1
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Shin B, Chang SJ, MacNabb BW, Rothenberg EV. Transcriptional network dynamics in early T cell development. J Exp Med 2024; 221:e20230893. [PMID: 39167073 PMCID: PMC11338287 DOI: 10.1084/jem.20230893] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2024] [Revised: 06/07/2024] [Accepted: 07/10/2024] [Indexed: 08/23/2024] Open
Abstract
The rate at which cells enter the T cell pathway depends not only on the immigration of hematopoietic precursors into the strong Notch signaling environment of the thymus but also on the kinetics with which each individual precursor cell reaches T-lineage commitment once it arrives. Notch triggers a complex, multistep gene regulatory network in the cells in which the steps are stereotyped but the transition speeds between steps are variable. Progenitor-associated transcription factors delay T-lineage differentiation even while Notch-induced transcription factors within the same cells push differentiation forward. Progress depends on regulator cross-repression, on breaching chromatin barriers, and on shifting, competitive collaborations between stage-specific and stably expressed transcription factors, as reviewed here.
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Affiliation(s)
- Boyoung Shin
- Division of Biology and Biological Engineering California Institute of Technology , Pasadena, CA, USA
| | - Samantha J Chang
- Division of Biology and Biological Engineering California Institute of Technology , Pasadena, CA, USA
| | - Brendan W MacNabb
- Division of Biology and Biological Engineering California Institute of Technology , Pasadena, CA, USA
| | - Ellen V Rothenberg
- Division of Biology and Biological Engineering California Institute of Technology , Pasadena, CA, USA
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2
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Zhang Q, Cao W, Wang J, Yin Y, Sun R, Tian Z, Hu Y, Tan Y, Zhang BG. Transcriptional bursting dynamics in gene expression. Front Genet 2024; 15:1451461. [PMID: 39346775 PMCID: PMC11437526 DOI: 10.3389/fgene.2024.1451461] [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: 06/19/2024] [Accepted: 08/30/2024] [Indexed: 10/01/2024] Open
Abstract
Gene transcription is a stochastic process that occurs in all organisms. Transcriptional bursting, a critical molecular dynamics mechanism, creates significant heterogeneity in mRNA and protein levels. This heterogeneity drives cellular phenotypic diversity. Currently, the lack of a comprehensive quantitative model limits the research on transcriptional bursting. This review examines various gene expression models and compares their strengths and weaknesses to guide researchers in selecting the most suitable model for their research context. We also provide a detailed summary of the key metrics related to transcriptional bursting. We compared the temporal dynamics of transcriptional bursting across species and the molecular mechanisms influencing these bursts, and highlighted the spatiotemporal patterns of gene expression differences by utilizing metrics such as burst size and burst frequency. We summarized the strategies for modeling gene expression from both biostatistical and biochemical reaction network perspectives. Single-cell sequencing data and integrated multiomics approaches drive our exploration of cutting-edge trends in transcriptional bursting mechanisms. Moreover, we examined classical methods for parameter estimation that help capture dynamic parameters in gene expression data, assessing their merits and limitations to facilitate optimal parameter estimation. Our comprehensive summary and review of the current transcriptional burst dynamics theories provide deeper insights for promoting research on the nature of cell processes, cell fate determination, and cancer diagnosis.
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Affiliation(s)
- Qiuyu Zhang
- Research Center of Nonlinear Sciences, School of Mathematical & Physical Sciences, Wuhan Textile University, Wu Han, China
| | - Wenjie Cao
- School of Mathematics, Sun Yat-sen University, Guangzhou, China
| | - Jiaqi Wang
- Research Center of Nonlinear Sciences, School of Mathematical & Physical Sciences, Wuhan Textile University, Wu Han, China
| | - Yihao Yin
- Research Center of Nonlinear Sciences, School of Mathematical & Physical Sciences, Wuhan Textile University, Wu Han, China
| | - Rui Sun
- Research Center of Nonlinear Sciences, School of Mathematical & Physical Sciences, Wuhan Textile University, Wu Han, China
| | - Zunyi Tian
- Research Center of Nonlinear Sciences, School of Mathematical & Physical Sciences, Wuhan Textile University, Wu Han, China
| | - Yuhan Hu
- Research Center of Nonlinear Sciences, School of Mathematical & Physical Sciences, Wuhan Textile University, Wu Han, China
| | - Yalan Tan
- School of Bioengineering & Health, Wuhan Textile University, Wu Han, China
| | - Ben-Gong Zhang
- Research Center of Nonlinear Sciences, School of Mathematical & Physical Sciences, Wuhan Textile University, Wu Han, China
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3
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Chen PT, Levo M, Zoller B, Gregor T. Gene activity fully predicts transcriptional bursting dynamics. ARXIV 2024:arXiv:2304.08770v3. [PMID: 37131882 PMCID: PMC10153294] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
Transcription commonly occurs in bursts, with alternating productive (ON) and quiescent (OFF) periods, governing mRNA production rates. Yet, how transcription is regulated through bursting dynamics remains unresolved. Here, we conduct real-time measurements of endogenous transcriptional bursting with single-mRNA sensitivity. Leveraging the diverse transcriptional activities in early fly embryos, we uncover stringent relationships between bursting parameters. Specifically, we find that the durations of ON and OFF periods are linked. Regardless of the developmental stage or body-axis position, gene activity levels predict individual alleles' average ON and OFF periods. Lowly transcribing alleles predominantly modulate OFF periods (burst frequency), while highly transcribing alleles primarily tune ON periods (burst size). These relationships persist even under perturbations of cis-regulatory elements or trans-factors and account for bursting dynamics measured in other species. Our results suggest a novel mechanistic constraint governing bursting dynamics rather than a modular control of distinct parameters by distinct regulatory processes.
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Affiliation(s)
- Po-Ta Chen
- Joseph Henry Laboratories of Physics & Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton, NJ 08544, USA
| | - Michal Levo
- Joseph Henry Laboratories of Physics & Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton, NJ 08544, USA
- Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY, USA
| | - Benjamin Zoller
- Joseph Henry Laboratories of Physics & Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton, NJ 08544, USA
- Department of Stem Cell and Developmental Biology, CNRS UMR3738 Paris Cité, Institut Pasteur, 25 rue du Docteur Roux, 75015 Paris, France
| | - Thomas Gregor
- Joseph Henry Laboratories of Physics & Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton, NJ 08544, USA
- Department of Stem Cell and Developmental Biology, CNRS UMR3738 Paris Cité, Institut Pasteur, 25 rue du Docteur Roux, 75015 Paris, France
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4
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Berrocal A, Lammers NC, Garcia HG, Eisen MB. Unified bursting strategies in ectopic and endogenous even-skipped expression patterns. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2023.02.09.527927. [PMID: 36798351 PMCID: PMC9934701 DOI: 10.1101/2023.02.09.527927] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 02/12/2023]
Abstract
Transcription often occurs in bursts as gene promoters switch stochastically between active and inactive states. Enhancers can dictate transcriptional activity in animal development through the modulation of burst frequency, duration, or amplitude. Previous studies observed that different enhancers can achieve a wide range of transcriptional outputs through the same strategies of bursting control. For example, despite responding to different transcription factors, all even-skipped enhancers increase transcription by upregulating burst frequency and amplitude while burst duration remains largely constant. These shared bursting strategies suggest that a unified molecular mechanism constraints how enhancers modulate transcriptional output. Alternatively, different enhancers could have converged on the same bursting control strategy because of natural selection favoring one of these particular strategies. To distinguish between these two scenarios, we compared transcriptional bursting between endogenous and ectopic gene expression patterns. Because enhancers act under different regulatory inputs in ectopic patterns, dissimilar bursting control strategies between endogenous and ectopic patterns would suggest that enhancers adapted their bursting strategies to their trans-regulatory environment. Here, we generated ectopic even-skipped transcription patterns in fruit fly embryos and discovered that bursting strategies remain consistent in endogenous and ectopic even-skipped expression. These results provide evidence for a unified molecular mechanism shaping even-skipped bursting strategies and serve as a starting point to uncover the realm of strategies employed by other enhancers.
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Affiliation(s)
- Augusto Berrocal
- Department of Molecular & Cell Biology, University of California at Berkeley, Berkeley, CA, United States
- Current Address: Department of Pharmaceutical Chemistry, University of California at San Francisco, San Francisco, CA, United States
| | - Nicholas C Lammers
- Biophysics Graduate Group, University of California at Berkeley, Berkeley, CA, United States
- Current Address: Department of Genome Sciences, University of Washington, Seattle, WA, United States
| | - Hernan G Garcia
- Department of Molecular & Cell Biology, University of California at Berkeley, Berkeley, CA, United States
- Biophysics Graduate Group, University of California at Berkeley, Berkeley, CA, United States
- Department of Physics, University of California at Berkeley, Berkeley, CA, United States
- California Institute for Quantitative Biosciences (QB3), University of California at Berkeley, Berkeley, CA, United States
- Chan Zuckerberg Biohub–San Francisco, San Francisco, California, CA, United States
| | - Michael B Eisen
- Department of Molecular & Cell Biology, University of California at Berkeley, Berkeley, CA, United States
- Biophysics Graduate Group, University of California at Berkeley, Berkeley, CA, United States
- California Institute for Quantitative Biosciences (QB3), University of California at Berkeley, Berkeley, CA, United States
- Howard Hughes Medical Institute, University of California at Berkeley, Berkeley, CA, United States
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5
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Li XC, Gandara L, Ekelöf M, Richter K, Alexandrov T, Crocker J. Rapid response of fly populations to gene dosage across development and generations. Nat Commun 2024; 15:4551. [PMID: 38811562 PMCID: PMC11137061 DOI: 10.1038/s41467-024-48960-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2023] [Accepted: 05/17/2024] [Indexed: 05/31/2024] Open
Abstract
Although the effects of genetic and environmental perturbations on multicellular organisms are rarely restricted to single phenotypic layers, our current understanding of how developmental programs react to these challenges remains limited. Here, we have examined the phenotypic consequences of disturbing the bicoid regulatory network in early Drosophila embryos. We generated flies with two extra copies of bicoid, which causes a posterior shift of the network's regulatory outputs and a decrease in fitness. We subjected these flies to EMS mutagenesis, followed by experimental evolution. After only 8-15 generations, experimental populations have normalized patterns of gene expression and increased survival. Using a phenomics approach, we find that populations were normalized through rapid increases in embryo size driven by maternal changes in metabolism and ovariole development. We extend our results to additional populations of flies, demonstrating predictability. Together, our results necessitate a broader view of regulatory network evolution at the systems level.
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Affiliation(s)
- Xueying C Li
- European Molecular Biology Laboratory (EMBL), Heidelberg, Germany.
- College of Life Sciences, Beijing Normal University, Beijing, China.
| | - Lautaro Gandara
- European Molecular Biology Laboratory (EMBL), Heidelberg, Germany
| | - Måns Ekelöf
- European Molecular Biology Laboratory (EMBL), Heidelberg, Germany
| | - Kerstin Richter
- European Molecular Biology Laboratory (EMBL), Heidelberg, Germany
| | - Theodore Alexandrov
- European Molecular Biology Laboratory (EMBL), Heidelberg, Germany
- Molecular Medicine Partnership Unit between EMBL and Heidelberg University, Heidelberg, Germany
- BioInnovation Institute, Copenhagen, Denmark
| | - Justin Crocker
- European Molecular Biology Laboratory (EMBL), Heidelberg, Germany.
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6
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Breimann L, Bahry E, Zouinkhi M, Kolyvanov K, Street LA, Preibisch S, Ercan S. Analysis of developmental gene expression using smFISH and in silico staging of C. elegans embryos. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.05.15.594414. [PMID: 38798598 PMCID: PMC11118362 DOI: 10.1101/2024.05.15.594414] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2024]
Abstract
Regulation of transcription during embryogenesis is key to development and differentiation. To study transcript expression throughout Caenorhabditis elegans embryogenesis at single-molecule resolution, we developed a high-throughput single-molecule fluorescence in situ hybridization (smFISH) method that relies on computational methods to developmentally stage embryos and quantify individual mRNA molecules in single embryos. We applied our system to sdc-2, a zygotically transcribed gene essential for hermaphrodite development and dosage compensation. We found that sdc-2 is rapidly activated during early embryogenesis by increasing both the number of mRNAs produced per transcription site and the frequency of sites engaged in transcription. Knockdown of sdc-2 and dpy-27, a subunit of the dosage compensation complex (DCC), increased the number of active transcription sites for the X chromosomal gene dpy-23 but not the autosomal gene mdh-1, suggesting that the DCC reduces the frequency of dpy-23 transcription. The temporal resolution from in silico staging of embryos showed that the deletion of a single DCC recruitment element near the dpy-23 gene causes higher dpy-23 mRNA expression after the start of dosage compensation, which could not be resolved using mRNAseq from mixed-stage embryos. In summary, we have established a computational approach to quantify temporal regulation of transcription throughout C. elegans embryogenesis and demonstrated its potential to provide new insights into developmental gene regulation.
