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Mittal N, Ataman M, Tintignac L, Ham DJ, Jörin L, Schmidt A, Sinnreich M, Ruegg MA, Zavolan M. Calorie restriction and rapamycin distinctly restore non-canonical ORF translation in the muscles of aging mice. NPJ Regen Med 2024; 9:23. [PMID: 39300171 DOI: 10.1038/s41536-024-00369-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2024] [Accepted: 09/10/2024] [Indexed: 09/22/2024] Open
Abstract
Loss of protein homeostasis is one of the hallmarks of aging. As such, interventions that restore proteostasis should slow down the aging process and improve healthspan. Two of the most broadly used anti-aging interventions that are effective in organisms from yeast to mammals are calorie restriction (CR) and rapamycin (RM) treatment. To identify the regulatory mechanisms by which these interventions improve the protein homeostasis, we carried out ribosome footprinting in the muscle of mice aged under standard conditions, or under long-term treatment with CR or RM. We found that the treatments distinctly impact the non-canonical translation, RM primarily remodeling the translation of upstream open reading frames (uORFs), while CR restores stop codon readthrough and the translation of downstream ORFs. Proteomics analysis revealed the expression of numerous non-canonical ORFs at the protein level. The corresponding peptides may provide entry points for therapies aiming to maintain muscle function and extend health span.
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Affiliation(s)
- Nitish Mittal
- Biozentrum, University of Basel, Basel, Switzerland.
| | - Meric Ataman
- Biozentrum, University of Basel, Basel, Switzerland
- Swiss Institute of Bioinformatics, Lausanne, Switzerland
| | - Lionel Tintignac
- Biozentrum, University of Basel, Basel, Switzerland
- Departments of Neurology and Biomedicine, University of Basel, Basel, Switzerland
- University Hospital Basel, Basel, Switzerland
| | - Daniel J Ham
- Biozentrum, University of Basel, Basel, Switzerland
| | - Lena Jörin
- Biozentrum, University of Basel, Basel, Switzerland
| | | | - Michael Sinnreich
- Departments of Neurology and Biomedicine, University of Basel, Basel, Switzerland
- University Hospital Basel, Basel, Switzerland
| | | | - Mihaela Zavolan
- Biozentrum, University of Basel, Basel, Switzerland.
- Swiss Institute of Bioinformatics, Lausanne, Switzerland.
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2
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Horvath A, Janapala Y, Woodward K, Mahmud S, Cleynen A, Gardiner E, Hannan R, Eyras E, Preiss T, Shirokikh N. Comprehensive translational profiling and STE AI uncover rapid control of protein biosynthesis during cell stress. Nucleic Acids Res 2024; 52:7925-7946. [PMID: 38721779 PMCID: PMC11260467 DOI: 10.1093/nar/gkae365] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2024] [Revised: 03/21/2024] [Accepted: 04/25/2024] [Indexed: 07/23/2024] Open
Abstract
Translational control is important in all life, but it remains a challenge to accurately quantify. When ribosomes translate messenger (m)RNA into proteins, they attach to the mRNA in series, forming poly(ribo)somes, and can co-localize. Here, we computationally model new types of co-localized ribosomal complexes on mRNA and identify them using enhanced translation complex profile sequencing (eTCP-seq) based on rapid in vivo crosslinking. We detect long disome footprints outside regions of non-random elongation stalls and show these are linked to translation initiation and protein biosynthesis rates. We subject footprints of disomes and other translation complexes to artificial intelligence (AI) analysis and construct a new, accurate and self-normalized measure of translation, termed stochastic translation efficiency (STE). We then apply STE to investigate rapid changes to mRNA translation in yeast undergoing glucose depletion. Importantly, we show that, well beyond tagging elongation stalls, footprints of co-localized ribosomes provide rich insight into translational mechanisms, polysome dynamics and topology. STE AI ranks cellular mRNAs by absolute translation rates under given conditions, can assist in identifying its control elements and will facilitate the development of next-generation synthetic biology designs and mRNA-based therapeutics.
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Affiliation(s)
- Attila Horvath
- Division of Genome Sciences and Cancer, The John Curtin School of Medical Research, and The Shine-Dalgarno Centre for RNA Innovation, The Australian National University, Canberra, ACT 2601, Australia
| | - Yoshika Janapala
- Division of Genome Sciences and Cancer, The John Curtin School of Medical Research, and The Shine-Dalgarno Centre for RNA Innovation, The Australian National University, Canberra, ACT 2601, Australia
| | - Katrina Woodward
- Division of Genome Sciences and Cancer, The John Curtin School of Medical Research, and The Shine-Dalgarno Centre for RNA Innovation, The Australian National University, Canberra, ACT 2601, Australia
| | - Shafi Mahmud
- Division of Genome Sciences and Cancer, The John Curtin School of Medical Research, and The Shine-Dalgarno Centre for RNA Innovation, The Australian National University, Canberra, ACT 2601, Australia
| | - Alice Cleynen
- Division of Genome Sciences and Cancer, The John Curtin School of Medical Research, and The Shine-Dalgarno Centre for RNA Innovation, The Australian National University, Canberra, ACT 2601, Australia
- Institut Montpelliérain Alexander Grothendieck, Université de Montpellier, CNRS, Montpellier, France
| | - Elizabeth E Gardiner
- Division of Genome Sciences and Cancer, The John Curtin School of Medical Research, and The National Platelet Research and Referral Centre, The Australian National University, Canberra, ACT 2601, Australia
| | - Ross D Hannan
- Division of Genome Sciences and Cancer, The John Curtin School of Medical Research, and The Shine-Dalgarno Centre for RNA Innovation, The Australian National University, Canberra, ACT 2601, Australia
- Department of Biochemistry and Molecular Biology, University of Melbourne, Parkville 3010, Australia
- Peter MacCallum Cancer Centre, Melbourne 3000, Australia
- Department of Biochemistry and Molecular Biology, Monash University, Clayton 3800, Australia
- School of Biomedical Sciences, University of Queensland, St Lucia 4067, Australia
| | - Eduardo Eyras
- Division of Genome Sciences and Cancer, The John Curtin School of Medical Research, and The Shine-Dalgarno Centre for RNA Innovation, The Australian National University, Canberra, ACT 2601, Australia
- Division of Genome Sciences and Cancer, The John Curtin School of Medical Research, and The Centre for Computational Biomedical Sciences, The Australian National University, Canberra, ACT 2601, Australia
- EMBL Australia Partner Laboratory Network at the Australian National University, Canberra, ACT 2601, Australia
| | - Thomas Preiss
- Division of Genome Sciences and Cancer, The John Curtin School of Medical Research, and The Shine-Dalgarno Centre for RNA Innovation, The Australian National University, Canberra, ACT 2601, Australia
- Victor Chang Cardiac Research Institute, Darlinghurst, NSW 2010, Australia
| | - Nikolay E Shirokikh
- Division of Genome Sciences and Cancer, The John Curtin School of Medical Research, and The Shine-Dalgarno Centre for RNA Innovation, The Australian National University, Canberra, ACT 2601, Australia
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3
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Lawrence RE, Shoemaker SR, Deal A, Sangwan S, Anand AA, Wang L, Marqusee S, Walter P. A helical fulcrum in eIF2B coordinates allosteric regulation of stress signaling. Nat Chem Biol 2024; 20:422-431. [PMID: 37945896 PMCID: PMC10972756 DOI: 10.1038/s41589-023-01453-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2023] [Accepted: 09/17/2023] [Indexed: 11/12/2023]
Abstract
The integrated stress response (ISR) enables cells to survive a variety of acute stresses, but chronic activation of the ISR underlies age-related diseases. ISR signaling downregulates translation and activates expression of stress-responsive factors that promote return to homeostasis and is initiated by inhibition of the decameric guanine nucleotide exchange factor eIF2B. Conformational and assembly transitions regulate eIF2B activity, but the allosteric mechanisms controlling these dynamic transitions and mediating the therapeutic effects of the small-molecule ISR inhibitor ISRIB are unknown. Using hydrogen-deuterium exchange-mass spectrometry and cryo-electron microscopy, we identified a central α-helix whose orientation allosterically coordinates eIF2B conformation and assembly. Biochemical and cellular signaling assays show that this 'switch-helix' controls eIF2B activity and signaling. In sum, the switch-helix acts as a fulcrum of eIF2B conformational regulation and is a highly conserved actuator of ISR signal transduction. This work uncovers a conserved allosteric mechanism and unlocks new therapeutic possibilities for ISR-linked diseases.
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Affiliation(s)
- Rosalie E Lawrence
- Department of Biochemistry and Biophysics, University of California, San Francisco, San Francisco, CA, USA.
- Howard Hughes Medical Institute, University of California, San Francisco, San Francisco, CA, USA.
| | - Sophie R Shoemaker
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA, USA
| | - Aniliese Deal
- Department of Biochemistry and Biophysics, University of California, San Francisco, San Francisco, CA, USA
- Howard Hughes Medical Institute, University of California, San Francisco, San Francisco, CA, USA
- Altos Laboratories, Bay Area Institute of Science, Redwood City, CA, USA
| | - Smriti Sangwan
- Department of Biochemistry and Biophysics, University of California, San Francisco, San Francisco, CA, USA
- Howard Hughes Medical Institute, University of California, San Francisco, San Francisco, CA, USA
| | - Aditya A Anand
- Department of Biochemistry and Biophysics, University of California, San Francisco, San Francisco, CA, USA
- Howard Hughes Medical Institute, University of California, San Francisco, San Francisco, CA, USA
- Genentech, Inc., South San Francisco, CA, USA
| | - Lan Wang
- Department of Biochemistry and Biophysics, University of California, San Francisco, San Francisco, CA, USA.
- Howard Hughes Medical Institute, University of California, San Francisco, San Francisco, CA, USA.
- The Hong Kong University of Science and Technology, Hong Kong, Hong Kong.
| | - Susan Marqusee
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA, USA.
- Department of Chemistry, University of California, Berkeley, Berkeley, CA, USA.
- Chan Zuckerberg Biohub, San Francisco, CA, USA.
- California Institute for Quantitative Biosciences, University of California, Berkeley, Berkeley, CA, USA.
| | - Peter Walter
- Department of Biochemistry and Biophysics, University of California, San Francisco, San Francisco, CA, USA.
- Howard Hughes Medical Institute, University of California, San Francisco, San Francisco, CA, USA.
- Altos Laboratories, Bay Area Institute of Science, Redwood City, CA, USA.
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4
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Meyer L, Courtin B, Gomard M, Namane A, Permal E, Badis G, Jacquier A, Fromont-Racine M. eIF2A represses cell wall biogenesis gene expression in Saccharomyces cerevisiae. PLoS One 2023; 18:e0293228. [PMID: 38011112 PMCID: PMC10681259 DOI: 10.1371/journal.pone.0293228] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2023] [Accepted: 10/07/2023] [Indexed: 11/29/2023] Open
Abstract
Translation initiation is a complex and highly regulated process that represents an important mechanism, controlling gene expression. eIF2A was proposed as an alternative initiation factor, however, its role and biological targets remain to be discovered. To further gain insight into the function of eIF2A in Saccharomyces cerevisiae, we identified mRNAs associated with the eIF2A complex and showed that 24% of the most enriched mRNAs encode proteins related to cell wall biogenesis and maintenance. In agreement with this result, we showed that an eIF2A deletion sensitized cells to cell wall damage induced by calcofluor white. eIF2A overexpression led to a growth defect, correlated with decreased synthesis of several cell wall proteins. In contrast, no changes were observed in the transcriptome, suggesting that eIF2A controls the expression of cell wall-related proteins at a translational level. The biochemical characterization of the eIF2A complex revealed that it strongly interacts with the RNA binding protein, Ssd1, which is a negative translational regulator, controlling the expression of cell wall-related genes. Interestingly, eIF2A and Ssd1 bind several common mRNA targets and we found that the binding of eIF2A to some targets was mediated by Ssd1. Surprisingly, we further showed that eIF2A is physically and functionally associated with the exonuclease Xrn1 and other mRNA degradation factors, suggesting an additional level of regulation. Altogether, our results highlight new aspects of this complex and redundant fine-tuned regulation of proteins expression related to the cell wall, a structure required to maintain cell shape and rigidity, providing protection against harmful environmental stress.
