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Abstract
Exonic splice enhancers (ESEs) are short nucleotide motifs, enriched near exon ends, that enhance the recognition of the splice site and thus promote splicing. Are intronless genes under selection to avoid these motifs so as not to attract the splicing machinery to an mRNA that should not be spliced, thereby preventing the production of an aberrant transcript? Consistent with this possibility, we find that ESEs in putative recent retrocopies are at a higher density and evolving faster than those in other intronless genes, suggesting that they are being lost. Moreover, intronless genes are less dense in putative ESEs than intron-containing ones. However, this latter difference is likely due to the skewed base composition of intronless sequences, a skew that is in line with the general GC richness of few exon genes. Indeed, after controlling for such biases, we find that both intronless and intron-containing genes are denser in ESEs than expected by chance. Importantly, nucleotide-controlled analysis of evolutionary rates at synonymous sites in ESEs indicates that the ESEs in intronless genes are under purifying selection in both human and mouse. We conclude that on the loss of introns, some but not all, ESE motifs are lost, the remainder having functions beyond a role in splice promotion. These results have implications for the design of intronless transgenes and for understanding the causes of selection on synonymous sites.
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Affiliation(s)
- Rosina Savisaar
- Department of Biology and Biochemistry, The Milner Centre for Evolution, University of Bath, Bath, United Kingdom
| | - Laurence D Hurst
- Department of Biology and Biochemistry, The Milner Centre for Evolution, University of Bath, Bath, United Kingdom
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252
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Mellor J, Woloszczuk R, Howe FS. The Interleaved Genome. Trends Genet 2016; 32:57-71. [DOI: 10.1016/j.tig.2015.10.006] [Citation(s) in RCA: 42] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2015] [Revised: 09/29/2015] [Accepted: 10/23/2015] [Indexed: 12/25/2022]
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253
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Wu Z, Zhu D, Lin X, Miao J, Gu L, Deng X, Yang Q, Sun K, Zhu D, Cao X, Tsuge T, Dean C, Aoyama T, Gu H, Qu LJ. RNA Binding Proteins RZ-1B and RZ-1C Play Critical Roles in Regulating Pre-mRNA Splicing and Gene Expression during Development in Arabidopsis. THE PLANT CELL 2016; 28:55-73. [PMID: 26721863 PMCID: PMC4746689 DOI: 10.1105/tpc.15.00949] [Citation(s) in RCA: 60] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/09/2015] [Revised: 12/18/2015] [Accepted: 12/28/2015] [Indexed: 05/19/2023]
Abstract
Nuclear-localized RNA binding proteins are involved in various aspects of RNA metabolism, which in turn modulates gene expression. However, the functions of nuclear-localized RNA binding proteins in plants are poorly understood. Here, we report the functions of two proteins containing RNA recognition motifs, RZ-1B and RZ-1C, in Arabidopsis thaliana. RZ-1B and RZ-1C were localized to nuclear speckles and interacted with a spectrum of serine/arginine-rich (SR) proteins through their C termini. RZ-1C preferentially bound to purine-rich RNA sequences in vitro through its N-terminal RNA recognition motif. Disrupting the RNA binding activity of RZ-1C with SR proteins through overexpression of the C terminus of RZ-1C conferred defective phenotypes similar to those observed in rz-1b rz-1c double mutants, including delayed seed germination, reduced stature, and serrated leaves. Loss of function of RZ-1B and RZ-1C was accompanied by defective splicing of many genes and global perturbation of gene expression. In addition, we found that RZ-1C directly targeted FLOWERING LOCUS C (FLC), promoting efficient splicing of FLC introns and likely also repressing FLC transcription. Our findings highlight the critical role of RZ-1B/1C in regulating RNA splicing, gene expression, and many key aspects of plant development via interaction with proteins including SR proteins.
