1
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Bano R, Mears P, Golding I, Chemla YR. Flagellar dynamics reveal fluctuations and kinetic limit in the Escherichia coli chemotaxis network. Sci Rep 2023; 13:22891. [PMID: 38129516 PMCID: PMC10739816 DOI: 10.1038/s41598-023-49784-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2023] [Accepted: 12/12/2023] [Indexed: 12/23/2023] Open
Abstract
The Escherichia coli chemotaxis network, by which bacteria modulate their random run/tumble swimming pattern to navigate their environment, must cope with unavoidable number fluctuations ("noise") in its molecular constituents like other signaling networks. The probability of clockwise (CW) flagellar rotation, or CW bias, is a measure of the chemotaxis network's output, and its temporal fluctuations provide a proxy for network noise. Here we quantify fluctuations in the chemotaxis signaling network from the switching statistics of flagella, observed using time-resolved fluorescence microscopy of individual optically trapped E. coli cells. This approach allows noise to be quantified across the dynamic range of the network. Large CW bias fluctuations are revealed at steady state, which may play a critical role in driving flagellar switching and cell tumbling. When the network is stimulated chemically to higher activity, fluctuations dramatically decrease. A stochastic theoretical model, inspired by work on gene expression noise, points to CheY activation occurring in bursts, driving CW bias fluctuations. This model also shows that an intrinsic kinetic ceiling on network activity places an upper limit on activated CheY and CW bias, which when encountered suppresses network fluctuations. This limit may also prevent cells from tumbling unproductively in steep gradients.
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Affiliation(s)
- Roshni Bano
- Center for Biophysics and Quantitative Biology, University of Illinois at Urbana-Champaign, Urbana, IL, USA
- Center for the Physics of Living Cells, University of Illinois at Urbana-Champaign, Urbana, IL, USA
| | - Patrick Mears
- Department of Physics, University of Illinois at Urbana-Champaign, Urbana, IL, USA
- Center for the Physics of Living Cells, University of Illinois at Urbana-Champaign, Urbana, IL, USA
| | - Ido Golding
- Center for Biophysics and Quantitative Biology, University of Illinois at Urbana-Champaign, Urbana, IL, USA
- Department of Physics, University of Illinois at Urbana-Champaign, Urbana, IL, USA
- Center for the Physics of Living Cells, University of Illinois at Urbana-Champaign, Urbana, IL, USA
| | - Yann R Chemla
- Center for Biophysics and Quantitative Biology, University of Illinois at Urbana-Champaign, Urbana, IL, USA.
- Department of Physics, University of Illinois at Urbana-Champaign, Urbana, IL, USA.
- Center for the Physics of Living Cells, University of Illinois at Urbana-Champaign, Urbana, IL, USA.
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2
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Keseroglu K, Zinani OQH, Keskin S, Seawall H, Alpay EE, Özbudak EM. Stochastic gene expression and environmental stressors trigger variable somite segmentation phenotypes. Nat Commun 2023; 14:6497. [PMID: 37838784 PMCID: PMC10576776 DOI: 10.1038/s41467-023-42220-7] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2023] [Accepted: 10/04/2023] [Indexed: 10/16/2023] Open
Abstract
Mutations of several genes cause incomplete penetrance and variable expressivity of phenotypes, which are usually attributed to modifier genes or gene-environment interactions. Here, we show stochastic gene expression underlies the variability of somite segmentation defects in embryos mutant for segmentation clock genes her1 or her7. Phenotypic strength is further augmented by low temperature and hypoxia. By performing live imaging of the segmentation clock reporters, we further show that groups of cells with higher oscillation amplitudes successfully form somites while those with lower amplitudes fail to do so. In unfavorable environments, the number of cycles with high amplitude oscillations and the number of successful segmentations proportionally decrease. These results suggest that individual oscillation cycles stochastically fail to pass a threshold amplitude, resulting in segmentation defects in mutants. Our quantitative methodology is adaptable to investigate variable phenotypes of mutant genes in different tissues.
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Affiliation(s)
- Kemal Keseroglu
- Division of Developmental Biology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, 45229, USA
| | - Oriana Q H Zinani
- Division of Developmental Biology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, 45229, USA
- Molecular and Developmental Biology Graduate Program, University of Cincinnati, College of Medicine, Cincinnati, OH, 45229, USA
| | - Sevdenur Keskin
- Allergy and Immunology, University of Arkansas for Medical Science and Arkansas Children's Hospital, Little Rock, AR, 72202, USA
| | - Hannah Seawall
- Division of Developmental Biology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, 45229, USA
| | - Eslim E Alpay
- Division of Developmental Biology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, 45229, USA
| | - Ertuğrul M Özbudak
- Division of Developmental Biology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, 45229, USA.
- Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, OH, 45229, USA.
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3
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Henrion L, Martinez JA, Vandenbroucke V, Delvenne M, Telek S, Zicler A, Grünberger A, Delvigne F. Fitness cost associated with cell phenotypic switching drives population diversification dynamics and controllability. Nat Commun 2023; 14:6128. [PMID: 37783690 PMCID: PMC10545768 DOI: 10.1038/s41467-023-41917-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2023] [Accepted: 09/23/2023] [Indexed: 10/04/2023] Open
Abstract
Isogenic cell populations can cope with stress conditions by switching to alternative phenotypes. Even if it can lead to increased fitness in a natural context, this feature is typically unwanted for a range of applications (e.g., bioproduction, synthetic biology, and biomedicine) where it tends to make cellular response unpredictable. However, little is known about the diversification profiles that can be adopted by a cell population. Here, we characterize the diversification dynamics for various systems (bacteria and yeast) and for different phenotypes (utilization of alternative carbon sources, general stress response and more complex development patterns). Our results suggest that the diversification dynamics and the fitness cost associated with cell switching are coupled. To quantify the contribution of the switching cost on population dynamics, we design a stochastic model that let us reproduce the dynamics observed experimentally and identify three diversification regimes, i.e., constrained (at low switching cost), dispersed (at medium and high switching cost), and bursty (for very high switching cost). Furthermore, we use a cell-machine interface called Segregostat to demonstrate that different levels of control can be applied to these diversification regimes, enabling applications involving more precise cellular responses.
