1
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Fonseca A, Riveras E, Moyano TC, Alvarez JM, Rosa S, Gutiérrez RA. Dynamic changes in mRNA nucleocytoplasmic localization in the nitrate response of Arabidopsis roots. PLANT, CELL & ENVIRONMENT 2024. [PMID: 38950037 DOI: 10.1111/pce.15018] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/31/2023] [Revised: 05/23/2024] [Accepted: 06/14/2024] [Indexed: 07/03/2024]
Abstract
Nitrate is a nutrient and signal that regulates gene expression. The nitrate response has been extensively characterized at the organism, organ, and cell-type-specific levels, but intracellular mRNA dynamics remain unexplored. To characterize nuclear and cytoplasmic transcriptome dynamics in response to nitrate, we performed a time-course expression analysis after nitrate treatment in isolated nuclei, cytoplasm, and whole roots. We identified 402 differentially localized transcripts (DLTs) in response to nitrate treatment. Induced DLT genes showed rapid and transient recruitment of the RNA polymerase II, together with an increase in the mRNA turnover rates. DLTs code for genes involved in metabolic processes, localization, and response to stimulus indicating DLTs include genes with relevant functions for the nitrate response that have not been previously identified. Using single-molecule RNA FISH, we observed early nuclear accumulation of the NITRATE REDUCTASE 1 (NIA1) transcripts in their transcription sites. We found that transcription of NIA1, a gene showing delayed cytoplasmic accumulation, is rapidly and transiently activated; however, its transcripts become unstable when they reach the cytoplasm. Our study reveals the dynamic localization of mRNAs between the nucleus and cytoplasm as an emerging feature in the temporal control of gene expression in response to nitrate treatment in Arabidopsis roots.
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Affiliation(s)
- Alejandro Fonseca
- Millennium Institute for Integrative Biology (iBio), Santiago, Chile
- Center for Genome Regulation, Millennium Institute Center for Genome Regulation (CRG), Santiago, Chile
- Departamento de Genética Molecular y Microbiología, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile
- Department of Plant Biology, Swedish University of Agricultural Sciences (SLU), Uppsala, Sweden
| | - Eleodoro Riveras
- Millennium Institute for Integrative Biology (iBio), Santiago, Chile
- Center for Genome Regulation, Millennium Institute Center for Genome Regulation (CRG), Santiago, Chile
- Departamento de Genética Molecular y Microbiología, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Tomás C Moyano
- Millennium Institute for Integrative Biology (iBio), Santiago, Chile
- Center for Genome Regulation, Millennium Institute Center for Genome Regulation (CRG), Santiago, Chile
- Departamento de Genética Molecular y Microbiología, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile
- Centro de Biotecnología Vegetal, Facultad de Ciencias de la Vida, Universidad Andrés Bello, Santiago, Chile
| | - José M Alvarez
- Millennium Institute for Integrative Biology (iBio), Santiago, Chile
- Centro de Biotecnología Vegetal, Facultad de Ciencias de la Vida, Universidad Andrés Bello, Santiago, Chile
| | - Stefanie Rosa
- Department of Plant Biology, Swedish University of Agricultural Sciences (SLU), Uppsala, Sweden
| | - Rodrigo A Gutiérrez
- Millennium Institute for Integrative Biology (iBio), Santiago, Chile
- Center for Genome Regulation, Millennium Institute Center for Genome Regulation (CRG), Santiago, Chile
- Departamento de Genética Molecular y Microbiología, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile
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2
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Ma M, Szavits-Nossan J, Singh A, Grima R. Analysis of a detailed multi-stage model of stochastic gene expression using queueing theory and model reduction. Math Biosci 2024; 373:109204. [PMID: 38710441 DOI: 10.1016/j.mbs.2024.109204] [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: 01/23/2024] [Revised: 04/03/2024] [Accepted: 04/29/2024] [Indexed: 05/08/2024]
Abstract
We introduce a biologically detailed, stochastic model of gene expression describing the multiple rate-limiting steps of transcription, nuclear pre-mRNA processing, nuclear mRNA export, cytoplasmic mRNA degradation and translation of mRNA into protein. The processes in sub-cellular compartments are described by an arbitrary number of processing stages, thus accounting for a significantly finer molecular description of gene expression than conventional models such as the telegraph, two-stage and three-stage models of gene expression. We use two distinct tools, queueing theory and model reduction using the slow-scale linear-noise approximation, to derive exact or approximate analytic expressions for the moments or distributions of nuclear mRNA, cytoplasmic mRNA and protein fluctuations, as well as lower bounds for their Fano factors in steady-state conditions. We use these to study the phase diagram of the stochastic model; in particular we derive parametric conditions determining three types of transitions in the properties of mRNA fluctuations: from sub-Poissonian to super-Poissonian noise, from high noise in the nucleus to high noise in the cytoplasm, and from a monotonic increase to a monotonic decrease of the Fano factor with the number of processing stages. In contrast, protein fluctuations are always super-Poissonian and show weak dependence on the number of mRNA processing stages. Our results delineate the region of parameter space where conventional models give qualitatively incorrect results and provide insight into how the number of processing stages, e.g. the number of rate-limiting steps in initiation, splicing and mRNA degradation, shape stochastic gene expression by modulation of molecular memory.
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Affiliation(s)
- Muhan Ma
- School of Biological Sciences, University of Edinburgh, Edinburgh EH9 3BF, UK
| | | | - Abhyudai Singh
- Department of Electrical and Computer Engineering, University of Delaware, Newark DE 19716, USA
| | - Ramon Grima
- School of Biological Sciences, University of Edinburgh, Edinburgh EH9 3BF, UK.
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3
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Nemsick S, Hansen AS. Molecular models of bidirectional promoter regulation. Curr Opin Struct Biol 2024; 87:102865. [PMID: 38905929 DOI: 10.1016/j.sbi.2024.102865] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2023] [Revised: 03/30/2024] [Accepted: 05/27/2024] [Indexed: 06/23/2024]
Abstract
Approximately 11% of human genes are transcribed by a bidirectional promoter (BDP), defined as two genes with <1 kb between their transcription start sites. Despite their evolutionary conservation and enrichment for housekeeping genes and oncogenes, the regulatory role of BDPs remains unclear. BDPs have been suggested to facilitate gene coregulation and/or decrease expression noise. This review discusses these potential regulatory functions through the context of six prospective underlying mechanistic models: a single nucleosome free region, shared transcription factor/regulator binding, cooperative negative supercoiling, bimodal histone marks, joint activation by enhancer(s), and RNA-mediated recruitment of regulators. These molecular mechanisms may act independently and/or cooperatively to facilitate the coregulation and/or decreased expression noise predicted of BDPs.
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Affiliation(s)
- Sarah Nemsick
- Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA; The Gene Regulation Observatory, Broad Institute of MIT and Harvard, Cambridge, MA 02139, USA; Koch Institute for Integrative Cancer Research, Cambridge, MA 02139, USA
| | - Anders S Hansen
- Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA; The Gene Regulation Observatory, Broad Institute of MIT and Harvard, Cambridge, MA 02139, USA; Koch Institute for Integrative Cancer Research, Cambridge, MA 02139, USA.
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4
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Grandi C, Emmaneel M, Nelissen FHT, Roosenboom LWM, Petrova Y, Elzokla O, Hansen MMK. Decoupled degradation and translation enables noise modulation by poly(A) tails. Cell Syst 2024; 15:526-543.e7. [PMID: 38901403 DOI: 10.1016/j.cels.2024.05.004] [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: 04/05/2023] [Revised: 11/24/2023] [Accepted: 05/16/2024] [Indexed: 06/22/2024]
Abstract
Poly(A) tails are crucial for mRNA translation and degradation, but the exact relationship between tail length and mRNA kinetics remains unclear. Here, we employ a small library of identical mRNAs that differ only in their poly(A)-tail length to examine their behavior in human embryonic kidney cells. We find that tail length strongly correlates with mRNA degradation rates but is decoupled from translation. Interestingly, an optimal tail length of ∼100 nt displays the highest translation rate, which is identical to the average endogenous tail length measured by nanopore sequencing. Furthermore, poly(A)-tail length variability-a feature of endogenous mRNAs-impacts translation efficiency but not mRNA degradation rates. Stochastic modeling combined with single-cell tracking reveals that poly(A) tails provide cells with an independent handle to tune gene expression fluctuations by decoupling mRNA degradation and translation. Together, this work contributes to the basic understanding of gene expression regulation and has potential applications in nucleic acid therapeutics.
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Affiliation(s)
- Carmen Grandi
- Institute for Molecules and Materials, Radboud University, Heyendaalseweg 135, 6525 AJ Nijmegen, the Netherlands; Oncode Institute, Nijmegen, the Netherlands
| | - Martin Emmaneel
- Institute for Molecules and Materials, Radboud University, Heyendaalseweg 135, 6525 AJ Nijmegen, the Netherlands; Oncode Institute, Nijmegen, the Netherlands
| | - Frank H T Nelissen
- Institute for Molecules and Materials, Radboud University, Heyendaalseweg 135, 6525 AJ Nijmegen, the Netherlands; Oncode Institute, Nijmegen, the Netherlands
| | - Laura W M Roosenboom
- Institute for Molecules and Materials, Radboud University, Heyendaalseweg 135, 6525 AJ Nijmegen, the Netherlands
| | - Yoanna Petrova
- Institute for Molecules and Materials, Radboud University, Heyendaalseweg 135, 6525 AJ Nijmegen, the Netherlands
| | - Omnia Elzokla
- Institute for Molecules and Materials, Radboud University, Heyendaalseweg 135, 6525 AJ Nijmegen, the Netherlands
| | - Maike M K Hansen
- Institute for Molecules and Materials, Radboud University, Heyendaalseweg 135, 6525 AJ Nijmegen, the Netherlands; Oncode Institute, Nijmegen, the Netherlands.
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5
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Lin WH, Opoc FJG, Liao CW, Roy KR, Steinmetz LM, Leu JY. Histone deacetylase Hos2 regulates protein expression noise by potentially modulating the protein translation machinery. Nucleic Acids Res 2024:gkae432. [PMID: 38783136 DOI: 10.1093/nar/gkae432] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2024] [Revised: 05/05/2024] [Accepted: 05/09/2024] [Indexed: 05/25/2024] Open
Abstract
Non-genetic variations derived from expression noise at transcript or protein levels can result in cell-to-cell heterogeneity within an isogenic population. Although cells have developed strategies to reduce noise in some cellular functions, this heterogeneity can also facilitate varying levels of regulation and provide evolutionary benefits in specific environments. Despite several general characteristics of cellular noise having been revealed, the detailed molecular pathways underlying noise regulation remain elusive. Here, we established a dual-fluorescent reporter system in Saccharomyces cerevisiae and performed experimental evolution to search for mutations that increase expression noise. By analyzing evolved cells using bulk segregant analysis coupled with whole-genome sequencing, we identified the histone deacetylase Hos2 as a negative noise regulator. A hos2 mutant down-regulated multiple ribosomal protein genes and exhibited partially compromised protein translation, indicating that Hos2 may regulate protein expression noise by modulating the translation machinery. Treating cells with translation inhibitors or introducing mutations into several Hos2-regulated ribosomal protein genes-RPS9A, RPS28B and RPL42A-enhanced protein expression noise. Our study provides an effective strategy for identifying noise regulators and also sheds light on how cells regulate non-genetic variation through protein translation.
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Affiliation(s)
- Wei-Han Lin
- Doctoral Program in Microbial Genomics, National Chung Hsing University and Academia Sinica, Taiwan
- Institute of Molecular Biology, Academia Sinica, Taipei 115, Taiwan
| | - Florica J G Opoc
- Institute of Molecular Biology, Academia Sinica, Taipei 115, Taiwan
| | - Chia-Wei Liao
- Institute of Molecular Biology, Academia Sinica, Taipei 115, Taiwan
| | - Kevin R Roy
- Stanford Genome Technology Center, Stanford University, Palo Alto, CA 94304, USA
- Department of Genetics, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Lars M Steinmetz
- Stanford Genome Technology Center, Stanford University, Palo Alto, CA 94304, USA
- Department of Genetics, Stanford University School of Medicine, Stanford, CA 94305, USA
- European Molecular Biology Laboratory (EMBL), Genome Biology Unit, Heidelberg 69117, Germany
| | - Jun-Yi Leu
- Doctoral Program in Microbial Genomics, National Chung Hsing University and Academia Sinica, Taiwan
- Institute of Molecular Biology, Academia Sinica, Taipei 115, Taiwan
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6
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Hu X, van Sluijs B, García-Blay Ó, Stepanov Y, Rietrae K, Huck WTS, Hansen MMK. ARTseq-FISH reveals position-dependent differences in gene expression of micropatterned mESCs. Nat Commun 2024; 15:3918. [PMID: 38724524 PMCID: PMC11082235 DOI: 10.1038/s41467-024-48107-5] [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: 02/17/2023] [Accepted: 04/19/2024] [Indexed: 05/12/2024] Open
Abstract
Differences in gene-expression profiles between individual cells can give rise to distinct cell fate decisions. Yet how localisation on a micropattern impacts initial changes in mRNA, protein, and phosphoprotein abundance remains unclear. To identify the effect of cellular position on gene expression, we developed a scalable antibody and mRNA targeting sequential fluorescence in situ hybridisation (ARTseq-FISH) method capable of simultaneously profiling mRNAs, proteins, and phosphoproteins in single cells. We studied 67 (phospho-)protein and mRNA targets in individual mouse embryonic stem cells (mESCs) cultured on circular micropatterns. ARTseq-FISH reveals relative changes in both abundance and localisation of mRNAs and (phospho-)proteins during the first 48 hours of exit from pluripotency. We confirm these changes by conventional immunofluorescence and time-lapse microscopy. Chemical labelling, immunofluorescence, and single-cell time-lapse microscopy further show that cells closer to the edge of the micropattern exhibit increased proliferation compared to cells at the centre. Together these data suggest that while gene expression is still highly heterogeneous position-dependent differences in mRNA and protein levels emerge as early as 12 hours after LIF withdrawal.