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Affiliation(s)
- Zhe Wu
- State Key Laboratory of Protein and Plant Gene Research, Peking-Tsinghua Center for Life Sciences, College of Life Sciences, Peking University, Beijing 100871, China Department of Cell and Developmental Biology, John Innes Centre, Norwich NR4 7UH, United Kingdom Institute for Chemical Research, Kyoto University, Gokasho Uji, Kyoto 611-0011, Japan
| | - Danling Zhu
- State Key Laboratory of Protein and Plant Gene Research, Peking-Tsinghua Center for Life Sciences, College of Life Sciences, Peking University, Beijing 100871, China
| | - Xiaoya Lin
- State Key Laboratory of Protein and Plant Gene Research, Peking-Tsinghua Center for Life Sciences, College of Life Sciences, Peking University, Beijing 100871, China
| | - Jin Miao
- State Key Laboratory of Protein and Plant Gene Research, Peking-Tsinghua Center for Life Sciences, College of Life Sciences, Peking University, Beijing 100871, China
| | - Lianfeng Gu
- Haixia Institute of Science and Technology, Fujian Agriculture and Forestry University, Fujian 350002, China
| | - Xian Deng
- State Key Laboratory of Plant Genomics and National Center for Plant Gene Research, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China
| | - Qian Yang
- State Key Laboratory of Protein and Plant Gene Research, Peking-Tsinghua Center for Life Sciences, College of Life Sciences, Peking University, Beijing 100871, China
| | - Kangtai Sun
- State Key Laboratory of Protein and Plant Gene Research, Peking-Tsinghua Center for Life Sciences, College of Life Sciences, Peking University, Beijing 100871, China
| | - Danmeng Zhu
- State Key Laboratory of Protein and Plant Gene Research, Peking-Tsinghua Center for Life Sciences, College of Life Sciences, Peking University, Beijing 100871, China
| | - Xiaofeng Cao
- State Key Laboratory of Plant Genomics and National Center for Plant Gene Research, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China
| | - Tomohiko Tsuge
- Institute for Chemical Research, Kyoto University, Gokasho Uji, Kyoto 611-0011, Japan
| | - Caroline Dean
- Department of Cell and Developmental Biology, John Innes Centre, Norwich NR4 7UH, United Kingdom
| | - Takashi Aoyama
- Institute for Chemical Research, Kyoto University, Gokasho Uji, Kyoto 611-0011, Japan
| | - Hongya Gu
- State Key Laboratory of Protein and Plant Gene Research, Peking-Tsinghua Center for Life Sciences, College of Life Sciences, Peking University, Beijing 100871, China National Plant Gene Research Center, Beijing 100101, China
| | - Li-Jia Qu
- State Key Laboratory of Protein and Plant Gene Research, Peking-Tsinghua Center for Life Sciences, College of Life Sciences, Peking University, Beijing 100871, China National Plant Gene Research Center, Beijing 100101, China
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254
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Kim TK, Shiekhattar R. Architectural and Functional Commonalities between Enhancers and Promoters. Cell 2015; 162:948-59. [PMID: 26317464 DOI: 10.1016/j.cell.2015.08.008] [Citation(s) in RCA: 221] [Impact Index Per Article: 24.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2015] [Indexed: 01/23/2023]
Abstract
With the explosion of genome-wide studies of regulated transcription, it has become clear that traditional definitions of enhancers and promoters need to be revisited. These control elements can now be characterized in terms of their local and regional architecture, their regulatory components, including histone modifications and associated binding factors, and their functional contribution to transcription. This Review discusses unifying themes between promoters and enhancers in transcriptional regulatory mechanisms.
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Affiliation(s)
- Tae-Kyung Kim
- Department of Neuroscience, University of Texas Southwestern Medical Center, Dallas, TX 75390-9111, USA.
| | - Ramin Shiekhattar
- University of Miami Miller School of Medicine, Sylvester Comprehensive Cancer Center, Department of Human Genetics, Biomedical Research Building, Room 719, 1501 NW 10(th) Avenue, Miami, FL 33136, USA.
