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Calabrese L, Ciandrini L, Cosentino Lagomarsino M. How total mRNA influences cell growth. Proc Natl Acad Sci U S A 2024; 121:e2400679121. [PMID: 38753514 PMCID: PMC11126920 DOI: 10.1073/pnas.2400679121] [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] [Accepted: 04/10/2024] [Indexed: 05/18/2024] Open
Abstract
Experimental observations tracing back to the 1960s imply that ribosome quantities play a prominent role in determining a cell's growth. Nevertheless, in biologically relevant scenarios, growth can also be influenced by the levels of mRNA and RNA polymerase. Here, we construct a quantitative model of biosynthesis providing testable scenarios for these situations. The model explores a theoretically motivated regime where RNA polymerases compete for genes and ribosomes for transcripts and gives general expressions relating growth rate, mRNA concentrations, ribosome, and RNA polymerase levels. On general grounds, the model predicts how the fraction of ribosomes in the proteome depends on total mRNA concentration and inspects an underexplored regime in which the trade-off between transcript levels and ribosome abundances sets the cellular growth rate. In particular, we show that the model predicts and clarifies three important experimental observations, in budding yeast and Escherichia coli bacteria: i) that the growth-rate cost of unneeded protein expression can be affected by mRNA levels, ii) that resource optimization leads to decreasing trends in mRNA levels at slow growth, and iii) that ribosome allocation may increase, stay constant, or decrease, in response to transcription-inhibiting antibiotics. Since the data indicate that a regime of joint limitation may apply in physiological conditions and not only to perturbations, we speculate that this regime is likely self-imposed.
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Affiliation(s)
- Ludovico Calabrese
- IFOM-ETS–The AIRC Institute of Molecular Oncology, The Associazione Italiana di Ricerca sul Cancro (AIRC) Institute of Molecular Oncology, Milan20139, Italy
| | - Luca Ciandrini
- Centre de Biologie Structurale, Université de Montpellier, CNRS, INSERM, Montpellier, France
- Institut Universitaire de France
| | - Marco Cosentino Lagomarsino
- IFOM-ETS–The AIRC Institute of Molecular Oncology, The Associazione Italiana di Ricerca sul Cancro (AIRC) Institute of Molecular Oncology, Milan20139, Italy
- Dipartimento di Fisica, Universitá degli Studi di Milano, Milano20133, Italy
- Istituto Nazionale di Fisica Nucleare (INFN) Sezione di Milano, Milano20133, Italy
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2
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Schweers S, Locher DF, Schütz GM, Maass P. Weak Pinning and Long-Range Anticorrelated Motion of Phase Boundaries in Driven Diffusive Systems. PHYSICAL REVIEW LETTERS 2024; 132:167101. [PMID: 38701467 DOI: 10.1103/physrevlett.132.167101] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/18/2023] [Accepted: 03/19/2024] [Indexed: 05/05/2024]
Abstract
We show that domain walls separating coexisting extremal current phases in driven diffusive systems exhibit complex stochastic dynamics with a subdiffusive temporal growth of position fluctuations due to long-range anticorrelated current fluctuations and a weak pinning at long times. This weak pinning manifests itself in a saturated width of the domain wall position fluctuations that increases sublinearly with the system size. As a function of time t and system size L, the width w(t,L) has a scaling behavior w(t,L)=L^{3/4}f(t/L^{9/4}), with f(u) constant for u≫1 and f(u)∼u^{1/3} for u≪1. An Orstein-Uhlenbeck process with long-range anticorrelated noise is shown to capture this scaling behavior. The exponent 9/4 is a new dynamical exponent for relaxation processes in driven diffusive systems.
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Affiliation(s)
- Sören Schweers
- Universität Osnabrück, Fachbereich Mathematik/Informatik/Physik, Institut für Physik, Barbarastraße 7, D-49076 Osnabrück, Germany
| | - David F Locher
- Universität Osnabrück, Fachbereich Mathematik/Informatik/Physik, Institut für Physik, Barbarastraße 7, D-49076 Osnabrück, Germany
- Institute for Quantum Information, RWTH Aachen University, 52056 Aachen, Germany
| | - Gunter M Schütz
- Departamento de Matemática, Instituto Superior Técnico, Universidade de Lisboa, Avenida Rovisco Pais 1, 1049-001 Lisbon, Portugal
| | - Philipp Maass
- Universität Osnabrück, Fachbereich Mathematik/Informatik/Physik, Institut für Physik, Barbarastraße 7, D-49076 Osnabrück, Germany
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3
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Lyons EF, Devanneaux LC, Muller RY, Freitas AV, Meacham ZA, McSharry MV, Trinh VN, Rogers AJ, Ingolia NT, Lareau LF. Codon optimality modulates protein output by tuning translation initiation. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.11.27.568910. [PMID: 38076849 PMCID: PMC10705293 DOI: 10.1101/2023.11.27.568910] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/19/2023]
Abstract
The impact of synonymous codon choice on protein output has important implications for understanding endogenous gene expression and design of synthetic mRNAs. Previously, we used a neural network model to design a series of synonymous fluorescent reporters whose protein output in yeast spanned a seven-fold range corresponding to their predicted translation speed. Here, we show that this effect is not due primarily to the established impact of slow elongation on mRNA stability, but rather, that an active mechanism further decreases the number of proteins made per mRNA. We combine simulations and careful experiments on fluorescent reporters to argue that translation initiation is limited on non-optimally encoded transcripts. Using a genome-wide CRISPRi screen to discover factors modulating the output from non-optimal transcripts, we identify a set of translation initiation factors including multiple subunits of eIF3 whose depletion restored protein output of a non-optimal reporter. Our results show that codon usage can directly limit protein production, across the full range of endogenous variability in codon usage, by limiting translation initiation.
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Affiliation(s)
| | | | | | | | | | | | - Van N Trinh
- Department of Bioengineering, University of California, Berkeley
| | | | | | - Liana F Lareau
- Department of Molecular and Cell Biology
- California Institute for Quantitative Biosciences
- Department of Bioengineering, University of California, Berkeley
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4
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Zhao Y, Liu L, Hassett R, Siepel A. Model-based characterization of the equilibrium dynamics of transcription initiation and promoter-proximal pausing in human cells. Nucleic Acids Res 2023; 51:e106. [PMID: 37889042 PMCID: PMC10681744 DOI: 10.1093/nar/gkad843] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2023] [Revised: 09/13/2023] [Accepted: 09/21/2023] [Indexed: 10/28/2023] Open
Abstract
In metazoans, both transcription initiation and the escape of RNA polymerase (RNAP) from promoter-proximal pausing are key rate-limiting steps in gene expression. These processes play out at physically proximal sites on the DNA template and appear to influence one another through steric interactions. Here, we examine the dynamics of these processes using a combination of statistical modeling, simulation, and analysis of real nascent RNA sequencing data. We develop a simple probabilistic model that jointly describes the kinetics of transcription initiation, pause-escape, and elongation, and the generation of nascent RNA sequencing read counts under steady-state conditions. We then extend this initial model to allow for variability across cells in promoter-proximal pause site locations and steric hindrance of transcription initiation from paused RNAPs. In an extensive series of simulations, we show that this model enables accurate estimation of initiation and pause-escape rates. Furthermore, we show by simulation and analysis of real data that pause-escape is often strongly rate-limiting and that steric hindrance can dramatically reduce initiation rates. Our modeling framework is applicable to a variety of inference problems, and our software for estimation and simulation is freely available.
