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Ponnusamy V, Sankaranarayanan M. Targeted gene manipulation of Leloir pathway genes for the constitutive expression of β-galactosidase and its transgalactosylation product galacto-oligosaccharides from Kluyveromyces lactis GG799 and knockout strains. Enzyme Microb Technol 2023; 169:110263. [PMID: 37311284 DOI: 10.1016/j.enzmictec.2023.110263] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2023] [Revised: 05/19/2023] [Accepted: 05/20/2023] [Indexed: 06/15/2023]
Abstract
Galacto-oligosaccharides (GOS) are used as prebiotic ingredients in various food and pharmaceutical industry. At present, production of GOS involves the enzymatic transformation of lactose by transgalactosylation using β-galactosidase. The yeast Kluyveromyces lactis can utilize lactose as its carbon and energy source. In this species lactose is hydrolyzed by an intracellular β-galactosidase (EC 3.2.1.23) which is induced by its substrate and related compounds like galactose. The molecular details of gene regulation in kluyveromyces lactis, we have used multiple knockout approaches to study the constitutive expression by which galactose induces β-galactosidase. The present study involved carrying out to a method of enhancing the constitutive expression of β-galactosidase through galactose induction and its trans-galactosylation reaction for the production of galacto-oligosaccharides (GOS) in Kluyveromyces lactis (K. Lactis) by applying a knockout based approach on Leloir pathway genes based on fusion-overlap extension polymerase chain reaction and transformation into its genome. The k.lactis strain subjected to Leloir pathway genes knockout, resulted in the accumulation of galactose intracellularly and this internal galactose acts as an inducer of galactose regulon for constitutive expression of β-galactosidase at early stationary phase was due to the positive regulatory function of mutant gal1p, gal7p and both. These resulted strains used for trans-galactosylation of lactose by β - galactosidase is characterized for the production of galacto-oligosaccharides. Galactose-induced constitutive expression of β-galactosidase during the early stationary phase of knockout strains was analysed qualitatively & quantitatively. The activity of β-galactosidase of wild type, gal1z, gal7k and gal1z & gal7k strains were 7, 8, 9 and 11 U/ml respectively using high cell density cultivation medium. Based on these expression differences in β-galactosidase, the trans-galactosylation reaction for GOS production and percentage yield of GOS were compared at 25% w/v of lactose. The percentage yield of GOS production of wild type, Δgal1z Lac4+, Δgal7k Lac4++ and Δgal1z Δgal7k Lac4+++mutants strains were 6.3, 13, 17 and 22 U/ml, respectively. Therefore, we propose that the availability of galactose can be used for constitutive over expression of β - galactosidase in Leloir pathway engineering applications and also for GOS production. Further, increased expression of β - galactosidases can be used in dairy industry by-products like whey to produce added value products such as galacto-oligosaccharides.
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Brouwer I, Kerklingh E, van Leeuwen F, Lenstra TL. Dynamic epistasis analysis reveals how chromatin remodeling regulates transcriptional bursting. Nat Struct Mol Biol 2023; 30:692-702. [PMID: 37127821 DOI: 10.1038/s41594-023-00981-1] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2022] [Accepted: 03/30/2023] [Indexed: 05/03/2023]
Abstract
Transcriptional bursting has been linked to the stochastic positioning of nucleosomes. However, how bursting is regulated by the remodeling of promoter nucleosomes is unknown. Here, we use single-molecule live-cell imaging of GAL10 transcription in Saccharomyces cerevisiae to measure how bursting changes upon combined perturbations of chromatin remodelers, the transcription factor Gal4 and preinitiation complex components. Using dynamic epistasis analysis, we reveal how the remodeling of different nucleosomes regulates transcriptional bursting parameters. At the nucleosome covering the Gal4 binding sites, RSC and Gal4 binding synergistically facilitate each burst. Conversely, nucleosome remodeling at the TATA box controls only the first burst upon galactose induction. At canonical TATA boxes, the nucleosomes are displaced by TBP binding to allow for transcription activation even in the absence of remodelers. Overall, our results reveal how promoter nucleosome remodeling together with Gal4 and preinitiation complex binding regulates transcriptional bursting.
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Affiliation(s)
- Ineke Brouwer
- Division of Gene Regulation, the Netherlands Cancer Institute, Oncode Institute, Amsterdam, the Netherlands
| | - Emma Kerklingh
- Division of Gene Regulation, the Netherlands Cancer Institute, Oncode Institute, Amsterdam, the Netherlands
| | - Fred van Leeuwen
- Division of Gene Regulation, the Netherlands Cancer Institute, Amsterdam, the Netherlands
- Department of Medical Biology, Amsterdam UMC, University of Amsterdam, Amsterdam, the Netherlands
| | - Tineke L Lenstra
- Division of Gene Regulation, the Netherlands Cancer Institute, Oncode Institute, Amsterdam, the Netherlands.
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3
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Fita-Torró J, Swamy KBS, Pascual-Ahuir A, Proft M. Divergence of alternative sugar preferences through modulation of the expression and activity of the Gal3 sensor in yeast. Mol Ecol 2023. [PMID: 37052375 DOI: 10.1111/mec.16954] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2023] [Revised: 04/03/2023] [Accepted: 04/05/2023] [Indexed: 04/14/2023]
Abstract
Optimized nutrient utilization is crucial for the progression of microorganisms in competing communities. Here we investigate how different budding yeast species and ecological isolates have established divergent preferences for two alternative sugar substrates: Glucose, which is fermented preferentially by yeast, and galactose, which is alternatively used upon induction of the relevant GAL metabolic genes. We quantified the dose-dependent induction of the GAL1 gene encoding the central galactokinase enzyme and found that a very large diversification exists between different yeast ecotypes and species. The sensitivity of GAL1 induction correlates with the growth performance of the respective yeasts with the alternative sugar. We further define some of the mechanisms, which have established different glucose/galactose consumption strategies in representative yeast strains by modulating the activity of the Gal3 inducer. (1) Optimal galactose consumers, such as Saccharomyces uvarum, contain a hyperactive GAL3 promoter, sustaining highly sensitive GAL1 expression, which is not further improved upon repetitive galactose encounters. (2) Desensitized galactose consumers, such as S. cerevisiae Y12, contain a less sensitive Gal3 sensor, causing a shift of the galactose response towards higher sugar concentrations even in galactose experienced cells. (3) Galactose insensitive sugar consumers, such as S. cerevisiae DBVPG6044, contain an interrupted GAL3 gene, causing extremely reluctant galactose consumption, which is, however, improved upon repeated galactose availability. In summary, different yeast strains and natural isolates have evolved galactose utilization strategies, which cover the whole range of possible sensitivities by modulating the expression and/or activity of the inducible galactose sensor Gal3.
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Affiliation(s)
- Josep Fita-Torró
- Department of Molecular and Cellular Pathology and Therapy, Instituto de Biomedicina de Valencia IBV-CSIC, Valencia, Spain
| | - Krishna B S Swamy
- Division of Biological and Life Sciences, School of Arts and Sciences, Ahmedabad University, Ahmedabad, India
| | - Amparo Pascual-Ahuir
- Department of Biotechnology, Instituto de Biología Molecular y Celular de Plantas, Universitat Politècnica de València, Valencia, Spain
| | - Markus Proft
- Department of Molecular and Cellular Pathology and Therapy, Instituto de Biomedicina de Valencia IBV-CSIC, Valencia, Spain
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4
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Li B, Zeis P, Zhang Y, Alekseenko A, Fürst E, Sanchez YP, Lin G, Tekkedil MM, Piazza I, Steinmetz LM, Pelechano V. Differential regulation of mRNA stability modulates transcriptional memory and facilitates environmental adaptation. Nat Commun 2023; 14:910. [PMID: 36801853 PMCID: PMC9936472 DOI: 10.1038/s41467-023-36586-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2022] [Accepted: 02/06/2023] [Indexed: 02/19/2023] Open
Abstract
Transcriptional memory, by which cells respond faster to repeated stimuli, is key for cellular adaptation and organism survival. Chromatin organization has been shown to play a role in the faster response of primed cells. However, the contribution of post-transcriptional regulation is not yet explored. Here we perform a genome-wide screen to identify novel factors modulating transcriptional memory in S. cerevisiae in response to galactose. We find that depletion of the nuclear RNA exosome increases GAL1 expression in primed cells. Our work shows that gene-specific differences in intrinsic nuclear surveillance factor association can enhance both gene induction and repression in primed cells. Finally, we show that primed cells present altered levels of RNA degradation machinery and that both nuclear and cytoplasmic mRNA decay modulate transcriptional memory. Our results demonstrate that mRNA post-transcriptional regulation, and not only transcription regulation, should be considered when investigating gene expression memory.
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Affiliation(s)
- Bingnan Li
- Department of Diagnostics, Medical Integration and Practice Center, Cheeloo College of Medicine, Shandong University, Jinan, Shandong, 250012, China.,SciLifeLab, Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, Solna, Sweden
| | - Patrice Zeis
- European Molecular Biology Laboratory (EMBL), Genome Biology Unit, Heidelberg, Germany.,Institute of Molecular and Clinical Ophthalmology Basel, Basel, Switzerland
| | - Yujie Zhang
- SciLifeLab, Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, Solna, Sweden
| | - Alisa Alekseenko
- SciLifeLab, Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, Solna, Sweden
| | - Eliska Fürst
- Max Delbrück Center for Molecular Medicine in the Helmholtz Association (MDC Berlin), Berlin, Germany
| | - Yerma Pareja Sanchez
- SciLifeLab, Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, Solna, Sweden
| | - Gen Lin
- European Molecular Biology Laboratory (EMBL), Genome Biology Unit, Heidelberg, Germany.,AbbVie Pte Ltd, Singapore, Singapore
| | - Manu M Tekkedil
- European Molecular Biology Laboratory (EMBL), Genome Biology Unit, Heidelberg, Germany
| | - Ilaria Piazza
- Max Delbrück Center for Molecular Medicine in the Helmholtz Association (MDC Berlin), Berlin, Germany
| | - Lars M Steinmetz
- European Molecular Biology Laboratory (EMBL), Genome Biology Unit, Heidelberg, Germany.,Stanford Genome Technology Center, Stanford University, Palo Alto, CA, USA.,Department of Genetics, School of Medicine, Stanford University, Stanford, CA, USA
| | - Vicent Pelechano
- SciLifeLab, Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, Solna, Sweden.
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5
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Tan YS, Zhang RK, Liu ZH, Li BZ, Yuan YJ. Microbial Adaptation to Enhance Stress Tolerance. Front Microbiol 2022; 13:888746. [PMID: 35572687 PMCID: PMC9093737 DOI: 10.3389/fmicb.2022.888746] [Citation(s) in RCA: 20] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2022] [Accepted: 03/18/2022] [Indexed: 01/28/2023] Open
Abstract
Microbial cell factories have been widely used in the production of various chemicals. Although synthetic biology is useful in improving the cell factories, adaptation is still widely applied to enhance its complex properties. Adaptation is an important strategy for enhancing stress tolerance in microbial cell factories. Adaptation involves gradual modifications of microorganisms in a stressful environment to enhance their tolerance. During adaptation, microorganisms use different mechanisms to enhance non-preferred substrate utilization and stress tolerance, thereby improving their ability to adapt for growth and survival. In this paper, the progress on the effects of adaptation on microbial substrate utilization capacity and environmental stress tolerance are reviewed, and the mechanisms involved in enhancing microbial adaptive capacity are discussed.