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Affiliation(s)
- Lucas Henrion
- Terra Research and Teaching Centre, Microbial Processes and Interactions (MiPI), Gembloux Agro-Bio Tech, University of Liège, Gembloux, Belgium
| | - Juan Andres Martinez
- Terra Research and Teaching Centre, Microbial Processes and Interactions (MiPI), Gembloux Agro-Bio Tech, University of Liège, Gembloux, Belgium
| | - Vincent Vandenbroucke
- Terra Research and Teaching Centre, Microbial Processes and Interactions (MiPI), Gembloux Agro-Bio Tech, University of Liège, Gembloux, Belgium
| | - Mathéo Delvenne
- Terra Research and Teaching Centre, Microbial Processes and Interactions (MiPI), Gembloux Agro-Bio Tech, University of Liège, Gembloux, Belgium
| | - Samuel Telek
- Terra Research and Teaching Centre, Microbial Processes and Interactions (MiPI), Gembloux Agro-Bio Tech, University of Liège, Gembloux, Belgium
| | - Andrew Zicler
- Terra Research and Teaching Centre, Microbial Processes and Interactions (MiPI), Gembloux Agro-Bio Tech, University of Liège, Gembloux, Belgium
| | - Alexander Grünberger
- Microsystems in Bioprocess Engineering, Institute of Process Engineering in Life Sciences, Karlsruhe Institute of Technology, Karlsruhe, Germany
| | - Frank Delvigne
- Terra Research and Teaching Centre, Microbial Processes and Interactions (MiPI), Gembloux Agro-Bio Tech, University of Liège, Gembloux, Belgium.
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4
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Morales-Rubio R, Bernal-Ramírez J, Rubio-Infante N, Luévano-Martínez LA, Ríos A, Escalante BA, García-Rivas G, Rodríguez González J. Cellular shortening and calcium dynamics are improved by noisy stimulus in a model of cardiomyopathy. Sci Rep 2023; 13:14898. [PMID: 37689752 PMCID: PMC10492796 DOI: 10.1038/s41598-023-41611-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2023] [Accepted: 08/29/2023] [Indexed: 09/11/2023] Open
Abstract
Noise is present in cell biology. The capability of cells to respond to noisy environment have become essential. This study aimed to investigate whether noise can enhance the contractile response and Ca2+ handling in cardiomyocytes from a cardiomyopathy model. Experiments were conducted in an experimental setup with Gaussian white noise, frequency, and amplitude control to stimulate myocytes. Cell shortening, maximal shortening velocity, time to peak shortening, and time to half relaxation variables were recorded to cell shortening. Ca2+ transient amplitude and raise rate variables were registered to measure Ca2+ transients. Our results for cell shortening, Ca2+ transient amplitude, and raise rate suggest that cell response improve when myocytes are noise stimulated. Also, cell shortening, maximal shortening velocity, Ca2+ transient amplitude, and raise improves in control cells. Altogether, these findings suggest novel characteristics in how cells improve their response in a noisy environment.
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Affiliation(s)
- Russell Morales-Rubio
- Centro de Investigación y de Estudios Avanzados del I.P.N-Unidad Monterrey, Vía del Conocimiento 201, Parque de Investigación e Innovación Tecnológica, 66600, Apodaca, NL, México
| | - Judith Bernal-Ramírez
- Tecnologico de Monterrey, Escuela de Medicina y Ciencias de la Salud, Cátedra de Cardiología, Hospital Zambrano Hellion, TecSalud, San Pedro Garza García, México
- The Institute for Obesity Research, Tecnologico de Monterrey, Monterrey, Mexico
| | - Nestor Rubio-Infante
- Tecnologico de Monterrey, Escuela de Medicina y Ciencias de la Salud, Cátedra de Cardiología, Hospital Zambrano Hellion, TecSalud, San Pedro Garza García, México
- The Institute for Obesity Research, Tecnologico de Monterrey, Monterrey, Mexico
| | - Luis A Luévano-Martínez
- Tecnologico de Monterrey, Escuela de Medicina y Ciencias de la Salud, Cátedra de Cardiología, Hospital Zambrano Hellion, TecSalud, San Pedro Garza García, México
- The Institute for Obesity Research, Tecnologico de Monterrey, Monterrey, Mexico
| | - Amelia Ríos
- Centro de Investigación y de Estudios Avanzados del I.P.N-Unidad Monterrey, Vía del Conocimiento 201, Parque de Investigación e Innovación Tecnológica, 66600, Apodaca, NL, México
| | - Bruno A Escalante
- Centro de Investigación y de Estudios Avanzados del I.P.N-Unidad Monterrey, Vía del Conocimiento 201, Parque de Investigación e Innovación Tecnológica, 66600, Apodaca, NL, México
| | - Gerardo García-Rivas
- Tecnologico de Monterrey, Escuela de Medicina y Ciencias de la Salud, Cátedra de Cardiología, Hospital Zambrano Hellion, TecSalud, San Pedro Garza García, México
- The Institute for Obesity Research, Tecnologico de Monterrey, Monterrey, Mexico
| | - Jesús Rodríguez González
- Centro de Investigación y de Estudios Avanzados del I.P.N-Unidad Monterrey, Vía del Conocimiento 201, Parque de Investigación e Innovación Tecnológica, 66600, Apodaca, NL, México.
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5
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Kumpost V, Hilbert L, Mikut R. Noise facilitates entrainment of a population of uncoupled limit cycle oscillators. J R Soc Interface 2023; 20:20220781. [PMID: 36628527 PMCID: PMC9832296 DOI: 10.1098/rsif.2022.0781] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
Many biological oscillators share two properties: they are subject to stochastic fluctuations (noise) and they must reliably adjust their period to changing environmental conditions (entrainment). While noise seems to distort the ability of single oscillators to entrain, in populations of uncoupled oscillators noise allows population-level entrainment for a wider range of input amplitudes and periods. Here, we investigate how this effect depends on the noise intensity and the number of oscillators in the population. We have found that, if a population consists of a sufficient number of oscillators, increasing noise intensity leads to faster entrainment after a phase change of the input signal (jet lag) and increases sensitivity to low-amplitude input signals.