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Affiliation(s)
- Yixin Zhao
- Simons Center for Quantitative Biology, Cold Spring Harbor Laboratory, Cold Spring Harbor, NY, USA
| | - Lingjie Liu
- Simons Center for Quantitative Biology, Cold Spring Harbor Laboratory, Cold Spring Harbor, NY, USA
- Graduate Program in Genetics, Stony Brook University, Stony Brook, NY, USA
| | - Rebecca Hassett
- Simons Center for Quantitative Biology, Cold Spring Harbor Laboratory, Cold Spring Harbor, NY, USA
| | - Adam Siepel
- Simons Center for Quantitative Biology, Cold Spring Harbor Laboratory, Cold Spring Harbor, NY, USA
- Graduate Program in Genetics, Stony Brook University, Stony Brook, NY, USA
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5
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Voráč D, Maass P, Ryabov A. Single-file transport of binary hard-sphere mixtures through periodic potentials. J Chem Phys 2023; 159:114114. [PMID: 37724725 DOI: 10.1063/5.0164401] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2023] [Accepted: 08/29/2023] [Indexed: 09/21/2023] Open
Abstract
Single-file transport occurs in various scientific fields, including diffusion through nanopores, nanofluidic devices, and cellular processes. We here investigate the impact of polydispersity on particle currents for single-file Brownian motion of hard spheres when they are driven through periodic potentials by a constant drag force. Through theoretical analysis and extensive Brownian dynamics simulations, we unveil the behavior of particle currents for random binary mixtures. The particle currents show a recurring pattern in dependence of the hard-sphere diameters and mixing ratio. We explain this recurrent behavior by showing that a basic unit cell exists in the space of the two hard-sphere diameters. Once the behavior of an observable inside the unit cell is determined, it can be inferred for any diameter. The overall variation of particle currents with the mixing ratio and hard-sphere diameters is reflected by their variation in the limit where the system is fully covered by hard spheres. In this limit, the currents can be predicted analytically. Our analysis explains the occurrence of pronounced maxima and minima of the currents by changes in the effective potential barrier for the center-of-mass motion.
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Affiliation(s)
- David Voráč
- Charles University, Faculty of Mathematics and Physics, Department of Macromolecular Physics, V Holešovičkách 2, CZ-18000 Praha 8, Czech Republic
| | - Philipp Maass
- Universität Osnabrück, Faculty of Mathematics, Informatics and Physics, Institute of Physics, Barbarastraße 7, D-49076 Osnabrück, Germany
| | - Artem Ryabov
- Charles University, Faculty of Mathematics and Physics, Department of Macromolecular Physics, V Holešovičkách 2, CZ-18000 Praha 8, Czech Republic
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6
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Cavallaro M, Wang Y, Hebenstreit D, Dutta R. Bayesian inference of polymerase dynamics over the exclusion process. ROYAL SOCIETY OPEN SCIENCE 2023; 10:221469. [PMID: 37538742 PMCID: PMC10394410 DOI: 10.1098/rsos.221469] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/14/2022] [Accepted: 07/12/2023] [Indexed: 08/05/2023]
Abstract
Transcription is a complex phenomenon that permits the conversion of genetic information into phenotype by means of an enzyme called RNA polymerase, which erratically moves along and scans the DNA template. We perform Bayesian inference over a paradigmatic mechanistic model of non-equilibrium statistical physics, i.e. the asymmetric exclusion processes in the hydrodynamic limit, assuming a Gaussian process prior for the polymerase progression rate as a latent variable. Our framework allows us to infer the speed of polymerases during transcription given their spatial distribution, while avoiding the explicit inversion of the system's dynamics. The results, which show processing rates strongly varying with genomic position and minor role of traffic-like congestion, may have strong implications for the understanding of gene expression.
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Affiliation(s)
- Massimo Cavallaro
- Mathematics Institute, University of Warwick, Coventry, UK
- School of Life Sciences, University of Warwick, Coventry, UK
- Zeeman Institute for Systems Biology and Infectious Disease Epidemiology Research, University of Warwick, Coventry, UK
| | - Yuexuan Wang
- Institute of Applied Statistics, Johannes Kepler Universität, Linz, Austria
| | | | - Ritabrata Dutta
- Department of Statistics, University of Warwick, Coventry, UK
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7
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Mok A, Tunney R, Benegas G, Wallace EWJ, Lareau LF. choros: correction of sequence-based biases for accurate quantification of ribosome profiling data. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.02.21.529452. [PMID: 36865295 PMCID: PMC9980091 DOI: 10.1101/2023.02.21.529452] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/24/2023]
Abstract
Ribosome profiling quantifies translation genome-wide by sequencing ribosome-protected fragments, or footprints. Its single-codon resolution allows identification of translation regulation, such as ribosome stalls or pauses, on individual genes. However, enzyme preferences during library preparation lead to pervasive sequence artifacts that obscure translation dynamics. Widespread over- and under-representation of ribosome footprints can dominate local footprint densities and skew estimates of elongation rates by up to five fold. To address these biases and uncover true patterns of translation, we present choros, a computational method that models ribosome footprint distributions to provide bias-corrected footprint counts. choros uses negative binomial regression to accurately estimate two sets of parameters: (i) biological contributions from codon-specific translation elongation rates; and (ii) technical contributions from nuclease digestion and ligation efficiencies. We use these parameter estimates to generate bias correction factors that eliminate sequence artifacts. Applying choros to multiple ribosome profiling datasets, we are able to accurately quantify and attenuate ligation biases to provide more faithful measurements of ribosome distribution. We show that a pattern interpreted as pervasive ribosome pausing near the beginning of coding regions is likely to arise from technical biases. Incorporating choros into standard analysis pipelines will improve biological discovery from measurements of translation.
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Affiliation(s)
- Amanda Mok
- Center for Computational Biology, University of California, Berkeley
| | - Robert Tunney
- Center for Computational Biology, University of California, Berkeley
| | - Gonzalo Benegas
- Center for Computational Biology, University of California, Berkeley
| | | | - Liana F. Lareau
- Center for Computational Biology, University of California, Berkeley
- Department of Bioengineering, University of California, Berkeley
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8
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Zhao W, Peng D, Li W, Chen S, Liu B, Huang P, Wu J, Du B, Li P. Probiotic-fermented Pueraria lobata (Willd.) Ohwi alleviates alcoholic liver injury by enhancing antioxidant defense and modulating gut microbiota. JOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE 2022; 102:6877-6888. [PMID: 35655427 DOI: 10.1002/jsfa.12049] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/08/2022] [Revised: 05/30/2022] [Accepted: 06/03/2022] [Indexed: 06/15/2023]
Abstract
BACKGROUND Pueraria lobata (Willd.) Ohwi (PL) has been used in China to detoxify alcohol and protect the liver for millennia, though its mechanism of liver protection has not been elucidated. However, fermentation is considered to be one of the effective ways to enhance the efficacy of traditional Chinese medicine. The aim of this study was to investigate the hepatoprotective mechanism of probiotic-fermented PL (FPL). Sprague Dawley rats were administered with FPL followed by gavage of alcohol for seven consecutive days; following that, liver injury levels were evaluated in rats. RESULTS FPL ameliorated lipid accumulation and inflammation levels in rats. Meanwhile, the levels of ethanol dehydrogenase, acetaldehyde dehydrogenase, and cytochrome P4502E1 were elevated by FPL treatment. It was observed that the levels of catalase, superoxide dismutase, and glutathione peroxidase were elevated, and the expression of nuclear transcriptional factor (erythroid-derived 2)-like 2 (Nrf2) and heme oxygenase-1 genes and proteins were increased by FPL treatment, demonstrating that the Nrf2-mediated signal pathway was activated. Furthermore, FPL restored the composition of the gut microbiota with an increase in the abundances of Firmicutes and Lactobacillus and a decrease in the abundances of Bacteroidota and Akkermansia. Additionally, a strong correlation was found between the gut microbiota and the antioxidant parameters. CONCLUSION The results indicate that FPL possesses an excellent protective effect in alcoholic liver injury. Our findings are beneficial to the development of hepatoprotective nutraceuticals for alcoholics. © 2022 Society of Chemical Industry.