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Affiliation(s)
- Yong-Shui Tan
- Frontiers Science Center for Synthetic Biology and Key Laboratory of Systems Bioengineering (Ministry of Education), School of Chemical Engineering and Technology, Tianjin University, Tianjin, China.,Synthetic Biology Research Platform, Collaborative Innovation Center of Chemical Science and Engineering (Tianjin), Tianjin University, Tianjin, China
| | - Ren-Kuan Zhang
- Frontiers Science Center for Synthetic Biology and Key Laboratory of Systems Bioengineering (Ministry of Education), School of Chemical Engineering and Technology, Tianjin University, Tianjin, China.,Synthetic Biology Research Platform, Collaborative Innovation Center of Chemical Science and Engineering (Tianjin), Tianjin University, Tianjin, China
| | - Zhi-Hua Liu
- Frontiers Science Center for Synthetic Biology and Key Laboratory of Systems Bioengineering (Ministry of Education), School of Chemical Engineering and Technology, Tianjin University, Tianjin, China.,Synthetic Biology Research Platform, Collaborative Innovation Center of Chemical Science and Engineering (Tianjin), Tianjin University, Tianjin, China
| | - Bing-Zhi Li
- Frontiers Science Center for Synthetic Biology and Key Laboratory of Systems Bioengineering (Ministry of Education), School of Chemical Engineering and Technology, Tianjin University, Tianjin, China.,Synthetic Biology Research Platform, Collaborative Innovation Center of Chemical Science and Engineering (Tianjin), Tianjin University, Tianjin, China
| | - Ying-Jin Yuan
- Frontiers Science Center for Synthetic Biology and Key Laboratory of Systems Bioengineering (Ministry of Education), School of Chemical Engineering and Technology, Tianjin University, Tianjin, China.,Synthetic Biology Research Platform, Collaborative Innovation Center of Chemical Science and Engineering (Tianjin), Tianjin University, Tianjin, China
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6
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Sump B, Brickner DG, D'Urso A, Kim SH, Brickner JH. Mitotically heritable, RNA polymerase II-independent H3K4 dimethylation stimulates INO1 transcriptional memory. eLife 2022; 11:e77646. [PMID: 35579426 PMCID: PMC9129879 DOI: 10.7554/elife.77646] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2022] [Accepted: 05/15/2022] [Indexed: 11/13/2022] Open
Abstract
For some inducible genes, the rate and molecular mechanism of transcriptional activation depend on the prior experiences of the cell. This phenomenon, called epigenetic transcriptional memory, accelerates reactivation, and requires both changes in chromatin structure and recruitment of poised RNA polymerase II (RNAPII) to the promoter. Memory of inositol starvation in budding yeast involves a positive feedback loop between transcription factor-dependent interaction with the nuclear pore complex and histone H3 lysine 4 dimethylation (H3K4me2). While H3K4me2 is essential for recruitment of RNAPII and faster reactivation, RNAPII is not required for H3K4me2. Unlike RNAPII-dependent H3K4me2 associated with transcription, RNAPII-independent H3K4me2 requires Nup100, SET3C, the Leo1 subunit of the Paf1 complex and, upon degradation of an essential transcription factor, is inherited through multiple cell cycles. The writer of this mark (COMPASS) physically interacts with the potential reader (SET3C), suggesting a molecular mechanism for the spreading and re-incorporation of H3K4me2 following DNA replication.
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Affiliation(s)
- Bethany Sump
- Department of Molecular Biosciences, Northwestern UniversityEvanstonUnited States
| | - Donna G Brickner
- Department of Molecular Biosciences, Northwestern UniversityEvanstonUnited States
| | - Agustina D'Urso
- Department of Molecular Biosciences, Northwestern UniversityEvanstonUnited States
| | - Seo Hyun Kim
- Department of Molecular Biosciences, Northwestern UniversityEvanstonUnited States
| | - Jason H Brickner
- Department of Molecular Biosciences, Northwestern UniversityEvanstonUnited States
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Pascual-Garcia P, Little SC, Capelson M. Nup98-dependent transcriptional memory is established independently of transcription. eLife 2022; 11:e63404. [PMID: 35289742 PMCID: PMC8923668 DOI: 10.7554/elife.63404] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2020] [Accepted: 02/26/2022] [Indexed: 12/31/2022] Open
Abstract
Cellular ability to mount an enhanced transcriptional response upon repeated exposure to external cues is termed transcriptional memory, which can be maintained epigenetically through cell divisions and can depend on a nuclear pore component Nup98. The majority of mechanistic knowledge on transcriptional memory has been derived from bulk molecular assays. To gain additional perspective on the mechanism and contribution of Nup98 to memory, we used single-molecule RNA FISH (smFISH) to examine the dynamics of transcription in Drosophila cells upon repeated exposure to the steroid hormone ecdysone. We combined smFISH with mathematical modeling and found that upon hormone exposure, cells rapidly activate a low-level transcriptional response, but simultaneously begin a slow transition into a specialized memory state characterized by a high rate of expression. Strikingly, our modeling predicted that this transition between non-memory and memory states is independent of the transcription stemming from initial activation. We confirmed this prediction experimentally by showing that inhibiting transcription during initial ecdysone exposure did not interfere with memory establishment. Together, our findings reveal that Nup98's role in transcriptional memory is to stabilize the forward rate of conversion from low to high expressing state, and that induced genes engage in two separate behaviors - transcription itself and the establishment of epigenetically propagated transcriptional memory.
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Affiliation(s)
- Pau Pascual-Garcia
- Department of Cell and Developmental Biology, Penn Epigenetics Institute, Perelman School of Medicine, University of PennsylvaniaPhiladelphiaUnited States
| | - Shawn C Little
- Department of Cell and Developmental Biology, Penn Epigenetics Institute, Perelman School of Medicine, University of PennsylvaniaPhiladelphiaUnited States
| | - Maya Capelson
- Department of Cell and Developmental Biology, Penn Epigenetics Institute, Perelman School of Medicine, University of PennsylvaniaPhiladelphiaUnited States
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8
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Tan YS, Wang L, Wang YY, He QE, Liu ZH, Zhu Z, Song K, Li BZ, Yuan YJ. Protein acetylation regulates xylose metabolism during adaptation of Saccharomyces cerevisiae. BIOTECHNOLOGY FOR BIOFUELS 2021; 14:241. [PMID: 34920742 PMCID: PMC8684234 DOI: 10.1186/s13068-021-02090-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/15/2021] [Accepted: 12/04/2021] [Indexed: 06/14/2023]
Abstract
BACKGROUND As the second most abundant polysaccharide in nature, hemicellulose can be degraded to xylose as the feedstock for bioconversion to fuels and chemicals. To enhance xylose conversion, the engineered Saccharomyces cerevisiae with xylose metabolic pathway is usually adapted with xylose as the carbon source in the laboratory. However, the mechanism under the adaptation phenomena of the engineered strain is still unclear. RESULTS In this study, xylose-utilizing S. cerevisiae was constructed and used for the adaptation study. It was found that xylose consumption rate increased 1.24-fold in the second incubation of the yYST12 strain in synthetic complete-xylose medium compared with the first incubation. The study figured out that it was observed at the single-cell level that the stagnation time for xylose utilization was reduced after adaptation with xylose medium in the microfluidic device. Such transient memory of xylose metabolism after adaptation with xylose medium, named "xylose consumption memory", was observed in the strains with both xylose isomerase pathway and xylose reductase and xylitol dehydrogenase pathways. In further, the proteomic acetylation of the strains before and after adaptation was investigated, and it was revealed that H4K5 was one of the most differential acetylation sites related to xylose consumption memory of engineered S. cerevisiae. We tested 8 genes encoding acetylase or deacetylase, and it was found that the knockout of the GCN5 and HPA2 encoding acetylases enhanced the xylose consumption memory. CONCLUSIONS The behavior of xylose consumption memory in engineered S. cerevisiae can be successfully induced with xylose in the adaptation. H4K5Ac and two genes of GCN5 and HPA2 are related to xylose consumption memory of engineered S. cerevisiae during adaptation. This study provides valuable insights into the xylose adaptation of engineered S. cerevisiae.
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Affiliation(s)
- Yong-Shui Tan
- Frontiers Science Center for Synthetic Biology and Key Laboratory of Systems Bioengineering (Ministry of Education), School of Chemical Engineering and Technology, Tianjin University, Tianjin, 300072 People’s Republic of China
- Synthetic Biology Research Platform, Collaborative Innovation Center of Chemical Science and Engineering (Tianjin), Tianjin University, Tianjin, 300072 People’s Republic of China
| | - Li Wang
- Frontiers Science Center for Synthetic Biology and Key Laboratory of Systems Bioengineering (Ministry of Education), School of Chemical Engineering and Technology, Tianjin University, Tianjin, 300072 People’s Republic of China
- Synthetic Biology Research Platform, Collaborative Innovation Center of Chemical Science and Engineering (Tianjin), Tianjin University, Tianjin, 300072 People’s Republic of China
| | - Ying-Ying Wang
- Key Laboratory of MEMS of Ministry of Education, Southeast University, Nanjing, 210096 People’s Republic of China
| | - Qi-En He
- School of Chemical Engineering and Technology, Tianjin University, Tianjin, 300072 People’s Republic of China
| | - Zhi-Hua Liu
- Frontiers Science Center for Synthetic Biology and Key Laboratory of Systems Bioengineering (Ministry of Education), School of Chemical Engineering and Technology, Tianjin University, Tianjin, 300072 People’s Republic of China
- Synthetic Biology Research Platform, Collaborative Innovation Center of Chemical Science and Engineering (Tianjin), Tianjin University, Tianjin, 300072 People’s Republic of China
| | - Zhen Zhu
- Key Laboratory of MEMS of Ministry of Education, Southeast University, Nanjing, 210096 People’s Republic of China
| | - Kai Song
- School of Chemical Engineering and Technology, Tianjin University, Tianjin, 300072 People’s Republic of China
| | - Bing-Zhi Li
- Frontiers Science Center for Synthetic Biology and Key Laboratory of Systems Bioengineering (Ministry of Education), School of Chemical Engineering and Technology, Tianjin University, Tianjin, 300072 People’s Republic of China
- Synthetic Biology Research Platform, Collaborative Innovation Center of Chemical Science and Engineering (Tianjin), Tianjin University, Tianjin, 300072 People’s Republic of China
| | - Ying-Jin Yuan
- Frontiers Science Center for Synthetic Biology and Key Laboratory of Systems Bioengineering (Ministry of Education), School of Chemical Engineering and Technology, Tianjin University, Tianjin, 300072 People’s Republic of China
- Synthetic Biology Research Platform, Collaborative Innovation Center of Chemical Science and Engineering (Tianjin), Tianjin University, Tianjin, 300072 People’s Republic of China
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9
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Wang RX, Li YM, Chen R, Du HN. Transcriptional memory of different types of genes is generally maintained under various environmental conditions in Saccharomyces cerevisiae. J Genet Genomics 2021; 49:173-176. [PMID: 34728416 DOI: 10.1016/j.jgg.2021.10.007] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2021] [Revised: 10/15/2021] [Accepted: 10/18/2021] [Indexed: 11/18/2022]
Affiliation(s)
- Ru-Xin Wang
- Hubei Key Laboratory of Cell Homeostasis, RNA Institute, College of Life Sciences, Wuhan University, Wuhan 430072, China
| | - Yu-Min Li
- Hubei Key Laboratory of Cell Homeostasis, RNA Institute, College of Life Sciences, Wuhan University, Wuhan 430072, China
| | - Runfa Chen
- Hubei Key Laboratory of Cell Homeostasis, RNA Institute, College of Life Sciences, Wuhan University, Wuhan 430072, China
| | - Hai-Ning Du
- Hubei Key Laboratory of Cell Homeostasis, RNA Institute, College of Life Sciences, Wuhan University, Wuhan 430072, China.
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10
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Weinhouse C. The roles of inducible chromatin and transcriptional memory in cellular defense system responses to redox-active pollutants. Free Radic Biol Med 2021; 170:85-108. [PMID: 33789123 PMCID: PMC8382302 DOI: 10.1016/j.freeradbiomed.2021.03.018] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/15/2020] [Revised: 03/12/2021] [Accepted: 03/15/2021] [Indexed: 12/17/2022]
Abstract
People are exposed to wide range of redox-active environmental pollutants. Air pollution, heavy metals, pesticides, and endocrine disrupting chemicals can disrupt cellular redox status. Redox-active pollutants in our environment all trigger their own sets of specific cellular responses, but they also activate a common set of general stress responses that buffer the cell against homeostatic insults. These cellular defense system (CDS) pathways include the heat shock response, the oxidative stress response, the hypoxia response, the unfolded protein response, the DNA damage response, and the general stress response mediated by the stress-activated p38 mitogen-activated protein kinase. Over the past two decades, the field of environmental epigenetics has investigated epigenetic responses to environmental pollutants, including redox-active pollutants. Studies of these responses highlight the role of chromatin modifications in controlling the transcriptional response to pollutants and the role of transcriptional memory, often referred to as "epigenetic reprogramming", in predisposing previously exposed individuals to more potent transcriptional responses on secondary challenge. My central thesis in this review is that high dose or chronic exposure to redox-active pollutants leads to transcriptional memories at CDS target genes that influence the cell's ability to mount protective responses. To support this thesis, I will: (1) summarize the known chromatin features required for inducible gene activation; (2) review the known forms of transcriptional memory; (3) discuss the roles of inducible chromatin and transcriptional memory in CDS responses that are activated by redox-active environmental pollutants; and (4) propose a conceptual framework for CDS pathway responsiveness as a readout of total cellular exposure to redox-active pollutants.