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Affiliation(s)
- Laura Meyer
- Institut Pasteur, Génétique des Interactions Macromoléculaires, Centre National de la Recherche Scientifique, UMR 3525, Paris, France
| | - Baptiste Courtin
- Institut Pasteur, Génétique des Interactions Macromoléculaires, Centre National de la Recherche Scientifique, UMR 3525, Paris, France
| | - Maïté Gomard
- Institut Pasteur, Génétique des Interactions Macromoléculaires, Centre National de la Recherche Scientifique, UMR 3525, Paris, France
| | - Abdelkader Namane
- Institut Pasteur, Génétique des Interactions Macromoléculaires, Centre National de la Recherche Scientifique, UMR 3525, Paris, France
| | - Emmanuelle Permal
- Institut Pasteur, Génétique des Interactions Macromoléculaires, Centre National de la Recherche Scientifique, UMR 3525, Paris, France
| | - Gwenael Badis
- Institut Pasteur, Génétique des Interactions Macromoléculaires, Centre National de la Recherche Scientifique, UMR 3525, Paris, France
| | - Alain Jacquier
- Institut Pasteur, Génétique des Interactions Macromoléculaires, Centre National de la Recherche Scientifique, UMR 3525, Paris, France
| | - Micheline Fromont-Racine
- Institut Pasteur, Génétique des Interactions Macromoléculaires, Centre National de la Recherche Scientifique, UMR 3525, Paris, France
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5
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Nguyen V, Xue P, Li Y, Zhao H, Lu T. Controlling circuitry underlies the growth optimization of Saccharomyces cerevisiae. Metab Eng 2023; 80:173-183. [PMID: 37739159 PMCID: PMC11089650 DOI: 10.1016/j.ymben.2023.09.013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2022] [Revised: 08/29/2023] [Accepted: 09/19/2023] [Indexed: 09/24/2023]
Abstract
Microbial growth emerges from coordinated synthesis of various cellular components from limited resources. In Saccharomyces cerevisiae, cyclic AMP (cAMP)-mediated signaling is shown to orchestrate cellular metabolism; however, it remains unclear quantitatively how the controlling circuit drives resource partition and subsequently shapes biomass growth. Here we combined experiment with mathematical modeling to dissect the signaling-mediated growth optimization of S. cerevisiae. We showed that, through cAMP-mediated control, the organism achieves maximal or nearly maximal steady-state growth during the utilization of multiple tested substrates as well as under perturbations impairing glucose uptake. However, the optimal cAMP concentration varies across cases, suggesting that different modes of resource allocation are adopted for varied conditions. Under settings with nutrient alterations, S. cerevisiae tunes its cAMP level to dynamically reprogram itself to realize rapid adaptation. Moreover, to achieve growth maximization, cells employ additional regulatory systems such as the GCN2-mediated amino acid control. This study establishes a systematic understanding of global resource allocation in S. cerevisiae, providing insights into quantitative yeast physiology as well as metabolic strain engineering for biotechnological applications.
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Affiliation(s)
- Viviana Nguyen
- Department of Physics, University of Illinois Urbana-Champaign, Urbana, IL, 61801, USA; Center for Advanced Bioenergy and Bioproducts Innovation, University of Illinois Urbana-Champaign, Urbana, IL, 61801, USA
| | - Pu Xue
- Center for Advanced Bioenergy and Bioproducts Innovation, University of Illinois Urbana-Champaign, Urbana, IL, 61801, USA; Department of Chemical and Biomolecular Engineering, University of Illinois Urbana-Champaign, Urbana, IL, 61801, USA; Carl R Woese Institute for Genomic Biology, University of Illinois Urbana-Champaign, Urbana, IL, 61801, USA
| | - Yifei Li
- Center for Advanced Bioenergy and Bioproducts Innovation, University of Illinois Urbana-Champaign, Urbana, IL, 61801, USA; Center for Biophysics and Quantitative Biology, University of Illinois Urbana-Champaign, Urbana, IL, 61801, USA
| | - Huimin Zhao
- Center for Advanced Bioenergy and Bioproducts Innovation, University of Illinois Urbana-Champaign, Urbana, IL, 61801, USA; Department of Chemical and Biomolecular Engineering, University of Illinois Urbana-Champaign, Urbana, IL, 61801, USA; Carl R Woese Institute for Genomic Biology, University of Illinois Urbana-Champaign, Urbana, IL, 61801, USA; Department of Biochemistry, University of Illinois Urbana-Champaign, Urbana, IL, 61801, USA; Department of Chemistry, University of Illinois Urbana-Champaign, Urbana, IL, 61801, USA.
| | - Ting Lu
- Department of Physics, University of Illinois Urbana-Champaign, Urbana, IL, 61801, USA; Center for Advanced Bioenergy and Bioproducts Innovation, University of Illinois Urbana-Champaign, Urbana, IL, 61801, USA; Carl R Woese Institute for Genomic Biology, University of Illinois Urbana-Champaign, Urbana, IL, 61801, USA; Center for Biophysics and Quantitative Biology, University of Illinois Urbana-Champaign, Urbana, IL, 61801, USA; Department of Bioengineering, University of Illinois Urbana-Champaign, Urbana, IL, 61801, USA; National Center for Supercomputing Applications, University of Illinois Urbana-Champaign, Urbana, IL, 61801, USA.
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6
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Makeeva DS, Riggs CL, Burakov AV, Ivanov PA, Kushchenko AS, Bykov DA, Popenko VI, Prassolov VS, Ivanov PV, Dmitriev SE. Relocalization of Translation Termination and Ribosome Recycling Factors to Stress Granules Coincides with Elevated Stop-Codon Readthrough and Reinitiation Rates upon Oxidative Stress. Cells 2023; 12:259. [PMID: 36672194 PMCID: PMC9856671 DOI: 10.3390/cells12020259] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2022] [Revised: 12/27/2022] [Accepted: 01/03/2023] [Indexed: 01/11/2023] Open
Abstract
Upon oxidative stress, mammalian cells rapidly reprogram their translation. This is accompanied by the formation of stress granules (SGs), cytoplasmic ribonucleoprotein condensates containing untranslated mRNA molecules, RNA-binding proteins, 40S ribosomal subunits, and a set of translation initiation factors. Here we show that arsenite-induced stress causes a dramatic increase in the stop-codon readthrough rate and significantly elevates translation reinitiation levels on uORF-containing and bicistronic mRNAs. We also report the recruitment of translation termination factors eRF1 and eRF3, as well as ribosome recycling and translation reinitiation factors ABCE1, eIF2D, MCT-1, and DENR to SGs upon arsenite treatment. Localization of these factors to SGs may contribute to a rapid resumption of mRNA translation after stress relief and SG disassembly. It may also suggest the presence of post-termination, recycling, or reinitiation complexes in SGs. This new layer of translational control under stress conditions, relying on the altered spatial distribution of translation factors between cellular compartments, is discussed.
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Affiliation(s)
- Desislava S. Makeeva
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, 119234 Moscow, Russia
| | - Claire L. Riggs
- Department of Medicine, Brigham and Women’s Hospital, Harvard Medical School, Boston, MA 02115, USA
| | - Anton V. Burakov
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, 119234 Moscow, Russia
| | - Pavel A. Ivanov
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, 119234 Moscow, Russia
| | - Artem S. Kushchenko
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, 119234 Moscow, Russia
- Faculty of Bioengineering and Bioinformatics, Lomonosov Moscow State University, 119234 Moscow, Russia
| | - Dmitri A. Bykov
- Faculty of Biology, Lomonosov Moscow State University, 119234 Moscow, Russia
- Engelhardt Institute of Molecular Biology, Russian Academy of Sciences, 119991 Moscow, Russia
| | - Vladimir I. Popenko
- Engelhardt Institute of Molecular Biology, Russian Academy of Sciences, 119991 Moscow, Russia
| | - Vladimir S. Prassolov
- Engelhardt Institute of Molecular Biology, Russian Academy of Sciences, 119991 Moscow, Russia
| | - Pavel V. Ivanov
- Department of Medicine, Brigham and Women’s Hospital, Harvard Medical School, Boston, MA 02115, USA
| | - Sergey E. Dmitriev
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, 119234 Moscow, Russia
- Faculty of Bioengineering and Bioinformatics, Lomonosov Moscow State University, 119234 Moscow, Russia
- Engelhardt Institute of Molecular Biology, Russian Academy of Sciences, 119991 Moscow, Russia
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7
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Tate JJ, Marsikova J, Vachova L, Palkova Z, Cooper TG. Effects of abolishing Whi2 on the proteome and nitrogen catabolite repression-sensitive protein production. G3 (BETHESDA, MD.) 2022; 12:jkab432. [PMID: 35100365 PMCID: PMC9210300 DOI: 10.1093/g3journal/jkab432] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/16/2021] [Accepted: 12/08/2021] [Indexed: 11/17/2022]
Abstract
In yeast physiology, a commonly used reference condition for many experiments, including those involving nitrogen catabolite repression (NCR), is growth in synthetic complete (SC) medium. Four SC formulations, SCCSH,1990, SCCSH,1994, SCCSH,2005, and SCME, have been used interchangeably as the nitrogen-rich medium of choice [Cold Spring Harbor Yeast Course Manuals (SCCSH) and a formulation in the methods in enzymology (SCME)]. It has been tacitly presumed that all of these formulations support equivalent responses. However, a recent report concluded that (i) TorC1 activity is downregulated by the lower concentration of primarily leucine in SCME relative to SCCSH. (ii) The Whi2-Psr1/2 complex is responsible for this downregulation. TorC1 is a primary nitrogen-responsive regulator in yeast. Among its downstream targets is control of NCR-sensitive transcription activators Gln3 and Gat1. They in turn control production of catabolic transporters and enzymes needed to scavenge poor nitrogen sources (e.g., Proline) and activate autophagy (ATG14). One of the reporters used in Chen et al. was an NCR-sensitive DAL80-GFP promoter fusion. This intrigued us because we expected minimal if any DAL80 expression in SC medium. Therefore, we investigated the source of the Dal80-GFP production and the proteomes of wild-type and whi2Δ cells cultured in SCCSH and SCME. We found a massive and equivalent reorientation of amino acid biosynthetic proteins in both wild-type and whi2Δ cells even though both media contained high overall concentrations of amino acids. Gcn2 appears to play a significant regulatory role in this reorientation. NCR-sensitive DAL80 expression and overall NCR-sensitive protein production were only marginally affected by the whi2Δ. In contrast, the levels of 58 proteins changed by an absolute value of log2 between 3 and 8 when Whi2 was abolished relative to wild type. Surprisingly, with only two exceptions could those proteins be related in GO analyses, i.e., GO terms associated with carbohydrate metabolism and oxidative stress after shifting a whi2Δ from SCCSH to SCME for 6 h. What was conspicuously missing were proteins related by TorC1- and NCR-associated GO terms.
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Affiliation(s)
- Jennifer J Tate
- Department of Microbiology, Immunology and Biochemistry, University of Tennessee Health Science Center, Memphis, TN 38163, USA
| | - Jana Marsikova
- Department of Genetics and Microbiology, Faculty of Science, Charles University, BIOCEV, 128 00 Prague, Czech Republic
| | - Libuse Vachova
- Institute of Microbiology of the Czech Academy of Sciences, BIOCEV, 142 20 Prague, Czech Republic
| | - Zdena Palkova
- Department of Genetics and Microbiology, Faculty of Science, Charles University, BIOCEV, 128 00 Prague, Czech Republic
| | - Terrance G Cooper
- Department of Microbiology, Immunology and Biochemistry, University of Tennessee Health Science Center, Memphis, TN 38163, USA
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8
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Functional characterization of 5' UTR cis-acting sequence elements that modulate translational efficiency in Plasmodium falciparum and humans. Malar J 2022; 21:15. [PMID: 34991611 PMCID: PMC8739713 DOI: 10.1186/s12936-021-04024-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2021] [Accepted: 12/14/2021] [Indexed: 11/10/2022] Open
Abstract
Background The eukaryotic parasite Plasmodium falciparum causes millions of malarial infections annually while drug resistance to common anti-malarials is further confounding eradication efforts. Translation is an attractive therapeutic target that will benefit from a deeper mechanistic understanding. As the rate limiting step of translation, initiation is a primary driver of translational efficiency. It is a complex process regulated by both cis and trans acting factors, providing numerous potential targets. Relative to model organisms and humans, P. falciparum mRNAs feature unusual 5′ untranslated regions suggesting cis-acting sequence complexity in this parasite may act to tune levels of protein synthesis through their effects on translational efficiency. Methods Here, in vitro translation is deployed to compare the role of cis-acting regulatory sequences in P. falciparum and humans. Using parasite mRNAs with high or low translational efficiency, the presence, position, and termination status of upstream “AUG”s, in addition to the base composition of the 5′ untranslated regions, were characterized. Results The density of upstream “AUG”s differed significantly among the most and least efficiently translated genes in P. falciparum, as did the average “GC” content of the 5′ untranslated regions. Using exemplars from highly translated and poorly translated mRNAs, multiple putative upstream elements were interrogated for impact on translational efficiency. Upstream “AUG”s were found to repress translation to varying degrees, depending on their position and context, while combinations of upstream “AUG”s had non-additive effects. The base composition of the 5′ untranslated regions also impacted translation, but to a lesser degree. Surprisingly, the effects of cis-acting sequences were remarkably conserved between P. falciparum and humans. Conclusions While translational regulation is inherently complex, this work contributes toward a more comprehensive understanding of parasite and human translational regulation by examining the impact of discrete cis-acting features, acting alone or in context. Supplementary Information The online version contains supplementary material available at 10.1186/s12936-021-04024-2.