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Affiliation(s)
- Wenjun Zhao
- College of Food Science, South China Agricultural University, Guangzhou, China
| | - Dong Peng
- College of Food Science, South China Agricultural University, Guangzhou, China
| | - Weijie Li
- College of Food Science, South China Agricultural University, Guangzhou, China
| | - Suiying Chen
- College of Food Science, South China Agricultural University, Guangzhou, China
| | - Bing Liu
- College of Food Science, South China Agricultural University, Guangzhou, China
| | - Pingxi Huang
- College of Food Science, South China Agricultural University, Guangzhou, China
| | - Junsong Wu
- Guangzhou Songyuan Agricultural Technology Co., Ltd, Guangzhou, China
| | - Bing Du
- College of Food Science, South China Agricultural University, Guangzhou, China
| | - Pan Li
- College of Food Science, South China Agricultural University, Guangzhou, China
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9
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Flanagan K, Li W, Greenblatt EJ, Dao Duc K. End-to-end pipeline for differential analysis of pausing in ribosome profiling data. STAR Protoc 2022; 3:101605. [PMID: 36035799 PMCID: PMC9405084 DOI: 10.1016/j.xpro.2022.101605] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Ribosome profiling is a powerful technique which maps the distribution of ribosomes along mRNAs to analyze translation genome-wide. Ribosome density can be affected by multiple factors, such as changes to translation initiation or elongation rates. We describe the application of a metric for identifying genes rate-limited by these rates by analyzing the relative distribution of ribosome footprints along transcripts. This protocol also details two sample analyses comparing gene translation efficiencies and the distribution of ribosome densities on downloadable datasets. For complete details on the use and execution of this protocol, please refer to Flanagan et al. (2022). Pipeline for measuring translation efficiency using ribosome profiling data Quantification of differential ribosome distributions along mRNAs Determine whether changes are consistent with altered initiation or elongation
Publisher’s note: Undertaking any experimental protocol requires adherence to local institutional guidelines for laboratory safety and ethics.
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10
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Flanagan K, Baradaran-Heravi A, Yin Q, Dao Duc K, Spradling AC, Greenblatt EJ. FMRP-dependent production of large dosage-sensitive proteins is highly conserved. Genetics 2022; 221:6613139. [PMID: 35731217 PMCID: PMC9339308 DOI: 10.1093/genetics/iyac094] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2022] [Accepted: 06/07/2022] [Indexed: 12/01/2022] Open
Abstract
Mutations in FMR1 are the most common heritable cause of autism spectrum disorder. FMR1 encodes an RNA-binding protein, FMRP, which binds to long, autism-relevant transcripts and is essential for normal neuronal and ovarian development. In contrast to the prevailing model that FMRP acts to block translation elongation, we previously found that FMRP activates the translation initiation of large proteins in Drosophila oocytes. We now provide evidence that FMRP-dependent translation is conserved and occurs in the mammalian brain. Our comparisons of the mammalian cortex and Drosophila oocyte ribosome profiling data show that translation of FMRP-bound mRNAs decreases to a similar magnitude in FMRP-deficient tissues from both species. The steady-state levels of several FMRP targets were reduced in the Fmr1 KO mouse cortex, including a ∼50% reduction of Auts2, a gene implicated in an autosomal dominant autism spectrum disorder. To distinguish between effects on elongation and initiation, we used a novel metric to detect the rate-limiting ribosome stalling. We found no evidence that FMRP target protein production is governed by translation elongation rates. FMRP translational activation of large proteins may be critical for normal human development, as more than 20 FMRP targets including Auts2 are dosage sensitive and are associated with neurodevelopmental disorders caused by haploinsufficiency.
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Affiliation(s)
- Keegan Flanagan
- Department of Biochemistry and Molecular Biology, University of British Columbia, 2350 Health Sciences Mall, Vancouver, British Columbia, V6T 1Z3 Canada.,Department of Mathematics, University of British Columbia, 1984 Mathematics Road, Vancouver, British Columbia, BC V6T 1Z2
| | - Alireza Baradaran-Heravi
- Department of Biochemistry and Molecular Biology, University of British Columbia, 2350 Health Sciences Mall, Vancouver, British Columbia, V6T 1Z3 Canada
| | - Qi Yin
- Howard Hughes Medical Institute Research Laboratories, Department of Embryology, Carnegie Institution for Science, 3520 San Martin Dr., Baltimore, Maryland 21218 USA
| | - Khanh Dao Duc
- Department of Mathematics, University of British Columbia, 1984 Mathematics Road, Vancouver, British Columbia, BC V6T 1Z2
| | - Allan C Spradling
- Howard Hughes Medical Institute Research Laboratories, Department of Embryology, Carnegie Institution for Science, 3520 San Martin Dr., Baltimore, Maryland 21218 USA
| | - Ethan J Greenblatt
- Department of Biochemistry and Molecular Biology, University of British Columbia, 2350 Health Sciences Mall, Vancouver, British Columbia, V6T 1Z3 Canada.,Howard Hughes Medical Institute Research Laboratories, Department of Embryology, Carnegie Institution for Science, 3520 San Martin Dr., Baltimore, Maryland 21218 USA
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11
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Mines RC, Lipniacki T, Shen X. Slow nucleosome dynamics set the transcriptional speed limit and induce RNA polymerase II traffic jams and bursts. PLoS Comput Biol 2022; 18:e1009811. [PMID: 35143483 PMCID: PMC8865691 DOI: 10.1371/journal.pcbi.1009811] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2021] [Revised: 02/23/2022] [Accepted: 01/06/2022] [Indexed: 11/19/2022] Open
Abstract
Nucleosomes are recognized as key regulators of transcription. However, the relationship between slow nucleosome unwrapping dynamics and bulk transcriptional properties has not been thoroughly explored. Here, an agent-based model that we call the dynamic defect Totally Asymmetric Simple Exclusion Process (ddTASEP) was constructed to investigate the effects of nucleosome-induced pausing on transcriptional dynamics. Pausing due to slow nucleosome dynamics induced RNAPII convoy formation, which would cooperatively prevent nucleosome rebinding leading to bursts of transcription. The mean first passage time (MFPT) and the variance of first passage time (VFPT) were analytically expressed in terms of the nucleosome rate constants, allowing for the direct quantification of the effects of nucleosome-induced pausing on pioneering polymerase dynamics. The mean first passage elongation rate γ(hc, ho) is inversely proportional to the MFPT and can be considered to be a new axis of the ddTASEP phase diagram, orthogonal to the classical αβ-plane (where α and β are the initiation and termination rates). Subsequently, we showed that, for β = 1, there is a novel jamming transition in the αγ-plane that separates the ddTASEP dynamics into initiation-limited and nucleosome pausing-limited regions. We propose analytical estimates for the RNAPII density ρ, average elongation rate v, and transcription flux J and verified them numerically. We demonstrate that the intra-burst RNAPII waiting times tin follow the time-headway distribution of a max flux TASEP and that the average inter-burst interval tIBI¯ correlates with the index of dispersion De. In the limit γ→0, the average burst size reaches a maximum set by the closing rate hc. When α≪1, the burst sizes are geometrically distributed, allowing large bursts even while the average burst size NB¯ is small. Last, preliminary results on the relative effects of static and dynamic defects are presented to show that dynamic defects can induce equal or greater pausing than static bottle necks. To perform specific functions, cells must express specific genes by copying the information in DNA into RNA via transcription. Structural proteins called nucleosomes are spaced every 200 base pairs along the length of a strand of DNA and play a crucial function in the regulation of gene activity by tightly binding DNA strands and condensing them into heterochromatin, preventing transcription by RNA polymerase II (RNAPII). Even on active genes where nucleosomes are loosely attached to DNA strands, the wrapping and unwrapping of nucleosomes pause transcription as RNAPII passes by. Previous mathematical models of transcription have compared this biological process to traffic on a one lane highway without obstructions. In contrast, our proposed model simulates transcription like traffic in a grid system where nucleosomes can be thought of as pedestrians or other vehicles crossing the road at regularly spaced intersections. Just as side street traffic and pedestrian crossings can cause cars to form convoys and cause jams limiting the max speed in an area, nucleosomes can cause RNAPII to form convoys that lead to bursts of mRNA production and limit the average polymerase flux through the gene.