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Affiliation(s)
- Laura Breimann
- Berlin Institute for Medical Systems Biology, Max Delbrück Center for Molecular Medicine, Berlin, Germany
- Department of Biology, Center for Genomics and Systems Biology, New York University, New York, NY, USA
- Department of Genetics, Harvard Medical School, Boston, MA, USA
| | - Ella Bahry
- Berlin Institute for Medical Systems Biology, Max Delbrück Center for Molecular Medicine, Berlin, Germany
- Helmholtz Imaging, Max-Delbrück-Center for Molecular Medicine (MDC), Berlin, Germany
| | - Marwan Zouinkhi
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA, USA
| | - Klim Kolyvanov
- Berlin Institute for Medical Systems Biology, Max Delbrück Center for Molecular Medicine, Berlin, Germany
| | - Lena Annika Street
- Department of Biology, Center for Genomics and Systems Biology, New York University, New York, NY, USA
| | - Stephan Preibisch
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA, USA
| | - Sevinç Ercan
- Department of Biology, Center for Genomics and Systems Biology, New York University, New York, NY, USA
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7
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Szavits-Nossan J, Grima R. Solving stochastic gene-expression models using queueing theory: A tutorial review. Biophys J 2024; 123:1034-1057. [PMID: 38594901 PMCID: PMC11079947 DOI: 10.1016/j.bpj.2024.04.004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2023] [Revised: 02/12/2024] [Accepted: 04/02/2024] [Indexed: 04/11/2024] Open
Abstract
Stochastic models of gene expression are typically formulated using the chemical master equation, which can be solved exactly or approximately using a repertoire of analytical methods. Here, we provide a tutorial review of an alternative approach based on queueing theory that has rarely been used in the literature of gene expression. We discuss the interpretation of six types of infinite-server queues from the angle of stochastic single-cell biology and provide analytical expressions for the stationary and nonstationary distributions and/or moments of mRNA/protein numbers and bounds on the Fano factor. This approach may enable the solution of complex models that have hitherto evaded analytical solution.
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Affiliation(s)
- Juraj Szavits-Nossan
- School of Biological Sciences, University of Edinburgh, Edinburgh, United Kingdom
| | - Ramon Grima
- School of Biological Sciences, University of Edinburgh, Edinburgh, United Kingdom.
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8
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Lee U, Li C, Langer CB, Svetec N, Zhao L. Comparative Single Cell Analysis of Transcriptional Bursting Reveals the Role of Genome Organization on de novo Transcript Origination. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.04.29.591771. [PMID: 38746255 PMCID: PMC11092510 DOI: 10.1101/2024.04.29.591771] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/16/2024]
Abstract
Spermatogenesis is a key developmental process underlying the origination of newly evolved genes. However, rapid cell type-specific transcriptomic divergence of the Drosophila germline has posed a significant technical barrier for comparative single-cell RNA-sequencing (scRNA-Seq) studies. By quantifying a surprisingly strong correlation between species-and cell type-specific divergence in three closely related Drosophila species, we apply a simple statistical procedure to identify a core set of 198 genes that are highly predictive of cell type identity while remaining robust to species-specific differences that span over 25-30 million years of evolution. We then utilize cell type classifications based on the 198-gene set to show how transcriptional divergence in cell type increases throughout spermatogenic developmental time, contrasting with traditional hourglass models of whole-organism development. With these cross-species cell type classifications, we then investigate the influence of genome organization on the molecular evolution of spermatogenesis vis-a-vis transcriptional bursting. We first demonstrate how mechanistic control of pre-meiotic transcription is achieved by altering transcriptional burst size while post-meiotic control is exerted via altered bursting frequency. We then report how global differences in autosomal vs. X chromosomal transcription likely arise in a developmental stage preceding full testis organogenesis by showing evolutionarily conserved decreases in X-linked transcription bursting kinetics in all examined somatic and germline cell types. Finally, we provide evidence supporting the cultivator model of de novo gene origination by demonstrating how the appearance of newly evolved testis-specific transcripts potentially provides short-range regulation of the transcriptional bursting properties of neighboring genes during key stages of spermatogenesis.
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9
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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: 4] [Impact Index Per Article: 4.0] [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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10
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Rekaik H, Duboule D. A CTCF-dependent mechanism underlies the Hox timer: relation to a segmented body plan. Curr Opin Genet Dev 2024; 85:102160. [PMID: 38377879 DOI: 10.1016/j.gde.2024.102160] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2024] [Revised: 01/27/2024] [Accepted: 01/28/2024] [Indexed: 02/22/2024]
Abstract
During gastrulation, Hox genes are activated in a time-sequence that follows the order of the genes along their clusters. This property, which is observed in all animals that develop following a progressive rostral-to-caudal morphogenesis, is associated with changes in the chromatin structure and epigenetic profiles of Hox clusters, suggesting a process at least partly based on sequential gene accessibility. Here, we discuss recent work on this issue, as well as a possible mechanism based on the surprising conservation in both the distribution and orientation of CTCF sites inside vertebrate Hox clusters.
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Affiliation(s)
- Hocine Rekaik
- School of Life Sciences, Ecole Polytechnique Fédérale de Lausanne (EPFL), 1015 Lausanne, Switzerland; Center for Interdisciplinary Research in Biology (CIRB), Collège de France, CNRS, INSERM, Université PSL, Paris, France. https://twitter.com/@hocine_Rekaik
| | - Denis Duboule
- School of Life Sciences, Ecole Polytechnique Fédérale de Lausanne (EPFL), 1015 Lausanne, Switzerland; Center for Interdisciplinary Research in Biology (CIRB), Collège de France, CNRS, INSERM, Université PSL, Paris, France.
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11
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Eck E, Moretti B, Schlomann BH, Bragantini J, Lange M, Zhao X, VijayKumar S, Valentin G, Loureiro C, Soroldoni D, Royer LA, Oates AC, Garcia HG. Single-cell transcriptional dynamics in a living vertebrate. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.01.03.574108. [PMID: 38260569 PMCID: PMC10802376 DOI: 10.1101/2024.01.03.574108] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/24/2024]
Abstract
The ability to quantify transcriptional dynamics in individual cells via live imaging has revolutionized our understanding of gene regulation. However, such measurements are lacking in the context of vertebrate embryos. We addressed this deficit by applying MS2-MCP mRNA labeling to the quantification of transcription in zebrafish, a model vertebrate. We developed a platform of transgenic organisms, light sheet fluorescence microscopy, and optimized image analysis that enables visualization and quantification of MS2 reporters. We used these tools to obtain the first single-cell, real-time measurements of transcriptional dynamics of the segmentation clock. Our measurements challenge the traditional view of smooth clock oscillations and instead suggest a model of discrete transcriptional bursts that are organized in space and time. Together, these results highlight how measuring single-cell transcriptional activity can reveal unexpected features of gene regulation and how this data can fuel the dialogue between theory and experiment.
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Affiliation(s)
- Elizabeth Eck
- Biophysics Graduate Group, University of California at Berkeley, Berkeley, USA
| | - Bruno Moretti
- Department of Molecular and Cell Biology, University of California, Berkeley, CA, USA
- Chan Zuckerberg Biohub – San Francisco, San Francisco, CA, USA
| | - Brandon H. Schlomann
- Department of Molecular and Cell Biology, University of California, Berkeley, CA, USA
| | | | - Merlin Lange
- Chan Zuckerberg Biohub – San Francisco, San Francisco, CA, USA
| | - Xiang Zhao
- Chan Zuckerberg Biohub – San Francisco, San Francisco, CA, USA
| | | | | | | | | | - Loïc A. Royer
- Chan Zuckerberg Biohub – San Francisco, San Francisco, CA, USA
| | - Andrew C. Oates
- Institute of Bioengineering, EPFL; Lausanne, CH
- Department of Cell and Developmental Biology, UCL; London, UK
- The Francis Crick Institute; London, UK
| | - Hernan G. Garcia
- Department of Molecular and Cell Biology, University of California, Berkeley, CA, USA
- Department of Physics, University of California, Berkeley, CA, USA
- Institute for Quantitative Biosciences-QB3, University of California, Berkeley, CA, USA
- Chan Zuckerberg Biohub – San Francisco, San Francisco, CA, USA
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12
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Nikolić M, Antonetti V, Liu F, Muhaxheri G, Petkova MD, Scheeler M, Smith EM, Bialek W, Gregor T. Scale invariance in early embryonic development. ARXIV 2023:arXiv:2312.17684v1. [PMID: 38235065 PMCID: PMC10793483] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Subscribe] [Scholar Register] [Indexed: 01/19/2024]
Abstract
The body plan of the fruit fly is determined by the expression of just a handful of genes. We show that the spatial patterns of expression for several of these genes scale precisely with the size of the embryo. Concretely, discrete positional markers such as the peaks in striped patterns have absolute positions along the anterior-posterior axis that are proportional to embryo length, with better than 1% accuracy. Further, the information (in bits) that graded patterns of expression provide about position can be decomposed into information about fractional or scaled position and information about absolute position or embryo length; all of the available information is about scaled position, again with ~ 1% accuracy. These observations suggest that the underlying genetic network exhibits scale invariance in a deeper mathematical sense. Taking this mathematical statement seriously requires that the network dynamics have a zero mode, which connects to many other observations on this system.
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Affiliation(s)
- Miloš Nikolić
- Joseph Henry Laboratories of Physics and Princeton University, Princeton NJ 08544 USA
- Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton NJ 08544 USA
| | - Victoria Antonetti
- Joseph Henry Laboratories of Physics and Princeton University, Princeton NJ 08544 USA
- Center for Quantitative Biology and School of Physics, Peking University, Beijing 100871 China
| | - Feng Liu
- Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton NJ 08544 USA
- Center for Quantitative Biology and School of Physics, Peking University, Beijing 100871 China
| | - Gentian Muhaxheri
- Joseph Henry Laboratories of Physics and Princeton University, Princeton NJ 08544 USA
- Department of Physics, Lehman College, City University of New York, Bronx, NY 10468 USA
| | | | - Martin Scheeler
- Joseph Henry Laboratories of Physics and Princeton University, Princeton NJ 08544 USA
| | - Eric M Smith
- Joseph Henry Laboratories of Physics and Princeton University, Princeton NJ 08544 USA
| | - William Bialek
- Joseph Henry Laboratories of Physics and Princeton University, Princeton NJ 08544 USA
- Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton NJ 08544 USA
- Initiative for the Theoretical Sciences, The Graduate Center, City University of New York, 365 Fifth Ave., New York, NY 10016 USA
| | - Thomas Gregor
- Joseph Henry Laboratories of Physics and Princeton University, Princeton NJ 08544 USA
- Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton NJ 08544 USA
- Department of Developmental and Stem Cell Biology UMR3738, Institut Pasteur, 75015 Paris, France
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13
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Syed S, Duan Y, Lim B. Modulation of protein-DNA binding reveals mechanisms of spatiotemporal gene control in early Drosophila embryos. eLife 2023; 12:e85997. [PMID: 37934571 PMCID: PMC10629816 DOI: 10.7554/elife.85997] [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: 01/06/2023] [Accepted: 10/19/2023] [Indexed: 11/08/2023] Open
Abstract
It is well known that enhancers regulate the spatiotemporal expression of their target genes by recruiting transcription factors (TFs) to the cognate binding sites in the region. However, the role of multiple binding sites for the same TFs and their specific spatial arrangement in determining the overall competency of the enhancer has yet to be fully understood. In this study, we utilized the MS2-MCP live imaging technique to quantitatively analyze the regulatory logic of the snail distal enhancer in early Drosophila embryos. Through systematic modulation of Dorsal and Twist binding motifs in this enhancer, we found that a mutation in any one of these binding sites causes a drastic reduction in transcriptional amplitude, resulting in a reduction in mRNA production of the target gene. We provide evidence of synergy, such that multiple binding sites with moderate affinities cooperatively recruit more TFs to drive stronger transcriptional activity than a single site. Moreover, a Hidden Markov-based stochastic model of transcription reveals that embryos with mutated binding sites have a higher probability of returning to the inactive promoter state. We propose that TF-DNA binding regulates spatial and temporal gene expression and drives robust pattern formation by modulating transcriptional kinetics and tuning bursting rates.