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9
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Woodward K, Shirokikh NE. Translational control in cell ageing: an update. Biochem Soc Trans 2021; 49:2853-2869. [PMID: 34913471 PMCID: PMC8786278 DOI: 10.1042/bst20210844] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2021] [Revised: 11/18/2021] [Accepted: 11/22/2021] [Indexed: 12/28/2022]
Abstract
Cellular ageing is one of the main drivers of organismal ageing and holds keys towards improving the longevity and quality of the extended life. Elucidating mechanisms underlying the emergence of the aged cells as well as their altered responses to the environment will help understanding the evolutionarily defined longevity preferences across species with different strategies of survival. Much is understood about the role of alterations in the DNA, including many epigenetic modifications such as methylation, in relation to the aged cell phenotype. While transcriptomes of the aged cells are beginning to be better-characterised, their translational responses remain under active investigation. Many of the translationally controlled homeostatic pathways are centred around mitigation of DNA damage, cell stress response and regulation of the proliferative potential of the cells, and thus are critical for the aged cell function. Translation profiling-type studies have boosted the opportunities in discovering the function of protein biosynthesis control and are starting to be applied to the aged cells. Here, we provide a summary of the current knowledge about translational mechanisms considered to be commonly altered in the aged cells, including the integrated stress response-, mechanistic target of Rapamycin- and elongation factor 2 kinase-mediated pathways. We enlist and discuss findings of the recent works that use broad profiling-type approaches to investigate the age-related translational pathways. We outline the limitations of the methods and the remaining unknowns in the established ageing-associated translation mechanisms, and flag translational mechanisms with high prospective importance in ageing, for future studies.
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Affiliation(s)
- Katrina Woodward
- Division of Genome Sciences and Cancer, The John Curtin School of Medical Research, The Australian National University, Acton, Canberra, ACT 2601, Australia
| | - Nikolay E. Shirokikh
- Division of Genome Sciences and Cancer, The John Curtin School of Medical Research, The Australian National University, Acton, Canberra, ACT 2601, Australia
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10
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Andreev DE, Baranov PV, Milogorodskii A, Rachinskii D. A deterministic model for non-monotone relationship between translation of upstream and downstream open reading frames. MATHEMATICAL MEDICINE AND BIOLOGY : A JOURNAL OF THE IMA 2021; 38:490-515. [PMID: 34718568 DOI: 10.1093/imammb/dqab015] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/30/2020] [Revised: 08/12/2021] [Accepted: 10/06/2021] [Indexed: 01/01/2023]
Abstract
Totally asymmetric simple exclusion process (TASEP) modelling was shown to offer a parsimonious explanation for the experimentally confirmed ability of a single upstream open reading frames (uORFs) to upregulate downstream translation during the integrated stress response. As revealed by numerical simulations, the model predicts that reducing the density of scanning ribosomes upstream of certain uORFs increases the flow of ribosomes downstream. To gain a better insight into the mechanism which ensures the non-monotone relation between the upstream and downstream flows, in this work, we propose a phenomenological deterministic model approximating the TASEP model of the translation process. We establish the existence of a stationary solution featuring the decreasing density along the uORF for the deterministic model. Further, we find an explicit non-monotone relation between the upstream ribosome density and the downstream flow for the stationary solution in the limit of increasing uORF length and increasingly leaky initiation. The stationary distribution of the TASEP model, the stationary solution of the deterministic model and the explicit limit are compared numerically.
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Affiliation(s)
- D E Andreev
- Lomonosov Moscow State University, GSP-1, Leninskie Gory, Moscow, 119991, Russian Federation, and Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, RAS, Moscow, Russia
| | - P V Baranov
- University College Cork, College Road, Cork, T12 K8AF, Ireland, and Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry (RAS), 16/10 Miklukho-Maklay str., Moscow, 117997, Russian Federation
| | - A Milogorodskii
- Lomonosov Moscow State University, GSP-1, Leninskie Gory, Moscow, 119991, Russian Federation, and Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, RAS, Moscow, Russia
| | - D Rachinskii
- Department of Mathematical Sciences, The University of Texas at Dallas, 800 W. Campbell Rd, Richardson, TX 75080, USA
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11
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Karasik A, Jones GD, DePass AV, Guydosh NR. Activation of the antiviral factor RNase L triggers translation of non-coding mRNA sequences. Nucleic Acids Res 2021; 49:6007-6026. [PMID: 33556964 DOI: 10.1093/nar/gkab036] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2020] [Revised: 01/06/2021] [Accepted: 02/03/2021] [Indexed: 11/15/2022] Open
Abstract
Ribonuclease L (RNase L) is activated as part of the innate immune response and plays an important role in the clearance of viral infections. When activated, it endonucleolytically cleaves both viral and host RNAs, leading to a global reduction in protein synthesis. However, it remains unknown how widespread RNA decay, and consequent changes in the translatome, promote the elimination of viruses. To study how this altered transcriptome is translated, we assayed the global distribution of ribosomes in RNase L activated human cells with ribosome profiling. We found that RNase L activation leads to a substantial increase in the fraction of translating ribosomes in ORFs internal to coding sequences (iORFs) and ORFs within 5' and 3' UTRs (uORFs and dORFs). Translation of these alternative ORFs was dependent on RNase L's cleavage activity, suggesting that mRNA decay fragments are translated to produce short peptides that may be important for antiviral activity.
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Affiliation(s)
- Agnes Karasik
- Laboratory of Biochemistry and Genetics, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892, USA.,Postdoctoral Research Associate Training Program, National Institute of General Medical Sciences, National Institutes of Health, Bethesda, MD 20892, USA
| | - Grant D Jones
- Laboratory of Biochemistry and Genetics, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892, USA
| | - Andrew V DePass
- Laboratory of Biochemistry and Genetics, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892, USA
| | - Nicholas R Guydosh
- Laboratory of Biochemistry and Genetics, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892, USA
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12
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Alghoul F, Laure S, Eriani G, Martin F. Translation inhibitory elements from Hoxa3 and Hoxa11 mRNAs use uORFs for translation inhibition. eLife 2021; 10:e66369. [PMID: 34076576 PMCID: PMC8172242 DOI: 10.7554/elife.66369] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2021] [Accepted: 05/20/2021] [Indexed: 01/20/2023] Open
Abstract
During embryogenesis, Hox mRNA translation is tightly regulated by a sophisticated molecular mechanism that combines two RNA regulons located in their 5'UTR. First, an internal ribosome entry site (IRES) enables cap-independent translation. The second regulon is a translation inhibitory element or TIE, which ensures concomitant cap-dependent translation inhibition. In this study, we deciphered the molecular mechanisms of mouse Hoxa3 and Hoxa11 TIEs. Both TIEs possess an upstream open reading frame (uORF) that is critical to inhibit cap-dependent translation. However, the molecular mechanisms used are different. In Hoxa3 TIE, we identify an uORF which inhibits cap-dependent translation and we show the requirement of the non-canonical initiation factor eIF2D for this process. The mode of action of Hoxa11 TIE is different, it also contains an uORF but it is a minimal uORF formed by an uAUG followed immediately by a stop codon, namely a 'start-stop'. The 'start-stop' sequence is species-specific and in mice, is located upstream of a highly stable stem loop structure which stalls the 80S ribosome and thereby inhibits cap-dependent translation of Hoxa11 main ORF.
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Affiliation(s)
- Fatima Alghoul
- Institut de Biologie Moléculaire et Cellulaire, “Architecture et Réactivité de l’ARN” CNRS UPR9002, Université de StrasbourgStrasbourgFrance
| | - Schaeffer Laure
- Institut de Biologie Moléculaire et Cellulaire, “Architecture et Réactivité de l’ARN” CNRS UPR9002, Université de StrasbourgStrasbourgFrance
| | - Gilbert Eriani
- Institut de Biologie Moléculaire et Cellulaire, “Architecture et Réactivité de l’ARN” CNRS UPR9002, Université de StrasbourgStrasbourgFrance
| | - Franck Martin
- Institut de Biologie Moléculaire et Cellulaire, “Architecture et Réactivité de l’ARN” CNRS UPR9002, Université de StrasbourgStrasbourgFrance
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13
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Barragan-Iglesias P, Kunder N, Wanghzou A, Black B, Ray PR, Lou TF, de la Peña JB, Atmaramani R, Shukla T, Pancrazio JJ, Price TJ, Campbell ZT. A peptide encoded within a 5' untranslated region promotes pain sensitization in mice. Pain 2021; 162:1864-1875. [PMID: 33449506 PMCID: PMC8119312 DOI: 10.1097/j.pain.0000000000002191] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2020] [Accepted: 01/04/2021] [Indexed: 12/23/2022]
Abstract
ABSTRACT Translational regulation permeates neuronal function. Nociceptors are sensory neurons responsible for the detection of harmful stimuli. Changes in their activity, termed plasticity, are intimately linked to the persistence of pain. Although inhibitors of protein synthesis robustly attenuate pain-associated behavior, the underlying targets that support plasticity are largely unknown. Here, we examine the contribution of protein synthesis in regions of RNA annotated as noncoding. Based on analyses of previously reported ribosome profiling data, we provide evidence for widespread translation in noncoding transcripts and regulatory regions of mRNAs. We identify an increase in ribosome occupancy in the 5' untranslated regions of the calcitonin gene-related peptide (CGRP/Calca). We validate the existence of an upstream open reading frame (uORF) using a series of reporter assays. Fusion of the uORF to a luciferase reporter revealed active translation in dorsal root ganglion neurons after nucleofection. Injection of the peptide corresponding to the calcitonin gene-related peptide-encoded uORF resulted in pain-associated behavioral responses in vivo and nociceptor sensitization in vitro. An inhibitor of heterotrimeric G protein signaling blocks both effects. Collectively, the data suggest pervasive translation in regions of the transcriptome annotated as noncoding in dorsal root ganglion neurons and identify a specific uORF-encoded peptide that promotes pain sensitization through GPCR signaling.
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Affiliation(s)
- Paulino Barragan-Iglesias
- University of Texas at Dallas, School of Behavioral and
Brain Sciences, Richardson, TX, 75080, USA
- Department of Physiology and Pharmacology, Center for Basic
Sciences, Autonomous University of Aguascalientes, Aguascalientes, 20130,
Mexico
| | - Nikesh Kunder
- University of Texas at Dallas, Department of Biological
Sciences, Richardson, TX, 75080, USA
| | - Andi Wanghzou
- University of Texas at Dallas, School of Behavioral and
Brain Sciences, Richardson, TX, 75080, USA
| | - Bryan Black
- University of Texas at Dallas, Department of
Bioengineering, Richardson, TX, 75080, USA
| | - Pradipta R. Ray
- University of Texas at Dallas, School of Behavioral and
Brain Sciences, Richardson, TX, 75080, USA
| | - Tzu-Fang Lou
- University of Texas at Dallas, Department of Biological
Sciences, Richardson, TX, 75080, USA
| | - June Bryan de la Peña
- University of Texas at Dallas, Department of Biological
Sciences, Richardson, TX, 75080, USA
| | - Rahul Atmaramani
- University of Texas at Dallas, Department of
Bioengineering, Richardson, TX, 75080, USA
| | - Tarjani Shukla
- University of Texas at Dallas, Department of Biological
Sciences, Richardson, TX, 75080, USA
| | - Joseph J. Pancrazio
- University of Texas at Dallas, Department of
Bioengineering, Richardson, TX, 75080, USA
- Center for Advanced Pain Studies, University of Texas at
Dallas, Richardson, TX, 75080, USA
| | - Theodore J. Price
- University of Texas at Dallas, School of Behavioral and
Brain Sciences, Richardson, TX, 75080, USA
- Center for Advanced Pain Studies, University of Texas at
Dallas, Richardson, TX, 75080, USA
| | - Zachary T. Campbell
- University of Texas at Dallas, Department of Biological
Sciences, Richardson, TX, 75080, USA
- Center for Advanced Pain Studies, University of Texas at
Dallas, Richardson, TX, 75080, USA
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14
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Yan LL, Zaher HS. Ribosome quality control antagonizes the activation of the integrated stress response on colliding ribosomes. Mol Cell 2020; 81:614-628.e4. [PMID: 33338396 DOI: 10.1016/j.molcel.2020.11.033] [Citation(s) in RCA: 85] [Impact Index Per Article: 21.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2020] [Revised: 11/17/2020] [Accepted: 11/17/2020] [Indexed: 12/28/2022]
Abstract
Stalling during translation triggers ribosome quality control (RQC) to maintain proteostasis. Recently, stalling has also been linked to the activation of integrated stress response (ISR) by Gcn2. How the two processes are coordinated is unclear. Here, we show that activation of RQC by Hel2 suppresses that of Gcn2. We further show that Hel2 and Gcn2 are activated by a similar set of agents that cause ribosome stalling, with maximal activation of Hel2 observed at a lower frequency of stalling. Interestingly, inactivation of one pathway was found to result in the overactivation of the other, suggesting that both are activated by the same signal of ribosome collisions. Notably, the processes do not appear to be in direct competition with each other; ISR prefers a vacant A site, whereas RQC displays no preference. Collectively, our findings provide important details about how multiple pathways that recognize stalled ribosomes coordinate to mount the appropriate response.