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Affiliation(s)
- Robert C. Mines
- Department of Biomedical Engineering, Duke University, Durham, North Carolina, United States of America
| | - Tomasz Lipniacki
- Department of Biosystems and Soft Matter, Institute of Fundamental Technological Research, Polish Academy of Sciences, Warsaw, Poland
- * E-mail: (TL); (XS)
| | - Xiling Shen
- Department of Biomedical Engineering, Duke University, Durham, North Carolina, United States of America
- Center for Genomic and Computational Biology, Duke University, Durham, North Carolina, United States of America
- Woo Center for Big Data and Precision Health, Duke University, Durham, North Carolina, United States of America
- * E-mail: (TL); (XS)
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12
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Wang C, Zhang W, Tian R, Zhang J, Zhang L, Deng Z, Lv X, Li J, Liu L, Du G, Liu Y. Model‐driven design of synthetic N‐terminal coding sequences for regulating gene expression in yeast and bacteria. Biotechnol J 2022; 17:e2100655. [DOI: 10.1002/biot.202100655] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2021] [Revised: 01/12/2022] [Accepted: 01/13/2022] [Indexed: 11/12/2022]
Affiliation(s)
- Chenyun Wang
- Key Laboratory of Carbohydrate Chemistry and Biotechnology, Ministry of Education, School of Biotechnology Jiangnan University Wuxi 214122 China
- Science Center for Future Foods Jiangnan University Wuxi 214122 China
- Engineering Research Center of Ministry of Education on Food Synthetic Biotechnology Jiangnan University Wuxi 214122 China
- Jiangsu Province Engineering Research Center of Food Synthetic Biotechnology Jiangnan University Wuxi 214122 China
| | - Wei Zhang
- School of Artificial Intelligence and Computer Science Jiangnan University Wuxi 214122 China
- Jiangsu Key Laboratory of Media Design and Software Technology Wuxi 214122 China
| | - Rongzhen Tian
- Key Laboratory of Carbohydrate Chemistry and Biotechnology, Ministry of Education, School of Biotechnology Jiangnan University Wuxi 214122 China
- Science Center for Future Foods Jiangnan University Wuxi 214122 China
- Engineering Research Center of Ministry of Education on Food Synthetic Biotechnology Jiangnan University Wuxi 214122 China
- Jiangsu Province Engineering Research Center of Food Synthetic Biotechnology Jiangnan University Wuxi 214122 China
| | - Jianing Zhang
- Key Laboratory of Carbohydrate Chemistry and Biotechnology, Ministry of Education, School of Biotechnology Jiangnan University Wuxi 214122 China
- Science Center for Future Foods Jiangnan University Wuxi 214122 China
- Engineering Research Center of Ministry of Education on Food Synthetic Biotechnology Jiangnan University Wuxi 214122 China
- Jiangsu Province Engineering Research Center of Food Synthetic Biotechnology Jiangnan University Wuxi 214122 China
| | - Linpei Zhang
- Key Laboratory of Carbohydrate Chemistry and Biotechnology, Ministry of Education, School of Biotechnology Jiangnan University Wuxi 214122 China
| | - Zhaohong Deng
- School of Artificial Intelligence and Computer Science Jiangnan University Wuxi 214122 China
- Jiangsu Key Laboratory of Media Design and Software Technology Wuxi 214122 China
| | - Xueqin Lv
- Key Laboratory of Carbohydrate Chemistry and Biotechnology, Ministry of Education, School of Biotechnology Jiangnan University Wuxi 214122 China
- Science Center for Future Foods Jiangnan University Wuxi 214122 China
- Engineering Research Center of Ministry of Education on Food Synthetic Biotechnology Jiangnan University Wuxi 214122 China
- Jiangsu Province Engineering Research Center of Food Synthetic Biotechnology Jiangnan University Wuxi 214122 China
| | - Jianghua Li
- Key Laboratory of Carbohydrate Chemistry and Biotechnology, Ministry of Education, School of Biotechnology Jiangnan University Wuxi 214122 China
- Science Center for Future Foods Jiangnan University Wuxi 214122 China
- Engineering Research Center of Ministry of Education on Food Synthetic Biotechnology Jiangnan University Wuxi 214122 China
- Jiangsu Province Engineering Research Center of Food Synthetic Biotechnology Jiangnan University Wuxi 214122 China
| | - Long Liu
- Key Laboratory of Carbohydrate Chemistry and Biotechnology, Ministry of Education, School of Biotechnology Jiangnan University Wuxi 214122 China
- Science Center for Future Foods Jiangnan University Wuxi 214122 China
- Engineering Research Center of Ministry of Education on Food Synthetic Biotechnology Jiangnan University Wuxi 214122 China
- Jiangsu Province Engineering Research Center of Food Synthetic Biotechnology Jiangnan University Wuxi 214122 China
| | - Guocheng Du
- Key Laboratory of Carbohydrate Chemistry and Biotechnology, Ministry of Education, School of Biotechnology Jiangnan University Wuxi 214122 China
- Science Center for Future Foods Jiangnan University Wuxi 214122 China
- Engineering Research Center of Ministry of Education on Food Synthetic Biotechnology Jiangnan University Wuxi 214122 China
- Jiangsu Province Engineering Research Center of Food Synthetic Biotechnology Jiangnan University Wuxi 214122 China
| | - Yanfeng Liu
- Key Laboratory of Carbohydrate Chemistry and Biotechnology, Ministry of Education, School of Biotechnology Jiangnan University Wuxi 214122 China
- Science Center for Future Foods Jiangnan University Wuxi 214122 China
- Engineering Research Center of Ministry of Education on Food Synthetic Biotechnology Jiangnan University Wuxi 214122 China
- Jiangsu Province Engineering Research Center of Food Synthetic Biotechnology Jiangnan University Wuxi 214122 China
- Qingdao Special Food Research Institute Wuxi 214122 China
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13
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Legrand C, Duc KD, Tuorto F. Analysis of Ribosome Profiling Data. Methods Mol Biol 2022; 2428:133-156. [PMID: 35171478 DOI: 10.1007/978-1-0716-1975-9_9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Ribosome profiling methods are based on high-throughput sequencing of ribosome-protected mRNA footprints and allow to study in detail translational changes. Bioinformatic and statistical tools are necessary to analyze sequencing data. Here, we describe our developed methods for a fast and reliable quality control of ribosome profiling data, to efficiently visualize ribosome positions and to estimate ribosome speed in an unbiased way. The methodology described here is applicable to several genetic and environmental conditions including stress and are based on the R package RiboVIEW and calculation of quantitative estimates of local and global translation speed, based on a biophysical model of translation dynamics.