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Affiliation(s)
- Sahla Syed
- Department of Chemical and Biomolecular Engineering, University of PennsylvaniaPhiladelphiaUnited States
| | - Yifei Duan
- Department of Chemical and Biomolecular Engineering, University of PennsylvaniaPhiladelphiaUnited States
- Master of Biotechnology Program, University of PennsylvaniaPhiladelphiaUnited States
| | - Bomyi Lim
- Department of Chemical and Biomolecular Engineering, University of PennsylvaniaPhiladelphiaUnited States
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14
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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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15
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Ibragimov A, Bing XY, Shidlovskii YV, Levine M, Georgiev P, Schedl P. lncRNA read-through regulates the BX-C insulator Fub-1. eLife 2023; 12:e84711. [PMID: 37643473 PMCID: PMC10497285 DOI: 10.7554/elife.84711] [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: 11/05/2022] [Accepted: 08/09/2023] [Indexed: 08/31/2023] Open
Abstract
Though long non-coding RNAs (lncRNAs) represent a substantial fraction of the Pol II transcripts in multicellular animals, only a few have known functions. Here we report that the blocking activity of the Bithorax complex (BX-C) Fub-1 boundary is segmentally regulated by its own lncRNA. The Fub-1 boundary is located between the Ultrabithorax (Ubx) gene and the bxd/pbx regulatory domain, which is responsible for regulating Ubx expression in parasegment PS6/segment A1. Fub-1 consists of two hypersensitive sites, HS1 and HS2. HS1 is an insulator while HS2 functions primarily as an lncRNA promoter. To activate Ubx expression in PS6/A1, enhancers in the bxd/pbx domain must be able to bypass Fub-1 blocking activity. We show that the expression of the Fub-1 lncRNAs in PS6/A1 from the HS2 promoter inactivates Fub-1 insulating activity. Inactivation is due to read-through as the HS2 promoter must be directed toward HS1 to disrupt blocking.
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Affiliation(s)
- Airat Ibragimov
- Department of Molecular Biology, Princeton UniversityPrincetonUnited States
- Center for Precision Genome Editing and Genetic Technologies for Biomedicine, Institute of Gene Biology, Russian Academy of SciencesMoscowRussian Federation
| | - Xin Yang Bing
- Lewis Sigler Institute, Princeton UniversityPrincetonUnited States
| | - Yulii V Shidlovskii
- Laboratory of Gene Expression Regulation in Development, Institute of Gene Biology Russian Academy of SciencesMoscowRussian Federation
- Department of Biology and General Genetics, Sechenov UniversityMoscowRussian Federation
| | - Michael Levine
- Lewis Sigler Institute, Princeton UniversityPrincetonUnited States
| | - Pavel Georgiev
- Department of the Control of Genetic Processes, Institute of Gene Biology Russian Academy of SciencesMoscowRussian Federation
| | - Paul Schedl
- Department of Molecular Biology, Princeton UniversityPrincetonUnited States
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16
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Zhao J, Perkins ML, Norstad M, Garcia HG. A bistable autoregulatory module in the developing embryo commits cells to binary expression fates. Curr Biol 2023; 33:2851-2864.e11. [PMID: 37453424 PMCID: PMC10428078 DOI: 10.1016/j.cub.2023.06.060] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2022] [Revised: 04/13/2023] [Accepted: 06/22/2023] [Indexed: 07/18/2023]
Abstract
Bistable autoactivation has been proposed as a mechanism for cells to adopt binary fates during embryonic development. However, it is unclear whether the autoactivating modules found within developmental gene regulatory networks are bistable, unless their parameters are quantitatively determined. Here, we combine in vivo live imaging with mathematical modeling to dissect the binary cell fate dynamics of the fruit fly pair-rule gene fushi tarazu (ftz), which is regulated by two known enhancers: the early (non-autoregulating) element and the autoregulatory element. Live imaging of transcription and protein concentration in the blastoderm revealed that binary Ftz fates are achieved as Ftz expression rapidly transitions from being dictated by the early element to the autoregulatory element. Moreover, we discovered that Ftz concentration alone is insufficient to activate the autoregulatory element, and that this element only becomes responsive to Ftz at a prescribed developmental time. Based on these observations, we developed a dynamical systems model and quantitated its kinetic parameters directly from experimental measurements. Our model demonstrated that the ftz autoregulatory module is indeed bistable and that the early element transiently establishes the content of the binary cell fate decision to which the autoregulatory module then commits. Further in silico analysis revealed that the autoregulatory element locks the Ftz fate quickly, within 35 min of exposure to the transient signal of the early element. Overall, our work confirms the widely held hypothesis that autoregulation can establish developmental fates through bistability and, most importantly, provides a framework for the quantitative dissection of cellular decision-making.
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Affiliation(s)
- Jiaxi Zhao
- Department of Physics, University of California, Berkeley, Berkeley, CA 94720, USA
| | - Mindy Liu Perkins
- Developmental Biology Unit, European Molecular Biology Laboratory, 69117 Heidelberg, Germany
| | - Matthew Norstad
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720, USA
| | - Hernan G Garcia
- Department of Physics, University of California, Berkeley, Berkeley, CA 94720, USA; Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720, USA; Biophysics Graduate Group, University of California, Berkeley, Berkeley, CA 94720, USA; Institute for Quantitative Biosciences-QB3, University of California, Berkeley, Berkeley, CA 94720, USA; Chan Zuckerberg Biohub - San Francisco, San Francisco, CA 94158, USA.
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17
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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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18
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Bhavna R, Sonawane M. A deep learning framework for quantitative analysis of actin microridges. NPJ Syst Biol Appl 2023; 9:21. [PMID: 37268613 DOI: 10.1038/s41540-023-00276-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2021] [Accepted: 05/03/2023] [Indexed: 06/04/2023] Open
Abstract
Microridges are evolutionarily conserved actin-rich protrusions present on the apical surface of squamous epithelial cells. In zebrafish epidermal cells, microridges form self-evolving patterns due to the underlying actomyosin network dynamics. However, their morphological and dynamic characteristics have remained poorly understood owing to a lack of computational methods. We achieved ~95% pixel-level accuracy with a deep learning microridge segmentation strategy enabling quantitative insights into their bio-physical-mechanical characteristics. From the segmented images, we estimated an effective microridge persistence length of ~6.1 μm. We discovered the presence of mechanical fluctuations and found relatively greater stresses stored within patterns of yolk than flank, indicating distinct regulation of their actomyosin networks. Furthermore, spontaneous formations and positional fluctuations of actin clusters within microridges were associated with pattern rearrangements over short length/time-scales. Our framework allows large-scale spatiotemporal analysis of microridges during epithelial development and probing of their responses to chemical and genetic perturbations to unravel the underlying patterning mechanisms.
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Affiliation(s)
- Rajasekaran Bhavna
- Department of Biological Sciences, Tata Institute of Fundamental Research, Colaba, Mumbai, 400005, India.
- Department of Data Science and Engineering, Indian Institute of Science Education and Research, Bhopal, Madhya Pradesh, 462066, India.
| | - Mahendra Sonawane
- Department of Biological Sciences, Tata Institute of Fundamental Research, Colaba, Mumbai, 400005, India
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19
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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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20
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Afzal Z, Lange JJ, Nolte C, McKinney S, Wood C, Paulson A, De Kumar B, Unruh J, Slaughter BD, Krumlauf R. Shared retinoic acid responsive enhancers coordinately regulate nascent transcription of Hoxb coding and non-coding RNAs in the developing mouse neural tube. Development 2023; 150:dev201259. [PMID: 37102683 PMCID: PMC10233718 DOI: 10.1242/dev.201259] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2022] [Accepted: 04/19/2023] [Indexed: 04/28/2023]
Abstract
Signaling pathways regulate the patterns of Hox gene expression that underlie their functions in the specification of axial identity. Little is known about the properties of cis-regulatory elements and underlying transcriptional mechanisms that integrate graded signaling inputs to coordinately control Hox expression. Here, we optimized a single molecule fluorescent in situ hybridization (smFISH) technique with probes spanning introns to evaluate how three shared retinoic acid response element (RARE)-dependent enhancers in the Hoxb cluster regulate patterns of nascent transcription in vivo at the level of single cells in wild-type and mutant embryos. We predominately detect nascent transcription of only a single Hoxb gene in each cell, with no evidence for simultaneous co-transcriptional coupling of all or specific subsets of genes. Single and/or compound RARE mutations indicate that each enhancer differentially impacts global and local patterns of nascent transcription, suggesting that selectivity and competitive interactions between these enhancers is important to robustly maintain the proper levels and patterns of nascent Hoxb transcription. This implies that rapid and dynamic regulatory interactions potentiate transcription of genes through combined inputs from these enhancers in coordinating the retinoic acid response.
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Affiliation(s)
- Zainab Afzal
- Stowers Institute for Medical Research, Kansas City, MO 64110, USA
- Anatomy and Cell Biology Department, Kansas University Medical Center, Kansas City, KS 66160, USA
| | - Jeffrey J. Lange
- Stowers Institute for Medical Research, Kansas City, MO 64110, USA
| | - Christof Nolte
- Stowers Institute for Medical Research, Kansas City, MO 64110, USA
| | - Sean McKinney
- Stowers Institute for Medical Research, Kansas City, MO 64110, USA
| | - Christopher Wood
- Stowers Institute for Medical Research, Kansas City, MO 64110, USA
| | - Ariel Paulson
- Stowers Institute for Medical Research, Kansas City, MO 64110, USA
| | - Bony De Kumar
- Stowers Institute for Medical Research, Kansas City, MO 64110, USA
| | - Jay Unruh
- Stowers Institute for Medical Research, Kansas City, MO 64110, USA
| | | | - Robb Krumlauf
- Stowers Institute for Medical Research, Kansas City, MO 64110, USA
- Anatomy and Cell Biology Department, Kansas University Medical Center, Kansas City, KS 66160, USA
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21
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Forbes Beadle L, Zhou H, Rattray M, Ashe HL. Modulation of transcription burst amplitude underpins dosage compensation in the Drosophila embryo. Cell Rep 2023; 42:112382. [PMID: 37060568 PMCID: PMC10283159 DOI: 10.1016/j.celrep.2023.112382] [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: 07/25/2022] [Revised: 02/03/2023] [Accepted: 03/27/2023] [Indexed: 04/16/2023] Open
Abstract
Dosage compensation, the balancing of X-linked gene expression between sexes and to the autosomes, is critical to an organism's fitness and survival. In Drosophila, dosage compensation involves hypertranscription of the male X chromosome. Here, we use quantitative live imaging and modeling at single-cell resolution to study X chromosome dosage compensation in Drosophila. We show that the four X chromosome genes studied undergo transcriptional bursting in male and female embryos. Mechanistically, our data reveal that transcriptional upregulation of male X chromosome genes is primarily mediated by a higher RNA polymerase II initiation rate and burst amplitude across the expression domain. In contrast, burst frequency is spatially modulated in nuclei within the expression domain in response to different transcription factor concentrations to tune the transcriptional response. Together, these data show how the local and global regulation of distinct burst parameters can establish the complex transcriptional outputs underpinning developmental patterning.
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Affiliation(s)
- Lauren Forbes Beadle
- Faculty of Biology, Medicine and Health, University of Manchester, Manchester M13 9PT, UK
| | - Hongpeng Zhou
- Faculty of Biology, Medicine and Health, University of Manchester, Manchester M13 9PT, UK
| | - Magnus Rattray
- Faculty of Biology, Medicine and Health, University of Manchester, Manchester M13 9PT, UK.
| | - Hilary L Ashe
- Faculty of Biology, Medicine and Health, University of Manchester, Manchester M13 9PT, UK.
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22
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Cosma MP, Neguembor MV. The magic of unraveling genome architecture and function. Cell Rep 2023; 42:112361. [PMID: 37059093 DOI: 10.1016/j.celrep.2023.112361] [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: 12/06/2022] [Revised: 02/20/2023] [Accepted: 03/22/2023] [Indexed: 04/16/2023] Open
Abstract
Over the last decades, technological breakthroughs in super-resolution microscopy have allowed us to reach molecular resolution and design experiments of unprecedented complexity. Investigating how chromatin is folded in 3D, from the nucleosome level up to the entire genome, is becoming possible by "magic" (imaging genomic), i.e., the combination of imaging and genomic approaches. This offers endless opportunities to delve into the relationship between genome structure and function. Here, we review recently achieved objectives and the conceptual and technical challenges the field of genome architecture is currently undertaking. We discuss what we have learned so far and where we are heading. We elucidate how the different super-resolution microscopy approaches and, more specifically, live-cell imaging have contributed to the understanding of genome folding. Moreover, we discuss how future technical developments could address remaining open questions.
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Affiliation(s)
- Maria Pia Cosma
- Medical Research Institute, Guangdong Provincial People's Hospital (Guangdong Academy of Medical Sciences), Southern Medical University, 106 Zhongshan Er Road, Yuexiu District, 510080 Guangzhou, China; Centre for Genomic Regulation (CRG), The Barcelona Institute of Science and Technology, 08003 Barcelona, Spain; Universitat Pompeu Fabra (UPF), Dr Aiguader 88, 08003 Barcelona, Spain; ICREA, Pg. Lluís Companys 23, 08010 Barcelona, Spain.
| | - Maria Victoria Neguembor
- Centre for Genomic Regulation (CRG), The Barcelona Institute of Science and Technology, 08003 Barcelona, Spain.