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Affiliation(s)
- Caren Weinhouse
- Oregon Institute of Occupational Health Sciences, Oregon Health & Science University, Portland, OR, 97214, USA.
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11
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Shaban K, Sauty SM, Yankulov K. Variation, Variegation and Heritable Gene Repression in S. cerevisiae. Front Genet 2021; 12:630506. [PMID: 33747046 PMCID: PMC7970126 DOI: 10.3389/fgene.2021.630506] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2020] [Accepted: 02/08/2021] [Indexed: 11/13/2022] Open
Abstract
Phenotypic heterogeneity provides growth advantages for a population upon changes of the environment. In S. cerevisiae, such heterogeneity has been observed as "on/off" states in the expression of individual genes in individual cells. These variations can persist for a limited or extended number of mitotic divisions. Such traits are known to be mediated by heritable chromatin structures, by the mitotic transmission of transcription factors involved in gene regulatory circuits or by the cytoplasmic partition of prions or other unstructured proteins. The significance of such epigenetic diversity is obvious, however, we have limited insight into the mechanisms that generate it. In this review, we summarize the current knowledge of epigenetically maintained heterogeneity of gene expression and point out similarities and converging points between different mechanisms. We discuss how the sharing of limiting repression or activation factors can contribute to cell-to-cell variations in gene expression and to the coordination between short- and long- term epigenetic strategies. Finally, we discuss the implications of such variations and strategies in adaptation and aging.
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Affiliation(s)
- Kholoud Shaban
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, ON, Canada
| | - Safia Mahabub Sauty
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, ON, Canada
| | - Krassimir Yankulov
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, ON, Canada
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12
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Capturing and Understanding the Dynamics and Heterogeneity of Gene Expression in the Living Cell. Int J Mol Sci 2020; 21:ijms21218278. [PMID: 33167354 PMCID: PMC7663833 DOI: 10.3390/ijms21218278] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2020] [Revised: 10/29/2020] [Accepted: 11/03/2020] [Indexed: 11/21/2022] Open
Abstract
The regulation of gene expression is a fundamental process enabling cells to respond to internal and external stimuli or to execute developmental programs. Changes in gene expression are highly dynamic and depend on many intrinsic and extrinsic factors. In this review, we highlight the dynamic nature of transient gene expression changes to better understand cell physiology and development in general. We will start by comparing recent in vivo procedures to capture gene expression in real time. Intrinsic factors modulating gene expression dynamics will then be discussed, focusing on chromatin modifications. Furthermore, we will dissect how cell physiology or age impacts on dynamic gene regulation and especially discuss molecular insights into acquired transcriptional memory. Finally, this review will give an update on the mechanisms of heterogeneous gene expression among genetically identical individual cells. We will mainly focus on state-of-the-art developments in the yeast model but also cover higher eukaryotic systems.
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13
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The past determines the future: sugar source history and transcriptional memory. Curr Genet 2020; 66:1029-1035. [PMID: 32686056 PMCID: PMC7599190 DOI: 10.1007/s00294-020-01094-8] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2020] [Revised: 06/30/2020] [Accepted: 07/07/2020] [Indexed: 11/20/2022]
Abstract
Transcriptional reinduction memory is a phenomenon whereby cells “remember” their transcriptional response to a previous stimulus such that subsequent encounters with the same stimulus can result in altered gene expression kinetics. Chromatin structure is thought to play a role in certain transcriptional memory mechanisms, leading to questions as to whether and how memory can be actively maintained and inherited to progeny through cell division. Here we summarize efforts towards dissecting chromatin-based transcriptional memory inheritance of GAL genes in Saccharomyces cerevisiae. We focus on methods and analyses of GAL (as well as MAL and INO) memory in single cells and discuss the challenges in unraveling the underlying mechanisms in yeast and higher eukaryotes.
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14
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Bheda P, Aguilar-Gómez D, Becker NB, Becker J, Stavrou E, Kukhtevich I, Höfer T, Maerkl S, Charvin G, Marr C, Kirmizis A, Schneider R. Single-Cell Tracing Dissects Regulation of Maintenance and Inheritance of Transcriptional Reinduction Memory. Mol Cell 2020; 78:915-925.e7. [DOI: 10.1016/j.molcel.2020.04.016] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2019] [Revised: 02/15/2020] [Accepted: 04/15/2020] [Indexed: 10/24/2022]
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15
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Abstract
Background Organisms can be primed by metabolic exposures to continue expressing response genes even once the metabolite is no longer available, and can affect the speed and magnitude of responsive gene expression during subsequent exposures. This “metabolic transcriptional memory” can have a profound impact on the survivability of organisms in fluctuating environments. Scope of review Here I present several examples of metabolic transcriptional memory in the microbial world and discuss what is known so far regarding the underlying mechanisms, which mainly focus on chromatin modifications, protein inheritance, and broad changes in metabolic network. From these lessons learned in microbes, some insights into the yet understudied human metabolic memory can be gained. I thus discuss the implications of metabolic memory in disease progression in humans – i.e., the memory of high blood sugar exposure and the resulting effects on diabetic complications. Major conclusions Carbon source shifts from glucose to other less preferred sugars such as lactose, galactose, and maltose for energy metabolism as well as starvation of a signal transduction precursor sugar inositol are well-studied examples of metabolic transcriptional memory in Escherichia coli and Saccharomyces cerevisiae. Although the specific factors guiding metabolic transcriptional memory are not necessarily conserved from microbes to humans, the same basic mechanisms are in play, as is observed in hyperglycemic memory. Exploration of new metabolic transcriptional memory systems as well as further detailed mechanistic analyses of known memory contexts in microbes is therefore central to understanding metabolic memory in humans, and may be of relevance for the successful treatment of the ever-growing epidemic of diabetes. Metabolic exposures can prime genes to have memory. Memory of carbon source shifts occurs in all kingdoms of life. Memory is maintained through multiple mechanisms including chromatin modifications, proteins, and metabolic network. Metabolic transcriptional memory in unicellular organisms is a part of “bet-hedging” strategies to ensure survival. Hyperglycemic memory in humans contributes to diabetes and aging.
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Affiliation(s)
- Poonam Bheda
- Institute of Functional Epigenetics, Helmholtz Zentrum München, Neuherberg, Germany.
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16
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Lee BB, Choi A, Kim JH, Jun Y, Woo H, Ha SD, Yoon CY, Hwang JT, Steinmetz L, Buratowski S, Lee S, Kim HY, Kim T. Rpd3L HDAC links H3K4me3 to transcriptional repression memory. Nucleic Acids Res 2019; 46:8261-8274. [PMID: 29982589 PMCID: PMC6144869 DOI: 10.1093/nar/gky573] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2018] [Accepted: 06/14/2018] [Indexed: 11/13/2022] Open
Abstract
Transcriptional memory is critical for the faster reactivation of necessary genes upon environmental changes and requires that the genes were previously in an active state. However, whether transcriptional repression also displays ‘memory’ of the prior transcriptionally inactive state remains unknown. In this study, we show that transcriptional repression of ∼540 genes in yeast occurs much more rapidly if the genes have been previously repressed during carbon source shifts. This novel transcriptional response has been termed transcriptional repression memory (TREM). Interestingly, Rpd3L histone deacetylase (HDAC), targeted to active promoters induces TREM. Mutants for Rpd3L exhibit increased acetylation at active promoters and delay TREM significantly. Surprisingly, the interaction between H3K4me3 and Rpd3L via the Pho23 PHD finger is critical to promote histone deacetylation and TREM by Rpd3L. Therefore, we propose that an active mark, H3K4me3 enriched at active promoters, instructs Rpd3L HDAC to induce histone deacetylation and TREM.
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Affiliation(s)
- Bo Bae Lee
- Department of Life Science and the Research Center for Cellular Homeostasis, Ewha Womans University, Seoul 03760, Korea
| | - Ahyoung Choi
- Department of Life Science and the Research Center for Cellular Homeostasis, Ewha Womans University, Seoul 03760, Korea
| | - Ji Hyun Kim
- Department of Life Science and the Research Center for Cellular Homeostasis, Ewha Womans University, Seoul 03760, Korea
| | - Yukyung Jun
- Department of Life Science and the Research Center for Cellular Homeostasis, Ewha Womans University, Seoul 03760, Korea
| | - Hyeonju Woo
- Department of Life Science and the Research Center for Cellular Homeostasis, Ewha Womans University, Seoul 03760, Korea
| | - So Dam Ha
- Department of Life Science and the Research Center for Cellular Homeostasis, Ewha Womans University, Seoul 03760, Korea
| | - Chae Young Yoon
- Department of Life Science and the Research Center for Cellular Homeostasis, Ewha Womans University, Seoul 03760, Korea
| | | | - Lars Steinmetz
- Genome Biology Unit, European Molecular Biology Laboratory, Meyerhofstrasse 1, 69117 Heidelberg, Germany, and Stanford Genome Technology Center and Department of Genetics, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Stephen Buratowski
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02115, USA
| | - Sanghyuk Lee
- Department of Life Science and the Research Center for Cellular Homeostasis, Ewha Womans University, Seoul 03760, Korea
| | - Hye Young Kim
- Department of Biomedical Sciences and Medical Science, Seoul National University College of Medicine, Seoul 03080, Korea
| | - TaeSoo Kim
- Department of Life Science and the Research Center for Cellular Homeostasis, Ewha Womans University, Seoul 03760, Korea
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17
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Abstract
Cells must fine-tune their gene expression programs for optimal cellular activities in their natural growth conditions. Transcriptional memory, a unique transcriptional response, plays a pivotal role in faster reactivation of genes upon environmental changes, and is facilitated if genes were previously in an active state. Hyper-activation of gene expression by transcriptional memory is critical for cellular differentiation, development, and adaptation. TREM (Transcriptional REpression Memory), a distinct type of transcriptional memory, promoting hyper-repression of unnecessary genes, upon environmental changes has been recently reported. These two transcriptional responses may optimize specific gene expression patterns, in rapidly changing environments. Emerging evidence suggests that they are also critical for immune responses. In addition to memory B and T cells, innate immune cells are transcriptionally hyperactivated by restimulation, with the same or different pathogens known as trained immunity. In this review, we briefly summarize recent progress in chromatin-based regulation of transcriptional memory, and its potential role in immune responses. [BMB Reports 2019; 52(2): 127-132].
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Affiliation(s)
- Min Young Kim
- Department of Life Science and the Research Center for Cellular Homeostasis, Ewha Womans University, Seoul 03760, Korea
| | - Ji Eun Lee
- Department of Life Science and the Research Center for Cellular Homeostasis, Ewha Womans University, Seoul 03760, Korea
| | - Lark Kyun Kim
- Severance Biomedical Science Institute and BK21 PLUS Project to Medical Sciences, Gangnam Severance Hospital, Yonsei University College of Medicine, Seoul 06230, Korea
| | - TaeSoo Kim
- Department of Life Science and the Research Center for Cellular Homeostasis, Ewha Womans University, Seoul 03760, Korea
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18
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Histone Methylation and Memory of Environmental Stress. Cells 2019; 8:cells8040339. [PMID: 30974922 PMCID: PMC6523599 DOI: 10.3390/cells8040339] [Citation(s) in RCA: 54] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2019] [Revised: 04/05/2019] [Accepted: 04/07/2019] [Indexed: 02/07/2023] Open
Abstract
Cellular adaptation to environmental stress relies on a wide range of tightly controlled regulatory mechanisms, including transcription. Changes in chromatin structure and organization accompany the transcriptional response to stress, and in some cases, can impart memory of stress exposure to subsequent generations through mechanisms of epigenetic inheritance. In the budding yeast Saccharomyces cerevisiae, histone post-translational modifications, and in particular histone methylation, have been shown to confer transcriptional memory of exposure to environmental stress conditions through mitotic divisions. Recent evidence from Caenorhabditis elegans also implicates histone methylation in transgenerational inheritance of stress responses, suggesting a more widely conserved role in epigenetic memory.