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Affiliation(s)
- Liewei L Yan
- Department of Biology, Washington University in St. Louis, St. Louis, MO 63130, USA
| | - Hani S Zaher
- Department of Biology, Washington University in St. Louis, St. Louis, MO 63130, USA.
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15
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The integrated stress response induces R-loops and hinders replication fork progression. Cell Death Dis 2020; 11:538. [PMID: 32678076 PMCID: PMC7366693 DOI: 10.1038/s41419-020-2727-2] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2020] [Accepted: 06/25/2020] [Indexed: 12/15/2022]
Abstract
The integrated stress response (ISR) allows cells to rapidly shutdown most of their protein synthesis in response to protein misfolding, amino acid deficiency, or virus infection. These stresses trigger the phosphorylation of the translation initiation factor eIF2alpha, which prevents the initiation of translation. Here we show that triggering the ISR drastically reduces the progression of DNA replication forks within 1 h, thus flanking the shutdown of protein synthesis with immediate inhibition of DNA synthesis. DNA replication is restored by compounds that inhibit eIF2alpha kinases or re-activate eIF2alpha. Mechanistically, the translational shutdown blocks histone synthesis, promoting the formation of DNA:RNA hybrids (R-loops), which interfere with DNA replication. R-loops accumulate upon histone depletion. Conversely, histone overexpression or R-loop removal by RNaseH1 each restores DNA replication in the context of ISR and histone depletion. In conclusion, the ISR rapidly stalls DNA synthesis through histone deficiency and R-loop formation. We propose that this shutdown mechanism prevents potentially detrimental DNA replication in the face of cellular stresses.
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16
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Nüske E, Marini G, Richter D, Leng W, Bogdanova A, Franzmann TM, Pigino G, Alberti S. Filament formation by the translation factor eIF2B regulates protein synthesis in starved cells. Biol Open 2020; 9:bio046391. [PMID: 32554487 PMCID: PMC7358136 DOI: 10.1242/bio.046391] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2020] [Accepted: 05/26/2020] [Indexed: 12/11/2022] Open
Abstract
Cells exposed to starvation have to adjust their metabolism to conserve energy and protect themselves. Protein synthesis is one of the major energy-consuming processes and as such has to be tightly controlled. Many mechanistic details about how starved cells regulate the process of protein synthesis are still unknown. Here, we report that the essential translation initiation factor eIF2B forms filaments in starved budding yeast cells. We demonstrate that filamentation is triggered by starvation-induced acidification of the cytosol, which is caused by an influx of protons from the extracellular environment. We show that filament assembly by eIF2B is necessary for rapid and efficient downregulation of translation. Importantly, this mechanism does not require the kinase Gcn2. Furthermore, analysis of site-specific variants suggests that eIF2B assembly results in enzymatically inactive filaments that promote stress survival and fast recovery of cells from starvation. We propose that translation regulation through filament assembly is an efficient mechanism that allows yeast cells to adapt to fluctuating environments.
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Affiliation(s)
- Elisabeth Nüske
- Max Planck Institute of Molecular Cell Biology and Genetics, Pfotenhauerstrasse 108, 01307 Dresden, Germany
| | - Guendalina Marini
- Max Planck Institute of Molecular Cell Biology and Genetics, Pfotenhauerstrasse 108, 01307 Dresden, Germany
| | - Doris Richter
- Department of Cellular Biochemistry Biotechnology Center (BIOTEC), Center for Molecular and Cellular Bioengineering (CMCB), Technische Universität Dresden, Tatzberg 47/49, 01307 Dresden, Germany
| | - Weihua Leng
- Max Planck Institute of Molecular Cell Biology and Genetics, Pfotenhauerstrasse 108, 01307 Dresden, Germany
| | - Aliona Bogdanova
- Max Planck Institute of Molecular Cell Biology and Genetics, Pfotenhauerstrasse 108, 01307 Dresden, Germany
| | - Titus M Franzmann
- Department of Cellular Biochemistry Biotechnology Center (BIOTEC), Center for Molecular and Cellular Bioengineering (CMCB), Technische Universität Dresden, Tatzberg 47/49, 01307 Dresden, Germany
| | - Gaia Pigino
- Max Planck Institute of Molecular Cell Biology and Genetics, Pfotenhauerstrasse 108, 01307 Dresden, Germany
| | - Simon Alberti
- Max Planck Institute of Molecular Cell Biology and Genetics, Pfotenhauerstrasse 108, 01307 Dresden, Germany
- Department of Cellular Biochemistry Biotechnology Center (BIOTEC), Center for Molecular and Cellular Bioengineering (CMCB), Technische Universität Dresden, Tatzberg 47/49, 01307 Dresden, Germany
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17
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Messenger RNAs with large numbers of upstream open reading frames are translated via leaky scanning and reinitiation in the asexual stages of Plasmodium falciparum. Parasitology 2020; 147:1100-1113. [DOI: 10.1017/s0031182020000840] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
AbstractThe genome of Plasmodium falciparum has one of the most skewed base-pair compositions of any eukaryote, with an AT content of 80–90%. As start and stop codons are AT-rich, the probability of finding upstream open reading frames (uORFs) in messenger RNAs (mRNAs) is high and parasite mRNAs have an average of 11 uORFs in their leader sequences. Similar to other eukaryotes, uORFs repress the translation of the downstream open reading frame (dORF) in P. falciparum, yet the parasite translation machinery is able to bypass these uORFs and reach the dORF to initiate translation. This can happen by leaky scanning and/or reinitiation.In this report, we assessed leaky scanning and reinitiation by studying the effect of uORFs on the translation of a dORF, in this case, the luciferase reporter gene, and showed that both mechanisms are employed in the asexual blood stages of P. falciparum. Furthermore, in addition to the codon usage of the uORF, translation of the dORF is governed by the Kozak sequence and length of the uORF, and inter-cistronic distance between the uORF and dORF. Based on these features whole-genome data was analysed to uncover classes of genes that might be regulated by uORFs. This study indicates that leaky scanning and reinitiation appear to be widespread in asexual stages of P. falciparum, which may require modifications of existing factors that are involved in translation initiation in addition to novel, parasite-specific proteins.
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18
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Aminoacyl-tRNA synthetase inhibition activates a pathway that branches from the canonical amino acid response in mammalian cells. Proc Natl Acad Sci U S A 2020; 117:8900-8911. [PMID: 32253314 DOI: 10.1073/pnas.1913788117] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Signaling pathways that sense amino acid abundance are integral to tissue homeostasis and cellular defense. Our laboratory has previously shown that halofuginone (HF) inhibits the prolyl-tRNA synthetase catalytic activity of glutamyl-prolyl-tRNA synthetase (EPRS), thereby activating the amino acid response (AAR). We now show that HF treatment selectively inhibits inflammatory responses in diverse cell types and that these therapeutic benefits occur in cells that lack GCN2, the signature effector of the AAR. Depletion of arginine, histidine, or lysine from cultured fibroblast-like synoviocytes recapitulates key aspects of HF treatment, without utilizing GCN2 or mammalian target of rapamycin complex 1 pathway signaling. Like HF, the threonyl-tRNA synthetase inhibitor borrelidin suppresses the induction of tissue remodeling and inflammatory mediators in cytokine-stimulated fibroblast-like synoviocytes without GCN2, but both aminoacyl-tRNA synthetase (aaRS) inhibitors are sensitive to the removal of GCN1. GCN1, an upstream component of the AAR pathway, binds to ribosomes and is required for GCN2 activation. These observations indicate that aaRS inhibitors, like HF, can modulate inflammatory response without the AAR/GCN2 signaling cassette, and that GCN1 has a role that is distinct from its activation of GCN2. We propose that GCN1 participates in a previously unrecognized amino acid sensor pathway that branches from the canonical AAR.
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19
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Horn M, Denzel SI, Srinivasan B, Allmeroth K, Schiffer I, Karthikaisamy V, Miethe S, Breuer P, Antebi A, Denzel MS. Hexosamine Pathway Activation Improves Protein Homeostasis through the Integrated Stress Response. iScience 2020; 23:100887. [PMID: 32086012 PMCID: PMC7033349 DOI: 10.1016/j.isci.2020.100887] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2019] [Revised: 10/24/2019] [Accepted: 01/08/2020] [Indexed: 12/15/2022] Open
Abstract
Activation of the hexosamine pathway (HP) through gain-of-function mutations in its rate-limiting enzyme glutamine fructose-6-phosphate amidotransferase (GFAT-1) ameliorates proteotoxicity and increases lifespan in Caenorhabditis elegans. Here, we investigate the role of the HP in mammalian protein quality control. In mouse neuronal cells, elevation of HP activity led to phosphorylation of both PERK and eIF2α as well as downstream ATF4 activation, identifying the HP as a modulator of the integrated stress response (ISR). Increasing uridine 5′-diphospho-N-acetyl-D-glucosamine (UDP-GlcNAc) levels through GFAT1 gain-of-function mutations or supplementation with the precursor GlcNAc reduces aggregation of the polyglutamine (polyQ) protein Ataxin-3. Blocking PERK signaling or autophagy suppresses this effect. In C. elegans, overexpression of gfat-1 likewise activates the ISR. Consistently, co-overexpression of gfat-1 and proteotoxic polyQ peptides in muscles reveals a strong protective cell-autonomous role of the HP. Thus, the HP has a conserved role in improving protein quality control through modulation of the ISR. Hexosamine pathway (HP) activation induces the integrated stress response (ISR) HP activation ameliorates poly-glutamine aggregation via the ISR and autophagy In C. elegans, the HP/ISR axis improves cell autonomous protein homeostasis The proteoprotective role of longevity-associated HP is evolutionarily conserved
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Affiliation(s)
- Moritz Horn
- Max Planck Institute for Biology of Ageing, Joseph-Stelzmann-Str. 9b, 50931 Cologne, Germany
| | - Sarah I Denzel
- Max Planck Institute for Biology of Ageing, Joseph-Stelzmann-Str. 9b, 50931 Cologne, Germany
| | - Balaji Srinivasan
- Max Planck Institute for Biology of Ageing, Joseph-Stelzmann-Str. 9b, 50931 Cologne, Germany
| | - Kira Allmeroth
- Max Planck Institute for Biology of Ageing, Joseph-Stelzmann-Str. 9b, 50931 Cologne, Germany
| | - Isabelle Schiffer
- Max Planck Institute for Biology of Ageing, Joseph-Stelzmann-Str. 9b, 50931 Cologne, Germany
| | - Vignesh Karthikaisamy
- Max Planck Institute for Biology of Ageing, Joseph-Stelzmann-Str. 9b, 50931 Cologne, Germany
| | - Stephan Miethe
- Max Planck Institute for Biology of Ageing, Joseph-Stelzmann-Str. 9b, 50931 Cologne, Germany
| | - Peter Breuer
- University of Bonn, Department of Neurology, Sigmund-Freud-Str. 25, 53105 Bonn, Germany.
| | - Adam Antebi
- Max Planck Institute for Biology of Ageing, Joseph-Stelzmann-Str. 9b, 50931 Cologne, Germany; CECAD - Cluster of Excellence, University of Cologne, Joseph-Stelzmann-Str. 26, 50931 Cologne, Germany.
| | - Martin S Denzel
- Max Planck Institute for Biology of Ageing, Joseph-Stelzmann-Str. 9b, 50931 Cologne, Germany; CECAD - Cluster of Excellence, University of Cologne, Joseph-Stelzmann-Str. 26, 50931 Cologne, Germany; Center for Molecular Medicine Cologne (CMMC), University of Cologne, Robert-Koch-Str. 21, 50931 Cologne, Germany.
