curie, 75005 Paris, France
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38
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Shah P, Bao Z, Zaidel-Bar R. Visualizing and quantifying molecular and cellular processes in C. elegans using light microscopy. Genetics 2022; 221:6619563. [PMID: 35766819 DOI: 10.1093/genetics/iyac068] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2021] [Accepted: 04/14/2022] [Indexed: 11/14/2022] Open
Abstract
Light microscopes are the cell and developmental biologists' "best friend", providing a means to see structures and follow dynamics from the protein to the organism level. A huge advantage of C. elegans as a model organism is its transparency, which coupled with its small size means that nearly every biological process can be observed and measured with the appropriate probe and light microscope. Continuous improvement in microscope technologies along with novel genome editing techniques to create transgenic probes have facilitated the development and implementation of a dizzying array of methods for imaging worm embryos, larvae and adults. In this review we provide an overview of the molecular and cellular processes that can be visualized in living worms using light microscopy. A partial inventory of fluorescent probes and techniques successfully used in worms to image the dynamics of cells, organelles, DNA, and protein localization and activity is followed by a practical guide to choosing between various imaging modalities, including widefield, confocal, lightsheet, and structured illumination microscopy. Finally, we discuss the available tools and approaches, including machine learning, for quantitative image analysis tasks, such as colocalization, segmentation, object tracking, and lineage tracing. Hopefully, this review will inspire worm researchers who have not yet imaged their worms to begin, and push those who are imaging to go faster, finer, and longer.
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Affiliation(s)
- Pavak Shah
- Department of Molecular, Cell, and Developmental Biology, University of California Los Angeles, Los Angeles 90095, USA
| | - Zhirong Bao
- Developmental Biology Program, Sloan Kettering Institute, New York, New York 10065, USA
| | - Ronen Zaidel-Bar
- Department of Cell and Developmental Biology, Faculty of Medicine, Tel Aviv University, Tel Aviv 6997801, Israel
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39
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Hajiabadi H, Mamontova I, Prizak R, Pancholi A, Koziolek A, Hilbert L. Deep-learning microscopy image reconstruction with quality control reveals second-scale rearrangements in RNA polymerase II clusters. PNAS NEXUS 2022; 1:pgac065. [PMID: 36741438 PMCID: PMC9896941 DOI: 10.1093/pnasnexus/pgac065] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/20/2022] [Accepted: 05/17/2022] [Indexed: 02/07/2023]
Abstract
Fluorescence microscopy, a central tool of biological research, is subject to inherent trade-offs in experiment design. For instance, image acquisition speed can only be increased in exchange for a lowered signal quality, or for an increased rate of photo-damage to the specimen. Computational denoising can recover some loss of signal, extending the trade-off margin for high-speed imaging. Recently proposed denoising on the basis of neural networks shows exceptional performance but raises concerns of errors typical of neural networks. Here, we present a work-flow that supports an empirically optimized reduction of exposure times, as well as per-image quality control to exclude images with reconstruction errors. We implement this work-flow on the basis of the denoising tool Noise2Void and assess the molecular state and 3D shape of RNA polymerase II (Pol II) clusters in live zebrafish embryos. Image acquisition speed could be tripled, achieving 2-s time resolution and 350-nm lateral image resolution. The obtained data reveal stereotyped events of approximately 10 s duration: initially, the molecular mark for recruited Pol II increases, then the mark for active Pol II increases, and finally Pol II clusters take on a stretched and unfolded shape. An independent analysis based on fixed sample images reproduces this sequence of events, and suggests that they are related to the transient association of genes with Pol II clusters. Our work-flow consists of procedures that can be implemented on commercial fluorescence microscopes without any hardware or software modification, and should, therefore, be transferable to many other applications.