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Affiliation(s)
- Vojtech Kumpost
- Institute for Automation and Applied Informatics, Karlsruhe Institute of Technology, Eggenstein-Leopoldshafen, Germany,Institute of Biological and Chemical Systems—Biological Information Processing, Karlsruhe Institute of Technology, Eggenstein-Leopoldshafen, Germany
| | - Lennart Hilbert
- Institute of Biological and Chemical Systems—Biological Information Processing, Karlsruhe Institute of Technology, Eggenstein-Leopoldshafen, Germany,Department of Systems Biology and Bioinformatics, Zoological Institute, Karlsruhe Institute of Technology, Karlsruhe, Germany
| | - Ralf Mikut
- Institute for Automation and Applied Informatics, Karlsruhe Institute of Technology, Eggenstein-Leopoldshafen, Germany
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6
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Hughes FA, Barr AR, Thomas P. Patterns of interdivision time correlations reveal hidden cell cycle factors. eLife 2022; 11:e80927. [PMID: 36377847 PMCID: PMC9822260 DOI: 10.7554/elife.80927] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2022] [Accepted: 11/14/2022] [Indexed: 11/16/2022] Open
Abstract
The time taken for cells to complete a round of cell division is a stochastic process controlled, in part, by intracellular factors. These factors can be inherited across cellular generations which gives rise to, often non-intuitive, correlation patterns in cell cycle timing between cells of different family relationships on lineage trees. Here, we formulate a framework of hidden inherited factors affecting the cell cycle that unifies known cell cycle control models and reveals three distinct interdivision time correlation patterns: aperiodic, alternator, and oscillator. We use Bayesian inference with single-cell datasets of cell division in bacteria, mammalian and cancer cells, to identify the inheritance motifs that underlie these datasets. From our inference, we find that interdivision time correlation patterns do not identify a single cell cycle model but generally admit a broad posterior distribution of possible mechanisms. Despite this unidentifiability, we observe that the inferred patterns reveal interpretable inheritance dynamics and hidden rhythmicity of cell cycle factors. This reveals that cell cycle factors are commonly driven by circadian rhythms, but their period may differ in cancer. Our quantitative analysis thus reveals that correlation patterns are an emergent phenomenon that impact cell proliferation and these patterns may be altered in disease.
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Affiliation(s)
- Fern A Hughes
- Department of Mathematics, Imperial College LondonLondonUnited Kingdom
- MRC London Institute of Medical SciencesLondonUnited Kingdom
| | - Alexis R Barr
- MRC London Institute of Medical SciencesLondonUnited Kingdom
- Institute of Clinical Sciences, Imperial College LondonLondonUnited Kingdom
| | - Philipp Thomas
- Department of Mathematics, Imperial College LondonLondonUnited Kingdom
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7
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Gerhardt KP, Rao SD, Olson EJ, Igoshin OA, Tabor JJ. Independent control of mean and noise by convolution of gene expression distributions. Nat Commun 2021; 12:6957. [PMID: 34845228 PMCID: PMC8630168 DOI: 10.1038/s41467-021-27070-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2021] [Accepted: 11/03/2021] [Indexed: 11/28/2022] Open
Abstract
Gene expression noise can reduce cellular fitness or facilitate processes such as alternative metabolism, antibiotic resistance, and differentiation. Unfortunately, efforts to study the impacts of noise have been hampered by a scaling relationship between noise and expression level from individual promoters. Here, we use theory to demonstrate that mean and noise can be controlled independently by expressing two copies of a gene from separate inducible promoters in the same cell. We engineer low and high noise inducible promoters to validate this result in Escherichia coli, and develop a model that predicts the experimental distributions. Finally, we use our method to reveal that the response of a promoter to a repressor is less sensitive with higher repressor noise and explain this result using a law from probability theory. Our approach can be applied to investigate the effects of noise on diverse biological pathways or program cellular heterogeneity for synthetic biology applications.
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Affiliation(s)
- Karl P Gerhardt
- Department of Bioengineering, Rice University, 6100 Main Street, Houston, TX, 77005, USA
| | - Satyajit D Rao
- Department of Bioengineering, Rice University, 6100 Main Street, Houston, TX, 77005, USA
| | - Evan J Olson
- Department of Bioengineering, Rice University, 6100 Main Street, Houston, TX, 77005, USA
| | - Oleg A Igoshin
- Department of Bioengineering, Rice University, 6100 Main Street, Houston, TX, 77005, USA
- Department of Biosciences, Rice University, 6100 Main Street, Houston, TX, 77005, USA
- Center for Theoretical Biophysics, Rice University, 6100 Main Street, Houston, TX, 77005, USA
- Department of Chemistry, Rice University, 6100 Main Street, Houston, TX, 77005, USA
| | - Jeffrey J Tabor
- Department of Bioengineering, Rice University, 6100 Main Street, Houston, TX, 77005, USA.
- Department of Biosciences, Rice University, 6100 Main Street, Houston, TX, 77005, USA.
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8
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Abstract
Monoallelic expression (MAE) or extreme allele bias can account for incomplete penetrance, missing heritability and non-Mendelian diseases. In cancer, MAE is associated with shorter patient survival times and higher tumor grade. Prior studies showed that stochastic MAE is caused by stochastic epigenetic silencing, in a gene and tissue-specific manner. Here, we used C. elegans to study stochastic MAE in vivo. We found allele bias/MAE to be widespread within C. elegans tissues, presenting as a continuum from fully biallelic to MAE. We discovered that the presence of introns within alleles robustly decreases MAE. We determined that introns control MAE at distinct loci, in distinct cell types, with distinct promoters, and within distinct coding sequences, using a 5'-intron position-dependent mechanism. Bioinformatic analysis showed human intronless genes are significantly enriched for MAE. Our experimental evidence demonstrates a role for introns in regulating MAE, possibly explaining why some mutations within introns result in disease.