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23
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Harden TT, Vincent BJ, DePace AH. Transcriptional activators in the early Drosophila embryo perform different kinetic roles. Cell Syst 2023; 14:258-272.e4. [PMID: 37080162 PMCID: PMC10473017 DOI: 10.1016/j.cels.2023.03.006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2021] [Revised: 06/26/2022] [Accepted: 03/21/2023] [Indexed: 04/22/2023]
Abstract
Combinatorial regulation of gene expression by transcription factors (TFs) may in part arise from kinetic synergy-wherein TFs regulate different steps in the transcription cycle. Kinetic synergy requires that TFs play distinguishable kinetic roles. Here, we used live imaging to determine the kinetic roles of three TFs that activate transcription in the Drosophila embryo-Zelda, Bicoid, and Stat92E-by introducing their binding sites into the even-skipped stripe 2 enhancer. These TFs influence different sets of kinetic parameters, and their influence can change over time. All three TFs increased the fraction of transcriptionally active nuclei; Zelda also shortened the first-passage time into transcription and regulated the interval between transcription events. Stat92E also increased the lifetimes of active transcription. Different TFs can therefore play distinct kinetic roles in activating the transcription. This has consequences for understanding the composition and flexibility of regulatory DNA sequences and the biochemical function of TFs. A record of this paper's transparent peer review process is included in the supplemental information.
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Affiliation(s)
- Timothy T Harden
- Department of Systems Biology, Harvard Medical School, Boston, MA 02115, USA
| | - Ben J Vincent
- 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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24
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Pecori F, Torres-Padilla ME. Dynamics of nuclear architecture during early embryonic development and lessons from liveimaging. Dev Cell 2023; 58:435-449. [PMID: 36977375 PMCID: PMC10062924 DOI: 10.1016/j.devcel.2023.02.018] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2022] [Revised: 11/29/2022] [Accepted: 02/27/2023] [Indexed: 03/29/2023]
Abstract
Nuclear organization has emerged as a potential key regulator of genome function. During development, the deployment of transcriptional programs must be tightly coordinated with cell division and is often accompanied by major changes in the repertoire of expressed genes. These transcriptional and developmental events are paralleled by changes in the chromatin landscape. Numerous studies have revealed the dynamics of nuclear organization underlying them. In addition, advances in live-imaging-based methodologies enable the study of nuclear organization with high spatial and temporal resolution. In this Review, we summarize the current knowledge of the changes in nuclear architecture in the early embryogenesis of various model systems. Furthermore, to highlight the importance of integrating fixed-cell and live approaches, we discuss how different live-imaging techniques can be applied to examine nuclear processes and their contribution to our understanding of transcription and chromatin dynamics in early development. Finally, we provide future avenues for outstanding questions in this field.
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Affiliation(s)
- Federico Pecori
- Institute of Epigenetics and Stem Cells, Helmholtz Zentrum München, Munich, Germany
| | - Maria-Elena Torres-Padilla
- Institute of Epigenetics and Stem Cells, Helmholtz Zentrum München, Munich, Germany; Faculty of Biology, Ludwig Maximilians University, Munich, Germany.
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25
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Alamos S, Reimer A, Westrum C, Turner MA, Talledo P, Zhao J, Luu E, Garcia HG. Minimal synthetic enhancers reveal control of the probability of transcriptional engagement and its timing by a morphogen gradient. Cell Syst 2023; 14:220-236.e3. [PMID: 36696901 PMCID: PMC10125799 DOI: 10.1016/j.cels.2022.12.008] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2021] [Revised: 09/03/2022] [Accepted: 12/21/2022] [Indexed: 01/26/2023]
Abstract
How enhancers interpret morphogen gradients to generate gene expression patterns is a central question in developmental biology. Recent studies have proposed that enhancers can dictate whether, when, and at what rate promoters engage in transcription, but the complexity of endogenous enhancers calls for theoretical models with too many free parameters to quantitatively dissect these regulatory strategies. To overcome this limitation, we established a minimal promoter-proximal synthetic enhancer in embryos of Drosophila melanogaster. Here, a gradient of the Dorsal activator is read by a single Dorsal DNA binding site. Using live imaging to quantify transcriptional activity, we found that a single binding site can regulate whether promoters engage in transcription in a concentration-dependent manner. By modulating the binding-site affinity, we determined that a gene's decision to transcribe and its transcriptional onset time can be explained by a simple model where the promoter traverses multiple kinetic barriers before transcription can ensue.
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Affiliation(s)
- Simon Alamos
- Department of Plant and Microbial Biology, University of California at Berkeley, Berkeley, CA, USA
| | - Armando Reimer
- Biophysics Graduate Group, University of California at Berkeley, Berkeley, CA, USA
| | - Clay Westrum
- Department of Physics, University of California at Berkeley, Berkeley, CA, USA
| | - Meghan A Turner
- Department of Plant and Microbial Biology, University of California at Berkeley, Berkeley, CA, USA
| | - Paul Talledo
- Department of Molecular and Cell Biology, University of California at Berkeley, Berkeley, CA, USA
| | - Jiaxi Zhao
- Department of Physics, University of California at Berkeley, Berkeley, CA, USA
| | - Emma Luu
- Department of Physics, University of California at Berkeley, Berkeley, CA, USA
| | - Hernan G Garcia
- Biophysics Graduate Group, University of California at Berkeley, Berkeley, CA, USA; Department of Physics, University of California at Berkeley, Berkeley, CA, USA; Department of Molecular and Cell Biology, University of California at Berkeley, Berkeley, CA, USA; Institute for Quantitative Biosciences-QB3, University of California at Berkeley, Berkeley, CA, USA; Chan Zuckerberg Biohub, San Francisco, CA, USA.
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26
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May D, Yun S, Gonzalez DG, Park S, Chen Y, Lathrop E, Cai B, Xin T, Zhao H, Wang S, Gonzalez LE, Cockburn K, Greco V. Live imaging reveals chromatin compaction transitions and dynamic transcriptional bursting during stem cell differentiation in vivo. eLife 2023; 12:83444. [PMID: 36880644 PMCID: PMC10027315 DOI: 10.7554/elife.83444] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2022] [Accepted: 03/06/2023] [Indexed: 03/08/2023] Open
Abstract
Stem cell differentiation requires dramatic changes in gene expression and global remodeling of chromatin architecture. How and when chromatin remodels relative to the transcriptional, behavioral, and morphological changes during differentiation remain unclear, particularly in an intact tissue context. Here, we develop a quantitative pipeline which leverages fluorescently-tagged histones and longitudinal imaging to track large-scale chromatin compaction changes within individual cells in a live mouse. Applying this pipeline to epidermal stem cells, we reveal that cell-to-cell chromatin compaction heterogeneity within the stem cell compartment emerges independent of cell cycle status, and instead is reflective of differentiation status. Chromatin compaction state gradually transitions over days as differentiating cells exit the stem cell compartment. Moreover, establishing live imaging of Keratin-10 (K10) nascent RNA, which marks the onset of stem cell differentiation, we find that Keratin-10 transcription is highly dynamic and largely precedes the global chromatin compaction changes associated with differentiation. Together, these analyses reveal that stem cell differentiation involves dynamic transcriptional states and gradual chromatin rearrangement.
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Affiliation(s)
- Dennis May
- Department of Genetics, Yale University School of Medicine, New Haven, United States
| | - Sangwon Yun
- Department of Genetics, Yale University School of Medicine, New Haven, United States
| | - David G Gonzalez
- Department of Genetics, Yale University School of Medicine, New Haven, United States
| | - Sangbum Park
- Department of Genetics, Yale University School of Medicine, New Haven, United States
- Institute for Quantitative Health Science & Engineering (IQ), Michigan State University, East Lansing, United States
- Division of Dermatology, Department of Medicine, College of Human Medicine, Michigan State University, East Lansing, United States
- Department of Pharmacology and Toxicology, College of Human Medicine, Michigan State University, East Lansing, United States
| | - Yanbo Chen
- Department of Genetics, Yale University School of Medicine, New Haven, United States
| | - Elizabeth Lathrop
- Department of Genetics, Yale University School of Medicine, New Haven, United States
| | - Biao Cai
- Department of Biostatistics, Yale University School of Public Health, New Haven, United States
| | - Tianchi Xin
- Department of Genetics, Yale University School of Medicine, New Haven, United States
| | - Hongyu Zhao
- Department of Genetics, Yale University School of Medicine, New Haven, United States
- Department of Biostatistics, Yale University School of Public Health, New Haven, United States
| | - Siyuan Wang
- Department of Genetics, Yale University School of Medicine, New Haven, United States
- Deparment of Cell Biology, Yale University School of Medicine, New Haven, United States
| | - Lauren E Gonzalez
- Department of Genetics, Yale University School of Medicine, New Haven, United States
| | - Katie Cockburn
- Department of Genetics, Yale University School of Medicine, New Haven, United States
- Department of Biochemistry and Rosalind & Morris Goodman Cancer Institute, McGill University, Montreal, Canada
| | - Valentina Greco
- Department of Genetics, Yale University School of Medicine, New Haven, United States
- Division of Dermatology, Department of Medicine, College of Human Medicine, Michigan State University, East Lansing, United States
- Departments of Cell Biology and Dermatology, Yale Stem Cell Center, Yale Cancer Center, Yale University School of Medicine, New Haven, United States
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27
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Huang Y, Gao BQ, Meng Q, Yang LZ, Ma XK, Wu H, Pan YH, Yang L, Li D, Chen LL. CRISPR-dCas13-tracing reveals transcriptional memory and limited mRNA export in developing zebrafish embryos. Genome Biol 2023; 24:15. [PMID: 36658633 PMCID: PMC9854193 DOI: 10.1186/s13059-023-02848-6] [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: 08/17/2022] [Accepted: 01/04/2023] [Indexed: 01/20/2023] Open
Abstract
BACKGROUND Understanding gene transcription and mRNA-protein (mRNP) dynamics in single cells in a multicellular organism has been challenging. The catalytically dead CRISPR-Cas13 (dCas13) system has been used to visualize RNAs in live cells without genetic manipulation. We optimize this system to track developmentally expressed mRNAs in zebrafish embryos and to understand features of endogenous transcription kinetics and mRNP export. RESULTS We report that zygotic microinjection of purified CRISPR-dCas13-fluorescent proteins and modified guide RNAs allows single- and dual-color tracking of developmentally expressed mRNAs in zebrafish embryos from zygotic genome activation (ZGA) until early segmentation period without genetic manipulation. Using this approach, we uncover non-synchronized de novo transcription between inter-alleles, synchronized post-mitotic re-activation in pairs of alleles, and transcriptional memory as an extrinsic noise that potentially contributes to synchronized post-mitotic re-activation. We also reveal rapid dCas13-engaged mRNP movement in the nucleus with a corralled and diffusive motion, but a wide varying range of rate-limiting mRNP export, which can be shortened by Alyref and Nxf1 overexpression. CONCLUSIONS This optimized dCas13-based toolkit enables robust spatial-temporal tracking of endogenous mRNAs and uncovers features of transcription and mRNP motion, providing a powerful toolkit for endogenous RNA visualization in a multicellular developmental organism.
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Affiliation(s)
- Youkui Huang
- State Key Laboratory of Molecular Biology, Shanghai Key Laboratory of Molecular Andrology, CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology, University of Chinese Academy of Sciences, Chinese Academy of Sciences, 320 Yueyang Road, Shanghai, China
| | - Bao-Qing Gao
- CAS Key Laboratory of Computational Biology, Shanghai Institute of Nutrition and Health, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Shanghai, China
| | - Quan Meng
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China
- College of Life Sciences, University of Chinese Academy of Sciences, Beijing, China
| | - Liang-Zhong Yang
- State Key Laboratory of Molecular Biology, Shanghai Key Laboratory of Molecular Andrology, CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology, University of Chinese Academy of Sciences, Chinese Academy of Sciences, 320 Yueyang Road, Shanghai, China
| | - Xu-Kai Ma
- Center for Molecular Medicine, Children's Hospital, Fudan University and Shanghai Key Laboratory of Medical Epigenetics, International Laboratory of Medical Epigenetics and Metabolism, Ministry of Science and Technology, Institutes of Biomedical Sciences, Fudan University, Shanghai, China
| | - Hao Wu
- State Key Laboratory of Molecular Biology, Shanghai Key Laboratory of Molecular Andrology, CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology, University of Chinese Academy of Sciences, Chinese Academy of Sciences, 320 Yueyang Road, Shanghai, China
| | - Yu-Hang Pan
- State Key Laboratory of Molecular Biology, Shanghai Key Laboratory of Molecular Andrology, CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology, University of Chinese Academy of Sciences, Chinese Academy of Sciences, 320 Yueyang Road, Shanghai, China
| | - Li Yang
- Center for Molecular Medicine, Children's Hospital, Fudan University and Shanghai Key Laboratory of Medical Epigenetics, International Laboratory of Medical Epigenetics and Metabolism, Ministry of Science and Technology, Institutes of Biomedical Sciences, Fudan University, Shanghai, China
| | - Dong Li
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China
- College of Life Sciences, University of Chinese Academy of Sciences, Beijing, China
| | - Ling-Ling Chen
- State Key Laboratory of Molecular Biology, Shanghai Key Laboratory of Molecular Andrology, CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology, University of Chinese Academy of Sciences, Chinese Academy of Sciences, 320 Yueyang Road, Shanghai, China.