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Affiliation(s)
| | - Khanh Dao Duc
- Department of Mathematics, University of British Columbia, Vancouver, BC, Canada
| | - Francesca Tuorto
- Division of Biochemistry, Mannheim Institute for Innate Immunoscience (MI3), Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany.
- Center for Molecular Biology of Heidelberg University (ZMBH), DKFZ-ZMBH Alliance, Mannheim, Germany.
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14
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Zuo X, Chou T. Density- and elongation speed-dependent error correction in RNA polymerization. Phys Biol 2021; 19. [PMID: 34937012 DOI: 10.1088/1478-3975/ac45e2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2021] [Accepted: 12/22/2021] [Indexed: 11/11/2022]
Abstract
Backtracking of RNA polymerase (RNAP) is an important pausing mechanism during DNA transcription that is part of the error correction process that enhances transcription fidelity. We model the backtracking mechanism of RNA polymerase, which usually happens when the polymerase tries to incorporate a noncognate or "mismatched" nucleotide triphosphate. Previous models have made simplifying assumptions such as neglecting the trailing polymerase behind the backtracking polymerase or assuming that the trailing polymerase is stationary. We derive exact analytic solutions of a stochastic model that includes locally interacting RNAPs by explicitly showing how a trailing RNAP influences the probability that an error is corrected or incorporated by the leading backtracking RNAP. We also provide two related methods for computing the mean times for error correction and incorporation given an initial local RNAP configuration. Using these results, we propose an effective interacting-RNAP lattice that can be readily simulated.
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Affiliation(s)
- Xinzhe Zuo
- Department of Mathematics, University of California - Los Angeles, Los Angeles, CA 90095-1555, USA, Los Angeles, California, 90095, UNITED STATES
| | - Tom Chou
- Department of Mathematics, University of California - Los Angeles, Los Angeles, CA 90095-1555, USA, Los Angeles, California, 90095, UNITED STATES
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15
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Andreev DE, Baranov PV, Milogorodskii A, Rachinskii D. A deterministic model for non-monotone relationship between translation of upstream and downstream open reading frames. MATHEMATICAL MEDICINE AND BIOLOGY : A JOURNAL OF THE IMA 2021; 38:490-515. [PMID: 34718568 DOI: 10.1093/imammb/dqab015] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/30/2020] [Revised: 08/12/2021] [Accepted: 10/06/2021] [Indexed: 01/01/2023]
Abstract
Totally asymmetric simple exclusion process (TASEP) modelling was shown to offer a parsimonious explanation for the experimentally confirmed ability of a single upstream open reading frames (uORFs) to upregulate downstream translation during the integrated stress response. As revealed by numerical simulations, the model predicts that reducing the density of scanning ribosomes upstream of certain uORFs increases the flow of ribosomes downstream. To gain a better insight into the mechanism which ensures the non-monotone relation between the upstream and downstream flows, in this work, we propose a phenomenological deterministic model approximating the TASEP model of the translation process. We establish the existence of a stationary solution featuring the decreasing density along the uORF for the deterministic model. Further, we find an explicit non-monotone relation between the upstream ribosome density and the downstream flow for the stationary solution in the limit of increasing uORF length and increasingly leaky initiation. The stationary distribution of the TASEP model, the stationary solution of the deterministic model and the explicit limit are compared numerically.
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Affiliation(s)
- D E Andreev
- Lomonosov Moscow State University, GSP-1, Leninskie Gory, Moscow, 119991, Russian Federation, and Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, RAS, Moscow, Russia
| | - P V Baranov
- University College Cork, College Road, Cork, T12 K8AF, Ireland, and Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry (RAS), 16/10 Miklukho-Maklay str., Moscow, 117997, Russian Federation
| | - A Milogorodskii
- Lomonosov Moscow State University, GSP-1, Leninskie Gory, Moscow, 119991, Russian Federation, and Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, RAS, Moscow, Russia
| | - D Rachinskii
- Department of Mathematical Sciences, The University of Texas at Dallas, 800 W. Campbell Rd, Richardson, TX 75080, USA
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16
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Jin YT, Jin TY, Zhang ZL, Ye YN, Deng Z, Wang J, Guo FB. Quantitative elucidation of associations between nucleotide identity and physicochemical properties of amino acids and the functional insight. Comput Struct Biotechnol J 2021; 19:4042-4048. [PMID: 34527183 PMCID: PMC8346530 DOI: 10.1016/j.csbj.2021.07.012] [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: 05/27/2021] [Revised: 07/12/2021] [Accepted: 07/13/2021] [Indexed: 11/25/2022] Open
Abstract
Studies on codon property would deepen our understanding of the origin of primitive life and enlighten biotechnical application. Here, we proposed a quantitative measurement of codon-amino acid association and found that seven out of 13 physicochemical properties have stronger associations with the nucleotide identity at the second codon position, indicating that protein structure and function may associate more closely with it than the other two sites. When extending the effect of codon-amino acid association to protein level, it was found that the correlation between the second codon position (measured by the relative frequencies of nucleobase T and A at this codon site) and hydrophobicity (by the form of GRAVY value) became stronger with 96% genomes having R > 0.90 and p < 1e-60. Furthermore, we revealed that informational genes encoding proteins have lower GRAVY values than operational proteins (p < 3e-37) in both prokaryotic and eukaryotic genomes. The above results reveal a complete link from codon identity (A2 versus T2) to amino acid property (hydrophilic versus hydrophobic) and then to protein functions (informational versus operational). Hence, our work may help to understand how the nucleotide sequence determines protein function.