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Affiliation(s)
| | | | - Roshan Prizak
- Institute of Biological and Chemical Systems, Department of Biological Information Processing, Karlsruhe Institute of Technology, 76344, Eggenstein-Leopoldshafen, Germany
| | - Agnieszka Pancholi
- Institute of Biological and Chemical Systems, Department of Biological Information Processing, Karlsruhe Institute of Technology, 76344, Eggenstein-Leopoldshafen, Germany
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40
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Wang J, Zhang S, Lu H, Xu H. Differential regulation of alternative promoters emerges from unified kinetics of enhancer-promoter interaction. Nat Commun 2022; 13:2714. [PMID: 35581264 PMCID: PMC9114328 DOI: 10.1038/s41467-022-30315-6] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2021] [Accepted: 04/25/2022] [Indexed: 11/25/2022] Open
Abstract
Many eukaryotic genes contain alternative promoters with distinct expression patterns. How these promoters are differentially regulated remains elusive. Here, we apply single-molecule imaging to quantify the transcriptional regulation of two alternative promoters (P1 and P2) of the Bicoid (Bcd) target gene hunchback in syncytial blastoderm Drosophila embryos. Contrary to the previous notion that Bcd only activates P2, we find that Bcd activates both promoters via the same two enhancers. P1 activation is less frequent and requires binding of more Bcd molecules than P2 activation. Using a theoretical model to relate promoter activity to enhancer states, we show that the two promoters follow common transcription kinetics driven by sequential Bcd binding at the two enhancers. Bcd binding at either enhancer primarily activates P2, while P1 activation relies more on Bcd binding at both enhancers. These results provide a quantitative framework for understanding the kinetic mechanisms of complex eukaryotic gene regulation. Alternative promoters differ in their expression patterns, whose mechanisms are not well understood. Here the authors show that alternative promoters of a Drosophila embryonic gene hunchback are regulated by different action modes of two enhancers.
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Affiliation(s)
- Jingyao Wang
- School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, 200240, Shanghai, China.,Institute of Natural Sciences, Shanghai Jiao Tong University, 200240, Shanghai, China
| | - Shihe Zhang
- Institute of Natural Sciences, Shanghai Jiao Tong University, 200240, Shanghai, China. .,School of Physics and Astronomy, Shanghai Jiao Tong University, 200240, Shanghai, China.
| | - Hongfang Lu
- School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, 200240, Shanghai, China.,Institute of Natural Sciences, Shanghai Jiao Tong University, 200240, Shanghai, China
| | - Heng Xu
- Institute of Natural Sciences, Shanghai Jiao Tong University, 200240, Shanghai, China. .,School of Physics and Astronomy, Shanghai Jiao Tong University, 200240, Shanghai, China.
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41
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de Jonge WJ, Patel HP, Meeussen JVW, Lenstra TL. Following the tracks: how transcription factor binding dynamics control transcription. Biophys J 2022; 121:1583-1592. [PMID: 35337845 PMCID: PMC9117886 DOI: 10.1016/j.bpj.2022.03.026] [Citation(s) in RCA: 16] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2022] [Revised: 02/28/2022] [Accepted: 03/21/2022] [Indexed: 11/29/2022] Open
Abstract
Transcription, the process of copying genetic information from DNA to messenger RNA, is regulated by sequence-specific DNA binding proteins known as transcription factors (TFs). Recent advances in single-molecule tracking (SMT) technologies have enabled visualization of individual TF molecules as they diffuse and interact with the DNA in the context of living cells. These SMT studies have uncovered multiple populations of DNA binding events characterized by their distinctive DNA residence times. In this perspective, we review recent insights into how these residence times relate to specific and non-specific DNA binding, as well as the contribution of TF domains on the DNA binding dynamics. We discuss different models that aim to link transient DNA binding by TFs to bursts of transcription and present an outlook for how future advances in microscopy development may broaden our understanding of the dynamics of the molecular steps that underlie transcription activation.
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Affiliation(s)
- Wim J de Jonge
- Division of Gene Regulation, The Netherlands Cancer Institute, Oncode Institute, 1066CX Amsterdam, the Netherlands
| | - Heta P Patel
- Division of Gene Regulation, The Netherlands Cancer Institute, Oncode Institute, 1066CX Amsterdam, the Netherlands
| | - Joseph V W Meeussen
- Division of Gene Regulation, The Netherlands Cancer Institute, Oncode Institute, 1066CX Amsterdam, the Netherlands
| | - Tineke L Lenstra
- Division of Gene Regulation, The Netherlands Cancer Institute, Oncode Institute, 1066CX Amsterdam, the Netherlands.