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255
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Albrecht AS, Ørom UA. Bidirectional expression of long ncRNA/protein-coding gene pairs in cancer. Brief Funct Genomics 2015; 15:167-73. [DOI: 10.1093/bfgp/elv048] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
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256
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Ravens S, Yu C, Ye T, Stierle M, Tora L. Tip60 complex binds to active Pol II promoters and a subset of enhancers and co-regulates the c-Myc network in mouse embryonic stem cells. Epigenetics Chromatin 2015; 8:45. [PMID: 26550034 PMCID: PMC4636812 DOI: 10.1186/s13072-015-0039-z] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2015] [Accepted: 10/29/2015] [Indexed: 01/24/2023] Open
Abstract
Background Tip60 (KAT5) is the histone acetyltransferase (HAT) of the mammalian Tip60/NuA4 complex. While Tip60 is important for early mouse development and mouse embryonic stem cell (mESC) pluripotency, the function of Tip60 as reflected in a genome-wide context is not yet well understood. Results Gel filtration of nuclear mESCs extracts indicate incorporation of Tip60 into large molecular complexes and exclude the existence of large quantities of “free” Tip60 within the nuclei of ESCs. Thus, monitoring of Tip60 binding to the genome should reflect the behaviour of Tip60-containing complexes. The genome-wide mapping of Tip60 binding in mESCs by chromatin immunoprecipitation (ChIP) coupled with high-throughput sequencing (ChIP-seq) shows that the Tip60 complex is present at promoter regions of predominantly active genes that are bound by RNA polymerase II (Pol II) and contain the H3K4me3 histone mark. The coactivator HAT complexes, Tip60- and Mof (KAT8)-containing (NSL and MSL), show a global overlap at promoters, whereas distinct binding profiles at enhancers suggest different regulatory functions of each essential HAT complex. Interestingly, Tip60 enrichment peaks at about 200 bp downstream of the transcription start sites suggesting a function for the Tip60 complexes in addition to histone acetylation. The comparison of genome-wide binding profiles of Tip60 and c-Myc, a somatic cell reprogramming factor that binds predominantly to active genes in mESCs, demonstrate that Tip60 and c-Myc co-bind at 50–60 % of their binding sites. We also show that the Tip60 complex binds to a subset of bivalent developmental genes and defines a set of mESC-specific enhancer as well as super-enhancer regions. Conclusions Our study suggests that the Tip60 complex functions as a global transcriptional co-activator at most active Pol II promoters, co-regulates the ESC-specific c-Myc network, important for ESC self-renewal and cell metabolism and acts at a subset of active distal regulatory elements, or super enhancers, in mESCs. Electronic supplementary material The online version of this article (doi:10.1186/s13072-015-0039-z) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Sarina Ravens
- Cellular Signalling and Nuclear Dynamics Programme, Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC), CNRS UMR 7104, INSERM U964, Université de Strasbourg (UdS), BP 10142, 1 Rue Laurent Fries, CU de Strasbourg, 67404 Illkirch Cedex, France
| | - Changwei Yu
- Cellular Signalling and Nuclear Dynamics Programme, Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC), CNRS UMR 7104, INSERM U964, Université de Strasbourg (UdS), BP 10142, 1 Rue Laurent Fries, CU de Strasbourg, 67404 Illkirch Cedex, France
| | - Tao Ye
- Microarrays and Deep Sequencing Platform, Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC), CNRS UMR 7104, INSERM U964, UdS, BP 10142, CU de Strasbourg, 67404 Illkirch Cedex, France
| | - Matthieu Stierle
- Cellular Signalling and Nuclear Dynamics Programme, Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC), CNRS UMR 7104, INSERM U964, Université de Strasbourg (UdS), BP 10142, 1 Rue Laurent Fries, CU de Strasbourg, 67404 Illkirch Cedex, France
| | - Laszlo Tora
- Cellular Signalling and Nuclear Dynamics Programme, Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC), CNRS UMR 7104, INSERM U964, Université de Strasbourg (UdS), BP 10142, 1 Rue Laurent Fries, CU de Strasbourg, 67404 Illkirch Cedex, France
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257
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Weber APM. Discovering New Biology through Sequencing of RNA. PLANT PHYSIOLOGY 2015; 169:1524-31. [PMID: 26353759 PMCID: PMC4634082 DOI: 10.1104/pp.15.01081] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/13/2015] [Accepted: 09/09/2015] [Indexed: 05/08/2023]
Abstract
Sequencing of RNA (RNA-Seq) was invented approximately 1 decade ago and has since revolutionized biological research. This update provides a brief historic perspective on the development of RNA-Seq and then focuses on the application of RNA-Seq in qualitative and quantitative analyses of transcriptomes. Particular emphasis is given to aspects of data analysis. Since the wet-lab and data analysis aspects of RNA-Seq are still rapidly evolving and novel applications are continuously reported, a printed review will be rapidly outdated and can only serve to provide some examples and general guidelines for planning and conducting RNA-Seq studies. Hence, selected references to frequently update online resources are given.