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Affiliation(s)
- Xinyu Hu
- Institute for Molecules and Materials, Radboud University, Heyendaalseweg 135, 6525 AJ, Nijmegen, the Netherlands
- Oncode Institute, Nijmegen, The Netherlands
| | - Bob van Sluijs
- Institute for Molecules and Materials, Radboud University, Heyendaalseweg 135, 6525 AJ, Nijmegen, the Netherlands
| | - Óscar García-Blay
- Institute for Molecules and Materials, Radboud University, Heyendaalseweg 135, 6525 AJ, Nijmegen, the Netherlands
- Oncode Institute, Nijmegen, The Netherlands
| | - Yury Stepanov
- Institute for Molecules and Materials, Radboud University, Heyendaalseweg 135, 6525 AJ, Nijmegen, the Netherlands
| | - Koen Rietrae
- Institute for Molecules and Materials, Radboud University, Heyendaalseweg 135, 6525 AJ, Nijmegen, the Netherlands
| | - Wilhelm T S Huck
- Institute for Molecules and Materials, Radboud University, Heyendaalseweg 135, 6525 AJ, Nijmegen, the Netherlands.
| | - Maike M K Hansen
- Institute for Molecules and Materials, Radboud University, Heyendaalseweg 135, 6525 AJ, Nijmegen, the Netherlands.
- Oncode Institute, Nijmegen, The Netherlands.
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7
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Pina C. Contributions of transcriptional noise to leukaemia evolution: KAT2A as a case-study. Philos Trans R Soc Lond B Biol Sci 2024; 379:20230052. [PMID: 38432321 PMCID: PMC10909511 DOI: 10.1098/rstb.2023.0052] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2023] [Accepted: 12/04/2023] [Indexed: 03/05/2024] Open
Abstract
Transcriptional noise is proposed to participate in cell fate changes, but contributions to mammalian cell differentiation systems, including cancer, remain associative. Cancer evolution is driven by genetic variability, with modulatory or contributory participation of epigenetic variants. Accumulation of epigenetic variants enhances transcriptional noise, which can facilitate cancer cell fate transitions. Acute myeloid leukaemia (AML) is an aggressive cancer with strong epigenetic dependencies, characterized by blocked differentiation. It constitutes an attractive model to probe links between transcriptional noise and malignant cell fate regulation. Gcn5/KAT2A is a classical epigenetic transcriptional noise regulator. Its loss increases transcriptional noise and modifies cell fates in stem and AML cells. By reviewing the analysis of KAT2A-depleted pre-leukaemia and leukaemia models, I discuss that the net result of transcriptional noise is diversification of cell fates secondary to alternative transcriptional programmes. Cellular diversification can enable or hinder AML progression, respectively, by differentiation of cell types responsive to mutations, or by maladaptation of leukaemia stem cells. KAT2A-dependent noise-responsive genes participate in ribosome biogenesis and KAT2A loss destabilizes translational activity. I discuss putative contributions of perturbed translation to AML biology, and propose KAT2A loss as a model for mechanistic integration of transcriptional and translational control of noise and fate decisions. This article is part of a discussion meeting issue 'Causes and consequences of stochastic processes in development and disease'.
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Affiliation(s)
- Cristina Pina
- College of Health, Medicine and Life Sciences, Brunel University London, Kingston Lane, Uxbridge, London, UB8 3PH, United Kingdom
- CenGEM – Centre for Genome Engineering and Maintenance, Brunel University London, Kingston Lane, Uxbridge, London, UB8 3PH, United Kingdom
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8
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García-Blay Ó, Verhagen PGA, Martin B, Hansen MMK. Exploring the role of transcriptional and post-transcriptional processes in mRNA co-expression. Bioessays 2023; 45:e2300130. [PMID: 37926676 DOI: 10.1002/bies.202300130] [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: 07/12/2023] [Revised: 09/18/2023] [Accepted: 10/09/2023] [Indexed: 11/07/2023]
Abstract
Co-expression of two or more genes at the single-cell level is usually associated with functional co-regulation. While mRNA co-expression-measured as the correlation in mRNA levels-can be influenced by both transcriptional and post-transcriptional events, transcriptional regulation is typically considered dominant. We review and connect the literature describing transcriptional and post-transcriptional regulation of co-expression. To enhance our understanding, we integrate four datasets spanning single-cell gene expression data, single-cell promoter activity data and individual transcript half-lives. Confirming expectations, we find that positive co-expression necessitates promoter coordination and similar mRNA half-lives. Surprisingly, negative co-expression is favored by differences in mRNA half-lives, contrary to initial predictions from stochastic simulations. Notably, this association manifests specifically within clusters of genes. We further observe a striking compensation between promoter coordination and mRNA half-lives, which additional stochastic simulations suggest might give rise to the observed co-expression patterns. These findings raise intriguing questions about the functional advantages conferred by this compensation between distal kinetic steps.
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Affiliation(s)
- Óscar García-Blay
- Institute for Molecules and Materials, Radboud University, AJ, Nijmegen, the Netherlands
| | - Pieter G A Verhagen
- Institute for Molecules and Materials, Radboud University, AJ, Nijmegen, the Netherlands
| | - Benjamin Martin
- Institute for Molecules and Materials, Radboud University, AJ, Nijmegen, the Netherlands
| | - Maike M K Hansen
- Institute for Molecules and Materials, Radboud University, AJ, Nijmegen, the Netherlands
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9
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Martin B, Suter DM. Gene expression flux analysis reveals specific regulatory modalities of gene expression. iScience 2023; 26:107758. [PMID: 37701574 PMCID: PMC10493597 DOI: 10.1016/j.isci.2023.107758] [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: 01/17/2023] [Revised: 06/02/2023] [Accepted: 08/24/2023] [Indexed: 09/14/2023] Open
Abstract
The level of a given protein is determined by the synthesis and degradation rates of its mRNA and protein. While several studies have quantified the contribution of different gene expression steps in regulating protein levels, these are limited by using equilibrium approximations in out-of-equilibrium biological systems. Here, we introduce gene expression flux analysis to quantitatively dissect the dynamics of the expression level for specific proteins and use it to analyze published transcriptomics and proteomics datasets. Our analysis reveals distinct regulatory modalities shared by sets of genes with clear functional signatures. We also find that protein degradation plays a stronger role than expected in the adaptation of protein levels. These findings suggest that shared regulatory strategies can lead to versatile responses at the protein level and highlight the importance of going beyond equilibrium approximations to dissect the quantitative contribution of different steps of gene expression to protein dynamics.
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Affiliation(s)
- Benjamin Martin
- Institute of Bioengineering, School of Life Sciences, Ecole Polytechnique Fédérale de Lausanne (EPFL), 1015 Lausanne, Switzerland
| | - David M. Suter
- Institute of Bioengineering, School of Life Sciences, Ecole Polytechnique Fédérale de Lausanne (EPFL), 1015 Lausanne, Switzerland
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10
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Gorin G, Yoshida S, Pachter L. Assessing Markovian and Delay Models for Single-Nucleus RNA Sequencing. Bull Math Biol 2023; 85:114. [PMID: 37828255 DOI: 10.1007/s11538-023-01213-9] [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: 11/22/2022] [Accepted: 09/11/2023] [Indexed: 10/14/2023]
Abstract
The serial nature of reactions involved in the RNA life-cycle motivates the incorporation of delays in models of transcriptional dynamics. The models couple a transcriptional process to a fairly general set of delayed monomolecular reactions with no feedback. We provide numerical strategies for calculating the RNA copy number distributions induced by these models, and solve several systems with splicing, degradation, and catalysis. An analysis of single-cell and single-nucleus RNA sequencing data using these models reveals that the kinetics of nuclear export do not appear to require invocation of a non-Markovian waiting time.
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Affiliation(s)
- Gennady Gorin
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, CA, 91125, USA
| | - Shawn Yoshida
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, CA, 91125, USA
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA, 91125, USA
| | - Lior Pachter
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA, 91125, USA.
- Department of Computing and Mathematical Sciences, California Institute of Technology, Pasadena, CA, 91125, USA.
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11
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Bartelds MW, García-Blay Ó, Verhagen PGA, Wubbolts EJ, van Sluijs B, Heus HA, de Greef TFA, Huck WTS, Hansen MMK. Noise Minimization in Cell-Free Gene Expression. ACS Synth Biol 2023; 12:2217-2225. [PMID: 37478000 PMCID: PMC10443034 DOI: 10.1021/acssynbio.3c00174] [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: 03/24/2023] [Indexed: 07/23/2023]
Abstract
Biochemical reactions that involve small numbers of molecules are accompanied by a degree of inherent randomness that results in noisy reaction outcomes. In synthetic biology, the ability to minimize noise particularly during the reconstitution of future synthetic protocells is an outstanding challenge to secure robust and reproducible behavior. Here we show that by encapsulation of a bacterial cell-free gene expression system in water-in-oil droplets, in vitro-synthesized MazF reduces cell-free gene expression noise >2-fold. With stochastic simulations we identify that this noise minimization acts through both increased degradation and the autoregulatory feedback of MazF. Specifically, we find that the expression of MazF enhances the degradation rate of mRNA up to 18-fold in a sequence-dependent manner. This sequence specificity of MazF would allow targeted noise control, making it ideal to integrate into synthetic gene networks. Therefore, including MazF production in synthetic biology can significantly minimize gene expression noise, impacting future design principles of more complex cell-free gene circuits.
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Affiliation(s)
- Mart W. Bartelds
- Institute
for Molecules and Materials, Radboud University, Heyendaalseweg 135, 6525 AJ Nijmegen, The Netherlands
| | - Óscar García-Blay
- Institute
for Molecules and Materials, Radboud University, Heyendaalseweg 135, 6525 AJ Nijmegen, The Netherlands
| | - Pieter G. A. Verhagen
- Institute
for Molecules and Materials, Radboud University, Heyendaalseweg 135, 6525 AJ Nijmegen, The Netherlands
| | - Elise J. Wubbolts
- Institute
for Molecules and Materials, Radboud University, Heyendaalseweg 135, 6525 AJ Nijmegen, The Netherlands
| | - Bob van Sluijs
- Institute
for Molecules and Materials, Radboud University, Heyendaalseweg 135, 6525 AJ Nijmegen, The Netherlands
| | - Hans A. Heus
- Institute
for Molecules and Materials, Radboud University, Heyendaalseweg 135, 6525 AJ Nijmegen, The Netherlands
| | - Tom F. A. de Greef
- Institute
for Molecules and Materials, Radboud University, Heyendaalseweg 135, 6525 AJ Nijmegen, The Netherlands
- Laboratory
of Chemical Biology, Department of Biomedical Engineering, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven, The Netherlands
- Institute
for Complex Molecular Systems, Eindhoven
University of Technology, P.O. Box 513, 5600 MB Eindhoven, The Netherlands
- Computational
Biology Group, Department of Biomedical Engineering, Eindhoven University of Technology,
P.O. Box 513, 5600 MB Eindhoven, The Netherlands
- Center
for Living Technologies, Eindhoven-Wageningen-Utrecht
Alliance, 5600 MB Eindhoven, The Netherlands
| | - Wilhelm T. S. Huck
- Institute
for Molecules and Materials, Radboud University, Heyendaalseweg 135, 6525 AJ Nijmegen, The Netherlands
| | - Maike M. K. Hansen
- Institute
for Molecules and Materials, Radboud University, Heyendaalseweg 135, 6525 AJ Nijmegen, The Netherlands
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12
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Weidemann DE, Holehouse J, Singh A, Grima R, Hauf S. The minimal intrinsic stochasticity of constitutively expressed eukaryotic genes is sub-Poissonian. SCIENCE ADVANCES 2023; 9:eadh5138. [PMID: 37556551 PMCID: PMC10411910 DOI: 10.1126/sciadv.adh5138] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/08/2023] [Accepted: 07/07/2023] [Indexed: 08/11/2023]
Abstract
Gene expression inherently gives rise to stochastic variation ("noise") in the production of gene products. Minimizing noise is crucial for ensuring reliable cellular functions. However, noise cannot be suppressed below a certain intrinsic limit. For constitutively expressed genes, this limit is typically assumed to be Poissonian noise, wherein the variance in mRNA numbers is equal to their mean. Here, we demonstrate that several cell division genes in fission yeast exhibit mRNA variances significantly below this limit. The reduced variance can be explained by a gene expression model incorporating multiple transcription and mRNA degradation steps. Notably, in this sub-Poissonian regime, distinct from Poissonian or super-Poissonian regimes, cytoplasmic noise is effectively suppressed through a higher mRNA export rate. Our findings redefine the lower limit of eukaryotic gene expression noise and uncover molecular requirements for achieving ultralow noise, which is expected to be important for vital cellular functions.