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Affiliation(s)
- Bryan Sands
- grid.34477.330000000122986657Department of Laboratory Medicine and Pathology, School of Medicine, University of Washington, Seattle, WA USA
| | - Soo Yun
- grid.34477.330000000122986657Department of Laboratory Medicine and Pathology, School of Medicine, University of Washington, Seattle, WA USA
| | - Alexander R. Mendenhall
- grid.34477.330000000122986657Department of Laboratory Medicine and Pathology, School of Medicine, University of Washington, Seattle, WA USA
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9
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Gao Z, Zhang W, Chang R, Zhang S, Yang G, Zhao G. Liquid-Liquid Phase Separation: Unraveling the Enigma of Biomolecular Condensates in Microbial Cells. Front Microbiol 2021; 12:751880. [PMID: 34759902 PMCID: PMC8573418 DOI: 10.3389/fmicb.2021.751880] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2021] [Accepted: 09/06/2021] [Indexed: 12/12/2022] Open
Abstract
Numerous examples of microbial phase-separated biomolecular condensates have now been identified following advances in fluorescence imaging and single molecule microscopy technologies. The structure, function, and potential applications of these microbial condensates are currently receiving a great deal of attention. By neatly compartmentalizing proteins and their interactors in membrane-less organizations while maintaining free communication between these macromolecules and the external environment, microbial cells are able to achieve enhanced metabolic efficiency. Typically, these condensates also possess the ability to rapidly adapt to internal and external changes. The biological functions of several phase-separated condensates in small bacterial cells show evolutionary convergence with the biological functions of their eukaryotic paralogs. Artificial microbial membrane-less organelles are being constructed with application prospects in biocatalysis, biosynthesis, and biomedicine. In this review, we provide an overview of currently known biomolecular condensates driven by liquid-liquid phase separation (LLPS) in microbial cells, and we elaborate on their biogenesis mechanisms and biological functions. Additionally, we highlight the major challenges and future research prospects in studying microbial LLPS.
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Affiliation(s)
| | | | | | | | - Guiwen Yang
- College of Life Science, Shandong Normal University, Jinan, China
| | - Guoyan Zhao
- College of Life Science, Shandong Normal University, Jinan, China
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10
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Kim MH, Kino-Oka M. Mechanobiological conceptual framework for assessing stem cell bioprocess effectiveness. Biotechnol Bioeng 2021; 118:4537-4549. [PMID: 34460101 DOI: 10.1002/bit.27929] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2021] [Revised: 08/22/2021] [Accepted: 08/27/2021] [Indexed: 12/12/2022]
Abstract
Fully realizing the enormous potential of stem cells requires developing efficient bioprocesses and optimizations founded in mechanobiological considerations. Here, we emphasize the importance of mechanotransduction as one of the governing principles of stem cell bioprocesses, underscoring the need to further explore the behavioral mechanisms involved in sensing mechanical cues and coordinating transcriptional responses. We identify the sources of intrinsic, extrinsic, and external noise in bioprocesses requiring further study, and discuss the criteria and indicators that may be used to assess and predict cell-to-cell variability resulting from environmental fluctuations. Specifically, we propose a conceptual framework to explain the impact of mechanical forces within the cellular environment, identify key cell state determinants in bioprocesses, and discuss downstream implementation challenges.
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Affiliation(s)
- Mee-Hae Kim
- Department of Biotechnology, Graduate School of Engineering, Osaka University, Suita, Japan
| | - Masahiro Kino-Oka
- Department of Biotechnology, Graduate School of Engineering, Osaka University, Suita, Japan
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11
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Tantale K, Garcia-Oliver E, Robert MC, L'Hostis A, Yang Y, Tsanov N, Topno R, Gostan T, Kozulic-Pirher A, Basu-Shrivastava M, Mukherjee K, Slaninova V, Andrau JC, Mueller F, Basyuk E, Radulescu O, Bertrand E. Stochastic pausing at latent HIV-1 promoters generates transcriptional bursting. Nat Commun 2021; 12:4503. [PMID: 34301927 PMCID: PMC8302722 DOI: 10.1038/s41467-021-24462-5] [Citation(s) in RCA: 27] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2020] [Accepted: 06/17/2021] [Indexed: 02/06/2023] Open
Abstract
Promoter-proximal pausing of RNA polymerase II is a key process regulating gene expression. In latent HIV-1 cells, it prevents viral transcription and is essential for latency maintenance, while in acutely infected cells the viral factor Tat releases paused polymerase to induce viral expression. Pausing is fundamental for HIV-1, but how it contributes to bursting and stochastic viral reactivation is unclear. Here, we performed single molecule imaging of HIV-1 transcription. We developed a quantitative analysis method that manages multiple time scales from seconds to days and that rapidly fits many models of promoter dynamics. We found that RNA polymerases enter a long-lived pause at latent HIV-1 promoters (>20 minutes), thereby effectively limiting viral transcription. Surprisingly and in contrast to current models, pausing appears stochastic and not obligatory, with only a small fraction of the polymerases undergoing long-lived pausing in absence of Tat. One consequence of stochastic pausing is that HIV-1 transcription occurs in bursts in latent cells, thereby facilitating latency exit and providing a rationale for the stochasticity of viral rebounds.