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Affiliation(s)
- Andreas P M Weber
- Institute of Plant Biochemistry, Cluster of Excellence on Plant Science, Heinrich-Heine-Universität, D-40231 Duesseldorf, Germany
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258
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Reeder JE, Kwak YT, McNamara RP, Forst CV, D'Orso I. HIV Tat controls RNA Polymerase II and the epigenetic landscape to transcriptionally reprogram target immune cells. eLife 2015; 4. [PMID: 26488441 PMCID: PMC4733046 DOI: 10.7554/elife.08955] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2015] [Accepted: 10/20/2015] [Indexed: 12/22/2022] Open
Abstract
HIV encodes Tat, a small protein that facilitates viral transcription by binding an RNA structure (trans-activating RNA [TAR]) formed on nascent viral pre-messenger RNAs. Besides this well-characterized mechanism, Tat appears to modulate cellular transcription, but the target genes and molecular mechanisms remain poorly understood. We report here that Tat uses unexpected regulatory mechanisms to reprogram target immune cells to promote viral replication and rewire pathways beneficial for the virus. Tat functions through master transcriptional regulators bound at promoters and enhancers, rather than through cellular ‘TAR-like’ motifs, to both activate and repress gene sets sharing common functional annotations. Despite the complexity of transcriptional regulatory mechanisms in the cell, Tat precisely controls RNA polymerase II recruitment and pause release to fine-tune the initiation and elongation steps in target genes. We propose that a virus with a limited coding capacity has optimized its genome by evolving a small but ‘multitasking’ protein to simultaneously control viral and cellular transcription. DOI:http://dx.doi.org/10.7554/eLife.08955.001 The human immunodeficiency virus (HIV) reproduces and spreads throughout the body by hijacking human immune cells and causing them to copy the virus’s genetic information. As the virus multiplies, it also causes the death of the immune system cells that help the human body recognize and eliminate viruses. This allows the virus to multiply unchecked. Studies of the genetic material of HIV – which is in the form of single-stranded RNA molecules and contains only a handful of genes – have begun to reveal how the virus can wreak such havoc to the human immune system. A small protein encoded by the virus, called Tat, boosts the expression of HIV genes in infected immune cells by binding to a structure that forms on newly synthesized viral RNAs. Recent evidence suggests that HIV also changes the expression of human genes to make immune cells more hospitable to the virus. However, it was not known exactly which specific genes are targeted, or how the virus alters their expression. Now, Reeder, Kwak et al. reveal how the Tat protein alters the expression of more than 400 human genes. Rather than bind to the same structure seen in newly forming HIV RNAs, Tat turns on or off the expression of its human target genes by interacting with proteins that regulate human gene expression. In doing so, Tat is able to precisely control the activity of an enzyme called RNA Polymerase II that is necessary for the early steps of gene expression. Tat’s multitasking ability – boosting HIV gene expression at the same time as reprogramming human gene expression – helps explain how a virus with so little genetic material of its own can perform such a wide range of activities in infected cells. The work of Reeder, Kwak et al. suggests that Tat reshapes the human genome to position target genes in ways that allow them to be efficiently turned on or off. Future studies will further reveal how Tat accomplishes this genome remodeling during different stages of infection. In addition, further research is also necessary to look closely into the sets of genes targeted by Tat to find patterns of genes that work together to alter cell behavior, and investigate how these new behaviors allow HIV to thrive. DOI:http://dx.doi.org/10.7554/eLife.08955.002
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Affiliation(s)
- Jonathan E Reeder
- Department of Biological Sciences, University of Texas at Dallas, Richardson, United States.,Department of Microbiology, University of Texas Southwestern Medical Center, Dallas, United States
| | - Youn-Tae Kwak
- Department of Microbiology, University of Texas Southwestern Medical Center, Dallas, United States
| | - Ryan P McNamara
- Department of Microbiology, University of Texas Southwestern Medical Center, Dallas, United States
| | - Christian V Forst
- Department of Genetics and Genomic Sciences, Institute for Genomics and Multiscale Biology, Icahn School of Medicine at Mount Sinai, New York, United States
| | - Iván D'Orso
- Department of Microbiology, University of Texas Southwestern Medical Center, Dallas, United States
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259
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Beyond the Linear Genome: Paired-End Sequencing as a Biophysical Tool. Trends Cell Biol 2015; 25:716-719. [PMID: 26437592 DOI: 10.1016/j.tcb.2015.08.004] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2015] [Revised: 08/17/2015] [Accepted: 08/18/2015] [Indexed: 11/23/2022]
Abstract
Paired-end sequencing has enabled a variety of new methods for high-throughput interrogation of both genome structure and chromatin architecture. Here, we discuss how the paired-end paradigm can be used to interpret sequencing data as biophysical measurements of in vivo chromatin structure that report on single molecules in single cells.