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20
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Neupane R, Pisareva VP, Rodriguez CF, Pisarev AV, Fernández IS. A complex IRES at the 5'-UTR of a viral mRNA assembles a functional 48S complex via an uAUG intermediate. eLife 2020; 9:54575. [PMID: 32286223 PMCID: PMC7190351 DOI: 10.7554/elife.54575] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2019] [Accepted: 04/13/2020] [Indexed: 01/21/2023] Open
Abstract
Taking control of the cellular apparatus for protein production is a requirement for virus progression. To ensure this control, diverse strategies of cellular mimicry and/or ribosome hijacking have evolved. The initiation stage of translation is especially targeted as it involves multiple steps and the engagement of numerous initiation factors. The use of structured RNA sequences, called Internal Ribosomal Entry Sites (IRES), in viral RNAs is a widespread strategy for the exploitation of eukaryotic initiation. Using a combination of electron cryo-microscopy (cryo-EM) and reconstituted translation initiation assays with native components, we characterized how a novel IRES at the 5'-UTR of a viral RNA assembles a functional initiation complex via an uAUG intermediate. The IRES features a novel extended, multi-domain architecture, that circles the 40S head. The structures and accompanying functional data illustrate the importance of 5'-UTR regions in translation regulation and underline the relevance of the untapped diversity of viral IRESs.
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Affiliation(s)
- Ritam Neupane
- Department of Biological Sciences, Columbia UniversityNew YorkUnited States,Department of Biochemistry and Molecular Biophysics, Columbia UniversityNew YorkUnited States
| | - Vera P Pisareva
- Department of Cell Biology, SUNY Downstate Medical CenterBrooklynUnited States
| | - Carlos F Rodriguez
- Structural Biology Programme, Centro Nacional de Investigaciones Oncológicas (CNIO)MadridSpain
| | - Andrey V Pisarev
- Department of Cell Biology, SUNY Downstate Medical CenterBrooklynUnited States
| | - Israel S Fernández
- Department of Biochemistry and Molecular Biophysics, Columbia UniversityNew YorkUnited States
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21
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Pan Y, Gao L, Zhang X, Qin Y, Liu G, Qu Y. The Role of Cross-Pathway Control Regulator CpcA in the Growth and Extracellular Enzyme Production of Penicillium oxalicum. Curr Microbiol 2019; 77:49-54. [PMID: 31701162 DOI: 10.1007/s00284-019-01803-8] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2018] [Accepted: 10/28/2019] [Indexed: 10/25/2022]
Abstract
CpcA is a conserved transcriptional activator for the cross-pathway control of amino acid biosynthetic genes in filamentous fungi. Previous studies of this regulator mainly revealed its function under amino acid starvation condition, where amino acid biosynthetic inhibitors were added in the culture. In this study, the biological function of CpcA in Penicillium oxalicum was investigated under different cultivation conditions. Disruption of cpcA led to decreased cell growth either in the presence or absence of histidine biosynthetic inhibitor, and the phenotype could be rescued by the addition of exogenous amino acid sources. In addition, CpcA was required for the rapid production of cellulase when cells were cultured on cellulose. Transcript abundance measurement showed that a set of amino acid biosynthetic genes as well as two major cellulase genes were significantly down-regulated in cpcA deletion mutant relative to wild type. Taken together, the results revealed the biological role of CpcA in supporting normal growth and extracellular enzyme production of P. oxalicum under amino acid non-starvation condition.
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Affiliation(s)
- Yunjun Pan
- State Key Laboratory of Microbial Technology, National Glycoengineering Research Center, Shandong University, Qingdao, 266237, Shandong, People's Republic of China
| | - Liwei Gao
- State Key Laboratory of Microbial Technology, National Glycoengineering Research Center, Shandong University, Qingdao, 266237, Shandong, People's Republic of China
| | - Xiujun Zhang
- State Key Laboratory of Microbial Technology, National Glycoengineering Research Center, Shandong University, Qingdao, 266237, Shandong, People's Republic of China
| | - Yuqi Qin
- State Key Laboratory of Microbial Technology, National Glycoengineering Research Center, Shandong University, Qingdao, 266237, Shandong, People's Republic of China.
| | - Guodong Liu
- State Key Laboratory of Microbial Technology, National Glycoengineering Research Center, Shandong University, Qingdao, 266237, Shandong, People's Republic of China.
| | - Yinbo Qu
- State Key Laboratory of Microbial Technology, National Glycoengineering Research Center, Shandong University, Qingdao, 266237, Shandong, People's Republic of China
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22
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Gordiyenko Y, Llácer JL, Ramakrishnan V. Structural basis for the inhibition of translation through eIF2α phosphorylation. Nat Commun 2019; 10:2640. [PMID: 31201334 PMCID: PMC6572841 DOI: 10.1038/s41467-019-10606-1] [Citation(s) in RCA: 53] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2018] [Accepted: 05/10/2019] [Indexed: 11/29/2022] Open
Abstract
One of the responses to stress by eukaryotic cells is the down-regulation of protein synthesis by phosphorylation of translation initiation factor eIF2. Phosphorylation results in low availability of the eIF2 ternary complex (eIF2-GTP-tRNAi) by affecting the interaction of eIF2 with its GTP-GDP exchange factor eIF2B. We have determined the cryo-EM structure of yeast eIF2B in complex with phosphorylated eIF2 at an overall resolution of 4.2 Å. Two eIF2 molecules bind opposite sides of an eIF2B hetero-decamer through eIF2α-D1, which contains the phosphorylated Ser51. eIF2α-D1 is mainly inserted between the N-terminal helix bundle domains of δ and α subunits of eIF2B. Phosphorylation of Ser51 enhances binding to eIF2B through direct interactions of phosphate groups with residues in eIF2Bα and indirectly by inducing contacts of eIF2α helix 58–63 with eIF2Bδ leading to a competition with Met-tRNAi. During stress, protein synthesis is inhibited through phosphorylation of the initiation factor eIF2 on its alpha subunit and its interaction with eIF2B. Here the authors describe a structure of the yeast eIF2B in complex with its substrate - the GDP-bound phosphorylated eIF2, providing insights into how phosphorylation results in a tighter interaction with eIF2B.
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Affiliation(s)
- Yuliya Gordiyenko
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge, CB2 0QH, UK
| | - José Luis Llácer
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge, CB2 0QH, UK. .,Instituto de Biomedicina de Valencia del Consejo Superior de Investigaciones Científicas and CIBERER-ISCIII, Valencia, 46010, Spain.
| | - V Ramakrishnan
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge, CB2 0QH, UK
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Pervasive, Coordinated Protein-Level Changes Driven by Transcript Isoform Switching during Meiosis. Cell 2019; 172:910-923.e16. [PMID: 29474919 DOI: 10.1016/j.cell.2018.01.035] [Citation(s) in RCA: 99] [Impact Index Per Article: 19.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2017] [Revised: 12/04/2017] [Accepted: 01/26/2018] [Indexed: 12/22/2022]
Abstract
To better understand the gene regulatory mechanisms that program developmental processes, we carried out simultaneous genome-wide measurements of mRNA, translation, and protein through meiotic differentiation in budding yeast. Surprisingly, we observed that the levels of several hundred mRNAs are anti-correlated with their corresponding protein products. We show that rather than arising from canonical forms of gene regulatory control, the regulation of at least 380 such cases, or over 8% of all measured genes, involves temporally regulated switching between production of a canonical, translatable transcript and a 5' extended isoform that is not efficiently translated into protein. By this pervasive mechanism for the modulation of protein levels through a natural developmental program, a single transcription factor can coordinately activate and repress protein synthesis for distinct sets of genes. The distinction is not based on whether or not an mRNA is induced but rather on the type of transcript produced.
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24
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Chen YC, Chang YW, Huang YS. Dysregulated Translation in Neurodevelopmental Disorders: An Overview of Autism-Risk Genes Involved in Translation. Dev Neurobiol 2018; 79:60-74. [PMID: 30430754 DOI: 10.1002/dneu.22653] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2018] [Revised: 09/17/2018] [Accepted: 10/25/2018] [Indexed: 01/08/2023]
Abstract
Regulated local translation-whereby specific mRNAs are transported and localized in subcellular domains where they are translated in response to regional signals-allows for remote control of gene expression to concentrate proteins in subcellular compartments. Neurons are highly polarized cells with unique features favoring local control for axonal pathfinding and synaptic plasticity, which are key processes involved in constructing functional circuits in the developing brain. Neurodevelopmental disorders are caused by genetic or environmental factors that disturb the nervous system's development during prenatal and early childhood periods. The growing list of genetic mutations that affect mRNA translation raises the question of whether aberrant translatomes in individuals with neurodevelopmental disorders share common molecular features underlying their stereotypical phenotypes and, vice versa, cause a certain degree of phenotypic heterogeneity. Here, we briefly give an overview of the role of local translation during neuronal development. We take the autism-risk gene list and discuss the molecules that (perhaps) are involved in mRNA transport and translation. Both exaggerated and suppressed translation caused by mutations in those genes have been identified or suggested. Finally, we discuss some proof-of-principle regimens for use in autism mouse models to correct dysregulated translation.
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Affiliation(s)
- Yan-Chu Chen
- Institute of Biomedical Sciences, Academia Sinica, Taipei, 11529, Taiwan
| | - Yu-Wei Chang
- Institute of Biomedical Sciences, Academia Sinica, Taipei, 11529, Taiwan
| | - Yi-Shuian Huang
- Institute of Biomedical Sciences, Academia Sinica, Taipei, 11529, Taiwan
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25
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Van Dalfsen KM, Hodapp S, Keskin A, Otto GM, Berdan CA, Higdon A, Cheunkarndee T, Nomura DK, Jovanovic M, Brar GA. Global Proteome Remodeling during ER Stress Involves Hac1-Driven Expression of Long Undecoded Transcript Isoforms. Dev Cell 2018; 46:219-235.e8. [PMID: 30016623 PMCID: PMC6140797 DOI: 10.1016/j.devcel.2018.06.016] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2018] [Revised: 05/16/2018] [Accepted: 06/20/2018] [Indexed: 11/30/2022]
Abstract
Cellular stress responses often require transcription-based activation of gene expression to promote cellular adaptation. Whether general mechanisms exist for stress-responsive gene downregulation is less clear. A recently defined mechanism enables both up- and downregulation of protein levels for distinct gene sets by the same transcription factor via coordinated induction of canonical mRNAs and long undecoded transcript isoforms (LUTIs). We analyzed parallel gene expression datasets to determine whether this mechanism contributes to the conserved Hac1-driven branch of the unfolded protein response (UPRER), indeed observing Hac1-dependent protein downregulation accompanying the upregulation of ER-related proteins that typifies UPRER activation. Proteins downregulated by Hac1-driven LUTIs include those with electron transport chain (ETC) function. Abrogated ETC function improves the fitness of UPRER-activated cells, suggesting functional importance to this regulation. We conclude that the UPRER drives large-scale proteome remodeling, including coordinated up- and downregulation of distinct protein classes, which is partly mediated by Hac1-induced LUTIs.
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Affiliation(s)
| | - Stefanie Hodapp
- Department of Biological Sciences, Columbia University, New York, NY 10027, USA
| | - Abdurrahman Keskin
- Department of Biological Sciences, Columbia University, New York, NY 10027, USA
| | - George Maxwell Otto
- Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720, USA
| | - Charles Andrew Berdan
- Departments of Chemistry and Nutritional Sciences and Toxicology, University of California, Berkeley, CA 94720, USA
| | - Andrea Higdon
- Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720, USA
| | - Tia Cheunkarndee
- Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720, USA
| | - Daniel Koji Nomura
- Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720, USA; Departments of Chemistry and Nutritional Sciences and Toxicology, University of California, Berkeley, CA 94720, USA
| | - Marko Jovanovic
- Department of Biological Sciences, Columbia University, New York, NY 10027, USA
| | - Gloria Ann Brar
- Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720, USA.