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42
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Uchino S, Ito Y, Sato Y, Handa T, Ohkawa Y, Tokunaga M, Kimura H. Live imaging of transcription sites using an elongating RNA polymerase II-specific probe. J Cell Biol 2022; 221:212888. [PMID: 34854870 PMCID: PMC8647360 DOI: 10.1083/jcb.202104134] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2021] [Revised: 10/12/2021] [Accepted: 11/10/2021] [Indexed: 12/15/2022] Open
Abstract
In eukaryotic nuclei, most genes are transcribed by RNA polymerase II (RNAP2), whose regulation is a key to understanding the genome and cell function. RNAP2 has a long heptapeptide repeat (Tyr1-Ser2-Pro3-Thr4-Ser5-Pro6-Ser7), and Ser2 is phosphorylated on an elongation form. To detect RNAP2 Ser2 phosphorylation (RNAP2 Ser2ph) in living cells, we developed a genetically encoded modification-specific intracellular antibody (mintbody) probe. The RNAP2 Ser2ph-mintbody exhibited numerous foci, possibly representing transcription “factories,” and foci were diminished during mitosis and in a Ser2 kinase inhibitor. An in vitro binding assay using phosphopeptides confirmed the mintbody’s specificity. RNAP2 Ser2ph-mintbody foci were colocalized with proteins associated with elongating RNAP2 compared with factors involved in the initiation. These results support the view that mintbody localization represents the sites of RNAP2 Ser2ph in living cells. RNAP2 Ser2ph-mintbody foci showed constrained diffusional motion like chromatin, but they were more mobile than DNA replication domains and p300-enriched foci, suggesting that the elongating RNAP2 complexes are separated from more confined chromatin domains.
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Affiliation(s)
- Satoshi Uchino
- School of Life Science and Technology, Tokyo Institute of Technology, Yokohama, Japan
| | - Yuma Ito
- School of Life Science and Technology, Tokyo Institute of Technology, Yokohama, Japan
| | - Yuko Sato
- School of Life Science and Technology, Tokyo Institute of Technology, Yokohama, Japan.,Cell Biology Center, Institute of Innovative Research, Tokyo Institute of Technology, Yokohama, Japan
| | - Tetsuya Handa
- Cell Biology Center, Institute of Innovative Research, Tokyo Institute of Technology, Yokohama, Japan
| | - Yasuyuki Ohkawa
- Division of Transcriptomics, Medical Institute of Bioregulation, Kyushu University, Fukuoka, Japan
| | - Makio Tokunaga
- School of Life Science and Technology, Tokyo Institute of Technology, Yokohama, Japan
| | - Hiroshi Kimura
- School of Life Science and Technology, Tokyo Institute of Technology, Yokohama, Japan.,Cell Biology Center, Institute of Innovative Research, Tokyo Institute of Technology, Yokohama, Japan
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43
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Direct-laser writing for subnanometer focusing and single-molecule imaging. Nat Commun 2022; 13:647. [PMID: 35115532 PMCID: PMC8813935 DOI: 10.1038/s41467-022-28219-6] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2020] [Accepted: 12/07/2021] [Indexed: 11/22/2022] Open
Abstract
Two-photon direct laser writing is an additive fabrication process that utilizes two-photon absorption of tightly focused femtosecond laser pulses to implement spatially controlled polymerization of a liquid-phase photoresist. Two-photon direct laser writing is capable of nanofabricating arbitrary three-dimensional structures with nanometer accuracy. Here, we explore direct laser writing for high-resolution optical microscopy by fabricating unique 3D optical fiducials for single-molecule tracking and 3D single-molecule localization microscopy. By having control over the position and three-dimensional architecture of the fiducials, we improve axial discrimination and demonstrate isotropic subnanometer 3D focusing (<0.8 nm) over tens of micrometers using a standard inverted microscope. We perform 3D single-molecule acquisitions over cellular volumes, unsupervised data acquisition and live-cell single-particle tracking with nanometer accuracy. Focus-locking improves localization precision in single-molecule microscopy, but fiducials are often deposited at random and provide limited 3D compensation. Here, the authors fabricate 3D optical fiducials with nanometer accuracy by two-photon direct laser writing, and demonstrate isotropic 3D focus locking.
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44
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Kimura H, Sato Y. Imaging transcription elongation dynamics by new technologies unveils the organization of initiation and elongation in transcription factories. Curr Opin Cell Biol 2022; 74:71-79. [DOI: 10.1016/j.ceb.2022.01.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2021] [Revised: 01/05/2022] [Accepted: 01/10/2022] [Indexed: 11/27/2022]
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45
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Johanson TM, Keenan CR, Allan RS. Shedding Structured Light on Molecular Immunity: The Past, Present and Future of Immune Cell Super Resolution Microscopy. Front Immunol 2021; 12:754200. [PMID: 34975842 PMCID: PMC8715013 DOI: 10.3389/fimmu.2021.754200] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2021] [Accepted: 11/23/2021] [Indexed: 12/16/2022] Open
Abstract
In the two decades since the invention of laser-based super resolution microscopy this family of technologies has revolutionised the way life is viewed and understood. Its unparalleled resolution, speed, and accessibility makes super resolution imaging particularly useful in examining the highly complex and dynamic immune system. Here we introduce the super resolution technologies and studies that have already fundamentally changed our understanding of a number of central immunological processes and highlight other immunological puzzles only addressable in super resolution.