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Affiliation(s)
- Douglas E. Weidemann
- Department of Biological Sciences, Virginia Tech, Blacksburg, VA 24061, USA
- Fralin Life Sciences Institute, Virginia Tech, Blacksburg, VA 24061, USA
| | - James Holehouse
- The Santa Fe Institute, 1399 Hyde Park Road, Santa Fe, NM 87510, USA
| | - Abhyudai Singh
- Department of Electrical and Computer Engineering, University of Delaware, Newark, DE 19716, USA
- Department of Biomedical Engineering, University of Delaware, Newark, DE 19716, USA
| | - Ramon Grima
- School of Biological Sciences, University of Edinburgh, Edinburgh EH9 3JR, UK
| | - Silke Hauf
- Department of Biological Sciences, Virginia Tech, Blacksburg, VA 24061, USA
- Fralin Life Sciences Institute, Virginia Tech, Blacksburg, VA 24061, USA
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13
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Carilli M, Gorin G, Choi Y, Chari T, Pachter L. Biophysical modeling with variational autoencoders for bimodal, single-cell RNA sequencing data. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.01.13.523995. [PMID: 36712140 PMCID: PMC9882246 DOI: 10.1101/2023.01.13.523995] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
We motivate and present biVI, which combines the variational autoencoder framework of scVI with biophysically motivated, bivariate models for nascent and mature RNA distributions. While previous approaches to integrate bimodal data via the variational autoencoder framework ignore the causal relationship between measurements, biVI models the biophysical processes that give rise to observations. We demonstrate through simulated benchmarking that biVI captures cell type structure in a low-dimensional space and accurately recapitulates parameter values and copy number distributions. On biological data, biVI provides a scalable route for identifying the biophysical mechanisms underlying gene expression. This analytical approach outlines a generalizable strategy for treating multimodal datasets generated by high-throughput, single-cell genomic assays.
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Affiliation(s)
- Maria Carilli
- Division of Biology and Biological Engineering, California Institute of Technology
| | - Gennady Gorin
- Division of Chemistry and Chemical Engineering, California Institute of Technology
| | - Yongin Choi
- Biomedical Engineering Graduate Group, University of California, Davis
- Genome Center, University of California, Davis
| | - Tara Chari
- Division of Biology and Biological Engineering, California Institute of Technology
| | - Lior Pachter
- Division of Biology and Biological Engineering, California Institute of Technology
- Department of Computing and Mathematical Sciences, California Institute of Technology
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14
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Calia GP, Chen X, Zuckerman B, Weinberger LS. Comparative analysis between single-cell RNA-seq and single-molecule RNA FISH indicates that the pyrimidine nucleobase idoxuridine (IdU) globally amplifies transcriptional noise. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.03.14.532632. [PMID: 36993609 PMCID: PMC10055090 DOI: 10.1101/2023.03.14.532632] [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: 04/29/2023]
Abstract
Stochastic fluctuations (noise) in transcription generate substantial cell-to-cell variability, but the physiological roles of noise have remained difficult to determine in the absence of generalized noise-modulation approaches. Previous single-cell RNA-sequencing (scRNA-seq) suggested that the pyrimidine-base analog (5'-iodo-2'-deoxyuridine, IdU) could generally amplify noise without substantially altering mean-expression levels but scRNA-seq technical drawbacks potentially obscured the penetrance of IdU-induced transcriptional noise amplification. Here we quantify global-vs.-partial penetrance of IdU-induced noise amplification by assessing scRNA-seq data using numerous normalization algorithms and directly quantifying noise using single-molecule RNA FISH (smFISH) for a panel of genes from across the transcriptome. Alternate scRNA-seq analyses indicate IdU-induced noise amplification for ~90% of genes, and smFISH data verified noise amplification for ~90% of tested genes. Collectively, this analysis indicates which scRNA-seq algorithms are appropriate for quantifying noise and argues that IdU is a globally penetrant noise-enhancer molecule that could enable investigations of the physiological impacts of transcriptional noise.
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Affiliation(s)
- Giuliana P. Calia
- Gladstone|UCSF Center for Cell Circuitry, University of California, San Francisco, CA 94158
| | - Xinyue Chen
- Gladstone|UCSF Center for Cell Circuitry, University of California, San Francisco, CA 94158
| | - Binyamin Zuckerman
- Gladstone|UCSF Center for Cell Circuitry, University of California, San Francisco, CA 94158
| | - Leor S. Weinberger
- Gladstone|UCSF Center for Cell Circuitry, University of California, San Francisco, CA 94158
- Department of Biochemistry and Biophysics, University of California, San Francisco, CA 94158
- Department of Pharmaceutical Chemistry, University of California, San Francisco, CA 94158
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15
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Weidemann DE, Singh A, Grima R, Hauf S. The minimal intrinsic stochasticity of constitutively expressed eukaryotic genes is sub-Poissonian. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.03.06.531283. [PMID: 36945401 PMCID: PMC10028819 DOI: 10.1101/2023.03.06.531283] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/18/2023]
Abstract
Stochastic variation in gene products ("noise") is an inescapable by-product of gene expression. Noise must be minimized to allow for the reliable execution of cellular functions. However, noise cannot be suppressed beyond an intrinsic lower limit. For constitutively expressed genes, this limit is believed to be Poissonian, meaning that the variance in mRNA numbers cannot be lower than their mean. Here, we show that several cell division genes in fission yeast have mRNA variances significantly below this limit, which cannot be explained by the classical gene expression model for low-noise genes. Our analysis reveals that multiple steps in both transcription and mRNA degradation are essential to explain this sub-Poissonian variance. The sub-Poissonian regime differs qualitatively from previously characterized noise regimes, a hallmark being that cytoplasmic noise is reduced when the mRNA export rate increases. Our study re-defines the lower limit of eukaryotic gene expression noise and identifies molecular requirements for ultra-low noise which are expected to support essential cell functions.
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Affiliation(s)
- Douglas E Weidemann
- Department of Biological Sciences, Virginia Tech, Blacksburg, VA 24061, USA
- Fralin Life Sciences Institute, Virginia Tech, Blacksburg, VA 24061, USA
| | - Abhyudai Singh
- Department of Electrical and Computer Engineering, University of Delaware, Newark, DE 19716, USA
- Department of Biomedical Engineering, University of Delaware, Newark, DE 19716, USA
| | - Ramon Grima
- School of Biological Sciences, University of Edinburgh, Edinburgh, EH9 3JR, Scotland, UK
| | - Silke Hauf
- Department of Biological Sciences, Virginia Tech, Blacksburg, VA 24061, USA
- Fralin Life Sciences Institute, Virginia Tech, Blacksburg, VA 24061, USA
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16
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Hu S, Metcalf E, Mahat DB, Chan L, Sohal N, Chakraborty M, Hamilton M, Singh A, Singh A, Lees JA, Sharp PA, Garg S. Transcription factor antagonism regulates heterogeneity in embryonic stem cell states. Mol Cell 2022; 82:4410-4427.e12. [PMID: 36356583 PMCID: PMC9722640 DOI: 10.1016/j.molcel.2022.10.022] [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: 04/15/2022] [Revised: 05/19/2022] [Accepted: 10/20/2022] [Indexed: 11/10/2022]
Abstract
Gene expression heterogeneity underlies cell states and contributes to developmental robustness. While heterogeneity can arise from stochastic transcriptional processes, the extent to which it is regulated is unclear. Here, we characterize the regulatory program underlying heterogeneity in murine embryonic stem cell (mESC) states. We identify differentially active and transcribed enhancers (DATEs) across states. DATEs regulate differentially expressed genes and are distinguished by co-binding of transcription factors Klf4 and Zfp281. In contrast to other factors that interact in a positive feedback network stabilizing mESC cell-type identity, Klf4 and Zfp281 drive opposing transcriptional and chromatin programs. Abrogation of factor binding to DATEs dampens variation in gene expression, and factor loss alters kinetics of switching between states. These results show antagonism between factors at enhancers results in gene expression heterogeneity and formation of cell states, with implications for the generation of diverse cell types during development.
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Affiliation(s)
- Sofia Hu
- Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, Cambridge, MA 02139, USA; Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02139, USA; Harvard-MIT Division of Health Sciences and Technology, Cambridge, MA 02139, USA
| | - Emily Metcalf
- Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Dig Bijay Mahat
- Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Lynette Chan
- Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Noor Sohal
- Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Meenakshi Chakraborty
- Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Maxwell Hamilton
- Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Arundeep Singh
- Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Abhyudai Singh
- Department of Electrical and Computer Engineering, University of Delaware, Newark, DE 19716, USA
| | - Jacqueline A Lees
- Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, Cambridge, MA 02139, USA; Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Phillip A Sharp
- Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, Cambridge, MA 02139, USA; Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
| | - Salil Garg
- Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, Cambridge, MA 02139, USA; Harvard-MIT Division of Health Sciences and Technology, Cambridge, MA 02139, USA; Department of Pathology, Massachusetts General Hospital, Boston, MA 02114, USA; Department of Laboratory Medicine, Yale Stem Cell Center and Center for RNA Science and Medicine, Yale School of Medicine, New Haven, CT 06510, USA.
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17
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Enhanced transcriptional heterogeneity mediated by NF-κB super-enhancers. PLoS Genet 2022; 18:e1010235. [PMID: 35648786 PMCID: PMC9191726 DOI: 10.1371/journal.pgen.1010235] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2021] [Revised: 06/13/2022] [Accepted: 05/03/2022] [Indexed: 11/19/2022] Open
Abstract
The transcription factor NF-κB, which plays an important role in cell fate determination, is involved in the activation of super-enhancers (SEs). However, the biological functions of the NF-κB SEs in gene control are not fully elucidated. We investigated the characteristics of NF-κB-mediated SE activity using fluorescence imaging of RelA, single-cell transcriptome and chromatin accessibility analyses in anti-IgM-stimulated B cells. The formation of cell stimulation-induced nuclear RelA foci was abolished in the presence of hexanediol, suggesting an underlying process of liquid-liquid phase separation. The gained SEs induced a switch-like expression and enhanced cell-to-cell variability in transcriptional response. These properties were correlated with the number of gained cis-regulatory interactions, while switch-like gene induction was associated with the number of NF-κB binding sites in SE. Our study suggests that NF-κB SEs have an important role in the transcriptional regulation of B cells possibly through liquid condensate formation consisting of macromolecular interactions. NF-κB produces an all-or-none activation response upon the activation of B cell receptors. These dynamics modulate the amplitude and frequency of target mRNA induction in cell populations. In this research, we performed single-cell assessment of chromatin accessibility and RNA expression, coupled with fluorescence imaging to characterize the nuclear dynamics of NF-κB proteins in B cell upon receptor stimulation. We found that upon cellular activation, NF-κB-mediated long-range activation of enhancers cooperatively evoked RNA production. In addition, predicted DNA contacts brought by open chromatin led to the high heterogeneity of RNA levels in cell populations. Stimuli-dependent NF-κB foci formation was further inhibited by 1,6-hexanediol (liquid-liquid phase separation inhibitor) and JQ1 (coactivator protein BRD4 inhibitor). We thus propose that nuclear NF-κB plays an important role in the transcriptional regulation of B cell development possibly through the formation of liquid condensates.