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19
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Dose dependent gene expression is dynamically modulated by the history, physiology and age of yeast cells. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2019; 1862:457-471. [DOI: 10.1016/j.bbagrm.2019.02.009] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/10/2018] [Revised: 02/21/2019] [Accepted: 02/23/2019] [Indexed: 12/14/2022]
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20
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Avramova Z. Defence-related priming and responses to recurring drought: Two manifestations of plant transcriptional memory mediated by the ABA and JA signalling pathways. PLANT, CELL & ENVIRONMENT 2019; 42:983-997. [PMID: 30299553 DOI: 10.1111/pce.13458] [Citation(s) in RCA: 37] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/01/2018] [Revised: 09/26/2018] [Accepted: 10/02/2018] [Indexed: 05/20/2023]
Abstract
Collective evidence from agricultural practices and from scientific research has demonstrated that plants can alter their phenotypic responses to repeated biotic and abiotic stresses or their elicitors. A coordinated reaction at the organismal, cellular, and genome levels has suggested that plants can "remember" an earlier stress and modify their future responses, accordingly. Stress memory may increase a plant's survival chances by improving its tolerance/avoidance abilities and may provide a mechanism for acclimation and adaptation. Understanding the mechanisms that regulate plant stress memory is not only an intellectually challenging topic but has important implications for agricultural practices as well. Here, I focus exclusively on specific aspects of the transcription memory in response to recurring dehydration stresses and the memory-type responses to insect damage in a process known as "priming." The questions discussed are (a) whether/how the two memory phenomena are connected at the level of transcriptional regulation; (b) how differential transcription is achieved mechanistically under a repeated stress; and (c) whether similar molecular and/or epigenetic mechanisms are involved. Possible biological relevance of transcriptional stress memory and its preservation in plant evolution are also discussed.
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Affiliation(s)
- Zoya Avramova
- School of Biological Sciences, UNL, Lincoln, Nebraska
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21
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Vermeersch L, Perez-Samper G, Cerulus B, Jariani A, Gallone B, Voordeckers K, Steensels J, Verstrepen KJ. On the duration of the microbial lag phase. Curr Genet 2019; 65:721-727. [PMID: 30666394 PMCID: PMC6510831 DOI: 10.1007/s00294-019-00938-2] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2018] [Revised: 01/11/2019] [Accepted: 01/11/2019] [Indexed: 12/19/2022]
Abstract
When faced with environmental changes, microbes enter a lag phase during which cell growth is arrested, allowing cells to adapt to the new situation. The discovery of the lag phase started the field of gene regulation and led to the unraveling of underlying mechanisms. However, the factors determining the exact duration and dynamics of the lag phase remain largely elusive. Naively, one would expect that cells adapt as quickly as possible, so they can resume growth and compete with other organisms. However, recent studies show that the lag phase can last from several hours up to several days. Moreover, some cells within the same population take much longer than others, despite being genetically identical. In addition, the lag phase duration is also influenced by the past, with recent exposure to a given environment leading to a quicker adaptation when that environment returns. Genome-wide screens in Saccharomyces cerevisiae on carbon source shifts now suggest that the length of the lag phase, the heterogeneity in lag times of individual cells, and the history-dependent behavior are not determined by the time it takes to induce a few specific genes related to uptake and metabolism of a new carbon source. Instead, a major shift in general metabolism, and in particular a switch between fermentation and respiration, is the major bottleneck that determines lag duration. This suggests that there may be a fitness trade-off between complete adaptation of a cell’s metabolism to a given environment, and a short lag phase when the environment changes.
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Affiliation(s)
- Lieselotte Vermeersch
- VIB Laboratory for Systems Biology, VIB-KU Leuven Center for Microbiology, Gaston Geenslaan 1, 3001, Leuven, Belgium.,CMPG Laboratory of Genetics and Genomics, Department M2S, KU Leuven, Gaston Geenslaan 1, 3001, Leuven, Belgium
| | - Gemma Perez-Samper
- VIB Laboratory for Systems Biology, VIB-KU Leuven Center for Microbiology, Gaston Geenslaan 1, 3001, Leuven, Belgium.,CMPG Laboratory of Genetics and Genomics, Department M2S, KU Leuven, Gaston Geenslaan 1, 3001, Leuven, Belgium
| | - Bram Cerulus
- VIB Laboratory for Systems Biology, VIB-KU Leuven Center for Microbiology, Gaston Geenslaan 1, 3001, Leuven, Belgium.,CMPG Laboratory of Genetics and Genomics, Department M2S, KU Leuven, Gaston Geenslaan 1, 3001, Leuven, Belgium
| | - Abbas Jariani
- VIB Laboratory for Systems Biology, VIB-KU Leuven Center for Microbiology, Gaston Geenslaan 1, 3001, Leuven, Belgium.,CMPG Laboratory of Genetics and Genomics, Department M2S, KU Leuven, Gaston Geenslaan 1, 3001, Leuven, Belgium
| | - Brigida Gallone
- VIB Laboratory for Systems Biology, VIB-KU Leuven Center for Microbiology, Gaston Geenslaan 1, 3001, Leuven, Belgium.,CMPG Laboratory of Genetics and Genomics, Department M2S, KU Leuven, Gaston Geenslaan 1, 3001, Leuven, Belgium.,Department of Plant Biotechnology and Bioinformatics, Ghent University, Technologiepark 927, 9052, Ghent, Belgium.,VIB Center for Plant Systems Biology, Technologiepark 927, 9052, Ghent, Belgium
| | - Karin Voordeckers
- VIB Laboratory for Systems Biology, VIB-KU Leuven Center for Microbiology, Gaston Geenslaan 1, 3001, Leuven, Belgium.,CMPG Laboratory of Genetics and Genomics, Department M2S, KU Leuven, Gaston Geenslaan 1, 3001, Leuven, Belgium
| | - Jan Steensels
- VIB Laboratory for Systems Biology, VIB-KU Leuven Center for Microbiology, Gaston Geenslaan 1, 3001, Leuven, Belgium.,CMPG Laboratory of Genetics and Genomics, Department M2S, KU Leuven, Gaston Geenslaan 1, 3001, Leuven, Belgium
| | - Kevin J Verstrepen
- VIB Laboratory for Systems Biology, VIB-KU Leuven Center for Microbiology, Gaston Geenslaan 1, 3001, Leuven, Belgium. .,CMPG Laboratory of Genetics and Genomics, Department M2S, KU Leuven, Gaston Geenslaan 1, 3001, Leuven, Belgium.
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22
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Cerulus B, Jariani A, Perez-Samper G, Vermeersch L, Pietsch JMJ, Crane MM, New AM, Gallone B, Roncoroni M, Dzialo MC, Govers SK, Hendrickx JO, Galle E, Coomans M, Berden P, Verbandt S, Swain PS, Verstrepen KJ. Transition between fermentation and respiration determines history-dependent behavior in fluctuating carbon sources. eLife 2018; 7:e39234. [PMID: 30299256 PMCID: PMC6211830 DOI: 10.7554/elife.39234] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2018] [Accepted: 10/05/2018] [Indexed: 01/24/2023] Open
Abstract
Cells constantly adapt to environmental fluctuations. These physiological changes require time and therefore cause a lag phase during which the cells do not function optimally. Interestingly, past exposure to an environmental condition can shorten the time needed to adapt when the condition re-occurs, even in daughter cells that never directly encountered the initial condition. Here, we use the molecular toolbox of Saccharomyces cerevisiae to systematically unravel the molecular mechanism underlying such history-dependent behavior in transitions between glucose and maltose. In contrast to previous hypotheses, the behavior does not depend on persistence of proteins involved in metabolism of a specific sugar. Instead, presence of glucose induces a gradual decline in the cells' ability to activate respiration, which is needed to metabolize alternative carbon sources. These results reveal how trans-generational transitions in central carbon metabolism generate history-dependent behavior in yeast, and provide a mechanistic framework for similar phenomena in other cell types.
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Affiliation(s)
- Bram Cerulus
- VIB Laboratory for Systems BiologyVIB-KU Leuven Center for MicrobiologyLeuvenBelgium
- Departement Microbiële en Moleculaire Systemen (M2S)CMPG Laboratory of Genetics and GenomicsLeuvenBelgium
| | - Abbas Jariani
- VIB Laboratory for Systems BiologyVIB-KU Leuven Center for MicrobiologyLeuvenBelgium
- Departement Microbiële en Moleculaire Systemen (M2S)CMPG Laboratory of Genetics and GenomicsLeuvenBelgium
| | - Gemma Perez-Samper
- VIB Laboratory for Systems BiologyVIB-KU Leuven Center for MicrobiologyLeuvenBelgium
- Departement Microbiële en Moleculaire Systemen (M2S)CMPG Laboratory of Genetics and GenomicsLeuvenBelgium
| | - Lieselotte Vermeersch
- VIB Laboratory for Systems BiologyVIB-KU Leuven Center for MicrobiologyLeuvenBelgium
- Departement Microbiële en Moleculaire Systemen (M2S)CMPG Laboratory of Genetics and GenomicsLeuvenBelgium
| | - Julian MJ Pietsch
- Centre for Synthetic and Systems Biology, School of Biological SciencesUniversity of EdinburghEdinburghUnited Kingdom
| | - Matthew M Crane
- Centre for Synthetic and Systems Biology, School of Biological SciencesUniversity of EdinburghEdinburghUnited Kingdom
- Department of PathologyUniversity of WashingtonWashingtonUnited States
| | - Aaron M New
- VIB Laboratory for Systems BiologyVIB-KU Leuven Center for MicrobiologyLeuvenBelgium
- Departement Microbiële en Moleculaire Systemen (M2S)CMPG Laboratory of Genetics and GenomicsLeuvenBelgium
| | - Brigida Gallone
- VIB Laboratory for Systems BiologyVIB-KU Leuven Center for MicrobiologyLeuvenBelgium
- Departement Microbiële en Moleculaire Systemen (M2S)CMPG Laboratory of Genetics and GenomicsLeuvenBelgium
- Department of Plant Biotechnology and BioinformaticsGhent UniversityGhentBelgium
- VIB Center for Plant Systems BiologyGhentBelgium
| | - Miguel Roncoroni
- VIB Laboratory for Systems BiologyVIB-KU Leuven Center for MicrobiologyLeuvenBelgium
- Departement Microbiële en Moleculaire Systemen (M2S)CMPG Laboratory of Genetics and GenomicsLeuvenBelgium
| | - Maria C Dzialo
- VIB Laboratory for Systems BiologyVIB-KU Leuven Center for MicrobiologyLeuvenBelgium
- Departement Microbiële en Moleculaire Systemen (M2S)CMPG Laboratory of Genetics and GenomicsLeuvenBelgium
| | - Sander K Govers
- VIB Laboratory for Systems BiologyVIB-KU Leuven Center for MicrobiologyLeuvenBelgium
- Departement Microbiële en Moleculaire Systemen (M2S)CMPG Laboratory of Genetics and GenomicsLeuvenBelgium
| | - Jhana O Hendrickx
- VIB Laboratory for Systems BiologyVIB-KU Leuven Center for MicrobiologyLeuvenBelgium
- Departement Microbiële en Moleculaire Systemen (M2S)CMPG Laboratory of Genetics and GenomicsLeuvenBelgium
| | - Eva Galle
- VIB Laboratory for Systems BiologyVIB-KU Leuven Center for MicrobiologyLeuvenBelgium
- Departement Microbiële en Moleculaire Systemen (M2S)CMPG Laboratory of Genetics and GenomicsLeuvenBelgium
| | - Maarten Coomans
- VIB Laboratory for Systems BiologyVIB-KU Leuven Center for MicrobiologyLeuvenBelgium
- Departement Microbiële en Moleculaire Systemen (M2S)CMPG Laboratory of Genetics and GenomicsLeuvenBelgium
| | - Pieter Berden
- VIB Laboratory for Systems BiologyVIB-KU Leuven Center for MicrobiologyLeuvenBelgium
- Departement Microbiële en Moleculaire Systemen (M2S)CMPG Laboratory of Genetics and GenomicsLeuvenBelgium
| | - Sara Verbandt
- VIB Laboratory for Systems BiologyVIB-KU Leuven Center for MicrobiologyLeuvenBelgium
- Departement Microbiële en Moleculaire Systemen (M2S)CMPG Laboratory of Genetics and GenomicsLeuvenBelgium
| | - Peter S Swain
- Centre for Synthetic and Systems Biology, School of Biological SciencesUniversity of EdinburghEdinburghUnited Kingdom
| | - Kevin J Verstrepen
- VIB Laboratory for Systems BiologyVIB-KU Leuven Center for MicrobiologyLeuvenBelgium
- Departement Microbiële en Moleculaire Systemen (M2S)CMPG Laboratory of Genetics and GenomicsLeuvenBelgium
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23
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Dultz E, Mancini R, Polles G, Vallotton P, Alber F, Weis K. Quantitative imaging of chromatin decompaction in living cells. Mol Biol Cell 2018; 29:1763-1777. [PMID: 29771637 DOI: 10.1101/219253] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/27/2023] Open
Abstract
Chromatin organization is highly dynamic and regulates transcription. Upon transcriptional activation, chromatin is remodeled and referred to as "open," but quantitative and dynamic data of this decompaction process are lacking. Here, we have developed a quantitative high resolution-microscopy assay in living yeast cells to visualize and quantify chromatin dynamics using the GAL7-10-1 locus as a model system. Upon transcriptional activation of these three clustered genes, we detect an increase of the mean distance across this locus by >100 nm. This decompaction is linked to active transcription but is not sensitive to the histone deacetylase inhibitor trichostatin A or to deletion of the histone acetyl transferase Gcn5. In contrast, the deletion of SNF2 (encoding the ATPase of the SWI/SNF chromatin remodeling complex) or the deactivation of the histone chaperone complex FACT lead to a strongly reduced decompaction without significant effects on transcriptional induction in FACT mutants. Our findings are consistent with nucleosome remodeling and eviction activities being major contributors to chromatin reorganization during transcription but also suggest that transcription can occur in the absence of detectable decompaction.