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Affiliation(s)
- Timothy M. Johanson
- The Walter and Eliza Hall Institute of Medical Research, Parkville, VIC, Australia
- Department of Medical Biology, The University of Melbourne, Parkville, VIC, Australia
| | - Christine R. Keenan
- The Walter and Eliza Hall Institute of Medical Research, Parkville, VIC, Australia
- Department of Medical Biology, The University of Melbourne, Parkville, VIC, Australia
| | - Rhys S. Allan
- The Walter and Eliza Hall Institute of Medical Research, Parkville, VIC, Australia
- Department of Medical Biology, The University of Melbourne, Parkville, VIC, Australia
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46
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Wang Z, Deng W. Dynamic transcription regulation at the single-molecule level. Dev Biol 2021; 482:67-81. [PMID: 34896367 DOI: 10.1016/j.ydbio.2021.11.004] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2021] [Revised: 11/14/2021] [Accepted: 11/15/2021] [Indexed: 02/07/2023]
Abstract
Cell fate changes during development, differentiation, and reprogramming are largely controlled at the transcription level. The DNA-binding transcription factors (TFs) often act in a combinatorial fashion to alter chromatin states and drive cell type-specific gene expression. Recent advances in fluorescent microscopy technologies have enabled direct visualization of biomolecules involved in the process of transcription and its regulatory events at the single-molecule level in living cells. Remarkably, imaging and tracking individual TF molecules at high temporal and spatial resolution revealed that they are highly dynamic in searching and binding cognate targets, rather than static and binding constantly. In combination with investigation using techniques from biochemistry, structure biology, genetics, and genomics, a more well-rounded view of transcription regulation is emerging. In this review, we briefly cover the technical aspects of live-cell single-molecule imaging and focus on the biological relevance and interpretation of the single-molecule dynamic features of transcription regulatory events observed in the native chromatin environment of living eukaryotic cells. We also discuss how these dynamic features might shed light on mechanistic understanding of transcription regulation.
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Affiliation(s)
- Zuhui Wang
- Biomedical Pioneering Innovation Center (BIOPIC), Peking University, Beijing, 100871, China; Academy for Advanced Interdisciplinary Studies, Peking University, Beijing, 100871, China
| | - Wulan Deng
- Biomedical Pioneering Innovation Center (BIOPIC), Peking University, Beijing, 100871, China; Academy for Advanced Interdisciplinary Studies, Peking University, Beijing, 100871, China; Beijing Advanced Innovation Center for Genomics (ICG), Peking University, Beijing, 100871, China; Peking-Tsinghua Center for Life Sciences (CLS), Peking University, Beijing, 100871, China; School of Life Sciences, Peking University, Beijing, 100871, China.
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Biswas J, Li W, Singer RH, Coleman RA. Imaging Organization of RNA Processing within the Nucleus. Cold Spring Harb Perspect Biol 2021; 13:a039453. [PMID: 34127450 PMCID: PMC8635003 DOI: 10.1101/cshperspect.a039453] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Within the nucleus, messenger RNA is generated and processed in a highly organized and regulated manner. Messenger RNA processing begins during transcription initiation and continues until the RNA is translated and degraded. Processes such as 5' capping, alternative splicing, and 3' end processing have been studied extensively with biochemical methods and more recently with single-molecule imaging approaches. In this review, we highlight how imaging has helped understand the highly dynamic process of RNA processing. We conclude with open questions and new technological developments that may further our understanding of RNA processing.