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26
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Andreev DE, Arnold M, Kiniry SJ, Loughran G, Michel AM, Rachinskii D, Baranov PV. TASEP modelling provides a parsimonious explanation for the ability of a single uORF to derepress translation during the integrated stress response. eLife 2018; 7:32563. [PMID: 29932418 PMCID: PMC6033536 DOI: 10.7554/elife.32563] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2017] [Accepted: 06/21/2018] [Indexed: 12/13/2022] Open
Abstract
Translation initiation is the rate-limiting step of protein synthesis that is downregulated during the Integrated Stress Response (ISR). Previously, we demonstrated that most human mRNAs that are resistant to this inhibition possess translated upstream open reading frames (uORFs), and that in some cases a single uORF is sufficient for the resistance. Here we developed a computational model of Initiation Complexes Interference with Elongating Ribosomes (ICIER) to gain insight into the mechanism. We explored the relationship between the flux of scanning ribosomes upstream and downstream of a single uORF depending on uORF features. Paradoxically, our analysis predicts that reducing ribosome flux upstream of certain uORFs increases initiation downstream. The model supports the derepression of downstream translation as a general mechanism of uORF-mediated stress resistance. It predicts that stress resistance can be achieved with long slowly decoded uORFs that do not favor translation reinitiation and that start with initiators of low leakiness.
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Affiliation(s)
- Dmitry E Andreev
- School of Biochemistry and Cell Biology, University College Cork, Cork, Ireland.,Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, Russia
| | - Maxim Arnold
- Department of Mathematical Sciences, The University of Texas at Dallas, Richardson, United States
| | - Stephen J Kiniry
- School of Biochemistry and Cell Biology, University College Cork, Cork, Ireland
| | - Gary Loughran
- School of Biochemistry and Cell Biology, University College Cork, Cork, Ireland
| | - Audrey M Michel
- School of Biochemistry and Cell Biology, University College Cork, Cork, Ireland
| | - Dmitrii Rachinskii
- Department of Mathematical Sciences, The University of Texas at Dallas, Richardson, United States
| | - Pavel V Baranov
- School of Biochemistry and Cell Biology, University College Cork, Cork, Ireland
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27
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A presumed homologue of the regulatory subunits of eIF2B functions as ribose-1,5-bisphosphate isomerase in Pyrococcus horikoshii OT3. Sci Rep 2018; 8:1891. [PMID: 29382938 PMCID: PMC5789824 DOI: 10.1038/s41598-018-20418-w] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2017] [Accepted: 01/17/2018] [Indexed: 02/06/2023] Open
Abstract
The homologues of the regulatory subunits of eukaryotic translation initiation factor 2B (eIF2B) are assumed to be present in archaea. Likewise, an ORF, PH0208 in Pyrococcus horikoshii OT3 have been proposed to encode one of the homologues of regulatory subunits of eIF2B. However, PH0208 protein also shares sequence similarity with a functionally non-related enzyme, ribose-1,5-bisphosphate isomerase (R15Pi), involved in conversion of ribose-1,5-bisphosphate (R15P) to ribulose-1,5-bisphosphate (RuBP) in an AMP-dependent manner. Herein, we have determined the crystal structure of PH0208 protein in order to decipher its true function. Although structurally similar to the regulatory subunits of eIF2B, the ability to bind R15P and RuBP suggests that PH0208 would function as R15Pi. Additionally, this study for the first time reports the binding sites of AMP and GMP in R15Pi. The AMP binding site in PH0208 protein clarified the role of AMP in providing structural stability to R15Pi. The binding of GMP to the 'AMP binding site' in addition to its own binding site indicates that GMP might also execute a similar function, though with less specificity. Furthermore, we have utilized the resemblance between PH0208 and the regulatory subunits of eIF2B to propose a model for the regulatory mechanism of eIF2B in eukaryotes.
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28
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Anda S, Zach R, Grallert B. Activation of Gcn2 in response to different stresses. PLoS One 2017; 12:e0182143. [PMID: 28771613 PMCID: PMC5542535 DOI: 10.1371/journal.pone.0182143] [Citation(s) in RCA: 53] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2017] [Accepted: 07/12/2017] [Indexed: 12/12/2022] Open
Abstract
All organisms have evolved pathways to respond to different forms of cellular stress. The Gcn2 kinase is best known as a regulator of translation initiation in response to starvation for amino acids. Work in budding yeast has showed that the molecular mechanism of GCN2 activation involves the binding of uncharged tRNAs, which results in a conformational change and GCN2 activation. This pathway requires GCN1, which ensures delivery of the uncharged tRNA onto GCN2. However, Gcn2 is activated by a number of other stresses which do not obviously involve accumulation of uncharged tRNAs, raising the question how Gcn2 is activated under these conditions. Here we investigate the requirement for ongoing translation and tRNA binding for Gcn2 activation after different stresses in fission yeast. We find that mutating the tRNA-binding site on Gcn2 or deleting Gcn1 abolishes Gcn2 activation under all the investigated conditions. These results suggest that tRNA binding to Gcn2 is required for Gcn2 activation not only in response to starvation but also after UV irradiation and oxidative stress.
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Affiliation(s)
- Silje Anda
- Department of Radiation Biology, Institute for Cancer Research, Oslo University Hospital, Oslo, Norway
| | - Róbert Zach
- Department of Radiation Biology, Institute for Cancer Research, Oslo University Hospital, Oslo, Norway
| | - Beáta Grallert
- Department of Radiation Biology, Institute for Cancer Research, Oslo University Hospital, Oslo, Norway
- * E-mail:
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29
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Doyle F, Leonardi A, Endres L, Tenenbaum SA, Dedon PC, Begley TJ. Gene- and genome-based analysis of significant codon patterns in yeast, rat and mice genomes with the CUT Codon UTilization tool. Methods 2016; 107:98-109. [PMID: 27245397 PMCID: PMC5014648 DOI: 10.1016/j.ymeth.2016.05.010] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2016] [Revised: 05/16/2016] [Accepted: 05/17/2016] [Indexed: 01/09/2023] Open
Abstract
The translation of mRNA in all forms of life uses a three-nucleotide codon and aminoacyl-tRNAs to synthesize a protein. There are 64 possible codons in the genetic code, with codons for the ∼20 amino acids and 3 stop codons having 1- to 6-fold degeneracy. Recent studies have shown that families of stress response transcripts, termed modification tunable transcripts (MoTTs), use distinct codon biases that match specifically modified tRNAs to regulate their translation during a stress. Similarly, translational reprogramming of the UGA stop codon to generate selenoproteins or to perform programmed translational read-through (PTR) that results in a longer protein, requires distinct codon bias (i.e., more than one stop codon) and, in the case of selenoproteins, a specifically modified tRNA. In an effort to identify transcripts that have codon usage patterns that could be subject to translational control mechanisms, we have used existing genome and transcript data to develop the gene-specific Codon UTilization (CUT) tool and database, which details all 1-, 2-, 3-, 4- and 5-codon combinations for all genes or transcripts in yeast (Saccharomyces cerevisiae), mice (Mus musculus) and rats (Rattus norvegicus). Here, we describe the use of the CUT tool and database to characterize significant codon usage patterns in specific genes and groups of genes. In yeast, we demonstrate how the CUT database can be used to identify genes that have runs of specific codons (e.g., AGA, GAA, AAG) linked to translational regulation by tRNA methyltransferase 9 (Trm9). We further demonstrate how groups of genes can be analyzed to find significant dicodon patterns, with the 80 Gcn4-regulated transcripts significantly (P<0.00001) over-represented with the AGA-GAA dicodon. We have also used the CUT database to identify mouse and rat transcripts with internal UGA codons, with the surprising finding of 45 and 120 such transcripts, respectively, which is much larger than expected. The UGA data suggest that there could be many more translationally reprogrammed transcripts than currently reported. CUT thus represents a multi-species codon-counting database that can be used with mRNA-, translation- and proteomics-based results to better understand and model translational control mechanisms.
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Affiliation(s)
- Frank Doyle
- State University of New York – SUNY Polytechnic Institute, College of Nanoscale Science and Engineering, Albany, NY
| | - Andrea Leonardi
- State University of New York – SUNY Polytechnic Institute, College of Nanoscale Science and Engineering, Albany, NY
| | - Lauren Endres
- State University of New York – SUNY Polytechnic Institute, College of Arts and Sciences, Utica, NY
| | - Scott A. Tenenbaum
- State University of New York – SUNY Polytechnic Institute, College of Nanoscale Science and Engineering, Albany, NY
| | - Peter C. Dedon
- Department of Biological Engineering and Center for Environmental Health Science, Massachusetts Institute of Technology, Cambridge, MA
- Singapore-MIT Alliance for Research and Technology, Singapore
| | - Thomas J. Begley
- State University of New York – SUNY Polytechnic Institute, College of Nanoscale Science and Engineering, Albany, NY
- RNA Institute, University at Albany, State University of New York
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30
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Exploring the Conserved Role of MANF in the Unfolded Protein Response in Drosophila melanogaster. PLoS One 2016; 11:e0151550. [PMID: 26975047 PMCID: PMC4790953 DOI: 10.1371/journal.pone.0151550] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2015] [Accepted: 03/01/2016] [Indexed: 01/05/2023] Open
Abstract
Disturbances in the homeostasis of endoplasmic reticulum (ER) referred to as ER stress is involved in a variety of human diseases. ER stress activates unfolded protein response (UPR), a cellular mechanism the purpose of which is to restore ER homeostasis. Previous studies show that Mesencephalic Astrocyte-derived Neurotrophic Factor (MANF) is an important novel component in the regulation of UPR. In vertebrates, MANF is upregulated by ER stress and protects cells against ER stress-induced cell death. Biochemical studies have revealed an interaction between mammalian MANF and GRP78, the major ER chaperone promoting protein folding. In this study we discovered that the upregulation of MANF expression in response to drug-induced ER stress is conserved between Drosophila and mammals. Additionally, by using a genetic in vivo approach we found genetic interactions between Drosophila Manf and genes encoding for Drosophila homologues of GRP78, PERK and XBP1, the key components of UPR. Our data suggest a role for Manf in the regulation of Drosophila UPR.
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31
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Brina D, Miluzio A, Ricciardi S, Clarke K, Davidsen PK, Viero G, Tebaldi T, Offenhäuser N, Rozman J, Rathkolb B, Neschen S, Klingenspor M, Wolf E, Gailus-Durner V, Fuchs H, Hrabe de Angelis M, Quattrone A, Falciani F, Biffo S. eIF6 coordinates insulin sensitivity and lipid metabolism by coupling translation to transcription. Nat Commun 2015; 6:8261. [PMID: 26383020 PMCID: PMC4595657 DOI: 10.1038/ncomms9261] [Citation(s) in RCA: 64] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2014] [Accepted: 08/04/2015] [Indexed: 02/07/2023] Open
Abstract
Insulin regulates glycaemia, lipogenesis and increases mRNA translation. Cells with reduced eukaryotic initiation factor 6 (eIF6) do not increase translation in response to insulin. The role of insulin-regulated translation is unknown. Here we show that reduction of insulin-regulated translation in mice heterozygous for eIF6 results in normal glycaemia, but less blood cholesterol and triglycerides. eIF6 controls fatty acid synthesis and glycolysis in a cell autonomous fashion. eIF6 acts by exerting translational control of adipogenic transcription factors like C/EBPβ, C/EBPδ and ATF4 that have G/C rich or uORF sequences in their 5' UTR. The outcome of the translational activation by eIF6 is a reshaping of gene expression with increased levels of lipogenic and glycolytic enzymes. Finally, eIF6 levels modulate histone acetylation and amounts of rate-limiting fatty acid synthase (Fasn) mRNA. Since obesity, type 2 diabetes, and cancer require a Fasn-driven lipogenic state, we propose that eIF6 could be a therapeutic target for these diseases.