- School of Life Science and Technology, ShanghaiTech University, Shanghai, China.
- School of Life Science, Hangzhou Institute for Advanced Study, University of Chinese Academy of Sciences, Hangzhou, China.
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28
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Syed S, Duan Y, Lim B. Modulation of protein-DNA binding reveals mechanisms of spatiotemporal gene control in early Drosophila embryos. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.01.05.522923. [PMID: 36711729 PMCID: PMC9881968 DOI: 10.1101/2023.01.05.522923] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
It is well known that enhancers regulate the spatiotemporal expression of their target genes by recruiting transcription factors (TFs) to the cognate binding sites in the region. However, the role of multiple binding sites for the same TFs and their specific spatial arrangement in determining the overall competency of the enhancer has yet to be fully understood. In this study, we utilized the MS2-MCP live imaging technique to quantitatively analyze the regulatory logic of the snail distal enhancer in early Drosophila embryos. Through systematic modulation of Dorsal and Twist binding motifs in this enhancer, we found that a mutation in any one of these binding sites causes a drastic reduction in transcriptional amplitude, resulting in a reduction in total mRNA production of the target gene. We provide evidence of synergy, such that multiple binding sites with moderate affinities cooperatively recruit more TFs to drive stronger transcriptional activity than a single site. Moreover, a Hidden Markov-based stochastic model of transcription reveals that embryos with mutated binding sites have a higher probability of returning to the inactive promoter state. We propose that TF-DNA binding regulates spatial and temporal gene expression and drives robust pattern formation by modulating transcriptional kinetics and tuning bursting rates.
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Affiliation(s)
- Sahla Syed
- Department of Chemical and Biomolecular Engineering, University of Pennsylvania, Philadelphia, PA 19104
| | - Yifei Duan
- Department of Chemical and Biomolecular Engineering, University of Pennsylvania, Philadelphia, PA 19104
- Master of Biotechnology Program, University of Pennsylvania, Philadelphia, PA 19104
| | - Bomyi Lim
- Department of Chemical and Biomolecular Engineering, University of Pennsylvania, Philadelphia, PA 19104
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29
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Chen PB, Fiaux PC, Zhang K, Li B, Kubo N, Jiang S, Hu R, Rooholfada E, Wu S, Wang M, Wang W, McVicker G, Mischel PS, Ren B. Systematic discovery and functional dissection of enhancers needed for cancer cell fitness and proliferation. Cell Rep 2022; 41:111630. [PMID: 36351387 PMCID: PMC9687083 DOI: 10.1016/j.celrep.2022.111630] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2022] [Revised: 07/21/2022] [Accepted: 10/18/2022] [Indexed: 11/09/2022] Open
Abstract
A scarcity of functionally validated enhancers in the human genome presents a significant hurdle to understanding how these cis-regulatory elements contribute to human diseases. We carry out highly multiplexed CRISPR-based perturbation and sequencing to identify enhancers required for cell proliferation and fitness in 10 human cancer cell lines. Our results suggest that the cell fitness enhancers, unlike their target genes, display high cell-type specificity of chromatin features. They typically adopt a modular structure, comprised of activating elements enriched for motifs of oncogenic transcription factors, surrounded by repressive elements enriched for motifs recognized by transcription factors with tumor suppressor functions. We further identify cell fitness enhancers that are selectively accessible in clinical tumor samples, and the levels of chromatin accessibility are associated with patient survival. These results reveal functional enhancers across multiple cancer cell lines, characterize their context-dependent chromatin organization, and yield insights into altered transcription programs in cancer cells.
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Affiliation(s)
- Poshen B Chen
- Department of Cellular and Molecular Medicine, University of California at San Diego, La Jolla, CA 92093, USA; Genome Institute of Singapore, Agency for Science, Technology and Research (A∗STAR), Singapore 138672, Singapore
| | - Patrick C Fiaux
- Bioinformatics and System Biology Graduate Program, University of California at San Diego, La Jolla, CA 92093, USA
| | - Kai Zhang
- Department of Cellular and Molecular Medicine, University of California at San Diego, La Jolla, CA 92093, USA
| | - Bin Li
- Department of Cellular and Molecular Medicine, University of California at San Diego, La Jolla, CA 92093, USA
| | - Naoki Kubo
- Department of Cellular and Molecular Medicine, University of California at San Diego, La Jolla, CA 92093, USA
| | - Shan Jiang
- Department of Cellular and Molecular Medicine, University of California at San Diego, La Jolla, CA 92093, USA
| | - Rong Hu
- Department of Cellular and Molecular Medicine, University of California at San Diego, La Jolla, CA 92093, USA
| | - Emma Rooholfada
- Department of Cellular and Molecular Medicine, University of California at San Diego, La Jolla, CA 92093, USA
| | - Sihan Wu
- Children's Medical Center Research Institute, University of Texas Southwestern Medical Center, Dallas, TX 75235, USA
| | - Mengchi Wang
- Bioinformatics and System Biology Graduate Program, University of California at San Diego, La Jolla, CA 92093, USA
| | - Wei Wang
- Department of Cellular and Molecular Medicine, University of California at San Diego, La Jolla, CA 92093, USA; Bioinformatics and System Biology Graduate Program, University of California at San Diego, La Jolla, CA 92093, USA
| | - Graham McVicker
- Integrative Biology Laboratory, Salk Institute for Biological Studies, La Jolla, CA 92037, USA
| | - Paul S Mischel
- Department of Pathology, Stanford Medicine, Stanford University, Stanford, CA 94305, USA; ChEM-H, Stanford University, Stanford, CA 94305, USA
| | - Bing Ren
- Department of Cellular and Molecular Medicine, University of California at San Diego, La Jolla, CA 92093, USA; Moores Cancer Center, University of California at San Diego, La Jolla, CA 92093, USA; Institute of Genome Medicine, UCSD School of Medicine, La Jolla, CA 92093, USA; Ludwig Institute for Cancer Research, San Diego, La Jolla, CA 92093, USA.
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30
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Jeziorska DM, Tunnacliffe EAJ, Brown JM, Ayyub H, Sloane-Stanley J, Sharpe JA, Lagerholm BC, Babbs C, Smith AJH, Buckle VJ, Higgs DR. On-microscope staging of live cells reveals changes in the dynamics of transcriptional bursting during differentiation. Nat Commun 2022; 13:6641. [PMID: 36333299 PMCID: PMC9636426 DOI: 10.1038/s41467-022-33977-4] [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: 12/08/2021] [Accepted: 10/07/2022] [Indexed: 11/06/2022] Open
Abstract
Determining the mechanisms by which genes are switched on and off during development is a key aim of current biomedical research. Gene transcription has been widely observed to occur in a discontinuous fashion, with short bursts of activity interspersed with periods of inactivity. It is currently not known if or how this dynamic behaviour changes as mammalian cells differentiate. To investigate this, using an on-microscope analysis, we monitored mouse α-globin transcription in live cells throughout erythropoiesis. We find that changes in the overall levels of α-globin transcription are most closely associated with changes in the fraction of time a gene spends in the active transcriptional state. We identify differences in the patterns of transcriptional bursting throughout differentiation, with maximal transcriptional activity occurring in the mid-phase of differentiation. Early in differentiation, we observe increased fluctuation in transcriptional activity whereas at the peak of gene expression, in early erythroblasts, transcription is relatively stable. Later during differentiation as α-globin expression declines, we again observe more variability in transcription within individual cells. We propose that the observed changes in transcriptional behaviour may reflect changes in the stability of active transcriptional compartments as gene expression is regulated during differentiation.
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Affiliation(s)
- D. M. Jeziorska
- grid.4991.50000 0004 1936 8948MRC Weatherall Institute for Molecular Medicine, University of Oxford, John Radcliffe Hospital, Oxford, OX3 9DS UK ,Present Address: Nucleome Therapeutics Ltd., BioEscalator, The Innovation Building, Old Road Campus, Oxford, OX3 7FZ UK
| | - E. A. J. Tunnacliffe
- grid.4991.50000 0004 1936 8948MRC Weatherall Institute for Molecular Medicine, University of Oxford, John Radcliffe Hospital, Oxford, OX3 9DS UK
| | - J. M. Brown
- grid.4991.50000 0004 1936 8948MRC Weatherall Institute for Molecular Medicine, University of Oxford, John Radcliffe Hospital, Oxford, OX3 9DS UK
| | - H. Ayyub
- grid.4991.50000 0004 1936 8948MRC Weatherall Institute for Molecular Medicine, University of Oxford, John Radcliffe Hospital, Oxford, OX3 9DS UK
| | - J. Sloane-Stanley
- grid.4991.50000 0004 1936 8948MRC Weatherall Institute for Molecular Medicine, University of Oxford, John Radcliffe Hospital, Oxford, OX3 9DS UK
| | - J. A. Sharpe
- grid.4991.50000 0004 1936 8948MRC Weatherall Institute for Molecular Medicine, University of Oxford, John Radcliffe Hospital, Oxford, OX3 9DS UK
| | - B. C. Lagerholm
- grid.4991.50000 0004 1936 8948Wolfson Imaging Centre, MRC Weatherall Institute for Molecular Medicine, University of Oxford, John Radcliffe Hospital, Oxford, OX3 9DS UK ,grid.4991.50000 0004 1936 8948Present Address: The Kennedy Institute Of Rheumatology, University of Oxford, Old Road Campus, Oxford, OX3 7FY UK
| | - C. Babbs
- grid.4991.50000 0004 1936 8948MRC Weatherall Institute for Molecular Medicine, University of Oxford, John Radcliffe Hospital, Oxford, OX3 9DS UK
| | - A. J. H. Smith
- grid.4991.50000 0004 1936 8948MRC Weatherall Institute for Molecular Medicine, University of Oxford, John Radcliffe Hospital, Oxford, OX3 9DS UK ,grid.4305.20000 0004 1936 7988Present Address: MRC Centre for Regenerative Medicine, University of Edinburgh, Edinburgh, EH16 4UU UK
| | - V. J. Buckle
- grid.4991.50000 0004 1936 8948MRC Weatherall Institute for Molecular Medicine, University of Oxford, John Radcliffe Hospital, Oxford, OX3 9DS UK
| | - D. R. Higgs
- grid.4991.50000 0004 1936 8948MRC Weatherall Institute for Molecular Medicine, University of Oxford, John Radcliffe Hospital, Oxford, OX3 9DS UK ,grid.4991.50000 0004 1936 8948Chinese Academy of Medical Sciences Oxford Institute, Nuffield Department of Medicine, University of Oxford, Old Road Campus, Oxford, OX3 7BN UK
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31
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RNA Polymerase II “Pause” Prepares Promoters for Upcoming Transcription during Drosophila Development. Int J Mol Sci 2022; 23:ijms231810662. [PMID: 36142573 PMCID: PMC9503990 DOI: 10.3390/ijms231810662] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2022] [Revised: 09/07/2022] [Accepted: 09/08/2022] [Indexed: 11/17/2022] Open
Abstract
According to previous studies, during Drosophila embryogenesis, the recruitment of RNA polymerase II precedes active gene transcription. This work is aimed at exploring whether this mechanism is used during Drosophila metamorphosis. In addition, the composition of the RNA polymerase II “paused” complexes associated with promoters at different developmental stages are described in detail. For this purpose, we performed ChIP-Seq analysis using antibodies for various modifications of RNA polymerase II (total, Pol II CTD Ser5P, and Pol II CTD Ser2P) as well as for subunits of the NELF, DSIF, and PAF complexes and Brd4/Fs(1)h that control transcription elongation. We found that during metamorphosis, similar to mid-embryogenesis, the promoters were bound by RNA polymerase II in the “paused” state, preparing for activation at later stages of development. During mid-embryogenesis, RNA polymerase II in a “pause” state was phosphorylated at Ser5 and Ser2 of Pol II CTD and bound the NELF, DSIF, and PAF complexes, but not Brd4/Fs(1)h. During metamorphosis, the “paused” RNA polymerase II complex included Brd4/Fs(1)h in addition to NELF, DSIF, and PAF. The RNA polymerase II in this complex was phosphorylated at Ser5 of Pol II CTD, but not at Ser2. These results indicate that, during mid-embryogenesis, RNA polymerase II stalls in the “post-pause” state, being phosphorylated at Ser2 of Pol II CTD (after the stage of p-TEFb action). During metamorphosis, the “pause” mechanism is closer to classical promoter-proximal pausing and is characterized by a low level of Pol II CTD Ser2P.