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Affiliation(s)
- Elisa Dultz
- Institute of Biochemistry, Department of Biology, ETH Zurich, 8093 Zurich, Switzerland
| | - Roberta Mancini
- Institute of Biochemistry, Department of Biology, ETH Zurich, 8093 Zurich, Switzerland
| | - Guido Polles
- Molecular and Computational Biology, University of Southern California, Los Angeles, CA 90089
| | - Pascal Vallotton
- Institute of Biochemistry, Department of Biology, ETH Zurich, 8093 Zurich, Switzerland
| | - Frank Alber
- Molecular and Computational Biology, University of Southern California, Los Angeles, CA 90089
| | - Karsten Weis
- Institute of Biochemistry, Department of Biology, ETH Zurich, 8093 Zurich, Switzerland
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24
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Dultz E, Mancini R, Polles G, Vallotton P, Alber F, Weis K. Quantitative imaging of chromatin decompaction in living cells. Mol Biol Cell 2018; 29:1763-1777. [PMID: 29771637 PMCID: PMC6080713 DOI: 10.1091/mbc.e17-11-0648] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Chromatin organization is highly dynamic and regulates transcription. Upon transcriptional activation, chromatin is remodeled and referred to as “open,” but quantitative and dynamic data of this decompaction process are lacking. Here, we have developed a quantitative high resolution–microscopy assay in living yeast cells to visualize and quantify chromatin dynamics using the GAL7-10-1 locus as a model system. Upon transcriptional activation of these three clustered genes, we detect an increase of the mean distance across this locus by >100 nm. This decompaction is linked to active transcription but is not sensitive to the histone deacetylase inhibitor trichostatin A or to deletion of the histone acetyl transferase Gcn5. In contrast, the deletion of SNF2 (encoding the ATPase of the SWI/SNF chromatin remodeling complex) or the deactivation of the histone chaperone complex FACT lead to a strongly reduced decompaction without significant effects on transcriptional induction in FACT mutants. Our findings are consistent with nucleosome remodeling and eviction activities being major contributors to chromatin reorganization during transcription but also suggest that transcription can occur in the absence of detectable decompaction.
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Affiliation(s)
- Elisa Dultz
- Institute of Biochemistry, Department of Biology, ETH Zurich, 8093 Zurich, Switzerland
| | - Roberta Mancini
- Institute of Biochemistry, Department of Biology, ETH Zurich, 8093 Zurich, Switzerland
| | - Guido Polles
- Molecular and Computational Biology, University of Southern California, Los Angeles, CA 90089
| | - Pascal Vallotton
- Institute of Biochemistry, Department of Biology, ETH Zurich, 8093 Zurich, Switzerland
| | - Frank Alber
- Molecular and Computational Biology, University of Southern California, Los Angeles, CA 90089
| | - Karsten Weis
- Institute of Biochemistry, Department of Biology, ETH Zurich, 8093 Zurich, Switzerland
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25
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Richard M, Chuffart F, Duplus-Bottin H, Pouyet F, Spichty M, Fulcrand E, Entrevan M, Barthelaix A, Springer M, Jost D, Yvert G. Assigning function to natural allelic variation via dynamic modeling of gene network induction. Mol Syst Biol 2018; 14:e7803. [PMID: 29335276 PMCID: PMC5787706 DOI: 10.15252/msb.20177803] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
More and more natural DNA variants are being linked to physiological traits. Yet, understanding what differences they make on molecular regulations remains challenging. Important properties of gene regulatory networks can be captured by computational models. If model parameters can be “personalized” according to the genotype, their variation may then reveal how DNA variants operate in the network. Here, we combined experiments and computations to visualize natural alleles of the yeast GAL3 gene in a space of model parameters describing the galactose response network. Alleles altering the activation of Gal3p by galactose were discriminated from those affecting its activity (production/degradation or efficiency of the activated protein). The approach allowed us to correctly predict that a non‐synonymous SNP would change the binding affinity of Gal3p with the Gal80p transcriptional repressor. Our results illustrate how personalizing gene regulatory models can be used for the mechanistic interpretation of genetic variants.
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Affiliation(s)
- Magali Richard
- Laboratoire de Biologie et de Modélisation de la Cellule, Ecole Normale Supérieure de Lyon, CNRS, Université Lyon 1 Université de Lyon, Lyon, France .,Univ. Grenoble Alpes, CNRS CHU Grenoble Alpes Grenoble INP TIMC-IMAG, Grenoble, France
| | - Florent Chuffart
- Laboratoire de Biologie et de Modélisation de la Cellule, Ecole Normale Supérieure de Lyon, CNRS, Université Lyon 1 Université de Lyon, Lyon, France
| | - Hélène Duplus-Bottin
- Laboratoire de Biologie et de Modélisation de la Cellule, Ecole Normale Supérieure de Lyon, CNRS, Université Lyon 1 Université de Lyon, Lyon, France
| | - Fanny Pouyet
- Laboratoire de Biologie et de Modélisation de la Cellule, Ecole Normale Supérieure de Lyon, CNRS, Université Lyon 1 Université de Lyon, Lyon, France
| | - Martin Spichty
- Laboratoire de Biologie et de Modélisation de la Cellule, Ecole Normale Supérieure de Lyon, CNRS, Université Lyon 1 Université de Lyon, Lyon, France
| | - Etienne Fulcrand
- Laboratoire de Biologie et de Modélisation de la Cellule, Ecole Normale Supérieure de Lyon, CNRS, Université Lyon 1 Université de Lyon, Lyon, France
| | - Marianne Entrevan
- Laboratoire de Biologie et de Modélisation de la Cellule, Ecole Normale Supérieure de Lyon, CNRS, Université Lyon 1 Université de Lyon, Lyon, France
| | - Audrey Barthelaix
- Laboratoire de Biologie et de Modélisation de la Cellule, Ecole Normale Supérieure de Lyon, CNRS, Université Lyon 1 Université de Lyon, Lyon, France
| | - Michael Springer
- Department of Systems Biology, Harvard Medical School, Boston, MA, USA
| | - Daniel Jost
- Univ. Grenoble Alpes, CNRS CHU Grenoble Alpes Grenoble INP TIMC-IMAG, Grenoble, France
| | - Gaël Yvert
- Laboratoire de Biologie et de Modélisation de la Cellule, Ecole Normale Supérieure de Lyon, CNRS, Université Lyon 1 Université de Lyon, Lyon, France
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26
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Bleuven C, Landry CR. Molecular and cellular bases of adaptation to a changing environment in microorganisms. Proc Biol Sci 2017; 283:rspb.2016.1458. [PMID: 27798299 DOI: 10.1098/rspb.2016.1458] [Citation(s) in RCA: 49] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2016] [Accepted: 10/04/2016] [Indexed: 12/27/2022] Open
Abstract
Environmental heterogeneity constitutes an evolutionary challenge for organisms. While evolutionary dynamics under variable conditions has been explored for decades, we still know relatively little about the cellular and molecular mechanisms involved. It is of paramount importance to examine these molecular bases because they may play an important role in shaping the course of evolution. In this review, we examine the diversity of adaptive mechanisms in the face of environmental changes. We exploit the recent literature on microbial systems because those have benefited the most from the recent emergence of genetic engineering and experimental evolution followed by genome sequencing. We identify four emerging trends: (i) an adaptive molecular change in a pathway often results in fitness trade-off in alternative environments but the effects are dependent on a mutation's genetic background; (ii) adaptive changes often modify transcriptional and signalling pathways; (iii) several adaptive changes may occur within the same molecular pathway but be associated with pleiotropy of different signs across environments; (iv) because of their large associated costs, macromolecular changes such as gene amplification and aneuploidy may be a rapid mechanism of adaptation in the short-term only. The course of adaptation in a variable environment, therefore, depends on the complexity of the environment but also on the molecular relationships among the genes involved and between the genes and the phenotypes under selection.
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Affiliation(s)
- Clara Bleuven
- Département de Biologie, Université Laval, Québec, Québec, Canada .,Institut de Biologie Intégrative et des Systèmes (IBIS), Université Laval, Québec, Québec, Canada.,PROTEO, The Quebec Network for Research on Protein Function, Engineering, and Applications, Québec, Québec, Canada
| | - Christian R Landry
- Département de Biologie, Université Laval, Québec, Québec, Canada.,Institut de Biologie Intégrative et des Systèmes (IBIS), Université Laval, Québec, Québec, Canada.,Big Data Research Center, Université Laval, Québec, Québec, Canada.,PROTEO, The Quebec Network for Research on Protein Function, Engineering, and Applications, Québec, Québec, Canada
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Sood V, Brickner JH. Genetic and Epigenetic Strategies Potentiate Gal4 Activation to Enhance Fitness in Recently Diverged Yeast Species. Curr Biol 2017; 27:3591-3602.e3. [PMID: 29153325 PMCID: PMC5846685 DOI: 10.1016/j.cub.2017.10.035] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2017] [Revised: 09/18/2017] [Accepted: 10/12/2017] [Indexed: 12/31/2022]
Abstract
Certain genes show more rapid reactivation for several generations following repression, a conserved phenomenon called epigenetic transcriptional memory. Following previous growth in galactose, GAL gene transcriptional memory confers a strong fitness benefit in Saccharomyces cerevisiae adapting to growth in galactose for up to 8 generations. A genetic screen for mutants defective for GAL gene memory revealed new insights into the molecular mechanism, adaptive consequences, and evolutionary history of memory. A point mutation in the Gal1 co-activator that disrupts the interaction with the Gal80 inhibitor specifically and completely disrupted memory. This mutation confirms that cytoplasmically inherited Gal1 produced during previous growth in galactose directly interferes with Gal80 repression to promote faster induction of GAL genes. This mitotically heritable mode of regulation is recently evolved; in a diverged Saccharomyces species, GAL genes show constitutively faster activation due to genetically encoded basal expression of Gal1. Thus, recently diverged species utilize either epigenetic or genetic strategies to regulate the same molecular mechanism. The screen also revealed that the central domain of the Gal4 transcription factor both regulates the stochasticity of GAL gene expression and potentiates stronger GAL gene activation in the presence of Gal1. The central domain is critical for GAL gene transcriptional memory; Gal4 lacking the central domain fails to potentiate GAL gene expression and is unresponsive to previous Gal1 expression.