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Affiliation(s)
- Katjana Tantale
- Institut de Génétique Moléculaire de Montpellier, University of Montpellier, CNRS, Montpellier, France
- Equipe labélisée Ligue Nationale Contre le Cancer, University of Montpellier, CNRS, Montpellier, France
| | - Encar Garcia-Oliver
- Institut de Génétique Moléculaire de Montpellier, University of Montpellier, CNRS, Montpellier, France
| | - Marie-Cécile Robert
- Institut de Génétique Moléculaire de Montpellier, University of Montpellier, CNRS, Montpellier, France
- Equipe labélisée Ligue Nationale Contre le Cancer, University of Montpellier, CNRS, Montpellier, France
- Institut de Génétique Humaine, University of Montpellier, CNRS, Montpellier, France
| | - Adèle L'Hostis
- LPHI, UMR CNRS 5235, University of Montpellier, Montpellier, France
| | - Yueyuxiao Yang
- LPHI, UMR CNRS 5235, University of Montpellier, Montpellier, France
| | - Nikolay Tsanov
- Institut de Génétique Moléculaire de Montpellier, University of Montpellier, CNRS, Montpellier, France
- Equipe labélisée Ligue Nationale Contre le Cancer, University of Montpellier, CNRS, Montpellier, France
| | - Rachel Topno
- Equipe labélisée Ligue Nationale Contre le Cancer, University of Montpellier, CNRS, Montpellier, France
- Institut de Génétique Humaine, University of Montpellier, CNRS, Montpellier, France
- LPHI, UMR CNRS 5235, University of Montpellier, Montpellier, France
| | - Thierry Gostan
- Institut de Génétique Moléculaire de Montpellier, University of Montpellier, CNRS, Montpellier, France
| | - Alja Kozulic-Pirher
- Institut de Génétique Moléculaire de Montpellier, University of Montpellier, CNRS, Montpellier, France
- Equipe labélisée Ligue Nationale Contre le Cancer, University of Montpellier, CNRS, Montpellier, France
| | - Meenakshi Basu-Shrivastava
- Institut de Génétique Moléculaire de Montpellier, University of Montpellier, CNRS, Montpellier, France
- Equipe labélisée Ligue Nationale Contre le Cancer, University of Montpellier, CNRS, Montpellier, France
| | - Kamalika Mukherjee
- Institut de Génétique Moléculaire de Montpellier, University of Montpellier, CNRS, Montpellier, France
- Equipe labélisée Ligue Nationale Contre le Cancer, University of Montpellier, CNRS, Montpellier, France
| | - Vera Slaninova
- Equipe labélisée Ligue Nationale Contre le Cancer, University of Montpellier, CNRS, Montpellier, France
- Institut de Génétique Humaine, University of Montpellier, CNRS, Montpellier, France
| | - Jean-Christophe Andrau
- Institut de Génétique Moléculaire de Montpellier, University of Montpellier, CNRS, Montpellier, France
| | - Florian Mueller
- Unité Imagerie et Modélisation, Institut Pasteur and CNRS UMR 3691, Paris, France
| | - Eugenia Basyuk
- Institut de Génétique Moléculaire de Montpellier, University of Montpellier, CNRS, Montpellier, France.
- Equipe labélisée Ligue Nationale Contre le Cancer, University of Montpellier, CNRS, Montpellier, France.
- Microbiology Fundamental and Pathogenicity CNRS UMR 5234, University of Bordeaux, Bordeaux, France.
| | - Ovidiu Radulescu
- LPHI, UMR CNRS 5235, University of Montpellier, Montpellier, France.
| | - Edouard Bertrand
- Institut de Génétique Moléculaire de Montpellier, University of Montpellier, CNRS, Montpellier, France.
- Equipe labélisée Ligue Nationale Contre le Cancer, University of Montpellier, CNRS, Montpellier, France.
- Institut de Génétique Humaine, University of Montpellier, CNRS, Montpellier, France.
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12
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Kumpošt V, Vallone D, Gondi SB, Foulkes NS, Mikut R, Hilbert L. A stochastic oscillator model simulates the entrainment of vertebrate cellular clocks by light. Sci Rep 2021; 11:14497. [PMID: 34262086 PMCID: PMC8280200 DOI: 10.1038/s41598-021-93913-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2021] [Accepted: 06/29/2021] [Indexed: 02/06/2023] Open
Abstract
The circadian clock is a cellular mechanism that synchronizes various biological processes with respect to the time of the day. While much progress has been made characterizing the molecular mechanisms underlying this clock, it is less clear how external light cues influence the dynamics of the core clock mechanism and thereby entrain it with the light-dark cycle. Zebrafish-derived cell cultures possess clocks that are directly light-entrainable, thus providing an attractive laboratory model for circadian entrainment. Here, we have developed a stochastic oscillator model of the zebrafish circadian clock, which accounts for the core clock negative feedback loop, light input, and the proliferation of single-cell oscillator noise into population-level luminescence recordings. The model accurately predicts the entrainment dynamics observed in bioluminescent clock reporter assays upon exposure to a wide range of lighting conditions. Furthermore, we have applied the model to obtain refitted parameter sets for cell cultures exposed to a variety of pharmacological treatments and predict changes in single-cell oscillator parameters. Our work paves the way for model-based, large-scale screens for genetic or pharmacologically-induced modifications to the entrainment of circadian clock function.
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Affiliation(s)
- Vojtěch Kumpošt
- grid.7892.40000 0001 0075 5874Institute for Automation and Applied Informatics, Karlsruhe Institute of Technology, Eggenstein-Leopoldshafen, Germany ,grid.7892.40000 0001 0075 5874Institute of Biological and Chemical Systems-Biological Information Processing, Karlsruhe Institute of Technology, Eggenstein-Leopoldshafen, Germany
| | - Daniela Vallone
- grid.7892.40000 0001 0075 5874Institute of Biological and Chemical Systems-Biological Information Processing, Karlsruhe Institute of Technology, Eggenstein-Leopoldshafen, Germany
| | | | - Nicholas S. Foulkes
- grid.7892.40000 0001 0075 5874Institute of Biological and Chemical Systems-Biological Information Processing, Karlsruhe Institute of Technology, Eggenstein-Leopoldshafen, Germany ,grid.7700.00000 0001 2190 4373Centre for Organismal Studies Heidelberg, Ruprecht-Karls-Universität Heidelberg, Heidelberg, Germany
| | - Ralf Mikut
- grid.7892.40000 0001 0075 5874Institute for Automation and Applied Informatics, Karlsruhe Institute of Technology, Eggenstein-Leopoldshafen, Germany
| | - Lennart Hilbert
- grid.7892.40000 0001 0075 5874Institute of Biological and Chemical Systems-Biological Information Processing, Karlsruhe Institute of Technology, Eggenstein-Leopoldshafen, Germany ,grid.7892.40000 0001 0075 5874Department of Systems Biology and Bioinformatics, Zoological Institute, Karlsruhe Institute of Technology, Karlsruhe, Germany
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13
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Muñoz-Rojas AR, Kelsey I, Pappalardo JL, Chen M, Miller-Jensen K. Co-stimulation with opposing macrophage polarization cues leads to orthogonal secretion programs in individual cells. Nat Commun 2021; 12:301. [PMID: 33436596 PMCID: PMC7804107 DOI: 10.1038/s41467-020-20540-2] [Citation(s) in RCA: 35] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2020] [Accepted: 12/07/2020] [Indexed: 12/13/2022] Open
Abstract
Macrophages are innate immune cells that contribute to fighting infections, tissue repair, and maintaining tissue homeostasis. To enable such functional diversity, macrophages resolve potentially conflicting cues in the microenvironment via mechanisms that are unclear. Here, we use single-cell RNA sequencing to explore how individual macrophages respond when co-stimulated with inflammatory stimuli LPS and IFN-γ and the resolving cytokine IL-4. These co-stimulated macrophages display a distinct global transcriptional program. However, variable negative cross-regulation between some LPS + IFN-γ-specific and IL-4-specific genes results in cell-to-cell heterogeneity in transcription. Interestingly, negative cross-regulation leads to mutually exclusive expression of the T-cell-polarizing cytokine genes Il6 and Il12b versus the IL-4-associated factors Arg1 and Chil3 in single co-stimulated macrophages, and single-cell secretion measurements show that these specialized functions are maintained for at least 48 h. This study suggests that increasing functional diversity in the population is one strategy macrophages use to respond to conflicting environmental cues.