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32
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Perkins ML, Gandara L, Crocker J. A synthetic synthesis to explore animal evolution and development. Philos Trans R Soc Lond B Biol Sci 2022; 377:20200517. [PMID: 35634925 PMCID: PMC9149795 DOI: 10.1098/rstb.2020.0517] [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] [Indexed: 12/12/2022] Open
Abstract
Identifying the general principles by which genotypes are converted into phenotypes remains a challenge in the post-genomic era. We still lack a predictive understanding of how genes shape interactions among cells and tissues in response to signalling and environmental cues, and hence how regulatory networks generate the phenotypic variation required for adaptive evolution. Here, we discuss how techniques borrowed from synthetic biology may facilitate a systematic exploration of evolvability across biological scales. Synthetic approaches permit controlled manipulation of both endogenous and fully engineered systems, providing a flexible platform for investigating causal mechanisms in vivo. Combining synthetic approaches with multi-level phenotyping (phenomics) will supply a detailed, quantitative characterization of how internal and external stimuli shape the morphology and behaviour of living organisms. We advocate integrating high-throughput experimental data with mathematical and computational techniques from a variety of disciplines in order to pursue a comprehensive theory of evolution. This article is part of the theme issue ‘Genetic basis of adaptation and speciation: from loci to causative mutations’.
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Affiliation(s)
- Mindy Liu Perkins
- Developmental Biology Unit, European Molecular Biology Laboratory, 69117 Heidelberg, Germany
| | - Lautaro Gandara
- Developmental Biology Unit, European Molecular Biology Laboratory, 69117 Heidelberg, Germany
| | - Justin Crocker
- Developmental Biology Unit, European Molecular Biology Laboratory, 69117 Heidelberg, Germany
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33
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Zhang K, Ramos AF, Wang E, Wang J. The rate of thermodynamic cost against adiabatic and nonadiabatic fluctuations of a single gene circuit in Drosophila embryos. J Chem Phys 2022; 156:225101. [DOI: 10.1063/5.0091710] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
We study the stochastic dynamics of the externally regulating gene circuit as an example of eve-skipped gene stripe in the development of Drosophila. Three gene regulation regimes are considered: adiabatic phase when the switching rate of the gene from the OFF to the ON state is faster than the rate of mRNA degradation; nonadiabatic phase when the switching rate from the OFF to the ON state is slower than that of the mRNA degradation; the bursting phase when the gene switching is fast and transcription is very fast, while the ON state probability is very low. We found that the rate of thermodynamic cost quantified by the entropy production rate can suppress the fluctuations of the gene circuit. Higher(lower) rate of thermodynamic cost leads to reduced (increased) fluctuations on the number of gene products in the adiabatic (nonadiabatic) regime. We also found that higher thermodynamic cost is often required to sustain the emergence of more gene states and therefore more heterogeneity coming from genetic mutations or epigenetics. We also study the stability of the gene state using the mean first passage time from one state to another. We found the monotonic decrease in time, i.e. on the stability of the state, in the transition from the nonadiabatic to the adiabatic regimes. Therefore, as the higher rate of thermodynamic cost suppresses the fluctuations, higher stability requires higher thermodynamics cost to maintain.
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Affiliation(s)
- Kun Zhang
- State Key Laboratory of Electroanalytical Chemistry, Changchun Institute of Applied Chemistry Chinese Academy of Sciences, China
| | | | - Erkang Wang
- Changchun Institute of Applied Chemistry Chinese Academy of Sciences, China
| | - Jin Wang
- Chemistry, Physics and Astronomy, Stony Brook University, United States of America
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34
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Nollmann M, Bennabi I, Götz M, Gregor T. The Impact of Space and Time on the Functional Output of the Genome. Cold Spring Harb Perspect Biol 2022; 14:a040378. [PMID: 34230036 PMCID: PMC8733053 DOI: 10.1101/cshperspect.a040378] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Over the past two decades, it has become clear that the multiscale spatial and temporal organization of the genome has important implications for nuclear function. This review centers on insights gained from recent advances in light microscopy on our understanding of transcription. We discuss spatial and temporal aspects that shape nuclear order and their consequences on regulatory components, focusing on genomic scales most relevant to function. The emerging picture is that spatiotemporal constraints increase the complexity in transcriptional regulation, highlighting new challenges, such as uncertainty about how information travels from molecular factors through the genome and space to generate a functional output.
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Affiliation(s)
- Marcelo Nollmann
- Centre de Biologie Structurale, CNRS UMR5048, INSERM U1054, Univ Montpellier, 34090 Montpellier, France
| | - Isma Bennabi
- Department of Stem Cell and Developmental Biology, CNRS UMR3738, Institut Pasteur, 75015 Paris, France
| | - Markus Götz
- Centre de Biologie Structurale, CNRS UMR5048, INSERM U1054, Univ Montpellier, 34090 Montpellier, France
| | - Thomas Gregor
- Department of Stem Cell and Developmental Biology, CNRS UMR3738, Institut Pasteur, 75015 Paris, France
- Joseph Henry Laboratory of Physics & Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton, New Jersey 08544, USA
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35
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Wu HW, Fajiculay E, Wu JF, Yan CCS, Hsu CP, Wu SH. Noise reduction by upstream open reading frames. NATURE PLANTS 2022; 8:474-480. [PMID: 35501454 PMCID: PMC9122824 DOI: 10.1038/s41477-022-01136-8] [Citation(s) in RCA: 19] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/22/2021] [Accepted: 03/15/2022] [Indexed: 05/05/2023]
Abstract
Gene expression is prone to burst production, making it a highly noisy process that requires additional controls. Upstream open reading frames (uORFs) are widely present in the 5' leader sequences of 30-50% of eukaryotic messenger RNAs1-3. The translation of uORFs can repress the translation efficiency of the downstream main coding sequences. Whether the low translation efficiency leads to a different variation, or noise, in gene expression has not been investigated, nor has the direct biological impact of uORF-repressed translation. Here we show that uORFs achieve low but precise protein production in plant cells, possibly by reducing the protein production rate. We also demonstrate that, by buffering a stable TIMING OF CAB EXPRESSION 1 (TOC1) protein production level, uORFs contribute to the robust operation of the plant circadian clock. Our results provide both an action model and the biological impact of uORFs in translational control to mitigate transcriptional noise for precise protein production.
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Affiliation(s)
- Ho-Wei Wu
- Institute of Plant and Microbial Biology, Academia Sinica, Taipei, Taiwan
- Genome and Systems Biology Degree Program, Academia Sinica and National Taiwan University, Taipei, Taiwan
| | - Erickson Fajiculay
- Institute of Chemistry, Academia Sinica, Taipei, Taiwan
- Bioinformatics Program, Institute of Information Science, Taiwan International Graduate Program, Academia Sinica, Taipei, Taiwan
- Institute of Bioinformatics and Structure Biology, National Tsinghua University, Hsinchu, Taiwan
| | - Jing-Fen Wu
- Institute of Plant and Microbial Biology, Academia Sinica, Taipei, Taiwan
| | | | - Chao-Ping Hsu
- Genome and Systems Biology Degree Program, Academia Sinica and National Taiwan University, Taipei, Taiwan.
- Institute of Chemistry, Academia Sinica, Taipei, Taiwan.
- Bioinformatics Program, Institute of Information Science, Taiwan International Graduate Program, Academia Sinica, Taipei, Taiwan.
- Division of Physics, National Center for Theoretical Sciences, National Taiwan University, Taipei, Taiwan.
| | - Shu-Hsing Wu
- Institute of Plant and Microbial Biology, Academia Sinica, Taipei, Taiwan.
- Genome and Systems Biology Degree Program, Academia Sinica and National Taiwan University, Taipei, Taiwan.
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36
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Fernandes G, Tran H, Andrieu M, Diaw Y, Perez Romero C, Fradin C, Coppey M, Walczak AM, Dostatni N. Synthetic reconstruction of the hunchback promoter specifies the role of Bicoid, Zelda and Hunchback in the dynamics of its transcription. eLife 2022; 11:74509. [PMID: 35363606 PMCID: PMC8975551 DOI: 10.7554/elife.74509] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2021] [Accepted: 03/10/2022] [Indexed: 11/23/2022] Open
Abstract
For over 40 years, the Bicoid-hunchback (Bcd-hb) system in the fruit fly embryo has been used as a model to study how positional information in morphogen concentration gradients is robustly translated into step-like responses. A body of quantitative comparisons between theory and experiment have since questioned the initial paradigm that the sharp hb transcription pattern emerges solely from diffusive biochemical interactions between the Bicoid transcription factor and the gene promoter region. Several alternative mechanisms have been proposed, such as additional sources of positional information, positive feedback from Hb proteins or out-of-equilibrium transcription activation. By using the MS2-MCP RNA-tagging system and analysing in real time, the transcription dynamics of synthetic reporters for Bicoid and/or its two partners Zelda and Hunchback, we show that all the early hb expression pattern features and temporal dynamics are compatible with an equilibrium model with a short decay length Bicoid activity gradient as a sole source of positional information. Meanwhile, Bicoid’s partners speed-up the process by different means: Zelda lowers the Bicoid concentration threshold required for transcriptional activation while Hunchback reduces burstiness and increases the polymerase firing rate.
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Affiliation(s)
- Gonçalo Fernandes
- Institut Curie, Université PSL, Sorbonne Université, CNRS, Nuclear Dynamics, Paris, France
| | - Huy Tran
- Institut Curie, Université PSL, Sorbonne Université, CNRS, Nuclear Dynamics, Paris, France.,Laboratoire de Physique de l'École Normale Supérieure, CNRS, Université PSL, Sorbonne Université and Université de Paris, Paris, France
| | - Maxime Andrieu
- Institut Curie, Université PSL, Sorbonne Université, CNRS, Nuclear Dynamics, Paris, France
| | - Youssoupha Diaw
- Institut Curie, Université PSL, Sorbonne Université, CNRS, Nuclear Dynamics, Paris, France
| | - Carmina Perez Romero
- Department of Biochemistry and Biomedical Sciences, McMaster University, Hamilton, Canada
| | - Cécile Fradin
- Department of Biochemistry and Biomedical Sciences, McMaster University, Hamilton, Canada.,Department of Physics and Astronomy, McMaster University, Hamilton, Canada
| | - Mathieu Coppey
- Institut Curie, Université PSL, Sorbonne Université, CNRS UMR168, Laboratoire Physico Chimie Curie, Paris, France
| | - Aleksandra M Walczak
- Laboratoire de Physique de l'École Normale Supérieure, CNRS, Université PSL, Sorbonne Université and Université de Paris, Paris, France
| | - Nathalie Dostatni
- Institut Curie, Université PSL, Sorbonne Université, CNRS, Nuclear Dynamics, Paris, France
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37
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Wen Y, Xie D, Liu Z. Advances in protein analysis in single live cells: principle, instrumentation and applications. Trends Analyt Chem 2022. [DOI: 10.1016/j.trac.2022.116619] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
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38
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Bowles JR, Hoppe C, Ashe HL, Rattray M. Scalable inference of transcriptional kinetic parameters from MS2 time series data. Bioinformatics 2022; 38:1030-1036. [PMID: 34788793 PMCID: PMC8796374 DOI: 10.1093/bioinformatics/btab765] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2020] [Revised: 07/22/2021] [Accepted: 11/03/2021] [Indexed: 02/04/2023] Open
Abstract
MOTIVATION The MS2-MCP (MS2 coat protein) live imaging system allows for visualization of transcription dynamics through the introduction of hairpin stem-loop sequences into a gene. A fluorescent signal at the site of nascent transcription in the nucleus quantifies mRNA production. Computational modelling can be used to infer the promoter states along with the kinetic parameters governing transcription, such as promoter switching frequency and polymerase loading rate. However, modelling of the fluorescent trace presents a challenge due its persistence; the observed fluorescence at a given time point depends on both current and previous promoter states. A compound state Hidden Markov Model (cpHMM) was recently introduced to allow inference of promoter activity from MS2-MCP data. However, the computational time for inference scales exponentially with gene length and the cpHMM is therefore not currently practical for application to many eukaryotic genes. RESULTS We present a scalable implementation of the cpHMM for fast inference of promoter activity and transcriptional kinetic parameters. This new method can model genes of arbitrary length through the use of a time-adaptive truncated compound state space. The truncated state space provides a good approximation to the full state space by retaining the most likely set of states at each time during the forward pass of the algorithm. Testing on MS2-MCP fluorescent data collected from early Drosophila melanogaster embryos indicates that the method provides accurate inference of kinetic parameters within a computationally feasible timeframe. The inferred promoter traces generated by the model can also be used to infer single-cell transcriptional parameters. AVAILABILITY AND IMPLEMENTATION Python implementation is available at https://github.com/ManchesterBioinference/burstInfer, along with code to reproduce the examples presented here. SUPPLEMENTARY INFORMATION Supplementary data are available at Bioinformatics online.