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260
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Abstract
While a role of promoter-proximal RNA Polymerase II (Pol II) pausing in regulation of eukaryotic gene expression is implied, the mechanisms and dynamics of this process are poorly understood. We performed genome-wide analysis of short capped RNAs (scRNAs) and Pol II chromatin immunoprecipitation sequencing (ChIP-seq) in human breast cancer MCF-7 cells to better understand Pol II pausing (Samarakkody, A., Abbas, A., Scheidegger, A., Warns, J., Nnoli, O., Jokinen, B., Zarns, K., Kubat, B., Dhasarathy, A. and Nechaev, S. (2015) RNA polymerase II pausing can be retained or acquired during activation of genes involved in the epithelial to mesenchymal transition. Nucleic Acids Res43, 3938–3949). The data are available at the NCBI Gene Expression Omnibus under accession number GSE67041. For both ChIP and scRNA samples, we used paired end sequencing on the Illumina MiSeq instrument. For ChIP-seq, the use of paired end sequencing allowed us to avoid ambiguities in center-read definition. For scRNA seq, this allowed us to identify both the 5′-end and the 3′-end in the same run that represent, respectively, the transcription start sites and the locations of Pol II pausing. The sharpening of Pol II ChIP-seq metagene profiles when aligned against 5′-ends of scRNAs indicates that these RNAs can be used to define the start sites for the majority of mRNA transcription events.
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261
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262
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Catching Pol II in the act. Nat Methods 2015; 12:597. [DOI: 10.1038/nmeth.3467] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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263
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Padovan-Merhar O, Nair GP, Biaesch AG, Mayer A, Scarfone S, Foley SW, Wu AR, Churchman LS, Singh A, Raj A. Single mammalian cells compensate for differences in cellular volume and DNA copy number through independent global transcriptional mechanisms. Mol Cell 2015; 58:339-52. [PMID: 25866248 DOI: 10.1016/j.molcel.2015.03.005] [Citation(s) in RCA: 291] [Impact Index Per Article: 32.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2014] [Revised: 01/16/2015] [Accepted: 03/04/2015] [Indexed: 10/23/2022]
Abstract
Individual mammalian cells exhibit large variability in cellular volume, even with the same absolute DNA content, and so must compensate for differences in DNA concentration in order to maintain constant concentration of gene expression products. Using single-molecule counting and computational image analysis, we show that transcript abundance correlates with cellular volume at the single-cell level due to increased global transcription in larger cells. Cell fusion experiments establish that increased cellular content itself can directly increase transcription. Quantitative analysis shows that this mechanism measures the ratio of cellular volume to DNA content, most likely through sequestration of a transcriptional factor to DNA. Analysis of transcriptional bursts reveals a separate mechanism for gene dosage compensation after DNA replication that enables proper transcriptional output during early and late S phase. Our results provide a framework for quantitatively understanding the relationships among DNA content, cell size, and gene expression variability in single cells.
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Affiliation(s)
- Olivia Padovan-Merhar
- Department of Physics and Astronomy, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Gautham P Nair
- Department of Bioengineering, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Andrew G Biaesch
- Department of Bioengineering, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Andreas Mayer
- Department of Genetics, Harvard Medical School, Boston, MA 02115, USA
| | - Steven Scarfone
- Department of Physics and Astronomy, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Shawn W Foley
- Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Angela R Wu
- Department of Bioengineering, Stanford University, Stanford, CA 94305, USA
| | | | - Abhyudai Singh
- Department of Electrical and Computer Engineering, University of Delaware, Newark, DE 19716, USA
| | - Arjun Raj
- Department of Bioengineering, University of Pennsylvania, Philadelphia, PA 19104, USA.
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