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Affiliation(s)
- Andrés R Muñoz-Rojas
- Department of Biomedical Engineering, Yale University, New Haven, CT, USA
- Department of Immunology, Harvard Medical School, Boston, MA, USA
| | - Ilana Kelsey
- Department of Biomedical Engineering, Yale University, New Haven, CT, USA
| | - Jenna L Pappalardo
- Department of Immunobiology, Yale University School of Medicine, New Haven, CT, USA
| | - Meibin Chen
- Department of Biomedical Engineering, Yale University, New Haven, CT, USA
| | - Kathryn Miller-Jensen
- Department of Biomedical Engineering, Yale University, New Haven, CT, USA.
- Department of Molecular, Cellular, and Developmental Biology, Yale University, New Haven, CT, USA.
- Systems Biology Institute, Yale University, New Haven, CT, USA.
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14
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Bonny AR, Fonseca JP, Park JE, El-Samad H. Orthogonal control of mean and variability of endogenous genes in a human cell line. Nat Commun 2021; 12:292. [PMID: 33436569 PMCID: PMC7804932 DOI: 10.1038/s41467-020-20467-8] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2020] [Accepted: 11/25/2020] [Indexed: 12/11/2022] Open
Abstract
Stochastic fluctuations at the transcriptional level contribute to isogenic cell-to-cell heterogeneity in mammalian cell populations. However, we still have no clear understanding of the repercussions of this heterogeneity, given the lack of tools to independently control mean expression and variability of a gene. Here, we engineer a synthetic circuit to modulate mean expression and heterogeneity of transgenes and endogenous human genes. The circuit, a Tunable Noise Rheostat (TuNR), consists of a transcriptional cascade of two inducible transcriptional activators, where the output mean and variance can be modulated by two orthogonal small molecule inputs. In this fashion, different combinations of the inputs can achieve the same mean but with different population variability. With TuNR, we achieve low basal expression, over 1000-fold expression of a transgene product, and up to 7-fold induction of the endogenous gene NGFR. Importantly, for the same mean expression level, we are able to establish varying degrees of heterogeneity in expression within an isogenic population, thereby decoupling gene expression noise from its mean. TuNR is therefore a modular tool that can be used in mammalian cells to enable direct interrogation of the implications of cell-to-cell variability.
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Affiliation(s)
- Alain R Bonny
- Department of Biochemistry and Biophysics, University of California, San Francisco, San Francisco, CA, 94158, USA
| | - João Pedro Fonseca
- Department of Biochemistry and Biophysics, University of California, San Francisco, San Francisco, CA, 94158, USA
- Amyris Bio Products Portugal, Porto, Portugal
| | - Jesslyn E Park
- Department of Biochemistry and Biophysics, University of California, San Francisco, San Francisco, CA, 94158, USA
| | - Hana El-Samad
- Department of Biochemistry and Biophysics, University of California, San Francisco, San Francisco, CA, 94158, USA.
- Chan Zuckerberg Biohub, San Francisco, CA, 94158, USA.
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15
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Abstract
Gene expression variability, differences in the number of mRNA per cell across a population of cells, is ubiquitous across diverse organisms with broad impacts on cellular phenotypes. The role of chromatin in regulating average gene expression has been extensively studied. However, what aspects of the chromatin contribute to gene expression variability is still underexplored. Here we addressed this problem by leveraging chromatin diversity and using a systematic investigation of randomly integrated expression reporters to identify what aspects of chromatin microenvironment contribute to gene expression variability. Using DNA barcoding and split-pool decoding, we created a large library of isogenic reporter clones and identified reporter integration sites in a massive and parallel manner. By mapping our measurements of reporter expression at different genomic loci with multiple epigenetic profiles including the enrichment of transcription factors and the distance to different chromatin states, we identified new factors that impact the regulation of gene expression distributions.
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Affiliation(s)
- Thanutra Zhang
- Institute for Quantitative and Computational Biosciences, UCLA, Los Angeles, CA, USA
| | - Robert Foreman
- Institute for Quantitative and Computational Biosciences, UCLA, Los Angeles, CA, USA
| | - Roy Wollman
- Institute for Quantitative and Computational Biosciences, UCLA, Los Angeles, CA, USA.
- Departments of Integrative Biology and Physiology and Chemistry and Biochemistry, UCLA, Los Angeles, CA, USA.
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16
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Abstract
From the time a cell was first placed under the microscope, it became apparent that identifying two clonal cells that "look" identical is extremely challenging. Since then, cell-to-cell differences in shape, size, and protein content have been carefully examined, informing us of the ultimate limits that hinder two cells from occupying an identical phenotypic state. Here, we present recent experimental and computational evidence that similar limits emerge also in cellular metabolism. These limits pertain to stochastic metabolic dynamics and, thus, cell-to-cell metabolic variability, including the resulting adapting benefits. We review these phenomena with a focus on microbial metabolism and conclude with a brief outlook on the potential relationship between metabolic noise and adaptive evolution. This article is categorized under: Metabolic Diseases > Computational Models Metabolic Diseases > Biomedical Engineering.