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Affiliation(s)
- Jonathan R Bowles
- Faculty of Biology, Medicine and Health, The University of Manchester, Manchester M13 9PT, UK
| | - Caroline Hoppe
- Faculty of Biology, Medicine and Health, The University of Manchester, Manchester M13 9PT, UK
- Department of Genetics, Yale University School of Medicine, New Haven, CT 06510, USA
| | - Hilary L Ashe
- Faculty of Biology, Medicine and Health, The University of Manchester, Manchester M13 9PT, UK
| | - Magnus Rattray
- Faculty of Biology, Medicine and Health, The University of Manchester, Manchester M13 9PT, UK
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39
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Transcriptional Regulation and Implications for Controlling Hox Gene Expression. J Dev Biol 2022; 10:jdb10010004. [PMID: 35076545 PMCID: PMC8788451 DOI: 10.3390/jdb10010004] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2021] [Revised: 01/04/2022] [Accepted: 01/06/2022] [Indexed: 02/06/2023] Open
Abstract
Hox genes play key roles in axial patterning and regulating the regional identity of cells and tissues in a wide variety of animals from invertebrates to vertebrates. Nested domains of Hox expression generate a combinatorial code that provides a molecular framework for specifying the properties of tissues along the A–P axis. Hence, it is important to understand the regulatory mechanisms that coordinately control the precise patterns of the transcription of clustered Hox genes required for their roles in development. New insights are emerging about the dynamics and molecular mechanisms governing transcriptional regulation, and there is interest in understanding how these may play a role in contributing to the regulation of the expression of the clustered Hox genes. In this review, we summarize some of the recent findings, ideas and emerging mechanisms underlying the regulation of transcription in general and consider how they may be relevant to understanding the transcriptional regulation of Hox genes.
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40
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Chen M, Luo S, Cao M, Guo C, Zhou T, Zhang J. Exact distributions for stochastic gene expression models with arbitrary promoter architecture and translational bursting. Phys Rev E 2022; 105:014405. [PMID: 35193181 DOI: 10.1103/physreve.105.014405] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2021] [Accepted: 12/14/2021] [Indexed: 11/07/2022]
Abstract
Gene expression in individual cells is inherently variable and sporadic, leading to cell-to-cell variability in mRNA and protein levels. Recent single-cell and single-molecule experiments indicate that promoter architecture and translational bursting play significant roles in controlling gene expression noise and generating the phenotypic diversity that life exhibits. To quantitatively understand the impact of these factors, it is essential to construct an accurate mathematical description of stochastic gene expression and find the exact analytical results, which is a formidable task. Here, we develop a stochastic model of bursty gene expression, which considers the complex promoter architecture governing the variability in mRNA expression and a general distribution characterizing translational burst. We derive the analytical expression for the corresponding protein steady-state distribution and all moment statistics of protein counts. We show that the total protein noise can be decomposed into three parts: the low-copy noise of protein due to probabilistic individual birth and death events, the noise due to stochastic switching between promoter states, and the noise resulting from translational busting. The theoretical results derived provide quantitative insights into the biochemical mechanisms of stochastic gene expression.
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Affiliation(s)
- Meiling Chen
- Guangdong Province Key Laboratory of Computational Science, Guangzhou 510275, People's Republic of China.,School of Mathematics, Sun Yat-Sen University, Guangzhou 510275, People's Republic of China
| | - Songhao Luo
- Guangdong Province Key Laboratory of Computational Science, Guangzhou 510275, People's Republic of China.,School of Mathematics, Sun Yat-Sen University, Guangzhou 510275, People's Republic of China
| | - Mengfang Cao
- Guangdong Province Key Laboratory of Computational Science, Guangzhou 510275, People's Republic of China.,School of Mathematics, Sun Yat-Sen University, Guangzhou 510275, People's Republic of China
| | - Chengjun Guo
- School of Mathematics and Statistics, Guangdong University of Technology, Guangzhou 510275, People's Republic of China
| | - Tianshou Zhou
- Guangdong Province Key Laboratory of Computational Science, Guangzhou 510275, People's Republic of China.,School of Mathematics, Sun Yat-Sen University, Guangzhou 510275, People's Republic of China
| | - Jiajun Zhang
- Guangdong Province Key Laboratory of Computational Science, Guangzhou 510275, People's Republic of China.,School of Mathematics, Sun Yat-Sen University, Guangzhou 510275, People's Republic of China
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41
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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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42
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Cable J, Elowitz MB, Domingos AI, Habib N, Itzkovitz S, Hamidzada H, Balzer MS, Yanai I, Liberali P, Whited J, Streets A, Cai L, Stergachis AB, Hong CKY, Keren L, Guilliams M, Alon U, Shalek AK, Hamel R, Pfau SJ, Raj A, Quake SR, Zhang NR, Fan J, Trapnell C, Wang B, Greenwald NF, Vento-Tormo R, Santos SDM, Spencer SL, Garcia HG, Arekatla G, Gaiti F, Arbel-Goren R, Rulands S, Junker JP, Klein AM, Morris SA, Murray JI, Galloway KE, Ratz M, Romeike M. Single cell biology-a Keystone Symposia report. Ann N Y Acad Sci 2021; 1506:74-97. [PMID: 34605044 DOI: 10.1111/nyas.14692] [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: 08/24/2021] [Accepted: 08/24/2021] [Indexed: 11/27/2022]
Abstract
Single cell biology has the potential to elucidate many critical biological processes and diseases, from development and regeneration to cancer. Single cell analyses are uncovering the molecular diversity of cells, revealing a clearer picture of the variation among and between different cell types. New techniques are beginning to unravel how differences in cell state-transcriptional, epigenetic, and other characteristics-can lead to different cell fates among genetically identical cells, which underlies complex processes such as embryonic development, drug resistance, response to injury, and cellular reprogramming. Single cell technologies also pose significant challenges relating to processing and analyzing vast amounts of data collected. To realize the potential of single cell technologies, new computational approaches are needed. On March 17-19, 2021, experts in single cell biology met virtually for the Keystone eSymposium "Single Cell Biology" to discuss advances both in single cell applications and technologies.
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Affiliation(s)
| | - Michael B Elowitz
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, California.,Howard Hughes Medical Institute, California Institute of Technology, Pasadena, California
| | - Ana I Domingos
- Department of Physiology, Anatomy & Genetics, Oxford University, Oxford, United Kingdom.,The Howard Hughes Medical Institute, New York, New York
| | - Naomi Habib
- Cell Circuits Program, Broad Institute, Cambridge, Massachusetts.,Edmond & Lily Safra Center for Brain Sciences, The Hebrew University of Jerusalem, Jerusalem, Israel
| | - Shalev Itzkovitz
- Department of Molecular Cell Biology, Weizmann Institute of Science, Rehovot, Israel
| | - Homaira Hamidzada
- Toronto General Hospital Research Institute, University Health Network; Translational Biology and Engineering Program, Ted Rogers Centre for Heart Research and Department of Immunology, University of Toronto, Toronto, Ontario, Canada
| | - Michael S Balzer
- Renal, Electrolyte, and Hypertension Division, Department of Medicine and Institute for Diabetes, Obesity, and Metabolism, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Itai Yanai
- Institute for Computational Medicine, NYU Langone Health, New York, New York
| | - Prisca Liberali
- Friedrich Miescher Institute for Biomedical Research (FMI), Basel, Switzerland
| | - Jessica Whited
- Department of Stem Cell and Regenerative Biology, Harvard University, Cambridge, Massachusetts
| | - Aaron Streets
- Department of Bioengineering and Center for Computational Biology, University of California, Berkeley, Berkeley, California.,Chan Zuckerberg Biohub, San Francisco, California
| | - Long Cai
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, California
| | - Andrew B Stergachis
- Division of Medical Genetics, Department of Medicine, University of Washington, Seattle, Washington; and Brotman Baty Institute for Precision Medicine, Seattle, Washington
| | - Clarice Kit Yee Hong
- Edison Center for Genome Sciences and Systems Biology, Washington University in St. Louis, St. Louis, Missouri.,Department of Genetics, Washington University in St. Louis, St. Louis, Missouri
| | - Leeat Keren
- Department of Molecular Cell Biology, Weizmann Institute of Science, Rehovot, Israel.,Department of Pathology, School of Medicine, Stanford University, Stanford, California
| | - Martin Guilliams
- Laboratory of Myeloid Cell Biology in Tissue Homeostasis and Regeneration, VIB-UGent Center for Inflammation Research, and Unit of Immunoregulation and Mucosal Immunology, VIB Inflammation Research Center, and Department of Biomedical Molecular Biology, Ghent University, Ghent, Belgium
| | - Uri Alon
- Faculty of Sciences, Department of Human Biology, University of Haifa, Haifa, Israel
| | - Alex K Shalek
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, Massachusetts
| | - Regan Hamel
- Department of Clinical Neurosciences and NIHR Biomedical Research Centre, University of Cambridge, Cambridge, United Kingdom
| | - Sarah J Pfau
- Department of Neurobiology, Harvard Medical School, Boston, Massachusetts
| | - Arjun Raj
- Department of Genetics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania.,Department of Bioengineering, School of Engineering and Applied Sciences, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Stephen R Quake
- Chan Zuckerberg Biohub, San Francisco, California.,Department of Bioengineering, Stanford University, Stanford, California.,Department of Applied Physics, Stanford University, Stanford, California
| | - Nancy R Zhang
- Graduate Group in Genomics and Computational Biology and Department of Statistics, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Jean Fan
- Department of Biomedical Engineering, Johns Hopkins University, Baltimore, Maryland
| | - Cole Trapnell
- Department of Genome Sciences, University of Washington School of Medicine; Brotman Baty Institute for Precision Medicine; and Allen Discovery Center for Cell Lineage Tracing, Seattle, Washington
| | - Bo Wang
- Department of Bioengineering, Stanford University, Stanford, California.,Department of Developmental Biology, Stanford University School of Medicine, Stanford, California
| | - Noah F Greenwald
- Department of Pathology, School of Medicine, Stanford University, Stanford, California
| | | | | | - Sabrina L Spencer
- Department of Biochemistry and BioFrontiers Institute, University of Colorado Boulder, Boulder, Colorado
| | - Hernan G Garcia
- Department of Physics; Biophysics Graduate Group; Department of Molecular and Cell Biology; and Institute for Quantitative Biosciences-QB3, University of California at Berkeley, Berkeley, California
| | | | - Federico Gaiti
- New York Genome Center and Meyer Cancer Center, Weill Cornell Medicine, New York, New York
| | - Rinat Arbel-Goren
- Department of Physics of Complex Systems, Weizmann Institute of Science, Rehovot, Israel
| | - Steffen Rulands
- Max Planck Institute for the Physics of Complex Systems, and Center for Systems Biology Dresden, Dresden, Germany
| | - Jan Philipp Junker
- Berlin Institute for Medical Systems Biology, Max Delbrück Center for Molecular Medicine, Berlin, Germany
| | - Allon M Klein
- Department of Systems Biology, Blavatnik Institute, Harvard Medical School, Boston, Massachusetts
| | - Samantha A Morris
- Department of Genetics, Washington University in St. Louis, St. Louis, Missouri.,Department of Developmental Biology and Center of Regenerative Medicine, Washington University School of Medicine, St. Louis, Missouri
| | - John I Murray
- Department of Genetics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Kate E Galloway
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts
| | - Michael Ratz
- Department of Cell and Molecular Biology, Karolinska Institute, Solna, Sweden
| | - Merrit Romeike
- Max Perutz Laboratories Vienna, University of Vienna, Vienna, Austria
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43
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Falo-Sanjuan J, Bray SJ. Membrane architecture and adherens junctions contribute to strong Notch pathway activation. Development 2021; 148:272068. [PMID: 34486648 PMCID: PMC8543148 DOI: 10.1242/dev.199831] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2021] [Accepted: 08/24/2021] [Indexed: 11/23/2022]
Abstract
The Notch pathway mediates cell-to-cell communication in a variety of tissues, developmental stages and organisms. Pathway activation relies on the interaction between transmembrane ligands and receptors on adjacent cells. As such, pathway activity could be influenced by the size, composition or dynamics of contacts between membranes. The initiation of Notch signalling in the Drosophila embryo occurs during cellularization, when lateral cell membranes and adherens junctions are first being deposited, allowing us to investigate the importance of membrane architecture and specific junctional domains for signalling. By measuring Notch-dependent transcription in live embryos, we established that it initiates while lateral membranes are growing and that signalling onset correlates with a specific phase in their formation. However, the length of the lateral membranes per se was not limiting. Rather, the adherens junctions, which assemble concurrently with membrane deposition, contributed to the high levels of signalling required for transcription, as indicated by the consequences of α-Catenin depletion. Together, these results demonstrate that the establishment of lateral membrane contacts can be limiting for Notch trans-activation and suggest that adherens junctions play an important role in modulating Notch activity. Summary: Measuring Notch-dependent transcription in live embryos reveals that features associated with lateral membranes are required for initiation of Notch signalling. Perturbing membrane growth or adherens junctions prevents normal activation.
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Affiliation(s)
- Julia Falo-Sanjuan
- Department of Physiology, Development and Neuroscience, University of Cambridge, Downing Street, Cambridge CB2 3DY, UK
| | - Sarah J Bray
- Department of Physiology, Development and Neuroscience, University of Cambridge, Downing Street, Cambridge CB2 3DY, UK
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44
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Wolf S, Wan Y, McDole K. Current approaches to fate mapping and lineage tracing using image data. Development 2021; 148:dev198994. [PMID: 34498046 DOI: 10.1242/dev.198994] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Visualizing, tracking and reconstructing cell lineages in developing embryos has been an ongoing effort for well over a century. Recent advances in light microscopy, labelling strategies and computational methods to analyse complex image datasets have enabled detailed investigations into the fates of cells. Combined with powerful new advances in genomics and single-cell transcriptomics, the field of developmental biology is able to describe the formation of the embryo like never before. In this Review, we discuss some of the different strategies and applications to lineage tracing in live-imaging data and outline software methodologies that can be applied to various cell-tracking challenges.