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18
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Hansberg W. A critical analysis on the conception of "Pre-existent gene expression programs" for cell differentiation and development. Differentiation 2022; 125:1-8. [DOI: 10.1016/j.diff.2022.02.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2021] [Revised: 02/17/2022] [Accepted: 02/23/2022] [Indexed: 11/15/2022]
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19
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Filatova T, Popović N, Grima R. Modulation of nuclear and cytoplasmic mRNA fluctuations by time-dependent stimuli: Analytical distributions. Math Biosci 2022; 347:108828. [DOI: 10.1016/j.mbs.2022.108828] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2022] [Revised: 04/15/2022] [Accepted: 04/15/2022] [Indexed: 10/18/2022]
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20
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Tanner RL, Gleason LU, Dowd WW. Environment-driven shifts in inter-individual variation and phenotypic integration within subnetworks of the mussel transcriptome and proteome. Mol Ecol 2022; 31:3112-3127. [PMID: 35363903 PMCID: PMC9321163 DOI: 10.1111/mec.16452] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2020] [Revised: 03/18/2022] [Accepted: 03/28/2022] [Indexed: 11/28/2022]
Abstract
The environment can alter the magnitude of phenotypic variation among individuals, potentially influencing evolutionary trajectories. However, environmental influences on variation are complex and remain understudied. Populations in heterogeneous environments might exhibit more variation, the amount of variation could differ between benign and stressful conditions, and/or variation might manifest in different ways among stages of the gene‐to‐protein expression cascade or among physiological functions. Here, we explore these three issues by quantifying patterns of inter‐individual variation in both transcript and protein expression levels among California mussels, Mytilus californianus Conrad. Mussels were exposed to five ecologically relevant treatments that varied in the mean and interindividual heterogeneity of body temperature. To target a diverse set of physiological functions, we assessed variation within 19 expression subnetworks, including canonical stress‐response pathways and empirically derived coexpression clusters that represent a diffuse set of cellular processes. Variation in expression was particularly pronounced in the treatments with high mean and heterogeneous body temperatures. However, with few exceptions, environment‐dependent shifts of variation in the transcriptome were not reflected in the proteome. A metric of phenotypic integration provided evidence for a greater degree of constraint on relative expression levels (i.e., stronger correlation) within expression subnetworks in benign, homogeneous environments. Our results suggest that environments that are more stressful on average – and which also tend to be more heterogeneous – can relax these expression constraints and reduce phenotypic integration within biochemical subnetworks. Context‐dependent “unmasking” of functional variation may contribute to interindividual differences in physiological phenotype and performance in stressful environments.
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Affiliation(s)
- Richelle L Tanner
- School of Biological Sciences, Washington State University, Pullman, WA, 99164, USA.,Environmental Science & Policy Program, Chapman University, Orange, CA, 92866, USA
| | - Lani U Gleason
- Department of Biological Sciences, California State University, Sacramento, Sacramento, CA, 95819, USA
| | - W Wesley Dowd
- School of Biological Sciences, Washington State University, Pullman, WA, 99164, USA
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21
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Chung ES, Johnson WC, Aldridge BB. Types and functions of heterogeneity in mycobacteria. Nat Rev Microbiol 2022; 20:529-541. [PMID: 35365812 DOI: 10.1038/s41579-022-00721-0] [Citation(s) in RCA: 16] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/01/2022] [Indexed: 12/24/2022]
Abstract
The remarkable ability of Mycobacterium tuberculosis to survive attacks from the host immune response and drug treatment is due to the resilience of a few bacilli rather than a result of survival of the entire population. Maintenance of mycobacterial subpopulations with distinct phenotypic characteristics is key for survival in the face of dynamic and variable stressors encountered during infection. Mycobacterial populations develop a wide range of phenotypes through an innate asymmetric growth pattern and adaptation to fluctuating microenvironments during infection that point to heterogeneity being a vital survival strategy. In this Review, we describe different types of mycobacterial heterogeneity and discuss how heterogeneity is generated and regulated in response to environmental cues. We discuss how this heterogeneity may have a key role in recording memory of their environment at both the single-cell level and the population level to give mycobacterial populations plasticity to withstand complex stressors.
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Affiliation(s)
- Eun Seon Chung
- Department of Molecular Biology and Microbiology, Tufts University School of Medicine, Boston, MA, USA
| | - William C Johnson
- Department of Molecular Biology and Microbiology, Tufts University School of Medicine, Boston, MA, USA.,Tufts University School of Graduate Biomedical Sciences, Boston, MA, USA
| | - Bree B Aldridge
- Department of Molecular Biology and Microbiology, Tufts University School of Medicine, Boston, MA, USA. .,Tufts University School of Graduate Biomedical Sciences, Boston, MA, USA. .,Stuart B. Levy Center for Integrated Management of Antimicrobial Resistance, Tufts University, Boston, MA, USA. .,Department of Biomedical Engineering, Tufts University School of Engineering, Medford, MA, USA.
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22
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Kulkarni P, Leite VBP, Roy S, Bhattacharyya S, Mohanty A, Achuthan S, Singh D, Appadurai R, Rangarajan G, Weninger K, Orban J, Srivastava A, Jolly MK, Onuchic JN, Uversky VN, Salgia R. Intrinsically disordered proteins: Ensembles at the limits of Anfinsen's dogma. BIOPHYSICS REVIEWS 2022; 3:011306. [PMID: 38505224 PMCID: PMC10903413 DOI: 10.1063/5.0080512] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/01/2021] [Accepted: 02/17/2022] [Indexed: 03/21/2024]
Abstract
Intrinsically disordered proteins (IDPs) are proteins that lack rigid 3D structure. Hence, they are often misconceived to present a challenge to Anfinsen's dogma. However, IDPs exist as ensembles that sample a quasi-continuum of rapidly interconverting conformations and, as such, may represent proteins at the extreme limit of the Anfinsen postulate. IDPs play important biological roles and are key components of the cellular protein interaction network (PIN). Many IDPs can interconvert between disordered and ordered states as they bind to appropriate partners. Conformational dynamics of IDPs contribute to conformational noise in the cell. Thus, the dysregulation of IDPs contributes to increased noise and "promiscuous" interactions. This leads to PIN rewiring to output an appropriate response underscoring the critical role of IDPs in cellular decision making. Nonetheless, IDPs are not easily tractable experimentally. Furthermore, in the absence of a reference conformation, discerning the energy landscape representation of the weakly funneled IDPs in terms of reaction coordinates is challenging. To understand conformational dynamics in real time and decipher how IDPs recognize multiple binding partners with high specificity, several sophisticated knowledge-based and physics-based in silico sampling techniques have been developed. Here, using specific examples, we highlight recent advances in energy landscape visualization and molecular dynamics simulations to discern conformational dynamics and discuss how the conformational preferences of IDPs modulate their function, especially in phenotypic switching. Finally, we discuss recent progress in identifying small molecules targeting IDPs underscoring the potential therapeutic value of IDPs. Understanding structure and function of IDPs can not only provide new insight on cellular decision making but may also help to refine and extend Anfinsen's structure/function paradigm.
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Affiliation(s)
- Prakash Kulkarni
- Department of Medical Oncology and Therapeutics Research, City of Hope National Medical Center, Duarte, California 91010, USA
| | - Vitor B. P. Leite
- Departamento de Física, Instituto de Biociências, Letras e Ciências Exatas, Universidade Estadual Paulista (UNESP), São José do Rio Preto, São Paulo 15054-000, Brazil
| | - Susmita Roy
- Department of Chemical Sciences, Indian Institute of Science Education and Research Kolkata, Mohanpur, West Bengal 741246, India
| | - Supriyo Bhattacharyya
- Translational Bioinformatics, Center for Informatics, Department of Computational and Quantitative Medicine, City of Hope National Medical Center, Duarte, California 91010, USA
| | - Atish Mohanty
- Department of Medical Oncology and Therapeutics Research, City of Hope National Medical Center, Duarte, California 91010, USA
| | - Srisairam Achuthan
- Center for Informatics, Division of Research Informatics, City of Hope National Medical Center, Duarte, California 91010, USA
| | - Divyoj Singh
- Center for BioSystems Science and Engineering, Indian Institute of Science, Bangalore 560012, India
| | - Rajeswari Appadurai
- Molecular Biophysics Unit, Indian Institute of Science, Bangalore, Karnataka, India
| | - Govindan Rangarajan
- Department of Mathematics, Indian Institute of Science, Bangalore 560012, India
| | - Keith Weninger
- Department of Physics, North Carolina State University, Raleigh, North Carolina 27695, USA
| | | | - Anand Srivastava
- Molecular Biophysics Unit, Indian Institute of Science, Bangalore, Karnataka, India
| | - Mohit Kumar Jolly
- Center for BioSystems Science and Engineering, Indian Institute of Science, Bangalore 560012, India
| | - Jose N. Onuchic
- Center for Theoretical Biological Physics, Rice University, Houston, Texas 77005-1892, USA
| | | | - Ravi Salgia
- Department of Medical Oncology and Therapeutics Research, City of Hope National Medical Center, Duarte, California 91010, USA
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23
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Chachoua I, Tzelepis I, Dai H, Lim JP, Lewandowska-Ronnegren A, Casagrande FB, Wu S, Vestlund J, Mallet de Lima CD, Bhartiya D, Scholz BA, Martino M, Mehmood R, Göndör A. Canonical WNT signaling-dependent gating of MYC requires a noncanonical CTCF function at a distal binding site. Nat Commun 2022; 13:204. [PMID: 35017527 PMCID: PMC8752836 DOI: 10.1038/s41467-021-27868-3] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2021] [Accepted: 12/19/2021] [Indexed: 01/21/2023] Open
Abstract
Abnormal WNT signaling increases MYC expression in colon cancer cells in part via oncogenic super-enhancer-(OSE)-mediated gating of the active MYC to the nuclear pore in a poorly understood process. We show here that the principal tenet of the WNT-regulated MYC gating, facilitating nuclear export of the MYC mRNA, is regulated by a CTCF binding site (CTCFBS) within the OSE to confer growth advantage in HCT-116 cells. To achieve this, the CTCFBS directs the WNT-dependent trafficking of the OSE to the nuclear pore from intra-nucleoplasmic positions in a stepwise manner. Once the OSE reaches a peripheral position, which is triggered by a CTCFBS-mediated CCAT1 eRNA activation, its final stretch (≤0.7 μm) to the nuclear pore requires the recruitment of AHCTF1, a key nucleoporin, to the CTCFBS. Thus, a WNT/ß-catenin-AHCTF1-CTCF-eRNA circuit enables the OSE to promote pathological cell growth by coordinating the trafficking of the active MYC gene within the 3D nuclear architecture. Gene-gating of a MYC oncogenic super-enhancer (OSE) increases its expression in colon cancer cells in a poorly understood process. Here the authors show that MYC gating requires a CTCF binding site (CTCFBS) within the OSE that directs the stepwise trafficking of the OSE to the nuclear pore to facilitate increased nuclear export of MYC mRNA, which results in a growth advantage.
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Affiliation(s)
- Ilyas Chachoua
- Department of Oncology and Pathology, Bioclinicum, Karolinska University Hospital, U2, Akademiska Stråket 1, Karolinska Institutet, Stockholm, Sweden
| | - Ilias Tzelepis
- Department of Oncology and Pathology, Bioclinicum, Karolinska University Hospital, U2, Akademiska Stråket 1, Karolinska Institutet, Stockholm, Sweden
| | - Hao Dai
- Department of Oncology and Pathology, Bioclinicum, Karolinska University Hospital, U2, Akademiska Stråket 1, Karolinska Institutet, Stockholm, Sweden.,Department of Breast Disease, Henan Breast Cancer Center, The affiliated Cancer Hospital of Zhengzhou University & Henan Cancer Hospital, Zhengzhou, China
| | - Jia Pei Lim
- Department of Oncology and Pathology, Bioclinicum, Karolinska University Hospital, U2, Akademiska Stråket 1, Karolinska Institutet, Stockholm, Sweden
| | - Anna Lewandowska-Ronnegren
- Department of Oncology and Pathology, Bioclinicum, Karolinska University Hospital, U2, Akademiska Stråket 1, Karolinska Institutet, Stockholm, Sweden
| | - Felipe Beccaria Casagrande
- Department of Oncology and Pathology, Bioclinicum, Karolinska University Hospital, U2, Akademiska Stråket 1, Karolinska Institutet, Stockholm, Sweden
| | - Shuangyang Wu
- Department of Oncology and Pathology, Bioclinicum, Karolinska University Hospital, U2, Akademiska Stråket 1, Karolinska Institutet, Stockholm, Sweden
| | - Johanna Vestlund
- Department of Oncology and Pathology, Bioclinicum, Karolinska University Hospital, U2, Akademiska Stråket 1, Karolinska Institutet, Stockholm, Sweden
| | - Carolina Diettrich Mallet de Lima
- Department of Oncology and Pathology, Bioclinicum, Karolinska University Hospital, U2, Akademiska Stråket 1, Karolinska Institutet, Stockholm, Sweden
| | - Deeksha Bhartiya
- Department of Oncology and Pathology, Bioclinicum, Karolinska University Hospital, U2, Akademiska Stråket 1, Karolinska Institutet, Stockholm, Sweden
| | - Barbara A Scholz
- Department of Oncology and Pathology, Bioclinicum, Karolinska University Hospital, U2, Akademiska Stråket 1, Karolinska Institutet, Stockholm, Sweden
| | - Mirco Martino
- Department of Oncology and Pathology, Bioclinicum, Karolinska University Hospital, U2, Akademiska Stråket 1, Karolinska Institutet, Stockholm, Sweden
| | - Rashid Mehmood
- Department of Oncology and Pathology, Bioclinicum, Karolinska University Hospital, U2, Akademiska Stråket 1, Karolinska Institutet, Stockholm, Sweden
| | - Anita Göndör
- Department of Oncology and Pathology, Bioclinicum, Karolinska University Hospital, U2, Akademiska Stråket 1, Karolinska Institutet, Stockholm, Sweden.