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Affiliation(s)
| | - Abhyudai Singh
- Department of Electrical and Computer Engineering, University of Delaware, Newark, Delaware, USA
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17
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Subedi NR, Jung PS, Bredeweg EL, Nemati S, Baker SE, Christodoulides DN, Vasdekis AE. Integrative quantitative-phase and airy light-sheet imaging. Sci Rep 2020; 10:20150. [PMID: 33214600 PMCID: PMC7678854 DOI: 10.1038/s41598-020-76730-x] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2020] [Accepted: 10/30/2020] [Indexed: 01/05/2023] Open
Abstract
Light-sheet microscopy enables considerable speed and phototoxicity gains, while quantitative-phase imaging confers label-free recognition of cells and organelles, and quantifies their number-density that, thermodynamically, is more representative of metabolism than size. Here, we report the fusion of these two imaging modalities onto a standard inverted microscope that retains compatibility with microfluidics and open-source software for image acquisition and processing. An accelerating Airy-beam light-sheet critically enabled imaging areas that were greater by more than one order of magnitude than a Gaussian beam illumination and matched exactly those of quantitative-phase imaging. Using this integrative imaging system, we performed a demonstrative multivariate investigation of live-cells in microfluidics that unmasked that cellular noise can affect the compartmental localization of metabolic reactions. We detail the design, assembly, and performance of the integrative imaging system, and discuss potential applications in biotechnology and evolutionary biology.
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Affiliation(s)
- N R Subedi
- Department of Physics, University of Idaho, Moscow, ID, 83844, USA
| | - P S Jung
- CREOL-The College of Optics and Photonics, University of Central Florida, Orlando, FL, 32816-2700, USA
- Faculty of Physics, Warsaw University of Technology, Warsaw, Poland
| | - E L Bredeweg
- Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory, Richland, WA, 99354, USA
| | - S Nemati
- Department of Physics, University of Idaho, Moscow, ID, 83844, USA
| | - S E Baker
- Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory, Richland, WA, 99354, USA
| | - D N Christodoulides
- CREOL-The College of Optics and Photonics, University of Central Florida, Orlando, FL, 32816-2700, USA
| | - A E Vasdekis
- Department of Physics, University of Idaho, Moscow, ID, 83844, USA.
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18
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Farahani RM, Rezaei-Lotfi S, Hunter N. Genomic competition for noise reduction shaped evolutionary landscape of mir-4673. NPJ Syst Biol Appl 2020; 6:12. [PMID: 32376854 PMCID: PMC7203229 DOI: 10.1038/s41540-020-0131-2] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2019] [Accepted: 04/09/2020] [Indexed: 12/24/2022] Open
Abstract
The genomic platform that informs evolution of microRNA cascades remains unknown. Here we capitalised on the recent evolutionary trajectory of hominin-specific miRNA-4673, encoded in intron 4 of notch-1, to uncover the identity of one such precursor genomic element and the selective forces acting upon it. The miRNA targets genes that regulate Wnt/β-catenin signalling cascade. Primary sequence of the microRNA and its target region in Wnt modulating genes evolved from homologous signatures mapped to homotypic cis-clusters recognised by TCF3/4 and TFAP2A/B/C families. Integration of homologous TFAP2A/B/C cis-clusters (short range inhibitor of β-catenin) into the transcriptional landscape of Wnt cascade genes can reduce noise in gene expression. Probabilistic adoption of miRNA secondary structure by one such cis-signature in notch-1 reflected selection for superhelical curvature symmetry of precursor DNA to localise a nucleosome that overlapped the latter cis-cluster. By replicating the cis-cluster signature, non-random interactions of the miRNA with key Wnt modulator genes expanded the transcriptional noise buffering capacity via a coherent feed-forward loop mechanism. In consequence, an autonomous transcriptional noise dampener (the cis-cluster/nucleosome) evolved into a post-transcriptional one (the miRNA). The findings suggest a latent potential for remodelling of transcriptional landscape by miRNAs that capitalise on non-random distribution of genomic cis-signatures.
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Affiliation(s)
- Ramin M Farahani
- IDR/Westmead Institute for Medical Research and Westmead Centre for Oral Health, Sydney, NSW, Australia.
- Faculty of Medicine and Health Sciences, University of Sydney, Sydney, NSW, 2006, Australia.
| | - Saba Rezaei-Lotfi
- Faculty of Medicine and Health Sciences, University of Sydney, Sydney, NSW, 2006, Australia
| | - Neil Hunter
- IDR/Westmead Institute for Medical Research and Westmead Centre for Oral Health, Sydney, NSW, Australia
- Faculty of Medicine and Health Sciences, University of Sydney, Sydney, NSW, 2006, Australia
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19
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Abstract
Mitochondrial DNA (mtDNA) mutations cause severe congenital diseases but may also be associated with healthy aging. mtDNA is stochastically replicated and degraded, and exists within organelles which undergo dynamic fusion and fission. The role of the resulting mitochondrial networks in the time evolution of the cellular proportion of mutated mtDNA molecules (heteroplasmy), and cell-to-cell variability in heteroplasmy (heteroplasmy variance), remains incompletely understood. Heteroplasmy variance is particularly important since it modulates the number of pathological cells in a tissue. Here, we provide the first wide-reaching theoretical framework which bridges mitochondrial network and genetic states. We show that, under a range of conditions, the (genetic) rate of increase in heteroplasmy variance and de novo mutation are proportionally modulated by the (physical) fraction of unfused mitochondria, independently of the absolute fission-fusion rate. In the context of selective fusion, we show that intermediate fusion:fission ratios are optimal for the clearance of mtDNA mutants. Our findings imply that modulating network state, mitophagy rate, and copy number to slow down heteroplasmy dynamics when mean heteroplasmy is low could have therapeutic advantages for mitochondrial disease and healthy aging.