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Affiliation(s)
- Yan-Ting Jin
- School of Life Science and Technology, University of Electronic Science and Technology of China, 611731 Chengdu, China.,Key Laboratory of Combinatorial Biosynthesis and Drug Discovery, Ministry of Education and School of Pharmaceutical Sciences, Wuhan University, 430071 Wuhan, China
| | - Tian-Yue Jin
- School of Life Science and Technology, University of Electronic Science and Technology of China, 611731 Chengdu, China
| | - Zhi-Li Zhang
- School of Life Science and Technology, University of Electronic Science and Technology of China, 611731 Chengdu, China
| | - Yuan-Nong Ye
- Department of Medical Informatics, Bioinformatics and BioMedical Bigdata Mining Laboratory, School of Big Health, Guizhou Medical University, 550025 Guiyang, China
| | - Zixin Deng
- Key Laboratory of Combinatorial Biosynthesis and Drug Discovery, Ministry of Education and School of Pharmaceutical Sciences, Wuhan University, 430071 Wuhan, China
| | - Ju Wang
- School of Biomedical Engineering, Tianjin Medical University, 300070 Tianjin, China
| | - Feng-Biao Guo
- Key Laboratory of Combinatorial Biosynthesis and Drug Discovery, Ministry of Education and School of Pharmaceutical Sciences, Wuhan University, 430071 Wuhan, China
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17
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Schellens R, de Vrieze E, Graave P, Broekman S, Nagel-Wolfrum K, Peters T, Kremer H, Collin RWJ, van Wijk E. Zebrafish as a Model to Evaluate a CRISPR/Cas9-Based Exon Excision Approach as a Future Treatment Option for EYS-Associated Retinitis Pigmentosa. Int J Mol Sci 2021; 22:ijms22179154. [PMID: 34502064 PMCID: PMC8431288 DOI: 10.3390/ijms22179154] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2021] [Revised: 08/18/2021] [Accepted: 08/18/2021] [Indexed: 12/26/2022] Open
Abstract
Retinitis pigmentosa (RP) is an inherited retinal disease (IRD) with an overall prevalence of 1 in 4000 individuals. Mutations in EYS (Eyes shut homolog) are among the most frequent causes of non-syndromic autosomal recessively inherited RP and act via a loss-of-function mechanism. In light of the recent successes for other IRDs, we investigated the therapeutic potential of exon skipping for EYS-associated RP. CRISPR/Cas9 was employed to generate zebrafish from which the region encompassing the orthologous exons 37-41 of human EYS (eys exons 40-44) was excised from the genome. The excision of these exons was predicted to maintain the open reading frame and to result in the removal of exactly one Laminin G and two EGF domains. Although the eysΔexon40-44 transcript was found at levels comparable to wild-type eys, and no unwanted off-target modifications were identified within the eys coding sequence after single-molecule sequencing, EysΔexon40-44 protein expression could not be detected. Visual motor response experiments revealed that eysΔexon40-44 larvae were visually impaired and histological analysis revealed a progressive degeneration of the retinal outer nuclear layer in these zebrafish. Altogether, the data obtained in our zebrafish model currently provide no indications for the skipping of EYS exons 37-41 as an effective future treatment strategy for EYS-associated RP.
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Affiliation(s)
- Renske Schellens
- Department of Otorhinolaryngology, Radboud University Medical Center, 6525 GA Nijmegen, The Netherlands; (R.S.); (E.d.V.); (S.B.); (T.P.); (H.K.)
- Donders Institute for Brain Cognition and Behaviour, 6500 GL Nijmegen, The Netherlands;
| | - Erik de Vrieze
- Department of Otorhinolaryngology, Radboud University Medical Center, 6525 GA Nijmegen, The Netherlands; (R.S.); (E.d.V.); (S.B.); (T.P.); (H.K.)
- Donders Institute for Brain Cognition and Behaviour, 6500 GL Nijmegen, The Netherlands;
| | - Pam Graave
- Department of Human Genetics, Radboud University Medical Center, 6525 GA Nijmegen, The Netherlands;
| | - Sanne Broekman
- Department of Otorhinolaryngology, Radboud University Medical Center, 6525 GA Nijmegen, The Netherlands; (R.S.); (E.d.V.); (S.B.); (T.P.); (H.K.)
| | - Kerstin Nagel-Wolfrum
- Institute for Molecular Physiology, Johannes Gutenberg-University Mainz, 55099 Mainz, Germany;
- Institute for Developmental Biology and Neurobiology, Johannes Gutenberg-University Mainz, 55099 Mainz, Germany
| | - Theo Peters
- Department of Otorhinolaryngology, Radboud University Medical Center, 6525 GA Nijmegen, The Netherlands; (R.S.); (E.d.V.); (S.B.); (T.P.); (H.K.)
| | - Hannie Kremer
- Department of Otorhinolaryngology, Radboud University Medical Center, 6525 GA Nijmegen, The Netherlands; (R.S.); (E.d.V.); (S.B.); (T.P.); (H.K.)
- Donders Institute for Brain Cognition and Behaviour, 6500 GL Nijmegen, The Netherlands;
- Department of Human Genetics, Radboud University Medical Center, 6525 GA Nijmegen, The Netherlands;
| | - Rob W. J. Collin
- Donders Institute for Brain Cognition and Behaviour, 6500 GL Nijmegen, The Netherlands;
- Department of Human Genetics, Radboud University Medical Center, 6525 GA Nijmegen, The Netherlands;
| | - Erwin van Wijk
- Department of Otorhinolaryngology, Radboud University Medical Center, 6525 GA Nijmegen, The Netherlands; (R.S.); (E.d.V.); (S.B.); (T.P.); (H.K.)
- Donders Institute for Brain Cognition and Behaviour, 6500 GL Nijmegen, The Netherlands;
- Correspondence:
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18
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McKendry J, Stokes T, Mcleod JC, Phillips SM. Resistance Exercise, Aging, Disuse, and Muscle Protein Metabolism. Compr Physiol 2021; 11:2249-2278. [PMID: 34190341 DOI: 10.1002/cphy.c200029] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Skeletal muscle is the organ of locomotion, its optimal function is critical for athletic performance, and is also important for health due to its contribution to resting metabolic rate and as a site for glucose uptake and storage. Numerous endogenous and exogenous factors influence muscle mass. Much of what is currently known regarding muscle protein turnover is owed to the development and use of stable isotope tracers. Skeletal muscle mass is determined by the meal- and contraction-induced alterations of muscle protein synthesis and muscle protein breakdown. Increased loading as resistance training is the most potent nonpharmacological strategy by which skeletal muscle mass can be increased. Conversely, aging (sarcopenia) and muscle disuse lead to the development of anabolic resistance and contribute to the loss of skeletal muscle mass. Nascent omics-based technologies have significantly improved our understanding surrounding the regulation of skeletal muscle mass at the gene, transcript, and protein levels. Despite significant advances surrounding the mechanistic intricacies that underpin changes in skeletal muscle mass, these processes are complex, and more work is certainly needed. In this article, we provide an overview of the importance of skeletal muscle, describe the influence that resistance training, aging, and disuse exert on muscle protein turnover and the molecular regulatory processes that contribute to changes in muscle protein abundance. © 2021 American Physiological Society. Compr Physiol 11:2249-2278, 2021.
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Affiliation(s)
- James McKendry
- Exercise Metabolism Research Group, Department of Kinesiology, McMaster University, Hamilton, Ontario, Canada
| | - Tanner Stokes
- Exercise Metabolism Research Group, Department of Kinesiology, McMaster University, Hamilton, Ontario, Canada
| | - Jonathan C Mcleod
- Exercise Metabolism Research Group, Department of Kinesiology, McMaster University, Hamilton, Ontario, Canada
| | - Stuart M Phillips
- Exercise Metabolism Research Group, Department of Kinesiology, McMaster University, Hamilton, Ontario, Canada
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19
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Wilkinson M, Yllanes D, Huber G. Polysomally protected viruses. Phys Biol 2021; 18. [PMID: 33827061 DOI: 10.1088/1478-3975/abf5b5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2021] [Accepted: 04/07/2021] [Indexed: 11/12/2022]
Abstract
It is conceivable that an RNA virus could use a polysome, that is, a string of ribosomes covering the RNA strand, to protect the genetic material from degradation inside a host cell. This paper discusses how such a virus might operate, and how its presence might be detected by ribosome profiling. There are two possible forms for such apolysomally protected virus, depending upon whether just the forward strand or both the forward and complementary strands can be encased by ribosomes (these will be termed type 1 and type 2, respectively). It is argued that in the type 2 case the viral RNA would evolve anambigrammaticproperty, whereby the viral genes are free of stop codons in a reverse reading frame (with forward and reverse codons aligned). Recent observations of ribosome profiles of ambigrammatic narnavirus sequences are consistent with our predictions for the type 2 case.