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Affiliation(s)
- Varun Sood
- Department of Molecular Biosciences, Northwestern University, Evanston, IL 60208, USA
| | - Jason H Brickner
- Department of Molecular Biosciences, Northwestern University, Evanston, IL 60208, USA.
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Avramova Z. The jasmonic acid-signalling and abscisic acid-signalling pathways cross talk during one, but not repeated, dehydration stress: a non-specific 'panicky' or a meaningful response? PLANT, CELL & ENVIRONMENT 2017; 40:1704-1710. [PMID: 28447364 DOI: 10.1111/pce.12967] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/01/2017] [Revised: 03/28/2017] [Accepted: 03/29/2017] [Indexed: 06/07/2023]
Abstract
Experiencing diverse and recurring biotic and abiotic stresses throughout life, plants have evolved mechanisms to respond, survive and, eventually, adapt to changing habitats. The initial response to drought involves a large number of genes that are involved also in response to other stresses. According to current models, this initial response is non-specific, becoming stress-specific only at later time points. The question, then, is whether non-specific activation of various stress-signalling systems leading to the expression of numerous stress-regulated genes is a false-alarm (panicky) response or whether it has biologically relevant consequences for the plant. Here, it is argued that the initial activation of genes associated other stresses reflects an important event during which stress-specific mechanisms are generated to prevent subsequent activation of non-drought signalling pathways. How plants discriminate between a first and a repeated dehydration stress and how repression of non-drought specific genes is achieved will be discussed on the example of jasmonic acid-associated Arabidopsis genes activated by a first, but not subsequent, dehydration stresses. Revealing how expression of various biotic/abiotic stress responding genes is prevented under recurring drought spells may be critical for our understanding of how plants respond to dynamically changing environments.
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Affiliation(s)
- Zoya Avramova
- School of Biological Sciences, University of Nebraska, Lincoln, NE, 68588, USA
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Epigenetic Transcriptional Memory of GAL Genes Depends on Growth in Glucose and the Tup1 Transcription Factor in Saccharomyces cerevisiae. Genetics 2017; 206:1895-1907. [PMID: 28607146 DOI: 10.1534/genetics.117.201632] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2017] [Accepted: 06/09/2017] [Indexed: 01/01/2023] Open
Abstract
Previously expressed inducible genes can remain poised for faster reactivation for multiple cell divisions, a conserved phenomenon called epigenetic transcriptional memory. The GAL genes in Saccharomyces cerevisiae show faster reactivation for up to seven generations after being repressed. During memory, previously produced Gal1 protein enhances the rate of reactivation of GAL1, GAL10, GAL2, and GAL7 These genes also interact with the nuclear pore complex (NPC) and localize to the nuclear periphery both when active and during memory. Peripheral localization of GAL1 during memory requires the Gal1 protein, a memory-specific cis-acting element in the promoter, and the NPC protein Nup100 However, unlike other examples of transcriptional memory, the interaction with NPC is not required for faster GAL gene reactivation. Rather, downstream of Gal1, the Tup1 transcription factor and growth in glucose promote GAL transcriptional memory. Cells only show signs of memory and only benefit from memory when growing in glucose. Tup1 promotes memory-specific chromatin changes at the GAL1 promoter: incorporation of histone variant H2A.Z and dimethylation of histone H3, lysine 4. Tup1 and H2A.Z function downstream of Gal1 to promote binding of a preinitiation form of RNA Polymerase II at the GAL1 promoter, poising the gene for faster reactivation. This mechanism allows cells to integrate a previous experience (growth in galactose, reflected by Gal1 levels) with current conditions (growth in glucose, potentially through Tup1 function) to overcome repression and to poise critical GAL genes for future reactivation.
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A Transcription Factor Pulse Can Prime Chromatin for Heritable Transcriptional Memory. Mol Cell Biol 2017; 37:MCB.00372-16. [PMID: 27920256 DOI: 10.1128/mcb.00372-16] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2016] [Accepted: 11/29/2016] [Indexed: 12/28/2022] Open
Abstract
Short-term and long-term transcriptional memory is the phenomenon whereby the kinetics or magnitude of gene induction is enhanced following a prior induction period. Short-term memory persists within one cell generation or in postmitotic cells, while long-term memory can survive multiple rounds of cell division. We have developed a tissue culture model to study the epigenetic basis for long-term transcriptional memory (LTTM) and subsequently used this model to better understand the epigenetic mechanisms that enable heritable memory of temporary stimuli. We find that a pulse of transcription factor CCAAT/enhancer-binding protein alpha (C/EBPα) induces LTTM on a subset of target genes that survives nine cell divisions. The chromatin landscape at genes that acquire LTTM is more repressed than at those genes that do not exhibit memory, akin to a latent state. We show through chromatin immunoprecipitation (ChIP) and chemical inhibitor studies that RNA polymerase II (Pol II) elongation is important for establishing memory in this model but that Pol II itself is not retained as part of the memory mechanism. More generally, our work reveals that a transcription factor involved in lineage specification can induce LTTM and that failure to rerepress chromatin is one epigenetic mechanism underlying transcriptional memory.
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Hu T, Jin Y, Li H, Amombo E, Fu J. Stress memory induced transcriptional and metabolic changes of perennial ryegrass (Lolium perenne) in response to salt stress. PHYSIOLOGIA PLANTARUM 2016; 156:54-69. [PMID: 25913889 DOI: 10.1111/ppl.12342] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/05/2015] [Revised: 04/02/2015] [Accepted: 04/02/2015] [Indexed: 05/18/2023]
Abstract
Preexposure to a stress could induce stable signals and reactions on plant physiology and gene expression during future encounters as a 'stress memory'. In this study, we found that two trainable genes, BPSP encoding putative brown plant hopper susceptibility protein and sucs encoding sucrose synthase displayed transcriptional memory for their considerably higher transcript levels during two or more subsequent stresses (S3, S4) relative to the initial stress (S0), and their expression returning to basal transcript levels (non-stressed) during the recovery states (R1, R2 and R3). Removing the repetitive stress/recovery exercise, activated transcriptional memory from two trainable genes persisted for at least 4 days in perennial ryegrass. The pretrainable genes with stress memory effort had higher response to the subsequent elevated NaCl concentration treatment than the non-trainable plants, which was confirmed by lower electrolyte leakage and minimum H2 O2 and O2 (-) accumulation. Salt stress elevated the content of 41 metabolites in perennial ryegrass leaves, and sugars and sugar alcohol accounted for more than 74.1% of the total metabolite content. The salt stress memory was associated with higher contents of 11 sugars and 1 sugar alcohol in the pretrainable grass leaves. Similarly, six sugars showed greater content in the pretrainable grass roots. These novel phenomena associated with transcriptional memory and metabolite profiles could lead to new insights into improving plant salinity acclimation process.
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Affiliation(s)
- Tao Hu
- Key Laboratory of Plant Germplasm Enhancement and Specialty Agriculture, Wuhan Botanical Garden, Chinese Academy of Science, Wuhan 430074, China
| | - Yupei Jin
- Institute of Molecular Biology, China Three Gorges University, Yichang 443002, China
| | - Huiying Li
- Key Laboratory of Plant Germplasm Enhancement and Specialty Agriculture, Wuhan Botanical Garden, Chinese Academy of Science, Wuhan 430074, China
| | - Erick Amombo
- Key Laboratory of Plant Germplasm Enhancement and Specialty Agriculture, Wuhan Botanical Garden, Chinese Academy of Science, Wuhan 430074, China
| | - Jinmin Fu
- Key Laboratory of Plant Germplasm Enhancement and Specialty Agriculture, Wuhan Botanical Garden, Chinese Academy of Science, Wuhan 430074, China
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Different Mechanisms Confer Gradual Control and Memory at Nutrient- and Stress-Regulated Genes in Yeast. Mol Cell Biol 2015; 35:3669-83. [PMID: 26283730 DOI: 10.1128/mcb.00729-15] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2015] [Accepted: 08/11/2015] [Indexed: 11/20/2022] Open
Abstract
Cells respond to environmental stimuli by fine-tuned regulation of gene expression. Here we investigated the dose-dependent modulation of gene expression at high temporal resolution in response to nutrient and stress signals in yeast. The GAL1 activity in cell populations is modulated in a well-defined range of galactose concentrations, correlating with a dynamic change of histone remodeling and RNA polymerase II (RNAPII) association. This behavior is the result of a heterogeneous induction delay caused by decreasing inducer concentrations across the population. Chromatin remodeling appears to be the basis for the dynamic GAL1 expression, because mutants with impaired histone dynamics show severely truncated dose-response profiles. In contrast, the GRE2 promoter operates like a rapid off/on switch in response to increasing osmotic stress, with almost constant expression rates and exclusively temporal regulation of histone remodeling and RNAPII occupancy. The Gal3 inducer and the Hog1 mitogen-activated protein (MAP) kinase seem to determine the different dose-response strategies at the two promoters. Accordingly, GAL1 becomes highly sensitive and dose independent if previously stimulated because of residual Gal3 levels, whereas GRE2 expression diminishes upon repeated stimulation due to acquired stress resistance. Our analysis reveals important differences in the way dynamic signals create dose-sensitive gene expression outputs.
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Avramova Z. Transcriptional 'memory' of a stress: transient chromatin and memory (epigenetic) marks at stress-response genes. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2015; 83:149-59. [PMID: 25788029 DOI: 10.1111/tpj.12832] [Citation(s) in RCA: 158] [Impact Index Per Article: 17.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/11/2015] [Revised: 03/10/2015] [Accepted: 03/13/2015] [Indexed: 05/17/2023]
Abstract
Drought, salinity, extreme temperature variations, pathogen and herbivory attacks are recurring environmental stresses experienced by plants throughout their life. To survive repeated stresses, plants provide responses that may be different from their response during the first encounter with the stress. A different response to a similar stress represents the concept of 'stress memory'. A coordinated reaction at the organismal, cellular and gene/genome levels is thought to increase survival chances by improving the plant's tolerance/avoidance abilities. Ultimately, stress memory may provide a mechanism for acclimation and adaptation. At the molecular level, the concept of stress memory indicates that the mechanisms responsible for memory-type transcription during repeated stresses are not based on repetitive activation of the same response pathways activated by the first stress. Some recent advances in the search for transcription 'memory factors' are discussed with an emphasis on super-induced dehydration stress memory response genes in Arabidopsis.
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Affiliation(s)
- Zoya Avramova
- School of Biological Sciences, University of Nebraska-Lincoln, Lincoln, NE, 68588, USA
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Abstract
Histones package and compact DNA by assembling into nucleosome core particles. Most histones are synthesized at S phase for rapid deposition behind replication forks. In addition, the replacement of histones deposited during S phase by variants that can be deposited independently of replication provide the most fundamental level of chromatin differentiation. Alternative mechanisms for depositing different variants can potentially establish and maintain epigenetic states. Variants have also evolved crucial roles in chromosome segregation, transcriptional regulation, DNA repair, and other processes. Investigations into the evolution, structure, and metabolism of histone variants provide a foundation for understanding the participation of chromatin in important cellular processes and in epigenetic memory.
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Affiliation(s)
- Steven Henikoff
- Howard Hughes Medical Institute, Fred Hutchinson Cancer Research Center, Seattle, Washington 98109-1024
| | - M Mitchell Smith
- Department of Microbiology, University of Virginia, Charlottesville, Virginia 22908
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Stockwell SR, Landry CR, Rifkin SA. The yeast galactose network as a quantitative model for cellular memory. MOLECULAR BIOSYSTEMS 2014; 11:28-37. [PMID: 25328105 DOI: 10.1039/c4mb00448e] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Recent experiments have revealed surprising behavior in the yeast galactose (GAL) pathway, one of the preeminent systems for studying gene regulation. Under certain circumstances, yeast cells display memory of their prior nutrient environments. We distinguish two kinds of cellular memory discovered by quantitative investigations of the GAL network and present a conceptual framework for interpreting new experiments and current ideas on GAL memory. Reinduction memory occurs when cells respond transcriptionally to one environment, shut down the response during several generations in a second environment, then respond faster and with less cell-to-cell variation when returned to the first environment. Persistent memory describes a long-term, arguably stable response in which cells adopt a bimodal or unimodal distribution of induction levels depending on their preceding environment. Deep knowledge of how the yeast GAL pathway responds to different sugar environments has enabled rapid progress in uncovering the mechanisms behind GAL memory, which include cytoplasmic inheritance of inducer proteins and positive feedback loops among regulatory genes. This network of genes, long used to study gene regulation, is now emerging as a model system for cellular memory.