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24
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Kulkarni P, Behal A, Mohanty A, Salgia R, Nedelcu AM, Uversky VN. Co-opting disorder into order: Intrinsically disordered proteins and the early evolution of complex multicellularity. Int J Biol Macromol 2022; 201:29-36. [PMID: 34998872 DOI: 10.1016/j.ijbiomac.2021.12.182] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2021] [Revised: 12/18/2021] [Accepted: 12/28/2021] [Indexed: 02/07/2023]
Abstract
Intrinsically disordered proteins (IDPs) are proteins that lack rigid structures yet play important roles in myriad biological phenomena. A distinguishing feature of IDPs is that they often mediate specific biological outcomes via multivalent weak cooperative interactions with multiple partners. Here, we show that several proteins specifically associated with processes that were key in the evolution of complex multicellularity in the lineage leading to the multicellular green alga Volvox carteri are IDPs. We suggest that, by rewiring cellular protein interaction networks, IDPs facilitated the co-option of ancestral pathways for specialized multicellular functions, underscoring the importance of IDPs in the early evolution of complex multicellularity.
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Affiliation(s)
- Prakash Kulkarni
- Department of Medical Oncology and Experimental Therapeutics, City of Hope National Medical Center, Duarte, CA, USA.
| | - Amita Behal
- Department of Medical Oncology and Experimental Therapeutics, City of Hope National Medical Center, Duarte, CA, USA
| | - Atish Mohanty
- Department of Medical Oncology and Experimental Therapeutics, City of Hope National Medical Center, Duarte, CA, USA
| | - Ravi Salgia
- Department of Medical Oncology and Experimental Therapeutics, City of Hope National Medical Center, Duarte, CA, USA
| | - Aurora M Nedelcu
- Department of Biology, University of New Brunswick, Fredericton, Canada.
| | - Vladimir N Uversky
- Department of Molecular Medicine, Morsani College of Medicine, University of South Florida, Tampa, FL, USA; Center for Molecular Mechanisms of Aging and Age-Related Diseases, Moscow Institute of Physics and Technology, Institutskiy pereulok, 9, Dolgoprudny, Moscow region 141700, Russia.
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25
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Protein conformational dynamics and phenotypic switching. Biophys Rev 2021; 13:1127-1138. [PMID: 35059032 PMCID: PMC8724335 DOI: 10.1007/s12551-021-00858-x] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2021] [Accepted: 10/18/2021] [Indexed: 12/14/2022] Open
Abstract
Intrinsically disordered proteins (IDPs) are proteins that lack rigid 3D structure but exist as conformational ensembles. Because of their structural plasticity, they can interact with multiple partners. The protein interactions between IDPs and their partners form scale-free protein interaction networks (PINs) that facilitate information flow in the cell. Because of their plasticity, IDPs typically occupy hub positions in cellular PINs. Furthermore, their conformational dynamics and propensity for post-translational modifications contribute to "conformational" noise which is distinct from the well-recognized transcriptional noise. Therefore, upregulation of IDPs in response to a specific input, such as stress, contributes to increased noise and, hence, an increase in stochastic, "promiscuous" interactions. These interactions lead to activation of latent pathways or can induce "rewiring" of the PIN to yield an optimal output underscoring the critical role of IDPs in regulating information flow. We have used PAGE4, a highly intrinsically disordered stress-response protein as a paradigm. Employing a variety of experimental and computational techniques, we have elucidated the role of PAGE4 in phenotypic switching of prostate cancer cells at a systems level. These cumulative studies over the past decade provide a conceptual framework to better understand how IDP conformational dynamics and conformational noise might facilitate cellular decision-making.
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26
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The switch of DNA states filtering the extrinsic noise in the system of frequency modulation. Sci Rep 2021; 11:16309. [PMID: 34381062 PMCID: PMC8357933 DOI: 10.1038/s41598-021-95365-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2021] [Accepted: 07/20/2021] [Indexed: 02/07/2023] Open
Abstract
There is a special node, which the large noise of the upstream element may not always lead to a broad distribution of downstream elements. This node is DNA, with upstream element TF and downstream elements mRNA and proteins. By applying the stochastic simulation algorithm (SSA) on gene circuits inspired by the fim operon in Escherichia coli, we found that cells exchanged the distribution of the upstream transcription factor (TF) for the transitional frequency of DNA. Then cells do an inverse transform, which exchanges the transitional frequency of DNA for the distribution of downstream products. Due to this special feature, DNA in the system of frequency modulation is able to reset the noise. By probability generating function, we know the ranges of parameter values that grant such an interesting phenomenon.
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27
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Desai RV, Chen X, Martin B, Chaturvedi S, Hwang DW, Li W, Yu C, Ding S, Thomson M, Singer RH, Coleman RA, Hansen MMK, Weinberger LS. A DNA repair pathway can regulate transcriptional noise to promote cell fate transitions. Science 2021; 373:science.abc6506. [PMID: 34301855 DOI: 10.1126/science.abc6506] [Citation(s) in RCA: 38] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2020] [Accepted: 07/08/2021] [Indexed: 12/13/2022]
Abstract
Stochastic fluctuations in gene expression ("noise") are often considered detrimental, but fluctuations can also be exploited for benefit (e.g., dither). We show here that DNA base excision repair amplifies transcriptional noise to facilitate cellular reprogramming. Specifically, the DNA repair protein Apex1, which recognizes both naturally occurring and unnatural base modifications, amplifies expression noise while homeostatically maintaining mean expression levels. This amplified expression noise originates from shorter-duration, higher-intensity transcriptional bursts generated by Apex1-mediated DNA supercoiling. The remodeling of DNA topology first impedes and then accelerates transcription to maintain mean levels. This mechanism, which we refer to as "discordant transcription through repair" ("DiThR," which is pronounced "dither"), potentiates cellular reprogramming and differentiation. Our study reveals a potential functional role for transcriptional fluctuations mediated by DNA base modifications in embryonic development and disease.
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Affiliation(s)
- Ravi V Desai
- Gladstone/UCSF Center for Cell Circuitry, Gladstone Institutes, San Francisco, CA 94158, USA.,Medical Scientist Training Program and Tetrad Graduate Program, University of California, San Francisco, CA 94158, USA
| | - Xinyue Chen
- Gladstone/UCSF Center for Cell Circuitry, Gladstone Institutes, San Francisco, CA 94158, USA
| | - Benjamin Martin
- Gladstone/UCSF Center for Cell Circuitry, Gladstone Institutes, San Francisco, CA 94158, USA.,Institute for Molecules and Materials, Radboud University, 6525 AJ Nijmegen, the Netherlands
| | - Sonali Chaturvedi
- Gladstone/UCSF Center for Cell Circuitry, Gladstone Institutes, San Francisco, CA 94158, USA
| | - Dong Woo Hwang
- Department of Anatomy and Structural Biology, Albert Einstein College of Medicine, Bronx, NY 10461, USA
| | - Weihan Li
- Department of Anatomy and Structural Biology, Albert Einstein College of Medicine, Bronx, NY 10461, USA
| | - Chen Yu
- Gladstone Institute of Cardiovascular Disease, Gladstone Institutes, San Francisco, CA 94158, USA
| | - Sheng Ding
- Gladstone Institute of Cardiovascular Disease, Gladstone Institutes, San Francisco, CA 94158, USA.,School of Pharmaceutical Sciences, Tsinghua University, Beijing 100084, China
| | - Matt Thomson
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA 91125, USA
| | - Robert H Singer
- Department of Anatomy and Structural Biology, Albert Einstein College of Medicine, Bronx, NY 10461, USA
| | - Robert A Coleman
- Department of Anatomy and Structural Biology, Albert Einstein College of Medicine, Bronx, NY 10461, USA
| | - Maike M K Hansen
- Institute for Molecules and Materials, Radboud University, 6525 AJ Nijmegen, the Netherlands
| | - Leor S Weinberger
- Gladstone/UCSF Center for Cell Circuitry, Gladstone Institutes, San Francisco, CA 94158, USA. .,Department of Pharmaceutical Chemistry, University of California, San Francisco, CA 94158, USA.,Department of Biochemistry and Biophysics, University of California, San Francisco, CA 94158, USA
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28
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Bass VL, Wong VC, Bullock ME, Gaudet S, Miller‐Jensen K. TNF stimulation primarily modulates transcriptional burst size of NF-κB-regulated genes. Mol Syst Biol 2021; 17:e10127. [PMID: 34288498 PMCID: PMC8290835 DOI: 10.15252/msb.202010127] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2020] [Revised: 06/03/2021] [Accepted: 06/07/2021] [Indexed: 12/12/2022] Open
Abstract
Cell-to-cell heterogeneity is a feature of the tumor necrosis factor (TNF)-stimulated inflammatory response mediated by the transcription factor NF-κB, motivating an exploration of the underlying sources of this noise. Here, we combined single-transcript measurements with computational models to study transcriptional noise at six NF-κB-regulated inflammatory genes. In the basal state, NF-κB-target genes displayed an inverse correlation between mean and noise characteristic of transcriptional bursting. By analyzing transcript distributions with a bursting model, we found that TNF primarily activated transcription by increasing burst size while maintaining burst frequency for gene promoters with relatively high basal histone 3 acetylation (AcH3) that marks open chromatin environments. For promoters with lower basal AcH3 or when AcH3 was decreased with a small molecule drug, the contribution of burst frequency to TNF activation increased. Finally, we used a mathematical model to show that TNF positive feedback amplified gene expression noise resulting from burst size-mediated transcription, leading to a subset of cells with high TNF protein expression. Our results reveal potential sources of noise underlying intercellular heterogeneity in the TNF-mediated inflammatory response.
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Affiliation(s)
- Victor L Bass
- Department of Molecular, Cellular, and Developmental BiologyYale UniversityNew HavenCTUSA
- Present address:
Neuro‐Immune Regulome UnitNational Eye InstituteNational Institutes of HealthBethesdaMDUSA
| | - Victor C Wong
- Department of Molecular, Cellular, and Developmental BiologyYale UniversityNew HavenCTUSA
- Present address:
Janelia Research CampusHoward Hughes Medical InstituteAshburnVAUSA
| | - M Elise Bullock
- Department of Biomedical EngineeringYale UniversityNew HavenCTUSA
| | - Suzanne Gaudet
- Department of Cancer Biology and Center for Cancer Systems BiologyDana‐Farber Cancer InstituteBostonMAUSA
- Department of GeneticsHarvard Medical SchoolBostonMAUSA
- Present address:
Novartis Institute for BioMedical ResearchCambridgeMAUSA
| | - Kathryn Miller‐Jensen
- Department of Molecular, Cellular, and Developmental BiologyYale UniversityNew HavenCTUSA
- Department of Biomedical EngineeringYale UniversityNew HavenCTUSA
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29
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Oguchi Y, Ozaki Y, Abdelmoez MN, Shintaku H. NanoSINC-seq dissects the isoform diversity in subcellular compartments of single cells. SCIENCE ADVANCES 2021; 7:7/15/eabe0317. [PMID: 33827812 PMCID: PMC8026137 DOI: 10.1126/sciadv.abe0317] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/27/2020] [Accepted: 02/19/2021] [Indexed: 06/12/2023]
Abstract
Alternative mRNA isoforms play a key role in generating diverse protein isoforms. To dissect isoform usage in the subcellular compartments of single cells, we introduced an novel approach, nanopore sequencing coupled with single-cell integrated nuclear and cytoplasmic RNA sequencing, that couples microfluidic fractionation, which separates cytoplasmic RNA from nuclear RNA, with full-length complementary DNA (cDNA) sequencing using a nanopore sequencer. Leveraging full-length cDNA reads, we found that the nuclear transcripts are notably more diverse than cytoplasmic transcripts. Our findings also indicated that transcriptional noise emanating from the nucleus is regulated across the nuclear membrane and then either attenuated or amplified in the cytoplasm depending on the function involved. Overall, our results provide the landscape that shows how the transcriptional noise arising from the nucleus propagates to the cytoplasm.
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Affiliation(s)
- Yusuke Oguchi
- Cluster for Pioneering Research, RIKEN, 2-1 Hirosawa, Wako, Saitama, Japan
- PRESTO, Japan Science and Technology Agency, 4-1-8, Honcho, Kawaguchi, Saitama 332-0012, Japan
| | - Yuka Ozaki
- Cluster for Pioneering Research, RIKEN, 2-1 Hirosawa, Wako, Saitama, Japan
| | | | - Hirofumi Shintaku
- Cluster for Pioneering Research, RIKEN, 2-1 Hirosawa, Wako, Saitama, Japan.