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Affiliation(s)
- Daniela Brina
- INGM, ‘Romeo ed Enrica Invernizzi', 20122 Milano, Italy
| | | | | | - Kim Clarke
- Centre for Computational Biology and Modeling, Institute of Integrative Biology, University of Liverpool, Liverpool L69 7ZB, UK
| | - Peter K. Davidsen
- Centre for Computational Biology and Modeling, Institute of Integrative Biology, University of Liverpool, Liverpool L69 7ZB, UK
| | - Gabriella Viero
- Institute of Biophysics, 38123 Trento, Italy
- Centre for Integrative Biology, University of Trento, 38123 Trento, Italy
| | - Toma Tebaldi
- Centre for Integrative Biology, University of Trento, 38123 Trento, Italy
| | | | - Jan Rozman
- German Mouse Clinic, Institute of Experimental Genetics, Helmholtz Center Munich, 85764 Neuherberg, Germany
| | - Birgit Rathkolb
- German Mouse Clinic, Institute of Experimental Genetics, Helmholtz Center Munich, 85764 Neuherberg, Germany
- Institute of Molecular Animal Breeding and Biotechnology, Gene Center, Ludwig-Maximilian-University, 81377 Munich, Germany
| | - Susanne Neschen
- German Mouse Clinic, Institute of Experimental Genetics, Helmholtz Center Munich, 85764 Neuherberg, Germany
| | - Martin Klingenspor
- Else Kröner-Fresenius Center, Technische Universität München, 85354 Freising, Germany
| | - Eckhard Wolf
- Institute of Molecular Animal Breeding and Biotechnology, Gene Center, Ludwig-Maximilian-University, 81377 Munich, Germany
| | - Valerie Gailus-Durner
- German Mouse Clinic, Institute of Experimental Genetics, Helmholtz Center Munich, 85764 Neuherberg, Germany
| | - Helmut Fuchs
- German Mouse Clinic, Institute of Experimental Genetics, Helmholtz Center Munich, 85764 Neuherberg, Germany
| | - Martin Hrabe de Angelis
- German Mouse Clinic, Institute of Experimental Genetics, Helmholtz Center Munich, 85764 Neuherberg, Germany
- Center of Life and Food Sciences Weihenstephan, Technische Universität München, 85354 Freising, Germany
- German Center for Diabetes Research, 85764 Neuherberg, Germany
| | | | - Francesco Falciani
- Centre for Computational Biology and Modeling, Institute of Integrative Biology, University of Liverpool, Liverpool L69 7ZB, UK
| | - Stefano Biffo
- INGM, ‘Romeo ed Enrica Invernizzi', 20122 Milano, Italy
- Department of Biosciences, University of Milan, 20133 Milan, Italy
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32
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Kuhle B, Eulig NK, Ficner R. Architecture of the eIF2B regulatory subcomplex and its implications for the regulation of guanine nucleotide exchange on eIF2. Nucleic Acids Res 2015; 43:9994-10014. [PMID: 26384431 PMCID: PMC4787765 DOI: 10.1093/nar/gkv930] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2015] [Accepted: 09/07/2015] [Indexed: 11/14/2022] Open
Abstract
Eukaryal translation initiation factor 2B (eIF2B) acts as guanine nucleotide exchange factor (GEF) for eIF2 and forms a central target for pathways regulating global protein synthesis. eIF2B consists of five non-identical subunits (α-ϵ), which assemble into a catalytic subcomplex (γ, ϵ) responsible for the GEF activity, and a regulatory subcomplex (α, β, δ) which regulates the GEF activity under stress conditions. Here, we provide new structural and functional insight into the regulatory subcomplex of eIF2B (eIF2B(RSC)). We report the crystal structures of eIF2Bβ and eIF2Bδ from Chaetomium thermophilum as well as the crystal structure of their tetrameric eIF2B(βδ)2 complex. Combined with mutational and biochemical data, we show that eIF2B(RSC) exists as a hexamer in solution, consisting of two eIF2Bβδ heterodimers and one eIF2Bα2 homodimer, which is homologous to homohexameric ribose 1,5-bisphosphate isomerases. This homology is further substantiated by the finding that eIF2Bα specifically binds AMP and GMP as ligands. Based on our data, we propose a model for eIF2B(RSC) and its interactions with eIF2 that is consistent with previous biochemical and genetic data and provides a framework to better understand eIF2B function, the molecular basis for Gcn(-), Gcd(-) and VWM/CACH mutations and the evolutionary history of the eIF2B complex.
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Affiliation(s)
- Bernhard Kuhle
- Abteilung für Molekulare Strukturbiologie, Institut für Mikrobiologie und Genetik, Göttinger Zentrum für Molekulare Biowissenschaften, Georg-August-Universität Göttingen, D-37077 Göttingen, Germany
| | - Nora K Eulig
- Abteilung für Molekulare Strukturbiologie, Institut für Mikrobiologie und Genetik, Göttinger Zentrum für Molekulare Biowissenschaften, Georg-August-Universität Göttingen, D-37077 Göttingen, Germany
| | - Ralf Ficner
- Abteilung für Molekulare Strukturbiologie, Institut für Mikrobiologie und Genetik, Göttinger Zentrum für Molekulare Biowissenschaften, Georg-August-Universität Göttingen, D-37077 Göttingen, Germany
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33
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eIF2 interactions with initiator tRNA and eIF2B are regulated by post-translational modifications and conformational dynamics. Cell Discov 2015; 1:15020. [PMID: 27462419 PMCID: PMC4860841 DOI: 10.1038/celldisc.2015.20] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2015] [Accepted: 06/12/2015] [Indexed: 12/18/2022] Open
Abstract
Translation of messenger RNA (mRNA) into proteins is key to eukaryotic gene expression and begins when initiation factor-2 (eIF2) delivers methionyl initiator tRNA (Met-tRNAiMet) to ribosomes. This first step is controlled by eIF2B mediating guanine nucleotide exchange on eIF2. We isolated eIF2 from yeast and used mass spectrometry to study the intact complex, and found that eIF2β is the most labile of the three subunits (eIF2α/β/γ). We then compared conformational dynamics of the ternary complex eIF2:GTP:Met-tRNAiMet with apo eIF2 using comparative chemical cross-linking. Results revealed high conformational dynamics for eIF2α in apo eIF2 while in the ternary complex all three subunits are constrained. Novel post-translational modifications identified here in both eIF2 and eIF2B were combined with established sites, and located within protein sequences and homology models. We found clustering at subunit interfaces and highly phosphorylated unstructured regions, at the N-terminus of eIF2β, and also between the eIF2Bε core and catalytic domains. We propose that modifications of these unstructured regions have a key role in regulating interactions between eIF2 and eIF2B, as well as other eIFs.
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34
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Abstract
Herpesviral mRNAs are produced and translated by cellular machinery, rendering them susceptible to the network of regulatory events that impact translation. In response, these viruses have evolved to infiltrate and hijack translational control pathways as well as to integrate specialized host translation strategies into their own repertoire. They are robust systems to dissect mechanisms of mammalian translational regulation and continue to offer insight into cis-acting mRNA features that impact assembly and activity of the translation apparatus. Here, I discuss recent advances revealing the extent to which the three herpesvirus subfamilies regulate both host and viral translation, thereby dramatically impacting the landscape of protein synthesis in infected cells.
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Affiliation(s)
- Britt A Glaunsinger
- Department of Plant and Microbial Biology, University of California, Berkeley, California 94720;
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35
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Chantranupong L, Wolfson RL, Sabatini DM. Nutrient-sensing mechanisms across evolution. Cell 2015; 161:67-83. [PMID: 25815986 DOI: 10.1016/j.cell.2015.02.041] [Citation(s) in RCA: 229] [Impact Index Per Article: 25.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2015] [Indexed: 12/11/2022]
Abstract
For organisms to coordinate their growth and development with nutrient availability, they must be able to sense nutrient levels in their environment. Here, we review select nutrient-sensing mechanisms in a few diverse organisms. We discuss how these mechanisms reflect the nutrient requirements of specific species and how they have adapted to the emergence of multicellularity in eukaryotes.
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Affiliation(s)
- Lynne Chantranupong
- Whitehead Institute for Biomedical Research and Massachusetts Institute of Technology, Department of Biology, 9 Cambridge Center, Cambridge, MA 02142, USA; Howard Hughes Medical Institute, Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02139, USA; Koch Institute for Integrative Cancer Research, 77 Massachusetts Avenue, Cambridge, MA 02139, USA
| | - Rachel L Wolfson
- Whitehead Institute for Biomedical Research and Massachusetts Institute of Technology, Department of Biology, 9 Cambridge Center, Cambridge, MA 02142, USA; Howard Hughes Medical Institute, Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02139, USA; Koch Institute for Integrative Cancer Research, 77 Massachusetts Avenue, Cambridge, MA 02139, USA
| | - David M Sabatini
- Whitehead Institute for Biomedical Research and Massachusetts Institute of Technology, Department of Biology, 9 Cambridge Center, Cambridge, MA 02142, USA; Howard Hughes Medical Institute, Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02139, USA; Koch Institute for Integrative Cancer Research, 77 Massachusetts Avenue, Cambridge, MA 02139, USA.
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36
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Abstract
Dysregulation of mRNA translation is a frequent feature of neoplasia. Many oncogenes and tumour suppressors affect the translation machinery, making aberrant translation a widespread characteristic of tumour cells, independent of the genetic make-up of the cancer. Therefore, therapeutic agents that target components of the protein synthesis apparatus hold promise as novel anticancer drugs that can overcome intra-tumour heterogeneity. In this Review, we discuss the role of translation in cancer, with a particular focus on the eIF4F (eukaryotic translation initiation factor 4F) complex, and provide an overview of recent efforts aiming to 'translate' these results to the clinic.
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Zach L, Braunstein I, Stanhill A. Stress-induced start codon fidelity regulates arsenite-inducible regulatory particle-associated protein (AIRAP) translation. J Biol Chem 2015; 289:20706-16. [PMID: 24898249 DOI: 10.1074/jbc.m114.547828] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Initial steps in protein synthesis are highly regulated processes as they define the reading frame of the translation machinery. Eukaryotic translation initiation is a process facilitated by numerous factors (eIFs), aimed to form a "scanning" mechanism toward the initiation codon. Translation initiation of the main open reading frame (ORF) in an mRNA transcript has been reported to be regulated by upstream open reading frames (uORFs) in a manner of re-initiation. This mode of regulation is governed by the phosphorylation status of eIF2α and controlled by cellular stresses. Another mode of translational initiation regulation is leaky scanning, and this regulatory process has not been extensively studied. We have identified arsenite- inducible regulatory particle-associated protein (AIRAP) transcript to be translationally induced during arsenite stress conditions. AIRAP transcript contains a single uORF in a poor-kozak context. AIRAP translation induction is governed by means of leaky scanning and not re-initiation. This induction of AIRAP is solely dependent on eIF1 and the uORF kozak context. We show that eIF1 is phosphorylated under specific conditions that induce protein misfolding and have biochemically characterized this site of phosphorylation. Our data indicate that leaky scanning like re-initiation is responsive to stress conditions and that leaky scanning can induce ORF translation by bypassing poor kozak context of a single uORF transcript.
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Abstract
In the 40 years since their discovery, dendritic cells (DCs) have been recognized as central players in immune regulation. DCs sense microbial stimuli through pathogen-recognition receptors (PRRs) and decode, integrate, and present information derived from such stimuli to T cells, thus stimulating immune responses. DCs can also regulate the quality of immune responses. Several functionally specialized subsets of DCs exist, but DCs also display functional plasticity in response to diverse stimuli. In addition to sensing pathogens via PRRs, emerging evidence suggests that DCs can also sense stress signals, such as amino acid starvation, through ancient stress and nutrient sensing pathways, to stimulate adaptive immunity. Here, I discuss these exciting advances in the context of a historic perspective on the discovery of DCs and their role in immune regulation. I conclude with a discussion of emerging areas in DC biology in the systems immunology era and suggest that the impact of DCs on immunity can be usefully contextualized in a hierarchy-of-organization model in which DCs, their receptors and signaling networks, cell-cell interactions, tissue microenvironment, and the host macroenvironment represent different levels of the hierarchy. Immunity or tolerance can then be represented as a complex function of each of these hierarchies.
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Affiliation(s)
- Bali Pulendran
- Emory Vaccine Center and Yerkes National Primate Research Center, Emory University, Atlanta, Georgia 30329;
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39
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Hurtado S, Kim Guisbert KS, Sontheimer EJ. SPO24 is a transcriptionally dynamic, small ORF-encoding locus required for efficient sporulation in Saccharomyces cerevisiae. PLoS One 2014; 9:e105058. [PMID: 25127041 PMCID: PMC4134269 DOI: 10.1371/journal.pone.0105058] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2013] [Accepted: 07/20/2014] [Indexed: 01/22/2023] Open
Abstract
In Saccharomyces cerevisiae, meiosis and sporulation are highly regulated responses that are driven in part by changes in RNA expression. Alternative mRNA forms with extended 5′ UTRs are atypical in S. cerevisiae, and 5′ extensions with upstream open reading frames (uORFs) are even more unusual. Here we characterize the gene YPR036W-A, now renamed SPO24, which encodes a very small (67-amino-acid) protein. This gene gives rise to two mRNA forms: a shorter form throughout meiosis and a longer, 5′-extended form in mid-late meiosis. The latter form includes a uORF for a 14-amino-acid peptide (Spo24u14). Deletion of the downstream ORF (dORF) leads to sporulation defects and the appearance of pseudohyphae-like projections. Experiments with luciferase reporters indicate that the uORF does not downregulate dORF translation. The protein encoded by the dORF (Spo24d67) localizes to the prospore membrane and is differentially phosphorylated during meiosis. Transcription of the 5′-extended mRNA in mid-meiosis depends upon the presence of two middle sporulation elements (MSEs). Removal of the MSEs severely inhibits the mid-meiotic appearance of the 5′-extended mRNA and limits the ability of plasmid-borne SPO24 to rescue the sporulation defect of a spo24Δ mutant, suggesting that the 5′-extended mRNA is functionally important. These results reveal Spo24d67 as a sporulation-related factor that is encoded by a transcriptionally dynamic, uORF-containing locus.