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Affiliation(s)
- Sarah R Stockwell
- Section of Ecology, Behavior, and Evolution, Division of Biology, University of California, San Diego, La Jolla, CA 92093-0116, USA.
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Virlouvet L, Ding Y, Fujii H, Avramova Z, Fromm M. ABA signaling is necessary but not sufficient for RD29B transcriptional memory during successive dehydration stresses in Arabidopsis thaliana. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2014; 79:150-61. [PMID: 24805058 DOI: 10.1111/tpj.12548] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/16/2013] [Revised: 03/07/2014] [Accepted: 04/28/2014] [Indexed: 05/18/2023]
Abstract
Plants subjected to a prior dehydration stress were seen to have altered transcriptional responses during a subsequent dehydration stress for up to 5 days after the initial stress. The abscisic acid (ABA) inducible RD29B gene of Arabidopsis thaliana was strongly induced after the first stress and displayed transcriptional memory with transcript levels nine-fold higher during the second dehydration stress. These increased transcript levels were due to an increased rate of transcription and are associated with an altered chromatin template during the recovery interval between the dehydration stresses. Here we use a combination of promoter deletion/substitutions, mutants in the trans-acting transcription factors and their upstream protein kinases, and treatments with exogenous ABA or dehydration stress to advance our understanding of the features required for transcriptional memory of RD29B. ABA Response Elements (ABREs) are sufficient to confer transcriptional memory on a minimal promoter, although there is a context effect from flanking sequences. Different mutations in Snf1 Related Protein Kinase 2 (SnRK2) genes positively and negatively affected the response, suggesting that this effect is important for transcriptional memory. Although exogenous ABA treatments could prime transcriptional memory, a second ABA treatment was not sufficient to activate transcriptional memory. Therefore, we concluded that transcriptional memory requires ABA and an ABA-independent factor that is induced or activated by a subsequent dehydration stress and directly or indirectly results in a more active RD29B chromatin template. These results advance our knowledge of the cis- and trans-acting factors that are required for transcriptional memory of RD29B.
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Affiliation(s)
- Laetitia Virlouvet
- University of Nebraska Center for Biotechnology and Center for Plant Science Innovation, 1901 Vine Street, Lincoln, NE, 68588, USA
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Jani D, Valkov E, Stewart M. Structural basis for binding the TREX2 complex to nuclear pores, GAL1 localisation and mRNA export. Nucleic Acids Res 2014; 42:6686-97. [PMID: 24705649 PMCID: PMC4041426 DOI: 10.1093/nar/gku252] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
The conserved Sac3:Thp1:Sem1:Sus1:Cdc31 (TREX2) complex binds to nuclear pore complexes (NPCs) and, in addition to integrating mRNA nuclear export with preceding steps in the gene expression pathway, facilitates re-positioning of highly regulated actively transcribing genes (such as GAL1) to NPCs. Although TREX2 is thought to bind NPC protein Nup1, defining the precise role of this interaction has been frustrated by the complex pleiotropic phenotype exhibited by nup1Δ strains. To provide a structural framework for understanding the binding of TREX2 to NPCs and its function in the gene expression pathway, we have determined the structure of the Nup1:TREX2 interaction interface and used this information to engineer a Sac3 variant that impairs NPC binding while not compromising TREX2 assembly. This variant inhibited the NPC association of both de-repressed and activated GAL1 and also produced mRNA export and growth defects. These results indicate that the TREX2:Nup1 interaction facilitates the efficient nuclear export of bulk mRNA together with the re-positioning of GAL1 to NPCs that is required for transcriptional control that is mediated by removal of SUMO from repressors by NPC-bound Ulp1.
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Affiliation(s)
- Divyang Jani
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge Biomedical Campus, Cambridge, CB2 0QH, UK
| | - Eugene Valkov
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge Biomedical Campus, Cambridge, CB2 0QH, UK
| | - Murray Stewart
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge Biomedical Campus, Cambridge, CB2 0QH, UK
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Liu N, Fromm M, Avramova Z. H3K27me3 and H3K4me3 chromatin environment at super-induced dehydration stress memory genes of Arabidopsis thaliana. MOLECULAR PLANT 2014; 7:502-13. [PMID: 24482435 DOI: 10.1093/mp/ssu001] [Citation(s) in RCA: 91] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
Pre-exposure to a stress may alter the plant's cellular, biochemical, and/or transcriptional responses during future encounters as a 'memory' from the previous stress. Genes increasing transcription in response to a first dehydration stress, but producing much higher transcript levels in a subsequent stress, represent the super-induced 'transcription memory' genes in Arabidopsis thaliana. The chromatin environment (histone H3 tri-methylations of Lys 4 and Lys 27, H3K4me3, and H3K27me3) studied at five dehydration stress memory genes revealed existence of distinct memory-response subclasses that responded differently to CLF deficiency and displayed different transcriptional activities during the watered recovery periods. Among the most important findings is the novel aspect of the H3K27me3 function observed at specific dehydration stress memory genes. In contrast to its well-known role as a chromatin repressive mechanism at developmentally regulated genes, H3K27me3 did not prevent transcription from the dehydration stress-responding genes. The high H3K27me3 levels present during transcriptionally inactive states did not interfere with the transition to active transcription and with H3K4me3 accumulation. H3K4me3 and H3K27me3 marks function independently and are not mutually exclusive at the dehydration stress-responding memory genes.
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Affiliation(s)
- Ning Liu
- University of Nebraska School of Biological Sciences, 1901 Vine Street, Lincoln, NE 68588, USA
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Billon P, Côté J. Precise deposition of histone H2A.Z in chromatin for genome expression and maintenance. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2014; 1819:290-302. [PMID: 24459731 DOI: 10.1016/j.bbagrm.2011.10.004] [Citation(s) in RCA: 81] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Histone variant H2A.Z is essential in higher eukaryotes and has different functions in the cell. Several studies indicate that H2A.Z is found at specific loci in the genome such as regulatory-gene regions, where it poises genes for transcription. Itsdeposition creates chromatin regions with particular structural characteristics which could favor rapid transcription activation. This review focuses on the highly regulated mechanism of H2A.Z deposition in chromatin which is essential for genome integrity. Chaperones escort H2A.Z to large ATP-dependent chromatin remodeling enzymes which are responsible for its deposition/eviction. Over the last ten years, biochemical, genetic and genomic studies helped us understand the precise role of these complexes in this process. It hasbeen suggested that a cooperation occurs between histone acetyltransferase and chromatin remodeling activities to incorporate H2A.Z in chromatin. Its regulated deposition near centromeres and telomeres also shows its implication in chromosomal structure integrity and parallels a role in DNA damage response. Thedynamics of H2A.Z deposition/eviction at specific loci was shown to be critical for genome expression andmaintenance, thus cell fate. Altogether, recent findings reassert the importance of the regulated depositionof this histone variant. This article is part of a Special Issue entitled: Histone chaperones and Chromatin assembly.
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Sood V, Brickner JH. Nuclear pore interactions with the genome. Curr Opin Genet Dev 2014; 25:43-9. [PMID: 24480294 DOI: 10.1016/j.gde.2013.11.018] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2013] [Accepted: 11/29/2013] [Indexed: 12/26/2022]
Abstract
Within the nucleus, chromatin is functionally organized into distinct nuclear compartments. The nuclear periphery, containing Nuclear Pore Complexes (NPCs), plays an important role in the spatial organization of chromatin and in transcriptional regulation. The role of Nuclear Pore Proteins (Nups) in transcription and their involvement in leukemia and viral integration has renewed interest in understanding their mechanism of action. Nups bind to both repressed and active genes, often in a regulated fashion. Nups can associate with chromatin both at the NPC and inside the nucleoplasm. These interactions are guided by evolutionarily conserved mechanisms that involve promoter DNA elements and trans-acting factors. These interactions can also lead to interchromosomal clustering of co-regulated genes. Nups affect gene expression by promoting stronger transcription, by limiting the spread of repressed chromatin or by altering chromatin structure. Nups can promote epigenetic regulation by establishing boundary elements and poising recently repressed genes for faster reactivation.
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Affiliation(s)
- Varun Sood
- Department of Molecular Biosciences, Northwestern University, Evanston, IL, United States
| | - Jason H Brickner
- Department of Molecular Biosciences, Northwestern University, Evanston, IL, United States.
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Lv YJ, Wang X, Ma Q, Bai X, Li BZ, Zhang W, Yuan YJ. Proteomic analysis reveals complex metabolic regulation in Saccharomyces cerevisiae cells against multiple inhibitors stress. Appl Microbiol Biotechnol 2014; 98:2207-21. [PMID: 24442506 DOI: 10.1007/s00253-014-5519-8] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2013] [Revised: 12/20/2013] [Accepted: 12/28/2013] [Indexed: 11/24/2022]
Abstract
Toxic compounds including acids, furans, and phenols (AFP) were generated from the pretreatment of lignocellulose. We cultivated Saccharomyces cerevisiae cells in a batch mode, besides the cell culture of original yeast strain in AFP-free medium which was referred as C0, three independent subcultures were cultivated under multiple inhibitors AFP and were referred as C1, C2, and C3 in time sequence. Comparing to C0, the cell density was lowered while the ethanol yield was maintained stably in the three yeast cultures under AFP stress, and the lag phase of C1 was extended while the lag phases of C2 and C3 were not extended. In proteomic analysis, 194 and 215 unique proteins were identified as differently expressed proteins at lag phase and exponential phase, respectively. Specifically, the yeast cells co-regulated protein folding and protein synthesis process to prevent the generation of misfolded proteins and to save cellular energy, they increased the activity of glycolysis, redirected metabolic flux towards phosphate pentose pathway and the biosynthesis of ethanol instead of the biosynthesis of glycerol and acetic acid, and they upregulated several oxidoreductases especially at lag phase and induced programmed cell death at exponential phase. When the yeast cells were cultivated under AFP stress, the new metabolism homeostasis in favor of cellular energy and redox homeostasis was generated in C1, then it was inherited and optimized in C2 and C3, enabling the yeast cells in C2 and C3 to enter the exponential phase in a short period after inoculation, which thus significantly shortened the fermentation time.
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Affiliation(s)
- Ya-Jin Lv
- Key Laboratory of Systems Bioengineering, Ministry of Education, Tianjin University, Tianjin, 300072, People's Republic of China
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Steglich B, Sazer S, Ekwall K. Transcriptional regulation at the yeast nuclear envelope. Nucleus 2013; 4:379-89. [PMID: 24021962 DOI: 10.4161/nucl.26394] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
The spatial organization of the genome inside the nucleus affects many nuclear processes, such as DNA replication, DNA repair, and gene transcription. In metazoans, the nuclear periphery harbors mainly repressed genes that associate with the nuclear lamina. This review discusses how peripheral positioning is connected to transcriptional regulation in yeasts. Tethering of reporter genes to the nuclear envelope was found to result in transcriptional silencing. Similarly, repression of the silent mating type loci and subtelomeric genes is influenced by their position close to the nuclear envelope. In contrast, active genes are bound by nucleoporins and inducible genes associate with the nuclear pore complex upon activation. Taken together, these results portray the nuclear envelope as a platform for transcriptional regulation, both through activation at nuclear pores and silencing at the nuclear envelope.