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30
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Phillips NE, Hugues A, Yeung J, Durandau E, Nicolas D, Naef F. The circadian oscillator analysed at the single-transcript level. Mol Syst Biol 2021; 17:e10135. [PMID: 33719202 PMCID: PMC7957410 DOI: 10.15252/msb.202010135] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2020] [Revised: 01/05/2021] [Accepted: 01/19/2021] [Indexed: 12/31/2022] Open
Abstract
The circadian clock is an endogenous and self-sustained oscillator that anticipates daily environmental cycles. While rhythmic gene expression of circadian genes is well-described in populations of cells, the single-cell mRNA dynamics of multiple core clock genes remain largely unknown. Here we use single-molecule fluorescence in situ hybridisation (smFISH) at multiple time points to measure pairs of core clock transcripts, Rev-erbα (Nr1d1), Cry1 and Bmal1, in mouse fibroblasts. The mean mRNA level oscillates over 24 h for all three genes, but mRNA numbers show considerable spread between cells. We develop a probabilistic model for multivariate mRNA counts using mixtures of negative binomials, which accounts for transcriptional bursting, circadian time and cell-to-cell heterogeneity, notably in cell size. Decomposing the mRNA variability into distinct noise sources shows that clock time contributes a small fraction of the total variability in mRNA number between cells. Thus, our results highlight the intrinsic biological challenges in estimating circadian phase from single-cell mRNA counts and suggest that circadian phase in single cells is encoded post-transcriptionally.
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Affiliation(s)
- Nicholas E Phillips
- Institute of BioengineeringSchool of Life SciencesEcole Polytechnique Fédérale de LausanneLausanneSwitzerland
| | - Alice Hugues
- Institute of BioengineeringSchool of Life SciencesEcole Polytechnique Fédérale de LausanneLausanneSwitzerland
- Master de BiologieÉcole Normale Supérieure de LyonUniversité Claude Bernard Lyon IUniversité de LyonLyonFrance
| | - Jake Yeung
- Institute of BioengineeringSchool of Life SciencesEcole Polytechnique Fédérale de LausanneLausanneSwitzerland
| | - Eric Durandau
- Institute of BioengineeringSchool of Life SciencesEcole Polytechnique Fédérale de LausanneLausanneSwitzerland
| | - Damien Nicolas
- Institute of BioengineeringSchool of Life SciencesEcole Polytechnique Fédérale de LausanneLausanneSwitzerland
| | - Felix Naef
- Institute of BioengineeringSchool of Life SciencesEcole Polytechnique Fédérale de LausanneLausanneSwitzerland
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31
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Guillemin A, Stumpf MPH. Noise and the molecular processes underlying cell fate decision-making. Phys Biol 2021; 18:011002. [PMID: 33181489 DOI: 10.1088/1478-3975/abc9d1] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Cell fate decision-making events involve the interplay of many molecular processes, ranging from signal transduction to genetic regulation, as well as a set of molecular and physiological feedback loops. Each aspect offers a rich field of investigation in its own right, but to understand the whole process, even in simple terms, we need to consider them together. Here we attempt to characterise this process by focussing on the roles of noise during cell fate decisions. We use a range of recent results to develop a view of the sequence of events by which a cell progresses from a pluripotent or multipotent to a differentiated state: chromatin organisation, transcription factor stoichiometry, and cellular signalling all change during this progression, and all shape cellular variability, which becomes maximal at the transition state.
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Affiliation(s)
- Anissa Guillemin
- School of BioSciences, University of Melbourne, Parkville, Australia
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32
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Kulkarni P. Intrinsically Disordered Proteins: Insights from Poincaré, Waddington, and Lamarck. Biomolecules 2020; 10:biom10111490. [PMID: 33126482 PMCID: PMC7692701 DOI: 10.3390/biom10111490] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2020] [Accepted: 10/12/2020] [Indexed: 12/28/2022] Open
Abstract
The past quarter-century may justly be referred to as a period analogous to the “Cambrian explosion” in the history of proteins. This period is marked by the appearance of the intrinsically disordered proteins (IDPs) on the scene since their discovery in the mid-1990s. Here, I first reflect on how we accidentally stumbled on these fascinating molecules. Next, I describe our research on the IDPs over the past decade and identify six areas as important for future research in this field. In addition, I draw on discoveries others in the field have made to present a more comprehensive essay. More specifically, I discuss the role of IDPs in two fundamental aspects of life: in phenotypic switching, and in multicellularity that marks one of the major evolutionary transitions. I highlight how serendipity, imagination, and an interdisciplinary approach embodying empirical evidence and theoretical insights from the works of Poincaré, Waddington, and Lamarck, shaped our thinking, and how this led us to propose the MRK hypothesis, a conceptual framework addressing phenotypic switching, the emergence of new traits, and adaptive evolution via nongenetic and IDP conformation-based mechanisms. Finally, I present a perspective on the evolutionary link between phenotypic switching and the origin of multicellularity.
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Affiliation(s)
- Prakash Kulkarni
- Department of Medical Oncology and Experimental Therapeutics, City of Hope, National Medical Center, Duarte, CA 91010, USA
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33
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Arede L, Pina C. Buffering noise: KAT2A modular contributions to stabilization of transcription and cell identity in cancer and development. Exp Hematol 2020; 93:25-37. [PMID: 33223444 DOI: 10.1016/j.exphem.2020.10.003] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2020] [Revised: 10/18/2020] [Accepted: 10/19/2020] [Indexed: 02/07/2023]
Abstract
KAT2A is a histone acetyltransferase recently identified as a vulnerability in at least some forms of Acute Myeloid Leukemia (AML). Its loss or inhibition prompts leukemia stem cells out of self-renewal and into differentiation with ultimate exhaustion of the leukemia pool. We have recently linked the Kat2a requirement in AML to control of transcriptional noise, reflecting an evolutionary-conserved role of Kat2a in promoting burst-like promoter activity and stabilizing gene expression. We suggest that through this role, Kat2a contributes to preservation of cell identity. KAT2A exerts its acetyltransferase activity in the context of two macromolecular complexes, Spt-Ada-Gcn5-Acetyltransferase (SAGA) and Ada-Two-A-Containing (ATAC), but the specific contribution of each complex to stabilization of gene expression is currently unknown. By reviewing specific gene targets and requirements of the two complexes in cancer and development, we suggest that SAGA regulates lineage-specific programs, and ATAC maintains biosynthetic activity through control of ribosomal protein and translation-associated genes, on which cells may be differentially dependent. While our data suggest that KAT2A-mediated regulation of transcriptional noise in AML may be exerted through ATAC, we discuss potential caveats and probe general vs. complex-specific contributions of KAT2A to transcriptional stability, with implications for control and perturbation of cell identity.
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Affiliation(s)
- Liliana Arede
- Departments of Haematology; Genetics, University of Cambridge, Cambridge, United Kingdom
| | - Cristina Pina
- College of Health, Medicine and Life Sciences - Life Sciences, Division of Biosciences, Brunel University London, Uxbridge, UB8 3PH, United Kingdom.
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34
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Cortijo S, Locke JCW. Does Gene Expression Noise Play a Functional Role in Plants? TRENDS IN PLANT SCIENCE 2020; 25:1041-1051. [PMID: 32467064 DOI: 10.1016/j.tplants.2020.04.017] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/22/2019] [Revised: 04/22/2020] [Accepted: 04/28/2020] [Indexed: 05/20/2023]
Abstract
Gene expression in individual cells can be surprisingly noisy. In unicellular organisms this noise can be functional; for example, by allowing a subfraction of the population to prepare for environmental stress. The role of gene expression noise in multicellular organisms has, however, remained unclear. In this review, we discuss how new techniques are revealing an unexpected level of variability in gene expression between and within genetically identical plants. We describe recent progress as well as speculate on the function of transcriptional noise as a mechanism for generating functional phenotypic diversity in plants.
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Affiliation(s)
- Sandra Cortijo
- Sainsbury Laboratory, University of Cambridge, Cambridge CB2 1LR, UK
| | - James C W Locke
- Sainsbury Laboratory, University of Cambridge, Cambridge CB2 1LR, UK.
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35
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Waymack R, Fletcher A, Enciso G, Wunderlich Z. Shadow enhancers can suppress input transcription factor noise through distinct regulatory logic. eLife 2020; 9:59351. [PMID: 32804082 PMCID: PMC7556877 DOI: 10.7554/elife.59351] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2020] [Accepted: 08/14/2020] [Indexed: 12/26/2022] Open
Abstract
Shadow enhancers, groups of seemingly redundant enhancers, are found in a wide range of organisms and are critical for robust developmental patterning. However, their mechanism of action is unknown. We hypothesized that shadow enhancers drive consistent expression levels by buffering upstream noise through a separation of transcription factor (TF) inputs at the individual enhancers. By measuring the transcriptional dynamics of several Kruppel shadow enhancer configurations in live Drosophila embryos, we showed that individual member enhancers act largely independently. We found that TF fluctuations are an appreciable source of noise that the shadow enhancer pair can better buffer than duplicated enhancers. The shadow enhancer pair is also uniquely able to maintain low levels of expression noise across a wide range of temperatures. A stochastic model demonstrated the separation of TF inputs is sufficient to explain these findings. Our results suggest the widespread use of shadow enhancers is partially due to their noise suppressing ability. In all higher organisms, life begins with a single cell. During the early stages of development, this single cell grows and divides multiple times to develop into the many different kinds of cells that make up an organism. This is a highly regulated process during which cells receive instructions telling them what kind of cell to become. These instructions are relayed via genes, and a particular combination of activated genes determines the cell’s fate. Specific pieces of DNA, known as enhancers, act as switches that control when and where genes are active, while so-called shadow enhancers are found in groups and work together to turn on the same gene in a similar way. Shadow enhancers are often active during the early stages of life to direct the formation of specialized cells in different parts of the body. But so far, it has been unclear why it is beneficial to the divide the role of activating genes across several shadow enhancers rather than a single one. Here, Waymack et al. examined shadow enhancers around a gene called Kruppel in embryos of the fruit fly Drosophila melanogaster. Manipulating the shadow enhancers showed that they help to make gene activity more resistant to changes. Factors such as fluctuations in temperature have different effects on each shadow enhancer. Having several shadow enhancers working together ensures that, whatever happens, the right genes still get activated. For genes like Kruppel, which are key for healthy development, the ability to withstand unexpected changes is a valuable evolutionary benefit. The study of Waymack et al. reveals why shadow enhancers are involved in the regulation of many genes, which may help to better understand developmental defects. Many conditions caused by such defects are influenced by both genetics and the environment. Genetic illnesses can vary in severity, which may be related to the roles of shadow enhancers. As such, studying shadow enhancers could lead to new approaches for treating genetic diseases.
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Affiliation(s)
- Rachel Waymack
- Department of Developmental and Cell Biology, University of California, Irvine, Irvine, United States
| | - Alvaro Fletcher
- Mathematical, Computational, and Systems Biology Graduate Program, University of California, Irvine, Irvine, United States
| | - German Enciso
- Department of Developmental and Cell Biology, University of California, Irvine, Irvine, United States.,Department of Mathematics, University of California, Irvine, Irvine, United States
| | - Zeba Wunderlich
- Department of Developmental and Cell Biology, University of California, Irvine, Irvine, United States
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36
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Emanuele MJ, Enrico TP, Mouery RD, Wasserman D, Nachum S, Tzur A. Complex Cartography: Regulation of E2F Transcription Factors by Cyclin F and Ubiquitin. Trends Cell Biol 2020; 30:640-652. [PMID: 32513610 PMCID: PMC7859860 DOI: 10.1016/j.tcb.2020.05.002] [Citation(s) in RCA: 33] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2020] [Revised: 05/01/2020] [Accepted: 05/06/2020] [Indexed: 02/07/2023]
Abstract
The E2F family of transcriptional regulators sits at the center of cell cycle gene expression and plays vital roles in normal and cancer cell cycles. Whereas control of E2Fs by the retinoblastoma family of proteins is well established, much less is known about their regulation by ubiquitin pathways. Recent studies placed the Skp1-Cul1-F-box-protein (SCF) family of E3 ubiquitin ligases with the F-box protein Cyclin F at the center of E2F regulation, demonstrating temporal proteolysis of both activator and atypical repressor E2Fs. Importantly, these E2F members, in particular activator E2F1 and repressors E2F7 and E2F8, form a feedback circuit at the crossroads of cell cycle and cell death. Moreover, Cyclin F functions in a reciprocal circuit with the cell cycle E3 ligase anaphase-promoting complex/cyclosome (APC/C), which also controls E2F7 and E2F8. This review focuses on the complex contours of feedback within this circuit, highlighting the deep crosstalk between E2F, SCF-Cyclin F, and APC/C in regulating the oscillator underlying human cell cycles.
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Affiliation(s)
- Michael J Emanuele
- Department of Pharmacology, The University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA; Lineberger Comprehensive Cancer Center, The University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA.
| | - Taylor P Enrico
- Department of Pharmacology, The University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA; Lineberger Comprehensive Cancer Center, The University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Ryan D Mouery
- Department of Pharmacology, The University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA; Genetics and Molecular Biology Program, The University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Danit Wasserman
- Faculty of Life Sciences and Institute of Nanotechnology and Advanced Materials, Bar-Ilan University, Ramat-Gan 5290002, Israel
| | - Sapir Nachum
- Faculty of Life Sciences and Institute of Nanotechnology and Advanced Materials, Bar-Ilan University, Ramat-Gan 5290002, Israel
| | - Amit Tzur
- Faculty of Life Sciences and Institute of Nanotechnology and Advanced Materials, Bar-Ilan University, Ramat-Gan 5290002, Israel.