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Affiliation(s)
- Michael Wilkinson
- Chan Zuckerberg Biohub, 499 Illinois Street, San Francisco, CA 94158, United States of America.,School of Mathematics and Statistics, The Open University, Walton Hall, Milton Keynes, MK7 6AA, United Kingdom
| | - David Yllanes
- Chan Zuckerberg Biohub, 499 Illinois Street, San Francisco, CA 94158, United States of America
| | - Greg Huber
- Chan Zuckerberg Biohub, 499 Illinois Street, San Francisco, CA 94158, United States of America
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20
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Tian T, Li S, Lang P, Zhao D, Zeng J. Full-length ribosome density prediction by a multi-input and multi-output model. PLoS Comput Biol 2021; 17:e1008842. [PMID: 33770074 PMCID: PMC8026034 DOI: 10.1371/journal.pcbi.1008842] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2020] [Revised: 04/07/2021] [Accepted: 03/01/2021] [Indexed: 11/29/2022] Open
Abstract
Translation elongation is regulated by a series of complicated mechanisms in both prokaryotes and eukaryotes. Although recent advance in ribosome profiling techniques has enabled one to capture the genome-wide ribosome footprints along transcripts at codon resolution, the regulatory codes of elongation dynamics are still not fully understood. Most of the existing computational approaches for modeling translation elongation from ribosome profiling data mainly focus on local contextual patterns, while ignoring the continuity of the elongation process and relations between ribosome densities of remote codons. Modeling the translation elongation process in full-length coding sequence (CDS) level has not been studied to the best of our knowledge. In this paper, we developed a deep learning based approach with a multi-input and multi-output framework, named RiboMIMO, for modeling the ribosome density distributions of full-length mRNA CDS regions. Through considering the underlying correlations in translation efficiency among neighboring and remote codons and extracting hidden features from the input full-length coding sequence, RiboMIMO can greatly outperform the state-of-the-art baseline approaches and accurately predict the ribosome density distributions along the whole mRNA CDS regions. In addition, RiboMIMO explores the contributions of individual input codons to the predictions of output ribosome densities, which thus can help reveal important biological factors influencing the translation elongation process. The analyses, based on our interpretable metric named codon impact score, not only identified several patterns consistent with the previously-published literatures, but also for the first time (to the best of our knowledge) revealed that the codons located at a long distance from the ribosomal A site may also have an association on the translation elongation rate. This finding of long-range impact on translation elongation velocity may shed new light on the regulatory mechanisms of protein synthesis. Overall, these results indicated that RiboMIMO can provide a useful tool for studying the regulation of translation elongation in the range of full-length CDS. Translation elongation is a process in which amino acids are linked into proteins by ribosomes in cells. Translation elongation rates along the mRNAs are not constant, and are regulated by a series of mechanisms, such as codon rarity and mRNA stability. In this study, we modeled the translation elongation process at a full-length coding sequence level and developed a deep learning based approach to predict the translation elongation rates from mRNA sequences, through extracting the regulatory codes of elongation rates from the contextual sequences. The analyses, based on our interpretable metric named codon impact score, for the first time (to the best of our knowledge), revealed that in addition to the neighboring codons of the ribosomal A sites, the remote codons may also have an important impact on the translation elongation rates. This new finding may stimulate additional experiments and shed light on the regulatory mechanisms of protein synthesis.
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Affiliation(s)
- Tingzhong Tian
- Institute for Interdisciplinary Information Sciences, Tsinghua University, Beijing, China
| | - Shuya Li
- Institute for Interdisciplinary Information Sciences, Tsinghua University, Beijing, China
| | - Peng Lang
- Institute for Interdisciplinary Information Sciences, Tsinghua University, Beijing, China
| | - Dan Zhao
- Institute for Interdisciplinary Information Sciences, Tsinghua University, Beijing, China
- * E-mail: (DZ); (JZ)
| | - Jianyang Zeng
- Institute for Interdisciplinary Information Sciences, Tsinghua University, Beijing, China
- MOE Key Laboratory of Bioinformatics, Tsinghua University, Beijing, China
- * E-mail: (DZ); (JZ)
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21
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Molecular motor traffic with a slow binding site. J Theor Biol 2021; 518:110644. [PMID: 33636200 DOI: 10.1016/j.jtbi.2021.110644] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2020] [Revised: 01/06/2021] [Accepted: 02/18/2021] [Indexed: 11/24/2022]
Abstract
We discuss how the presence of a slow binding site in molecular motor traffic gives rise to defect-induced "traffic jams" that have properties different from those of the well-studied boundary-induced jams that originate from an imbalance between initiation and termination. To this end we analyze in detail the stationary distribution of a lattice gas model for traffic of molecular motors with a defect. In particular, we obtain analytically the exact spatial distribution of motors, the probability distribution of the random position of the molecular traffic jam and we report unexpected spatial anticorrelations between local molecular motor densities near the defect.
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22
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EGGTART: A tool to visualize the dynamics of biophysical transport under the inhomogeneous l-TASEP. Biophys J 2021; 120:1309-1313. [PMID: 33582139 DOI: 10.1016/j.bpj.2021.02.004] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2020] [Revised: 01/31/2021] [Accepted: 02/03/2021] [Indexed: 11/21/2022] Open
Abstract
The totally asymmetric simple exclusion process (TASEP), which describes the stochastic dynamics of interacting particles on a lattice, has been actively studied over the past several decades and applied to model important biological transport processes. Here, we present a software package, called EGGTART (Extensive GUI gives TASEP-realization in Real Time), which quantifies and visualizes the dynamics associated with a generalized version of the TASEP with an extended particle size and heterogeneous jump rates. This computational tool is based on analytic formulas obtained from deriving and solving the hydrodynamic limit of the process. It allows an immediate quantification of the particle density, flux, and phase diagram, as a function of a few key parameters associated with the system, which would be difficult to achieve via conventional stochastic simulations. Our software should therefore be of interest to biophysicists studying general transport processes and can in particular be used in the context of gene expression to model and quantify mRNA translation of different coding sequences.
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23
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Neelagandan N, Lamberti I, Carvalho HJF, Gobet C, Naef F. What determines eukaryotic translation elongation: recent molecular and quantitative analyses of protein synthesis. Open Biol 2020; 10:200292. [PMID: 33292102 PMCID: PMC7776565 DOI: 10.1098/rsob.200292] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2020] [Accepted: 11/10/2020] [Indexed: 12/14/2022] Open
Abstract
Protein synthesis from mRNA is an energy-intensive and tightly controlled cellular process. Translation elongation is a well-coordinated, multifactorial step in translation that undergoes dynamic regulation owing to cellular state and environmental determinants. Recent studies involving genome-wide approaches have uncovered some crucial aspects of translation elongation including the mRNA itself and the nascent polypeptide chain. Additionally, these studies have fuelled quantitative and mathematical modelling of translation elongation. In this review, we provide a comprehensive overview of the key determinants of translation elongation. We discuss consequences of ribosome stalling or collision, and how the cells regulate translation in case of such events. Next, we review theoretical approaches and widely used mathematical models that have become an essential ingredient to interpret complex molecular datasets and study translation dynamics quantitatively. Finally, we review recent advances in live-cell reporter and related analysis techniques, to monitor the translation dynamics of single cells and single-mRNA molecules in real time.