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Affiliation(s)
- Babett Steglich
- Department of Biosciences and Nutrition; Center for Biosciences; Karolinska Institutet; Huddinge, Sweden; Verna and Marrs McLean Department of Biochemistry and Molecular Biology; Baylor College of Medicine; Houston, TX USA; Department of Molecular and Cellular Biology; Baylor College of Medicine; Houston, TX USA
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Light WH, Freaney J, Sood V, Thompson A, D'Urso A, Horvath CM, Brickner JH. A conserved role for human Nup98 in altering chromatin structure and promoting epigenetic transcriptional memory. PLoS Biol 2013; 11:e1001524. [PMID: 23555195 PMCID: PMC3608542 DOI: 10.1371/journal.pbio.1001524] [Citation(s) in RCA: 135] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2012] [Accepted: 02/14/2013] [Indexed: 11/29/2022] Open
Abstract
In yeast and humans, interaction of a nuclear pore protein with promoters alters chromatin structure and allows RNA polymerase II to bind, poising them for faster reactivation for several generations. The interaction of nuclear pore proteins (Nups) with active genes can promote their transcription. In yeast, some inducible genes interact with the nuclear pore complex both when active and for several generations after being repressed, a phenomenon called epigenetic transcriptional memory. This interaction promotes future reactivation and requires Nup100, a homologue of human Nup98. A similar phenomenon occurs in human cells; for at least four generations after treatment with interferon gamma (IFN-γ), many IFN-γ-inducible genes are induced more rapidly and more strongly than in cells that have not previously been exposed to IFN-γ. In both yeast and human cells, the recently expressed promoters of genes with memory exhibit persistent dimethylation of histone H3 lysine 4 (H3K4me2) and physically interact with Nups and a poised form of RNA polymerase II. However, in human cells, unlike yeast, these interactions occur in the nucleoplasm. In human cells transiently depleted of Nup98 or yeast cells lacking Nup100, transcriptional memory is lost; RNA polymerase II does not remain associated with promoters, H3K4me2 is lost, and the rate of transcriptional reactivation is reduced. These results suggest that Nup100/Nup98 binding to recently expressed promoters plays a conserved role in promoting epigenetic transcriptional memory. Cells respond to changes in nutrients or signaling molecules by altering the expression of genes. The rate at which genes are turned on is not uniform; some genes are induced rapidly and others are induced slowly. In brewer's yeast, previous experience can enhance the rate at which genes are turned on again, a phenomenon called “transcriptional memory.” After repression, such genes physically interact with the nuclear pore complex, leading to altered chromatin structure and binding of a poised RNA polymerase II. Human genes that are induced by interferon gamma show a similar behavior. In both cases, the phenomenon persists through several cell divisions, suggesting that it is epigenetically inherited. Here, we find that yeast and human cells utilize a similar molecular mechanism to prime genes for reactivation. In both species, the nuclear pore protein Nup100/Nup98 binds to the promoters of genes that exhibit transcriptional memory. This leads to an altered chromatin state in the promoter and binding of RNA polymerase II, poising genes for future expression. We conclude that both unicellular and multicellular organisms use nuclear pore proteins in a novel way to alter transcription based on previous experiences.
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Affiliation(s)
- William H. Light
- Department of Molecular Biosciences, Northwestern University, Evanston, Illinois, United States of America
| | - Jonathan Freaney
- Department of Molecular Biosciences, Northwestern University, Evanston, Illinois, United States of America
| | - Varun Sood
- Department of Molecular Biosciences, Northwestern University, Evanston, Illinois, United States of America
| | - Abbey Thompson
- Department of Molecular Biosciences, Northwestern University, Evanston, Illinois, United States of America
| | - Agustina D'Urso
- Department of Molecular Biosciences, Northwestern University, Evanston, Illinois, United States of America
| | - Curt M. Horvath
- Department of Molecular Biosciences, Northwestern University, Evanston, Illinois, United States of America
| | - Jason H. Brickner
- Department of Molecular Biosciences, Northwestern University, Evanston, Illinois, United States of America
- * E-mail:
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Pannala VR, Hazarika SJ, Bhat PJ, Bhartiya S, Venkatesh KV. Growth-related model of the GAL system in Saccharomyces cerevisiae predicts behaviour of several mutant strains. IET Syst Biol 2012; 6:44-53. [PMID: 22519357 DOI: 10.1049/iet-syb.2010.0060] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The genetic regulatory network responds dynamically to perturbations in the intracellular and extracellular environments of an organism. The GAL system in the yeast Saccharomyces cerevisiae has evolved to utilise galactose as an alternative carbon and energy source, in the absence of glucose in the environment. This work contains a modified dynamic model for GAL system in S. cerevisiae, which includes a novel mechanism for Gal3p activation upon induction with galactose. The modification enables the model to simulate the experimental observation that in absence of galactose, oversynthesis of Gal3p can also induce the GAL system. Subsequently, the model is related to growth on galactose and glucose in a structured manner. The growth-related models are validated with experimental data for growth on individual substrates as well as mixed substrates. Finally, the model is tested for its prediction of a variety of known mutant behaviours. The exercise shows that the authors' model with a single set of parameters is able to capture the rich behaviour of the GAL system in S. cerevisiae. [Includes supplementary material].
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Affiliation(s)
- V R Pannala
- Department of Chemical Engineering, Indian Institute of Technology Bombay, Mumbai, India
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Abstract
Cellular memory of past experiences has been observed in several organisms and across a variety of experiences, including bacteria "remembering" prior nutritional status and amoeba "learning" to anticipate future environmental conditions. Here, we show that Saccharomyces cerevisiae maintains a multifaceted memory of prior stress exposure. We previously demonstrated that yeast cells exposed to a mild dose of salt acquire subsequent tolerance to severe doses of H(2)O(2). We set out to characterize the retention of acquired tolerance and in the process uncovered two distinct aspects of cellular memory. First, we found that H(2)O(2) resistance persisted for four to five generations after cells were removed from the prior salt treatment and was transmitted to daughter cells that never directly experienced the pretreatment. Maintenance of this memory did not require nascent protein synthesis after the initial salt pretreatment, but rather required long-lived cytosolic catalase Ctt1p that was synthesized during salt exposure and then distributed to daughter cells during subsequent cell divisions. In addition to and separable from the memory of H(2)O(2) resistance, these cells also displayed a faster gene-expression response to subsequent stress at >1000 genes, representing transcriptional memory. The faster gene-expression response requires the nuclear pore component Nup42p and serves an important function by facilitating faster reacquisition of H(2)O(2) tolerance after a second cycle of salt exposure. Memory of prior stress exposure likely provides a significant advantage to microbial populations living in ever-changing environments.
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Abstract
Understanding the mechanisms by which chromatin structure controls eukaryotic transcription has been an intense area of investigation for the past 25 years. Many of the key discoveries that created the foundation for this field came from studies of Saccharomyces cerevisiae, including the discovery of the role of chromatin in transcriptional silencing, as well as the discovery of chromatin-remodeling factors and histone modification activities. Since that time, studies in yeast have continued to contribute in leading ways. This review article summarizes the large body of yeast studies in this field.
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Rienzo A, Pascual-Ahuir A, Proft M. The use of a real-time luciferase assay to quantify gene expression dynamics in the living yeast cell. Yeast 2012; 29:219-31. [PMID: 22674776 DOI: 10.1002/yea.2905] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2012] [Revised: 03/22/2012] [Accepted: 04/27/2012] [Indexed: 01/05/2023] Open
Abstract
A destabilized version of firefly luciferase was used in living yeast cells as a real-time reporter for gene expression. This highly sensitive and non-invasive system can be simultaneously used upon many different experimental conditions in small culture aliquots. This allows the dose-response behaviour of gene expression driven by any yeast promoter to be reported and can be used to quantify important parameters, such as the threshold, sensitivity, response time, maximal activity and synthesis rate for a given stimulus. We applied the luciferase assay to the nutrient-regulated GAL1 promoter and the stress-responsive GRE2 promoter. We find that luciferase expression driven by the GAL1 promoter responds dynamically to growing galactose concentrations, with increasing synthesis rates determined by the light increment in the initial linear phase of activation. In the case of the GRE2 promoter, we demonstrate that the very short-lived version of luciferase used here is an excellent tool to quantitatively describe transient transcriptional activation. The luciferase expression controlled by the GRE2 promoter responds dynamically to a gradual increase of osmotic or oxidative stress stimuli, which is mainly based on the progressive increase of the time the promoter remains active. Finally, we determined the dose-response behaviour of a single transcription factor binding site in a synthetic promoter context, using the stress response element (STRE) as an example. Taken together, the luciferase assay described here is an attractive tool to rapidly and precisely determine and compare kinetic parameters of gene expression.
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Affiliation(s)
- Alessandro Rienzo
- Instituto de Biología Molecular y Celular de Plantas, CSIC-Universidad Politécnica de Valencia, Ciudad Politécnica de la Innovación, Valencia, Spain
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Freddolino PL, Tavazoie S. Beyond homeostasis: a predictive-dynamic framework for understanding cellular behavior. Annu Rev Cell Dev Biol 2012; 28:363-84. [PMID: 22559263 DOI: 10.1146/annurev-cellbio-092910-154129] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Microbial regulatory strategies have long been understood in terms of the homeostatic framework, in which a response is interpreted as a restoring force counteracting the immediate intracellular consequences of a change in the environment. In this review, we summarize the breadth of recent discoveries of cellular behavior extending beyond the homeostatic framework. We argue that the nonrandom structure of native habitats makes environmental fluctuations inherently multidimensional. Beyond its utility for accurate perception of immediate events, the temporal regularity of this multidimensional correlation structure allows microbes to make predictions about the trajectory of their sensory environment. We describe recently discovered examples of such predictive behavior, their physiological benefits, and the underlying evolutionary forces shaping them. These observations compel us to go beyond homeostasis and consider a predictive-dynamic framework in which cellular behavior is orchestrated in response to the meaning of an environmental perturbation, not only its direct and immediate fitness consequences.
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Affiliation(s)
- Peter L Freddolino
- Joint Centers for Systems Biology, Columbia University, New York, New York 10032, USA.
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Multiple exposures to drought 'train' transcriptional responses in Arabidopsis. Nat Commun 2012; 3:740. [PMID: 22415831 DOI: 10.1038/ncomms1732] [Citation(s) in RCA: 316] [Impact Index Per Article: 26.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2011] [Accepted: 02/06/2012] [Indexed: 11/08/2022] Open
Abstract
Pre-exposure to stress may alter plants' subsequent responses by producing faster and/or stronger reactions implying that plants exercise a form of 'stress memory'. The mechanisms of plants' stress memory responses are poorly understood leaving this fundamental biological question unanswered. Here we show that during recurring dehydration stresses Arabidopsis plants display transcriptional stress memory demonstrated by an increase in the rate of transcription and elevated transcript levels of a subset of the stress-response genes (trainable genes). During recovery (watered) states, trainable genes produce transcripts at basal (preinduced) levels, but remain associated with atypically high H3K4me3 and Ser5P polymerase II levels, indicating that RNA polymerase II is stalled. This is the first example of a stalled RNA polymerase II and its involvement in transcriptional memory in plants. These newly discovered phenomena might be a general feature of plant stress-response systems and could lead to novel approaches for increasing the flexibility of a plant's ability to respond to the environment.
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Hsu C, Scherrer S, Buetti-Dinh A, Ratna P, Pizzolato J, Jaquet V, Becskei A. Stochastic signalling rewires the interaction map of a multiple feedback network during yeast evolution. Nat Commun 2012; 3:682. [PMID: 22353713 PMCID: PMC3293423 DOI: 10.1038/ncomms1687] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2011] [Accepted: 01/17/2012] [Indexed: 01/18/2023] Open
Abstract
During evolution, genetic networks are rewired through strengthening or weakening their interactions to develop new regulatory schemes. In the galactose network, the GAL1/GAL3 paralogues and the GAL2 gene enhance their own expression mediated by the Gal4p transcriptional activator. The wiring strength in these feedback loops is set by the number of Gal4p binding sites. Here we show using synthetic circuits that multiplying the binding sites increases the expression of a gene under the direct control of an activator, but this enhancement is not fed back in the circuit. The feedback loops are rather activated by genes that have frequent stochastic bursts and fast RNA decay rates. In this way, rapid adaptation to galactose can be triggered even by weakly expressed genes. Our results indicate that nonlinear stochastic transcriptional responses enable feedback loops to function autonomously, or contrary to what is dictated by the strength of interactions enclosing the circuit.
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Affiliation(s)
- Chieh Hsu
- Biozentrum, University of Basel, Klingelbergstrasse 50/70, Basel 4056, Switzerland
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