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Abstract
Probabilistic bet hedging is a generalized diversification strategy to maximize fitness in unpredictable environments and has been proposed as an evolutionary basis for herpesvirus latency. However, the molecular mechanisms enabling probabilistic bet hedging have remained elusive. Here, we find that the human herpesvirus cytomegalovirus—a major cause of birth defects and transplant failures—utilizes stochastic variability in the abundance of a protein packaged into individual viral particles to enable probabilistic bet hedging between alternate viral states. Probabilistic bet hedging, a strategy to maximize fitness in unpredictable environments by matching phenotypic variability to environmental variability, is theorized to account for the evolution of various fate-specification decisions, including viral latency. However, the molecular mechanisms underlying bet hedging remain unclear. Here, we report that large variability in protein abundance within individual herpesvirus virion particles enables probabilistic bet hedging between viral replication and latency. Superresolution imaging of individual virions of the human herpesvirus cytomegalovirus (CMV) showed that virion-to-virion levels of pp71 tegument protein—the major viral transactivator protein—exhibit extreme variability. This super-Poissonian tegument variability promoted alternate replicative strategies: high virion pp71 levels enhance viral replicative fitness but, strikingly, impede silencing, whereas low virion pp71 levels reduce fitness but promote silencing. Overall, the results indicate that stochastic tegument packaging provides a mechanism enabling probabilistic bet hedging between viral replication and latency.
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38
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Gene Architecture and Sequence Composition Underpin Selective Dependency of Nuclear Export of Long RNAs on NXF1 and the TREX Complex. Mol Cell 2020; 79:251-267.e6. [PMID: 32504555 DOI: 10.1016/j.molcel.2020.05.013] [Citation(s) in RCA: 75] [Impact Index Per Article: 18.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2019] [Revised: 03/23/2020] [Accepted: 05/11/2020] [Indexed: 12/14/2022]
Abstract
The core components of the nuclear RNA export pathway are thought to be required for export of virtually all polyadenylated RNAs. Here, we depleted different proteins that act in nuclear export in human cells and quantified the transcriptome-wide consequences on RNA localization. Different genes exhibited substantially variable sensitivities, with depletion of NXF1 and TREX components causing some transcripts to become strongly retained in the nucleus while others were not affected. Specifically, NXF1 is preferentially required for export of single- or few-exon transcripts with long exons or high A/U content, whereas depletion of TREX complex components preferentially affects spliced and G/C-rich transcripts. Using massively parallel reporter assays, we identified short sequence elements that render transcripts dependent on NXF1 for their export and identified synergistic effects of splicing and NXF1. These results revise the current model of how nuclear export shapes the distribution of RNA within human cells.
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Abstract
Our findings have revealed a previously unrecognized link between circadian oscillations and intercellular variation and provide experimental evidence that stochastic transcriptional noise contributes significantly to cell-autonomous circadian periodicity. Interestingly, in separate studies, aging and cancer have been associated with increased transcriptional noise and less robust circadian rhythms. Here, we establish a direct association between transcriptional noise and circadian period. These findings may provide additional directions for researchers in the aging and cancer fields. Furthermore, circadian period may also be used as an indicator of variance in heterogeneity research and drug screening for noise control. Nongenetic cellular heterogeneity is associated with aging and disease. However, the origins of cell-to-cell variability are complex and the individual contributions of different factors to total phenotypic variance are still unclear. Here, we took advantage of clear phenotypic heterogeneity of circadian oscillations in clonal cell populations to investigate the underlying mechanisms of cell-to-cell variability. Using a fully automated tracking and analysis pipeline, we examined circadian period length in thousands of single cells and hundreds of clonal cell lines and found that longer circadian period is associated with increased intercellular heterogeneity. Based on our experimental results, we then estimated the contributions of heritable and nonheritable factors to this variation in circadian period length using a variance partitioning model. We found that nonheritable noise predominantly drives intercellular circadian period variation in clonal cell lines, thereby revealing a previously unrecognized link between circadian oscillations and intercellular heterogeneity. Moreover, administration of a noise-enhancing drug reversibly increased both period length and variance. These findings suggest that circadian period may be used as an indicator of cellular noise and drug screening for noise control.
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40
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Gorin G, Wang M, Golding I, Xu H. Stochastic simulation and statistical inference platform for visualization and estimation of transcriptional kinetics. PLoS One 2020; 15:e0230736. [PMID: 32214380 PMCID: PMC7098607 DOI: 10.1371/journal.pone.0230736] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2019] [Accepted: 03/06/2020] [Indexed: 12/20/2022] Open
Abstract
Recent advances in single-molecule fluorescent imaging have enabled quantitative measurements of transcription at a single gene copy, yet an accurate understanding of transcriptional kinetics is still lacking due to the difficulty of solving detailed biophysical models. Here we introduce a stochastic simulation and statistical inference platform for modeling detailed transcriptional kinetics in prokaryotic systems, which has not been solved analytically. The model includes stochastic two-state gene activation, mRNA synthesis initiation and stepwise elongation, release to the cytoplasm, and stepwise co-transcriptional degradation. Using the Gillespie algorithm, the platform simulates nascent and mature mRNA kinetics of a single gene copy and predicts fluorescent signals measurable by time-lapse single-cell mRNA imaging, for different experimental conditions. To approach the inverse problem of estimating the kinetic parameters of the model from experimental data, we develop a heuristic optimization method based on the genetic algorithm and the empirical distribution of mRNA generated by simulation. As a demonstration, we show that the optimization algorithm can successfully recover the transcriptional kinetics of simulated and experimental gene expression data. The platform is available as a MATLAB software package at https://data.caltech.edu/records/1287.
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Affiliation(s)
- Gennady Gorin
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California, United States of America
| | - Mengyu Wang
- Department of Physics, Grainger College of Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois, United States of America
- Center for the Physics of Living Cells, University of Illinois at Urbana-Champaign, Urbana, Illinois, United States of America
| | - Ido Golding
- Department of Physics, Grainger College of Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois, United States of America
- Center for the Physics of Living Cells, University of Illinois at Urbana-Champaign, Urbana, Illinois, United States of America
| | - Heng Xu
- School of Physics and Astronomy, Shanghai Jiao Tong University, Minhang District, Shanghai, China
- Institute of Natural Sciences, Shanghai Jiao Tong University, Minhang District, Shanghai, China
- * E-mail:
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41
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Giri R, Papadopoulos DK, Posadas DM, Potluri HK, Tomancak P, Mani M, Carthew RW. Ordered patterning of the sensory system is susceptible to stochastic features of gene expression. eLife 2020; 9:e53638. [PMID: 32101167 PMCID: PMC7064346 DOI: 10.7554/elife.53638] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2019] [Accepted: 02/25/2020] [Indexed: 01/23/2023] Open
Abstract
Sensory neuron numbers and positions are precisely organized to accurately map environmental signals in the brain. This precision emerges from biochemical processes within and between cells that are inherently stochastic. We investigated impact of stochastic gene expression on pattern formation, focusing on senseless (sens), a key determinant of sensory fate in Drosophila. Perturbing microRNA regulation or genomic location of sens produced distinct noise signatures. Noise was greatly enhanced when both sens alleles were present in homologous loci such that each allele was regulated in trans by the other allele. This led to disordered patterning. In contrast, loss of microRNA repression of sens increased protein abundance but not sensory pattern disorder. This suggests that gene expression stochasticity is a critical feature that must be constrained during development to allow rapid yet accurate cell fate resolution.
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Affiliation(s)
- Ritika Giri
- Department of Molecular Biosciences, Northwestern UniversityEvanstonUnited States
- NSF-Simons Center for Quantitative Biology, Northwestern UniversityEvanstonUnited States
| | | | - Diana M Posadas
- Department of Molecular Biosciences, Northwestern UniversityEvanstonUnited States
| | - Hemanth K Potluri
- Department of Molecular Biosciences, Northwestern UniversityEvanstonUnited States
| | - Pavel Tomancak
- Max Planck Institute of Cell Biology and GeneticsDresdenGermany
| | - Madhav Mani
- Department of Molecular Biosciences, Northwestern UniversityEvanstonUnited States
- NSF-Simons Center for Quantitative Biology, Northwestern UniversityEvanstonUnited States
- Department of Engineering Sciences and Applied Mathematics, Northwestern UniversityEvanstonUnited States
| | - Richard W Carthew
- Department of Molecular Biosciences, Northwestern UniversityEvanstonUnited States
- NSF-Simons Center for Quantitative Biology, Northwestern UniversityEvanstonUnited States
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42
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Rodrigo G. Ab initio scaling laws between noise and mean of gene expression. Phys Rev E 2020; 100:032415. [PMID: 31640034 DOI: 10.1103/physreve.100.032415] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2019] [Indexed: 12/17/2022]
Abstract
Gene expression is inherently noisy due to fluctuations occurring at the molecular level. From a top-down perspective, noise has been traditionally decomposed into an intrinsic component that scales inversely with the mean expression level and an extrinsic component that is constant in absence of regulatory changes. Here, we adopt a bottom-up approach to reveal that extrinsic noise, by itself, can follow the aforementioned decomposition, which entails that one component of it can be confounded with intrinsic noise. Analytical expressions of the noise-mean relationship were derived for different scenarios, which were in part supported by numerical simulations.
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Affiliation(s)
- Guillermo Rodrigo
- Institute for Integrative Systems Biology (I2SysBio), CSIC-University Valencia, 46980 Paterna, Spain
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43
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Cardelli L, Laurenti L, Csikasz-Nagy A. Coupled membrane transporters reduce noise. Phys Rev E 2020; 101:012414. [PMID: 32069604 DOI: 10.1103/physreve.101.012414] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2019] [Indexed: 11/07/2022]
Abstract
Molecular systems are inherently probabilistic and operate in a noisy environment, yet, despite all these uncertainties, molecular functions are surprisingly reliable and robust. The principles used by natural systems to deal with noise are still not well understood, especially in a nonhomogeneous environment where molecules can diffuse across different compartments. In this paper we show that membrane transport mechanisms have very effective properties of noise reduction. In particular, we show that active transport mechanisms (those that can transport against a gradient of concentration by using energy or by means of the concentration gradient of other substances), such as symporters and antiporters, have surprising efficiency in noise reduction, which outperforms passive diffusion mechanisms and are well below Poisson levels. We link our results to the coupled transport of potassium, sodium, and glucose to show that the noise in internal glucose level can be greatly reduced. Our results show that compartmentalization can be a highly effective mechanism of noise reduction and suggests that membrane transport could give this extra benefit, contributing to the emergence of complex compartmentalization in eukaryotes.
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Affiliation(s)
- Luca Cardelli
- Department of Computer Science, University of Oxford, Oxford OX1 3QD, United Kingdom
| | - Luca Laurenti
- Department of Computer Science, University of Oxford, Oxford OX1 3QD, United Kingdom
| | - Attila Csikasz-Nagy
- Randall Division of Cell and Molecular Biophysics and Institute of Mathematical and Molecular Biomedicine, King's College London, London, United Kingdom and Pázmány Péter Catholic University, Faculty of Information Technology and Bionics Budapest, Hungary
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44
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Foreman R, Wollman R. Mammalian gene expression variability is explained by underlying cell state. Mol Syst Biol 2020; 16:e9146. [PMID: 32043799 PMCID: PMC7011657 DOI: 10.15252/msb.20199146] [Citation(s) in RCA: 39] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2019] [Revised: 12/04/2019] [Accepted: 01/07/2020] [Indexed: 02/06/2023] Open
Abstract
Gene expression variability in mammalian systems plays an important role in physiological and pathophysiological conditions. This variability can come from differential regulation related to cell state (extrinsic) and allele-specific transcriptional bursting (intrinsic). Yet, the relative contribution of these two distinct sources is unknown. Here, we exploit the qualitative difference in the patterns of covariance between these two sources to quantify their relative contributions to expression variance in mammalian cells. Using multiplexed error robust RNA fluorescent in situ hybridization (MERFISH), we measured the multivariate gene expression distribution of 150 genes related to Ca2+ signaling coupled with the dynamic Ca2+ response of live cells to ATP. We show that after controlling for cellular phenotypic states such as size, cell cycle stage, and Ca2+ response to ATP, the remaining variability is effectively at the Poisson limit for most genes. These findings demonstrate that the majority of expression variability results from cell state differences and that the contribution of transcriptional bursting is relatively minimal.