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Affiliation(s)
- Steffen Wolf
- MRC Laboratory of Molecular Biology, Cambridge Biomedical Campus, Cambridge CB2 0QH, UK
| | - Yinan Wan
- Biozentrum, University of Basel, Basel, 4056, Switzerland
| | - Katie McDole
- MRC Laboratory of Molecular Biology, Cambridge Biomedical Campus, Cambridge CB2 0QH, UK
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45
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Sloutskin A, Shir-Shapira H, Freiman RN, Juven-Gershon T. The Core Promoter Is a Regulatory Hub for Developmental Gene Expression. Front Cell Dev Biol 2021; 9:666508. [PMID: 34568311 PMCID: PMC8461331 DOI: 10.3389/fcell.2021.666508] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2021] [Accepted: 08/25/2021] [Indexed: 11/13/2022] Open
Abstract
The development of multicellular organisms and the uniqueness of each cell are achieved by distinct transcriptional programs. Multiple processes that regulate gene expression converge at the core promoter region, an 80 bp region that directs accurate transcription initiation by RNA polymerase II (Pol II). In recent years, it has become apparent that the core promoter region is not a passive DNA component, but rather an active regulatory module of transcriptional programs. Distinct core promoter compositions were demonstrated to result in different transcriptional outputs. In this mini-review, we focus on the role of the core promoter, particularly its downstream region, as the regulatory hub for developmental genes. The downstream core promoter element (DPE) was implicated in the control of evolutionarily conserved developmental gene regulatory networks (GRNs) governing body plan in both the anterior-posterior and dorsal-ventral axes. Notably, the composition of the basal transcription machinery is not universal, but rather promoter-dependent, highlighting the importance of specialized transcription complexes and their core promoter target sequences as key hubs that drive embryonic development, differentiation and morphogenesis across metazoan species. The extent of transcriptional activation by a specific enhancer is dependent on its compatibility with the relevant core promoter. The core promoter content also regulates transcription burst size. Overall, while for many years it was thought that the specificity of gene expression is primarily determined by enhancers, it is now clear that the core promoter region comprises an important regulatory module in the intricate networks of developmental gene expression.
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Affiliation(s)
- Anna Sloutskin
- The Mina and Everard Goodman Faculty of Life Sciences, Bar-Ilan University, Ramat Gan, Israel
| | - Hila Shir-Shapira
- The Mina and Everard Goodman Faculty of Life Sciences, Bar-Ilan University, Ramat Gan, Israel
| | - Richard N. Freiman
- Department of Molecular Biology, Cell Biology and Biochemistry, Brown University, Providence, RI, United States
| | - Tamar Juven-Gershon
- The Mina and Everard Goodman Faculty of Life Sciences, Bar-Ilan University, Ramat Gan, Israel
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46
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Basyuk E, Rage F, Bertrand E. RNA transport from transcription to localized translation: a single molecule perspective. RNA Biol 2021; 18:1221-1237. [PMID: 33111627 PMCID: PMC8354613 DOI: 10.1080/15476286.2020.1842631] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2020] [Revised: 10/21/2020] [Accepted: 10/22/2020] [Indexed: 12/21/2022] Open
Abstract
Transport of mRNAs is an important step of gene expression, which brings the genetic message from the DNA in the nucleus to a precise cytoplasmic location in a regulated fashion. Perturbation of this process can lead to pathologies such as developmental and neurological disorders. In this review, we discuss recent advances in the field of mRNA transport made using single molecule fluorescent imaging approaches. We present an overview of these approaches in fixed and live cells and their input in understanding the key steps of mRNA journey: transport across the nucleoplasm, export through the nuclear pores and delivery to its final cytoplasmic location. This review puts a particular emphasis on the coupling of mRNA transport with translation, such as localization-dependent translational regulation and translation-dependent mRNA localization. We also highlight the recently discovered translation factories, and how cellular and viral RNAs can hijack membrane transport systems to travel in the cytoplasm.
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Affiliation(s)
- Eugenia Basyuk
- Institut de Génétique Humaine, CNRS-UMR9002, Univ Montpellier, Montpellier, France
- Present address: Laboratoire de Microbiologie Fondamentale et Pathogénicité, CNRS-UMR 5234, Université de Bordeaux, Bordeaux, France
| | - Florence Rage
- Institut de Génétique Moléculaire de Montpellier, CNRS-UMR5535, Univ Montpellier, Montpellier, France
| | - Edouard Bertrand
- Institut de Génétique Humaine, CNRS-UMR9002, Univ Montpellier, Montpellier, France
- Institut de Génétique Moléculaire de Montpellier, CNRS-UMR5535, Univ Montpellier, Montpellier, France
- Equipe Labélisée Ligue Nationale Contre Le Cancer, Montpellier, France
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47
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Alamos S, Reimer A, Niyogi KK, Garcia HG. Quantitative imaging of RNA polymerase II activity in plants reveals the single-cell basis of tissue-wide transcriptional dynamics. NATURE PLANTS 2021; 7:1037-1049. [PMID: 34373604 PMCID: PMC8616715 DOI: 10.1038/s41477-021-00976-0] [Citation(s) in RCA: 27] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/15/2020] [Accepted: 06/22/2021] [Indexed: 05/18/2023]
Abstract
The responses of plants to their environment are often dependent on the spatiotemporal dynamics of transcriptional regulation. While live-imaging tools have been used extensively to quantitatively capture rapid transcriptional dynamics in living animal cells, the lack of implementation of these technologies in plants has limited concomitant quantitative studies in this kingdom. Here, we applied the PP7 and MS2 RNA-labelling technologies for the quantitative imaging of RNA polymerase II activity dynamics in single cells of living plants as they respond to experimental treatments. Using this technology, we counted nascent RNA transcripts in real time in Nicotiana benthamiana (tobacco) and Arabidopsis thaliana. Examination of heat shock reporters revealed that plant tissues respond to external signals by modulating the proportion of cells that switch from an undetectable basal state to a high-transcription state, instead of modulating the rate of transcription across all cells in a graded fashion. This switch-like behaviour, combined with cell-to-cell variability in transcription rate, results in mRNA production variability spanning three orders of magnitude. We determined that cellular heterogeneity stems mainly from stochasticity intrinsic to individual alleles instead of variability in cellular composition. Together, our results demonstrate that it is now possible to quantitatively study the dynamics of transcriptional programs in single cells of living plants.
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Affiliation(s)
- Simon Alamos
- Department of Plant and Microbial Biology, University of California Berkeley, Berkeley, CA, USA
| | - Armando Reimer
- Biophysics Graduate Group, University of California Berkeley, Berkeley, CA, USA
| | - Krishna K Niyogi
- Department of Plant and Microbial Biology, University of California Berkeley, Berkeley, CA, USA.
- Howard Hughes Medical Institute, University of California Berkeley, Berkeley, CA, USA.
- Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA.
| | - Hernan G Garcia
- Biophysics Graduate Group, University of California Berkeley, Berkeley, CA, USA.
- Department of Molecular and Cell Biology, University of California Berkeley, Berkeley, CA, USA.
- Department of Physics, University of California Berkeley, Berkeley, CA, USA.
- Institute for Quantitative Biosciences-QB3, University of California Berkeley, Berkeley, CA, USA.
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48
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Zhang Z, Deng Q, Wang Z, Chen Y, Zhou T. Exact results for queuing models of stochastic transcription with memory and crosstalk. Phys Rev E 2021; 103:062414. [PMID: 34271765 DOI: 10.1103/physreve.103.062414] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2021] [Accepted: 06/03/2021] [Indexed: 11/07/2022]
Abstract
Gene transcription is a complex multistep biochemical process, which can create memory between individual reaction events. On the other hand, many inducible genes, when activated by external cues, are often coregulated by several competitive pathways with crosstalk. This raises an unexplored question: how do molecular memory and crosstalk together affect gene expressions? To address this question, we introduce a queuing model of stochastic transcription, where two crossing signaling pathways are used to direct gene activation in response to external signals and memory functions to model multistep reaction processes involved in transcription. We first establish, based on the total probability principle, the chemical master equation for this queuing model, and then we derive, based on the binomial moment approach, exact expressions for statistical quantities (including distributions) of mRNA, which provide insights into the roles of crosstalk and memory in controlling the mRNA level and noise. We find that molecular memory of gene activation decreases the mRNA level but increases the mRNA noise, and double activation pathways always reduce the mRNA noise in contrast to a single pathway. In addition, we find that molecular memory can make the mRNA bimodality disappear.
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Affiliation(s)
- Zhenquan Zhang
- Guangdong Province Key Laboratory of Computational Science, School of Mathematics, Sun Yat-sen University, Guangzhou 510275, China
| | - Qiqi Deng
- Guangdong Province Key Laboratory of Computational Science, School of Mathematics, Sun Yat-sen University, Guangzhou 510275, China
| | - Zihao Wang
- Guangdong Province Key Laboratory of Computational Science, School of Mathematics, Sun Yat-sen University, Guangzhou 510275, China
| | - Yiren Chen
- College of Mathematics and Statistics, Shenzhen University, Shenzhen 518060, China
| | - Tianshou Zhou
- Guangdong Province Key Laboratory of Computational Science, School of Mathematics, Sun Yat-sen University, Guangzhou 510275, China
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49
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Alvarez JM, Brooks MD, Swift J, Coruzzi GM. Time-Based Systems Biology Approaches to Capture and Model Dynamic Gene Regulatory Networks. ANNUAL REVIEW OF PLANT BIOLOGY 2021; 72:105-131. [PMID: 33667112 PMCID: PMC9312366 DOI: 10.1146/annurev-arplant-081320-090914] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
All aspects of transcription and its regulation involve dynamic events. However, capturing these dynamic events in gene regulatory networks (GRNs) offers both a promise and a challenge. The promise is that capturing and modeling the dynamic changes in GRNs will allow us to understand how organisms adapt to a changing environment. The ability to mount a rapid transcriptional response to environmental changes is especially important in nonmotile organisms such as plants. The challenge is to capture these dynamic, genome-wide events and model them in GRNs. In this review, we cover recent progress in capturing dynamic interactions of transcription factors with their targets-at both the local and genome-wide levels-and how they are used to learn how GRNs operate as a function of time. We also discuss recent advances that employ time-based machine learning approaches to forecast gene expression at future time points, a key goal of systems biology.
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Affiliation(s)
- Jose M Alvarez
- Centro de Genómica y Bioinformática, Facultad de Ciencias, Universidad Mayor, Santiago, Chile
- ANID-Millennium Science Initiative Program-Millennium Institute for Integrative Biology (iBio), Santiago, Chile
| | - Matthew D Brooks
- Global Change and Photosynthesis Research Unit, US Department of Agriculture Agricultural Research Service, Urbana, Illinois 61801, USA
| | - Joseph Swift
- Salk Institute for Biological Studies, La Jolla, California 92037, USA
| | - Gloria M Coruzzi
- Center for Genomics and Systems Biology, Department of Biology, New York University, New York, NY 10003, USA;
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Toudji-Zouaz A, Bertrand V, Barrière A. Imaging of native transcription and transcriptional dynamics in vivo using a tagged Argonaute protein. Nucleic Acids Res 2021; 49:e86. [PMID: 34107044 PMCID: PMC8421136 DOI: 10.1093/nar/gkab469] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2020] [Revised: 04/16/2021] [Accepted: 05/18/2021] [Indexed: 12/26/2022] Open
Abstract
A flexible method to image unmodified transcripts and transcription in vivo would be a valuable tool to understand the regulation and dynamics of transcription. Here, we present a novel approach to follow native transcription, with fluorescence microscopy, in live C. elegans. By using the fluorescently tagged Argonaute protein NRDE-3, programmed by exposure to defined dsRNA to bind to nascent transcripts of the gene of interest, we demonstrate transcript labelling of multiple genes, at the transcription site and in the cytoplasm. This flexible approach does not require genetic manipulation, and can be easily scaled up by relying on whole-genome dsRNA libraries. We apply this method to image the transcriptional dynamics of the heat-shock inducible gene hsp-4 (a member of the hsp70 family), as well as two transcription factors: ttx-3 (a LHX2/9 orthologue) in embryos, and hlh-1 (a MyoD orthologue) in larvae, respectively involved in neuronal and muscle development.
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Affiliation(s)
- Amel Toudji-Zouaz
- Aix Marseille University, CNRS, IBDM, Turing Centre for Living Systems, Marseille, France
| | - Vincent Bertrand
- Aix Marseille University, CNRS, IBDM, Turing Centre for Living Systems, Marseille, France
| | - Antoine Barrière
- Aix Marseille University, CNRS, IBDM, Turing Centre for Living Systems, Marseille, France
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