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Affiliation(s)
| | | | | | | | - Felix Naef
- Institute of Bioengineering, School of Life Sciences, Ecole Polytechnique Fédérale de Lausanne (EPFL), Lausanne CH-1015, Switzerland
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24
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Szavits-Nossan J, Ciandrini L. Inferring efficiency of translation initiation and elongation from ribosome profiling. Nucleic Acids Res 2020; 48:9478-9490. [PMID: 32821926 PMCID: PMC7515720 DOI: 10.1093/nar/gkaa678] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2020] [Revised: 07/29/2020] [Accepted: 08/15/2020] [Indexed: 01/13/2023] Open
Abstract
One of the main goals of ribosome profiling is to quantify the rate of protein synthesis at the level of translation. Here, we develop a method for inferring translation elongation kinetics from ribosome profiling data using recent advances in mathematical modelling of mRNA translation. Our method distinguishes between the elongation rate intrinsic to the ribosome’s stepping cycle and the actual elongation rate that takes into account ribosome interference. This distinction allows us to quantify the extent of ribosomal collisions along the transcript and identify individual codons where ribosomal collisions are likely. When examining ribosome profiling in yeast, we observe that translation initiation and elongation are close to their optima and traffic is minimized at the beginning of the transcript to favour ribosome recruitment. However, we find many individual sites of congestion along the mRNAs where the probability of ribosome interference can reach \documentclass[12pt]{minimal}
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}{}$50\%$\end{document}. Our work provides new measures of translation initiation and elongation efficiencies, emphasizing the importance of rating these two stages of translation separately.
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Affiliation(s)
- Juraj Szavits-Nossan
- SUPA, School of Physics and Astronomy, University of Edinburgh, Peter Guthrie Tait Road, Edinburgh EH9 3FD, UK
| | - Luca Ciandrini
- Centre de Biologie Structurale (CBS), CNRS, INSERM, Univ Montpellier, Montpellier 34090, France
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25
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Szavits-Nossan J, Waclaw B. Current-density relation in the exclusion process with dynamic obstacles. Phys Rev E 2020; 102:042117. [PMID: 33212664 DOI: 10.1103/physreve.102.042117] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2020] [Accepted: 09/17/2020] [Indexed: 06/11/2023]
Abstract
We investigate the totally asymmetric simple exclusion process (TASEP) in the presence of obstacles that dynamically bind and unbind from the lattice. The model is motivated by biological processes such as transcription in the presence of DNA-binding proteins. Similar models have been studied before using the mean-field approximation, but the exact relation between the particle current and density remains elusive. Here, we first show using extensive Monte Carlo simulations that the current-density relation in this model assumes a quasiparabolic form similar to that of the ordinary TASEP without obstacles. We then attempt to explain this relation using exact calculations in the limit of low and high density of particles. Our results suggest that the symmetric, quasiparabolic current-density relation arises through a nontrivial cancellation of higher-order terms, similarly as in the standard TASEP.
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Affiliation(s)
- J Szavits-Nossan
- School of Physics and Astronomy, University of Edinburgh, Peter Guthrie Tait Road, Edinburgh EH9 3FD, United Kingdom
| | - B Waclaw
- School of Physics and Astronomy, University of Edinburgh, Peter Guthrie Tait Road, Edinburgh EH9 3FD, United Kingdom
- Centre for Synthetic and Systems Biology, University of Edinburgh, Edinburgh EH9 3BF, United Kingdom
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26
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Szavits-Nossan J, Evans MR. Dynamics of ribosomes in mRNA translation under steady- and nonsteady-state conditions. Phys Rev E 2020; 101:062404. [PMID: 32688522 DOI: 10.1103/physreve.101.062404] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2020] [Accepted: 05/20/2020] [Indexed: 11/07/2022]
Abstract
Recent advances in DNA sequencing and fluorescence imaging have made it possible to monitor the dynamics of ribosomes actively engaged in messenger RNA (mRNA) translation. Here, we model these experiments within the inhomogeneous totally asymmetric simple exclusion process (TASEP) using realistic kinetic parameters. In particular, we present analytic expressions to describe the following three cases: (a) translation of a newly transcribed mRNA, (b) translation in the steady state and, specifically, the dynamics of individual (tagged) ribosomes, and (c) runoff translation after inhibition of translation initiation. In cases (b) and (c) we develop an effective medium approximation to describe many-ribosome dynamics in terms of a single tagged ribosome in an effective medium. The predictions are in good agreement with stochastic simulations.
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Affiliation(s)
- Juraj Szavits-Nossan
- SUPA, School of Physics and Astronomy, University of Edinburgh, Peter Guthrie Tait Road, Edinburgh EH9 3FD, United Kingdom
| | - Martin R Evans
- SUPA, School of Physics and Astronomy, University of Edinburgh, Peter Guthrie Tait Road, Edinburgh EH9 3FD, United Kingdom
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Fischer J, Song YS, Yosef N, di Iulio J, Churchman LS, Choder M. The yeast exoribonuclease Xrn1 and associated factors modulate RNA polymerase II processivity in 5' and 3' gene regions. J Biol Chem 2020; 295:11435-11454. [PMID: 32518159 DOI: 10.1074/jbc.ra120.013426] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2020] [Revised: 06/05/2020] [Indexed: 11/06/2022] Open
Abstract
mRNA levels are determined by the balance between mRNA synthesis and decay. Protein factors that mediate both processes, including the 5'-3' exonuclease Xrn1, are responsible for a cross-talk between the two processes that buffers steady-state mRNA levels. However, the roles of these proteins in transcription remain elusive and controversial. Applying native elongating transcript sequencing (NET-seq) to yeast cells, we show that Xrn1 functions mainly as a transcriptional activator and that its disruption manifests as a reduction of RNA polymerase II (Pol II) occupancy downstream of transcription start sites. By combining our sequencing data and mathematical modeling of transcription, we found that Xrn1 modulates transcription initiation and elongation of its target genes. Furthermore, Pol II occupancy markedly increased near cleavage and polyadenylation sites in xrn1Δ cells, whereas its activity decreased, a characteristic feature of backtracked Pol II. We also provide indirect evidence that Xrn1 is involved in transcription termination downstream of polyadenylation sites. We noted that two additional decay factors, Dhh1 and Lsm1, seem to function similarly to Xrn1 in transcription, perhaps as a complex, and that the decay factors Ccr4 and Rpb4 also perturb transcription in other ways. Interestingly, the decay factors could differentiate between SAGA- and TFIID-dominated promoters. These two classes of genes responded differently to XRN1 deletion in mRNA synthesis and were differentially regulated by mRNA decay pathways, raising the possibility that one distinction between these two gene classes lies in the mechanisms that balance mRNA synthesis with mRNA decay.
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Affiliation(s)
- Jonathan Fischer
- Computer Science Division, University of California, Berkeley, California, USA.,Department of Statistics, University of California, Berkeley, California, USA
| | - Yun S Song
- Computer Science Division, University of California, Berkeley, California, USA.,Department of Statistics, University of California, Berkeley, California, USA.,Chan Zuckerberg BioHub, San Francisco, California, USA
| | - Nir Yosef
- Chan Zuckerberg BioHub, San Francisco, California, USA.,Department of Electrical Engineering and Computer Sciences, University of California, Berkeley, California, USA.,Ragon Institute of MGH, MIT, and Harvard, Cambridge, Massachusetts, USA
| | - Julia di Iulio
- Department of Genetics, Harvard Medical School, Boston, Massachusetts, USA
| | | | - Mordechai Choder
- Department of Molecular Microbiology, Rappaport Faculty of Medicine, Technion-Israel Institute of Technology, Haifa, Israel
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