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Affiliation(s)
- Robert Foreman
- Institute for Quantitative and Computational BiosciencesUniversity of California, Los AngelesLos AngelesCAUSA
- Program in Bioinformatics and Systems BiologyUniversity of California, San DiegoSan DiegoCAUSA
| | - Roy Wollman
- Institute for Quantitative and Computational BiosciencesUniversity of California, Los AngelesLos AngelesCAUSA
- Program in Bioinformatics and Systems BiologyUniversity of California, San DiegoSan DiegoCAUSA
- Department of Integrative Biology and PhysiologyDepartment of Chemistry and BiochemistryUniversity of California, Los AngelesLos AngelesCAUSA
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45
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Controlling cell-to-cell variability with synthetic gene circuits. Biochem Soc Trans 2019; 47:1795-1804. [DOI: 10.1042/bst20190295] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2019] [Revised: 11/05/2019] [Accepted: 11/06/2019] [Indexed: 02/05/2023]
Abstract
Cell-to-cell variability originating, for example, from the intrinsic stochasticity of gene expression, presents challenges for designing synthetic gene circuits that perform robustly. Conversely, synthetic biology approaches are instrumental in uncovering mechanisms underlying variability in natural systems. With a focus on reducing noise in individual genes, the field has established a broad synthetic toolset. This includes noise control by engineering of transcription and translation mechanisms either individually, or in combination to achieve independent regulation of mean expression and its variability. Synthetic feedback circuits use these components to establish more robust operation in closed-loop, either by drawing on, but also by extending traditional engineering concepts. In this perspective, we argue that major conceptual advances will require new theory of control adapted to biology, extensions from single genes to networks, more systematic considerations of origins of variability other than intrinsic noise, and an exploration of how noise shaping, instead of noise reduction, could establish new synthetic functions or help understanding natural functions.
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46
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Friedrich D, Friedel L, Finzel A, Herrmann A, Preibisch S, Loewer A. Stochastic transcription in the p53-mediated response to DNA damage is modulated by burst frequency. Mol Syst Biol 2019; 15:e9068. [PMID: 31885199 PMCID: PMC6886302 DOI: 10.15252/msb.20199068] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2019] [Revised: 11/04/2019] [Accepted: 11/07/2019] [Indexed: 12/15/2022] Open
Abstract
Discontinuous transcription has been described for different mammalian cell lines and numerous promoters. However, our knowledge of how the activity of individual promoters is adjusted by dynamic signaling inputs from transcription factors is limited. To address this question, we characterized the activity of selected target genes that are regulated by pulsatile accumulation of the tumor suppressor p53 in response to ionizing radiation. We performed time-resolved measurements of gene expression at the single-cell level by smFISH and used the resulting data to inform a mathematical model of promoter activity. We found that p53 target promoters are regulated by frequency modulation of stochastic bursting and can be grouped along three archetypes of gene expression. The occurrence of these archetypes cannot solely be explained by nuclear p53 abundance or promoter binding of total p53. Instead, we provide evidence that the time-varying acetylation state of p53's C-terminal lysine residues is critical for gene-specific regulation of stochastic bursting.
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Affiliation(s)
- Dhana Friedrich
- Department for BiologyTechnische Universität DarmstadtDarmstadtGermany
- Berlin Institute for Medical Systems BiologyMax Delbrück Center in the Helmholtz AssociationBerlinGermany
- Department for BiologyHumboldt Universität zu BerlinBerlinGermany
| | - Laura Friedel
- Department for BiologyTechnische Universität DarmstadtDarmstadtGermany
| | - Ana Finzel
- Berlin Institute for Medical Systems BiologyMax Delbrück Center in the Helmholtz AssociationBerlinGermany
| | - Andreas Herrmann
- Department for BiologyHumboldt Universität zu BerlinBerlinGermany
| | - Stephan Preibisch
- Berlin Institute for Medical Systems BiologyMax Delbrück Center in the Helmholtz AssociationBerlinGermany
- Janelia Research CampusHoward Hughes Medical InstituteVAAshburnUSA
| | - Alexander Loewer
- Department for BiologyTechnische Universität DarmstadtDarmstadtGermany
- Berlin Institute for Medical Systems BiologyMax Delbrück Center in the Helmholtz AssociationBerlinGermany
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47
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Scholz BA, Sumida N, de Lima CDM, Chachoua I, Martino M, Tzelepis I, Nikoshkov A, Zhao H, Mehmood R, Sifakis EG, Bhartiya D, Göndör A, Ohlsson R. WNT signaling and AHCTF1 promote oncogenic MYC expression through super-enhancer-mediated gene gating. Nat Genet 2019; 51:1723-1731. [DOI: 10.1038/s41588-019-0535-3] [Citation(s) in RCA: 35] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2018] [Accepted: 10/23/2019] [Indexed: 01/10/2023]
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48
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Guillemin A, Duchesne R, Crauste F, Gonin-Giraud S, Gandrillon O. Drugs modulating stochastic gene expression affect the erythroid differentiation process. PLoS One 2019; 14:e0225166. [PMID: 31751364 PMCID: PMC6872177 DOI: 10.1371/journal.pone.0225166] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2019] [Accepted: 10/30/2019] [Indexed: 12/30/2022] Open
Abstract
To better understand the mechanisms behind cells decision-making to differentiate, we assessed the influence of stochastic gene expression (SGE) modulation on the erythroid differentiation process. It has been suggested that stochastic gene expression has a role in cell fate decision-making which is revealed by single-cell analyses but studies dedicated to demonstrate the consistency of this link are still lacking. Recent observations showed that SGE significantly increased during differentiation and a few showed that an increase of the level of SGE is accompanied by an increase in the differentiation process. However, a consistent relation in both increasing and decreasing directions has never been shown in the same cellular system. Such demonstration would require to be able to experimentally manipulate simultaneously the level of SGE and cell differentiation in order to observe if cell behavior matches with the current theory. We identified three drugs that modulate SGE in primary erythroid progenitor cells. Both Artemisinin and Indomethacin decreased SGE and reduced the amount of differentiated cells. On the contrary, a third component called MB-3 simultaneously increased the level of SGE and the amount of differentiated cells. We then used a dynamical modelling approach which confirmed that differentiation rates were indeed affected by the drug treatment. Using single-cell analysis and modeling tools, we provide experimental evidence that, in a physiologically relevant cellular system, SGE is linked to differentiation.
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Affiliation(s)
- Anissa Guillemin
- Laboratoire de biologie et modélisation de la cellule. LBMC - Ecole Normale Supérieure - Lyon, Université Claude Bernard Lyon 1, Centre National de la Recherche Scientifique: UMR5239, Institut National de la Santé et de la Recherche Médicale: U1210 - Ecole Normale Supérieure de Lyon 46 allée d’Italie 69007 Lyon, France
| | - Ronan Duchesne
- Laboratoire de biologie et modélisation de la cellule. LBMC - Ecole Normale Supérieure - Lyon, Université Claude Bernard Lyon 1, Centre National de la Recherche Scientifique: UMR5239, Institut National de la Santé et de la Recherche Médicale: U1210 - Ecole Normale Supérieure de Lyon 46 allée d’Italie 69007 Lyon, France
- Inria Dracula, Villeurbanne, France
| | - Fabien Crauste
- Inria Dracula, Villeurbanne, France
- Univ. Bordeaux, CNRS, Bordeaux INP, IMB, UMR 5251, F-33400, Talence, France
| | - Sandrine Gonin-Giraud
- Laboratoire de biologie et modélisation de la cellule. LBMC - Ecole Normale Supérieure - Lyon, Université Claude Bernard Lyon 1, Centre National de la Recherche Scientifique: UMR5239, Institut National de la Santé et de la Recherche Médicale: U1210 - Ecole Normale Supérieure de Lyon 46 allée d’Italie 69007 Lyon, France
| | - Olivier Gandrillon
- Laboratoire de biologie et modélisation de la cellule. LBMC - Ecole Normale Supérieure - Lyon, Université Claude Bernard Lyon 1, Centre National de la Recherche Scientifique: UMR5239, Institut National de la Santé et de la Recherche Médicale: U1210 - Ecole Normale Supérieure de Lyon 46 allée d’Italie 69007 Lyon, France
- Inria Dracula, Villeurbanne, France
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49
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Telwatte S, Morón-López S, Aran D, Kim P, Hsieh C, Joshi S, Montano M, Greene WC, Butte AJ, Wong JK, Yukl SA. Heterogeneity in HIV and cellular transcription profiles in cell line models of latent and productive infection: implications for HIV latency. Retrovirology 2019; 16:32. [PMID: 31711503 PMCID: PMC6849327 DOI: 10.1186/s12977-019-0494-x] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2019] [Accepted: 11/04/2019] [Indexed: 12/14/2022] Open
Abstract
Background HIV-infected cell lines are widely used to study latent HIV infection, which is considered the main barrier to HIV cure. We hypothesized that these cell lines differ from each other and from cells from HIV-infected individuals in the mechanisms underlying latency. Results To quantify the degree to which HIV expression is inhibited by blocks at different stages of HIV transcription, we employed a recently-described panel of RT-ddPCR assays to measure levels of 7 HIV transcripts (“read-through,” initiated, 5′ elongated, mid-transcribed/unspliced [Pol], distal-transcribed [Nef], polyadenylated, and multiply-sliced [Tat-Rev]) in bulk populations of latently-infected (U1, ACH-2, J-Lat) and productively-infected (8E5, activated J-Lat) cell lines. To assess single-cell variation and investigate cellular genes associated with HIV transcriptional blocks, we developed a novel multiplex qPCR panel and quantified single cell levels of 7 HIV targets and 89 cellular transcripts in latently- and productively-infected cell lines. The bulk cell HIV transcription profile differed dramatically between cell lines and cells from ART-suppressed individuals. Compared to cells from ART-suppressed individuals, latent cell lines showed lower levels of HIV transcriptional initiation and higher levels of polyadenylation and splicing. ACH-2 and J-Lat cells showed different forms of transcriptional interference, while U1 cells showed a block to elongation. Single-cell studies revealed marked variation between/within cell lines in expression of HIV transcripts, T cell phenotypic markers, antiviral factors, and genes implicated in latency. Expression of multiply-spliced HIV Tat-Rev was associated with expression of cellular genes involved in activation, tissue retention, T cell transcription, and apoptosis/survival. Conclusions HIV-infected cell lines differ from each other and from cells from ART-treated individuals in the mechanisms governing latent HIV infection. These differences in viral and cellular gene expression must be considered when gauging the suitability of a given cell line for future research on HIV. At the same time, some features were shared across cell lines, such as low expression of antiviral defense genes and a relationship between productive infection and genes involved in survival. These features may contribute to HIV latency or persistence in vivo, and deserve further study using novel single cell assays such as those described in this manuscript.
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Affiliation(s)
- Sushama Telwatte
- San Francisco VA Medical Center, San Francisco, CA, USA.,University of California San Francisco, San Francisco, CA, USA
| | - Sara Morón-López
- San Francisco VA Medical Center, San Francisco, CA, USA.,University of California San Francisco, San Francisco, CA, USA
| | - Dvir Aran
- Bakar Computational Health Sciences Institute, University of California, San Francisco, San Francisco, CA, USA
| | - Peggy Kim
- San Francisco VA Medical Center, San Francisco, CA, USA
| | - Christine Hsieh
- San Francisco VA Medical Center, San Francisco, CA, USA.,University of California San Francisco, San Francisco, CA, USA
| | - Sunil Joshi
- San Francisco VA Medical Center, San Francisco, CA, USA.,University of California San Francisco, San Francisco, CA, USA
| | - Mauricio Montano
- University of California San Francisco, San Francisco, CA, USA.,Gladstone Institute of Virology and Immunology, San Francisco, CA, USA
| | - Warner C Greene
- University of California San Francisco, San Francisco, CA, USA.,Gladstone Institute of Virology and Immunology, San Francisco, CA, USA
| | - Atul J Butte
- Bakar Computational Health Sciences Institute, University of California, San Francisco, San Francisco, CA, USA
| | - Joseph K Wong
- San Francisco VA Medical Center, San Francisco, CA, USA.,University of California San Francisco, San Francisco, CA, USA
| | - Steven A Yukl
- San Francisco VA Medical Center, San Francisco, CA, USA. .,University of California San Francisco, San Francisco, CA, USA.
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50
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Ali MZ, Choubey S. Decoding the grammar of transcriptional regulation from RNA polymerase measurements: models and their applications. Phys Biol 2019; 16:061001. [PMID: 31603077 DOI: 10.1088/1478-3975/ab45bf] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
The genomic revolution has indubitably brought about a paradigm shift in the field of molecular biology, wherein we can sequence, write and re-write genomes. In spite of achieving such feats, we still lack a quantitative understanding of how cells integrate environmental and intra-cellular signals at the promoter and accordingly regulate the production of messenger RNAs. This current state of affairs is being redressed by recent experimental breakthroughs which enable the counting of RNA polymerase molecules (or the corresponding nascent RNAs) engaged in the process of transcribing a gene at the single-cell level. Theorists, in conjunction, have sought to unravel the grammar of transcriptional regulation by harnessing the various statistical properties of these measurements. In this review, we focus on the recent progress in developing falsifiable models of transcription that aim to connect the molecular mechanisms of transcription to single-cell polymerase measurements. We discuss studies where the application of such models to the experimental data have led to novel mechanistic insights into the process of transcriptional regulation. Such interplay between theory and experiments will likely contribute towards the exciting journey of unfurling the governing principles of transcriptional regulation ranging from bacteria to higher organisms.
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Affiliation(s)
- Md Zulfikar Ali
- Program in Systems Biology, University of Massachusetts Medical School, Worcester, MA, United States of America. Department of Microbiology and Physiological Systems, University of Massachusetts Medical School, Worcester, MA, United States of America
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