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Affiliation(s)
- Jeetayu Biswas
- Department of Anatomy and Structural Biology, Albert Einstein College of Medicine, Bronx, New York 10461, USA
| | - Weihan Li
- Department of Anatomy and Structural Biology, Albert Einstein College of Medicine, Bronx, New York 10461, USA
| | - Robert H Singer
- Department of Anatomy and Structural Biology, Albert Einstein College of Medicine, Bronx, New York 10461, USA
| | - Robert A Coleman
- Department of Anatomy and Structural Biology, Albert Einstein College of Medicine, Bronx, New York 10461, USA
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48
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Huang SK, Whitney PH, Dutta S, Shvartsman SY, Rushlow CA. Spatial organization of transcribing loci during early genome activation in Drosophila. Curr Biol 2021; 31:5102-5110.e5. [PMID: 34614388 DOI: 10.1016/j.cub.2021.09.027] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2021] [Revised: 07/19/2021] [Accepted: 09/09/2021] [Indexed: 10/20/2022]
Abstract
The early Drosophila embryo provides unique experimental advantages for addressing fundamental questions of gene regulation at multiple levels of organization, from individual gene loci to the entire genome. Using 1.5-h-old Drosophila embryos undergoing the first wave of genome activation,1 we detected ∼110 discrete "speckles" of RNA polymerase II (RNA Pol II) per nucleus, two of which were larger and localized to the histone locus bodies (HLBs).2,3 In the absence of the primary driver of Drosophila genome activation, the pioneer factor Zelda (Zld),1,4,5 70% fewer speckles were present; however, the HLBs tended to be larger than wild-type (WT) HLBs, indicating that RNA Pol II accumulates at the HLBs in the absence of robust early-gene transcription. We observed a uniform distribution of distances between active genes in the nuclei of both WT and zld mutant embryos, indicating that early co-regulated genes do not cluster into nuclear sub-domains. However, in instances whereby transcribing genes did come into close 3D proximity (within 400 nm), they were found to have distinct RNA Pol II speckles. In contrast to the emerging model whereby active genes are clustered to facilitate co-regulation and sharing of transcriptional resources, our data support an "individualist" model of gene control at early genome activation in Drosophila. This model is in contrast to a "collectivist" model, where active genes are spatially clustered and share transcriptional resources, motivating rigorous tests of both models in other experimental systems.
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Affiliation(s)
- Shao-Kuei Huang
- Department of Biology, New York University, New York, NY 10003, USA
| | - Peter H Whitney
- Department of Biology, New York University, New York, NY 10003, USA
| | - Sayantan Dutta
- The Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton, NJ 08544, USA; Department of Chemical and Biological Engineering, Princeton University, Princeton, NJ 08544, USA
| | - Stanislav Y Shvartsman
- The Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton, NJ 08544, USA; Department of Chemical and Biological Engineering, Princeton University, Princeton, NJ 08544, USA; Center for Computational Biology, Flatiron Research Institute, New York, NY 10010, USA
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Abstract
To predict transcription, one needs a mechanistic understanding of how the numerous required transcription factors (TFs) explore the nuclear space to find their target genes, assemble, cooperate, and compete with one another. Advances in fluorescence microscopy have made it possible to visualize real-time TF dynamics in living cells, leading to two intriguing observations: first, most TFs contact chromatin only transiently; and second, TFs can assemble into clusters through their intrinsically disordered regions. These findings suggest that highly dynamic events and spatially structured nuclear microenvironments might play key roles in transcription regulation that are not yet fully understood. The emerging model is that while some promoters directly convert TF-binding events into on/off cycles of transcription, many others apply complex regulatory layers that ultimately lead to diverse phenotypic outputs. Cracking this kinetic code is an ongoing and challenging task that is made possible by combining innovative imaging approaches with biophysical models.
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Affiliation(s)
- Feiyue Lu
- Institute for Systems Genetics and Cell Biology Department, NYU School of Medicine, New York, New York 10016, USA
| | - Timothée Lionnet
- Institute for Systems Genetics and Cell Biology Department, NYU School of Medicine, New York, New York 10016, USA
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50
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Volumetric interferometric lattice light-sheet imaging. Nat Biotechnol 2021; 39:1385-1393. [PMID: 34635835 PMCID: PMC8595582 DOI: 10.1038/s41587-021-01042-y] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2019] [Accepted: 07/29/2021] [Indexed: 01/20/2023]
Abstract
Live-cell imaging with high spatiotemporal resolution and high detection sensitivity facilitates the study of the dynamics of cellular structure and function. However, extracting high-resolution 4D (3D space plus time) information from live cells remains challenging, because current methods are slow, require high peak excitation intensities or suffer from high out-of-focus background. Here we present 3D interferometric lattice light-sheet (3D-iLLS) imaging, a technique that requires low excitation light levels and provides high background suppression and substantially improved volumetric resolution by combining 4Pi interferometry with selective plane illumination. We demonstrate that 3D-iLLS has an axial resolution and single-particle localization precision of 100 nm (FWHM) and <10 nm (1σ), respectively. We illustrate the performance of 3D-iLLS in a range of systems: single messenger RNA molecules, nanoscale assemblies of transcription regulators in the nucleus, the microtubule cytoskeleton, and mitochondria organelles. The enhanced 4D resolution and increased signal-to-noise ratio (SNR) of 3D-iLLS will facilitate the analysis of biological processes at the sub-cellular level.
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