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Affiliation(s)
- Juvid Aryaman
- Department of Mathematics, Imperial College London, SW7 2AZ, United Kingdom
- Department of Clinical Neurosciences, University of Cambridge, CB2 0QQ, United Kingdom
- Medical Research Council Mitochondrial Biology Unit, University of Cambridge, CB2 0XY, United Kingdom
| | - Charlotte Bowles
- School of Biosciences, University of Birmingham, B15 2TT, United Kingdom
| | - Nick S Jones
- Department of Mathematics, Imperial College London, SW7 2AZ, United Kingdom
- Engineering and Physical Sciences Research Council Centre for the Mathematics of Precision Healthcare, Imperial College London, SW7 2AZ, United Kingdom
| | - Iain G Johnston
- Faculty of Mathematics and Natural Sciences, University of Bergen, 5007, Norway
- Alan Turing Institute, London NW1 2DB, United Kingdom
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20
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Abstract
Cell-to-cell heterogeneity drives a range of (patho)physiologically important phenomena, such as cell fate and chemotherapeutic resistance. The role of metabolism, and particularly of mitochondria, is increasingly being recognized as an important explanatory factor in cell-to-cell heterogeneity. Most eukaryotic cells possess a population of mitochondria, in the sense that mitochondrial DNA (mtDNA) is held in multiple copies per cell, where the sequence of each molecule can vary. Hence, intra-cellular mitochondrial heterogeneity is possible, which can induce inter-cellular mitochondrial heterogeneity, and may drive aspects of cellular noise. In this review, we discuss sources of mitochondrial heterogeneity (variations between mitochondria in the same cell, and mitochondrial variations between supposedly identical cells) from both genetic and non-genetic perspectives, and mitochondrial genotype-phenotype links. We discuss the apparent homeostasis of mtDNA copy number, the observation of pervasive intra-cellular mtDNA mutation (which is termed "microheteroplasmy"), and developments in the understanding of inter-cellular mtDNA mutation ("macroheteroplasmy"). We point to the relationship between mitochondrial supercomplexes, cristal structure, pH, and cardiolipin as a potential amplifier of the mitochondrial genotype-phenotype link. We also discuss mitochondrial membrane potential and networks as sources of mitochondrial heterogeneity, and their influence upon the mitochondrial genome. Finally, we revisit the idea of mitochondrial complementation as a means of dampening mitochondrial genotype-phenotype links in light of recent experimental developments. The diverse sources of mitochondrial heterogeneity, as well as their increasingly recognized role in contributing to cellular heterogeneity, highlights the need for future single-cell mitochondrial measurements in the context of cellular noise studies.
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Affiliation(s)
- Juvid Aryaman
- Department of Mathematics, Imperial College London, London, United Kingdom
- Department of Clinical Neurosciences, University of Cambridge, Cambridge, United Kingdom
- MRC Mitochondrial Biology Unit, University of Cambridge, Cambridge, United Kingdom
| | - Iain G. Johnston
- School of Biosciences, University of Birmingham, Birmingham, United Kingdom
- EPSRC Centre for the Mathematics of Precision Healthcare, Imperial College London, London, United Kingdom
| | - Nick S. Jones
- Department of Mathematics, Imperial College London, London, United Kingdom
- EPSRC Centre for the Mathematics of Precision Healthcare, Imperial College London, London, United Kingdom
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21
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Boada Y, Vignoni A, Picó J. Engineered Control of Genetic Variability Reveals Interplay among Quorum Sensing, Feedback Regulation, and Biochemical Noise. ACS Synth Biol 2017; 6:1903-1912. [PMID: 28581725 DOI: 10.1021/acssynbio.7b00087] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Stochastic fluctuations in gene expression trigger both beneficial and harmful consequences for cell behavior. Therefore, achieving a desired mean protein expression level while minimizing noise is of interest in many applications, including robust protein production systems in industrial biotechnology. Here, we consider a synthetic gene circuit combining intracellular negative feedback and cell-to-cell communication based on quorum sensing. Accounting for both intrinsic and extrinsic noise, stochastic simulations allow us to analyze the capability of the circuit to reduce noise strength as a function of its parameters. We obtain mean expression levels and noise strengths for all species under different scenarios, showing good agreement with system-wide available experimental data of protein abundance and noise in Escherichia coli. Our in silico experiments, validated by preliminary in vivo results, reveal significant noise attenuation in gene expression through the interplay between quorum sensing and negative feedback and highlight the differential role that they play in regard to intrinsic and extrinsic noise.
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Affiliation(s)
- Yadira Boada
- Institut
d’Automàtica i Informàtica Industrial, Universitat Politècnica de València, Camino de Vera s/n, 46022 Valencia, Spain
| | - Alejandro Vignoni
- Center
for Systems Biology Dresden, Max Planck Institute of Molecular Cell Biology and Genetics, Pfotenhaurstr. 108, 01307 Dresden, Germany
| | - Jesús Picó
- Institut
d’Automàtica i Informàtica Industrial, Universitat Politècnica de València, Camino de Vera s/n, 46022 Valencia, Spain
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22
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Abstract
Biological networks contain overrepresented small-scale topologies, typically called motifs. A frequently appearing motif is the transcriptional negative-feedback loop, where a gene product represses its own transcription. Here, using synthetic circuits stably integrated in human kidney cells, we study the effect of negative-feedback regulation on cell-wide (extrinsic) and gene-specific (intrinsic) sources of uncertainty. We develop a theoretical approach to extract the two noise components from experiments and show that negative feedback results in significant total noise reduction by reducing extrinsic noise while marginally increasing intrinsic noise. We compare the results to simple negative regulation, where a constitutively transcribed transcription factor represses a reporter protein. We observe that the control architecture also reduces the extrinsic noise but results in substantially higher intrinsic fluctuations. We conclude that negative feedback is the most efficient way to mitigate the effects of extrinsic fluctuations by a sole regulatory wiring.
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Affiliation(s)
- Vinay Shimoga
- Bioengineering Department, The University of Texas at Dallas, Richardson, TX, USA
- Center for Systems Biology, The University of Texas at Dallas, Richardson, TX, USA
| | - Jacob T White
- Bioengineering Department, The University of Texas at Dallas, Richardson, TX, USA
- Center for Systems Biology, The University of Texas at Dallas, Richardson, TX, USA
| | - Yi Li
- Bioengineering Department, The University of Texas at Dallas, Richardson, TX, USA
- Center for Systems Biology, The University of Texas at Dallas, Richardson, TX, USA
| | - Eduardo Sontag
- Department of Mathematics, Rutgers University, New Brunswick, NJ, USA
| | - Leonidas Bleris
- Bioengineering Department, The University of Texas at Dallas, Richardson, TX, USA
- Center for Systems Biology, The University of Texas at Dallas, Richardson, TX, USA
- Electrical Engineering Department, The University of Texas at Dallas, Richardson, TX, USA
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