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Affiliation(s)
- Sara Hurtado
- Department of Molecular Biosciences, Northwestern University, Evanston, Illinois, United States of America
| | - Karen S. Kim Guisbert
- Department of Molecular Biosciences, Northwestern University, Evanston, Illinois, United States of America
| | - Erik J. Sontheimer
- Department of Molecular Biosciences, Northwestern University, Evanston, Illinois, United States of America
- * E-mail:
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40
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Abstract
Translation initiation plays a critical role in the regulation of cell growth and tumorigenesis. We report here that inhibiting translation initiation through induction of eIF2α phosphorylation by small-molecular-weight compounds restricts the availability of the eIF2·GTP·Met-tRNAi ternary complex and abrogates the proliferation of cancer cells in vitro and tumor growth in vivo. Restricting the availability of the ternary complex preferentially down-regulates the expression of growth-promoting proteins and up-regulates the expression of ER stress response genes in cancer cells as well as in tumors excised from either animal models of human cancer or cancer patients. These findings provide the first direct evidence for translational control of gene-specific expression by small molecules in vivo and indicate that translation initiation factors are bona fide targets for development of mechanism-specific anti-cancer agents.
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41
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Gordiyenko Y, Schmidt C, Jennings MD, Matak-Vinkovic D, Pavitt GD, Robinson CV. eIF2B is a decameric guanine nucleotide exchange factor with a γ2ε2 tetrameric core. Nat Commun 2014; 5:3902. [PMID: 24852487 PMCID: PMC4046112 DOI: 10.1038/ncomms4902] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2014] [Accepted: 04/15/2014] [Indexed: 01/21/2023] Open
Abstract
eIF2B facilitates and controls protein synthesis in eukaryotes by mediating guanine nucleotide exchange on its partner eIF2. We combined mass spectrometry (MS) with chemical cross-linking, surface accessibility measurements and homology modelling to define subunit stoichiometry and interactions within eIF2B and eIF2. Although it is generally accepted that eIF2B is a pentamer of five non-identical subunits (α–ε), here we show that eIF2B is a decamer. MS and cross-linking of eIF2B complexes allows us to propose a model for the subunit arrangements within eIF2B where the subunit assembly occurs through catalytic γ- and ε-subunits, with regulatory subunits arranged in asymmetric trimers associated with the core. Cross-links between eIF2 and eIF2B allow modelling of interactions that contribute to nucleotide exchange and its control by eIF2 phosphorylation. Finally, we identify that GTP binds to eIF2Bγ, prompting us to propose a multi-step mechanism for nucleotide exchange. Eukaryotic Initiation Factor 2 (eIF2) initiates protein synthesis aided by its partner eIF2B, which stimulates guanine nucleotide exchange on eIF2. Here, Gordiyenko et al. show that eIF2B exists as a decamer and propose a model for its subunit arrangement that provides new insight into its function.
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Affiliation(s)
- Yuliya Gordiyenko
- 1] Department of Chemistry, Physical and Theoretical Chemistry Laboratory, University of Oxford, South Parks Road, Oxford OX1 3QZ, UK [2] MRC Laboratory of Molecular Biology, University of Cambridge, Francis Crick Avenue, Cambridge CB2 0QH, UK [3]
| | - Carla Schmidt
- 1] Department of Chemistry, Physical and Theoretical Chemistry Laboratory, University of Oxford, South Parks Road, Oxford OX1 3QZ, UK [2]
| | - Martin D Jennings
- Faculty of Life Sciences, Michael Smith Building, University of Manchester, Oxford Road, Manchester M13 9PT, UK
| | - Dijana Matak-Vinkovic
- Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, UK
| | - Graham D Pavitt
- Faculty of Life Sciences, Michael Smith Building, University of Manchester, Oxford Road, Manchester M13 9PT, UK
| | - Carol V Robinson
- Department of Chemistry, Physical and Theoretical Chemistry Laboratory, University of Oxford, South Parks Road, Oxford OX1 3QZ, UK
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42
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Hypothalamic eIF2α signaling regulates food intake. Cell Rep 2014; 6:438-44. [PMID: 24485657 DOI: 10.1016/j.celrep.2014.01.006] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2013] [Revised: 11/28/2013] [Accepted: 01/06/2014] [Indexed: 01/13/2023] Open
Abstract
The reversible phosphorylation of the α subunit of eukaryotic initiation factor 2 (eIF2α) is a highly conserved signal implicated in the cellular adaptation to numerous stresses such as the one caused by amino acid limitation. In response to dietary amino acid deficiency, the brain-specific activation of the eIF2α kinase GCN2 leads to food intake inhibition. We report here that GCN2 is rapidly activated in the mediobasal hypothalamus (MBH) after consumption of a leucine-deficient diet. Furthermore, knockdown of GCN2 in this particular area shows that MBH GCN2 activity controls the onset of the aversive response. Importantly, pharmacological experiments demonstrate that the sole phosphorylation of eIF2α in the MBH is sufficient to regulate food intake. eIF2α signaling being at the crossroad of stress pathways activated in several pathological states, our study indicates that hypothalamic eIF2α phosphorylation could play a critical role in the onset of anorexia associated with certain diseases.
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43
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Vasquez JJ, Hon CC, Vanselow JT, Schlosser A, Siegel TN. Comparative ribosome profiling reveals extensive translational complexity in different Trypanosoma brucei life cycle stages. Nucleic Acids Res 2014; 42:3623-37. [PMID: 24442674 PMCID: PMC3973304 DOI: 10.1093/nar/gkt1386] [Citation(s) in RCA: 126] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
While gene expression is a fundamental and tightly controlled cellular process that is regulated at multiple steps, the exact contribution of each step remains unknown in any organism. The absence of transcription initiation regulation for RNA polymerase II in the protozoan parasite Trypanosoma brucei greatly simplifies the task of elucidating the contribution of translation to global gene expression. Therefore, we have sequenced ribosome-protected mRNA fragments in T. brucei, permitting the genome-wide analysis of RNA translation and translational efficiency. We find that the latter varies greatly between life cycle stages of the parasite and ∼100-fold between genes, thus contributing to gene expression to a similar extent as RNA stability. The ability to map ribosome positions at sub-codon resolution revealed extensive translation from upstream open reading frames located within 5' UTRs and enabled the identification of hundreds of previously un-annotated putative coding sequences (CDSs). Evaluation of existing proteomics and genome-wide RNAi data confirmed the translation of previously un-annotated CDSs and suggested an important role for >200 of those CDSs in parasite survival, especially in the form that is infective to mammals. Overall our data show that translational control plays a prevalent and important role in different parasite life cycle stages of T. brucei.
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Affiliation(s)
- Juan-José Vasquez
- Research Center for Infectious Diseases, University of Wuerzburg, Wuerzburg 97080, Germany, Département Biologie cellulaire et infection, Institut Pasteur, Unité Biologie Cellulaire du Parasitisme, Paris 75015, France, INSERM U786, Paris 75015, France and Rudolf Virchow Center, University of Wuerzburg, Wuerzburg 97080, Germany
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44
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Rødland GE, Tvegård T, Boye E, Grallert B. Crosstalk between the Tor and Gcn2 pathways in response to different stresses. Cell Cycle 2013; 13:453-61. [PMID: 24280780 DOI: 10.4161/cc.27270] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
Regulating growth and the cell cycle in response to environmental fluctuations is important for all organisms in order to maintain viability. Two major pathways for translational regulation are found in higher eukaryotes: the Tor signaling pathway and those operating through the eIF2α kinases. Studies from several organisms indicate that the two pathways are interlinked, in that Tor complex 1 (TORC1) negatively regulates the Gcn2 kinase. Furthermore, inactivation of TORC1 may be required for activation of Gcn2 in response to stress. Here, we use the model organism Schizosaccharomyces pombe to investigate this crosstalk further. We find that the relationship is more complex than previously thought. First, in response to UV irradiation and oxidative stress, Gcn2 is fully activated in the presence of TORC1 signaling. Second, during amino-acid starvation, activation of Gcn2 is dependent on Tor2 activity, and Gcn2 is required for timely inactivation of the Tor pathway. Our data show that the crosstalk between the two pathways varies with the actual stress applied.
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Affiliation(s)
- Gro Elise Rødland
- Department of Cell Biology; Institute for Cancer Research; Oslo University Hospital; Oslo, Norway
| | - Tonje Tvegård
- Department of Cell Biology; Institute for Cancer Research; Oslo University Hospital; Oslo, Norway
| | - Erik Boye
- Department of Cell Biology; Institute for Cancer Research; Oslo University Hospital; Oslo, Norway; Institute for Molecular Biosciences; University of Oslo; Oslo, Norway
| | - Beáta Grallert
- Department of Cell Biology; Institute for Cancer Research; Oslo University Hospital; Oslo, Norway
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45
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Dual short upstream open reading frames control translation of a herpesviral polycistronic mRNA. PLoS Pathog 2013; 9:e1003156. [PMID: 23382684 PMCID: PMC3561293 DOI: 10.1371/journal.ppat.1003156] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2012] [Accepted: 12/11/2012] [Indexed: 12/21/2022] Open
Abstract
The Kaposi's sarcoma-associated herpesvirus (KSHV) protein kinase, encoded by ORF36, functions to phosphorylate cellular and viral targets important in the KSHV lifecycle and to activate the anti-viral prodrug ganciclovir. Unlike the vast majority of mapped KSHV genes, no viral transcript has been identified with ORF36 positioned as the 5′-proximal gene. Here we report that ORF36 is robustly translated as a downstream cistron from the ORF35–37 polycistronic transcript in a cap-dependent manner. We identified two short, upstream open reading frames (uORFs) within the 5′ UTR of the polycistronic mRNA. While both uORFs function as negative regulators of ORF35, unexpectedly, the second allows for the translation of the downstream ORF36 gene by a termination-reinitiation mechanism. Positional conservation of uORFs within a number of related viruses suggests that this may be a common γ-herpesviral adaptation of a host translational regulatory mechanism. Kaposi's sarcoma-associated herpesvirus (KSHV) is the etiologic agent of multicentric Castleman's disease, primary effusion lymphoma and Kaposi's sarcoma. KSHV expresses a number of transcripts with the potential to generate multiple proteins, yet relies on the cellular translation machinery that is primed to synthesize only one protein per mRNA. Here we report that the viral transcript encompassing ORF35–37 is able to direct synthesis of two proteins and that the translational switch is regulated by two short upstream open reading frames (uORFs) in the native 5′ untranslated region. uORFs are elements commonly found upstream of mammalian genes that function to interfere with unrestrained ribosomal scanning and thus repress translation of the major ORF. The sequence of the viral uORF appears unimportant, and instead functions to position the translation machinery in a location that favors translation of the downstream major ORF, via a reinitiation mechanism. Thus, KSHV uses a host strategy generally reserved to repress translation to instead allow for the expression of an internal gene.
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46
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Plasmodium falciparum responds to amino acid starvation by entering into a hibernatory state. Proc Natl Acad Sci U S A 2012; 109:E3278-87. [PMID: 23112171 DOI: 10.1073/pnas.1209823109] [Citation(s) in RCA: 115] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
The human malaria parasite Plasmodium falciparum is auxotrophic for most amino acids. Its amino acid needs are met largely through the degradation of host erythrocyte hemoglobin; however the parasite must acquire isoleucine exogenously, because this amino acid is not present in adult human hemoglobin. We report that when isoleucine is withdrawn from the culture medium of intraerythrocytic P. falciparum, the parasite slows its metabolism and progresses through its developmental cycle at a reduced rate. Isoleucine-starved parasites remain viable for 72 h and resume rapid growth upon resupplementation. Protein degradation during starvation is important for maintenance of this hibernatory state. Microarray analysis of starved parasites revealed a 60% decrease in the rate of progression through the normal transcriptional program but no other apparent stress response. Plasmodium parasites do not possess a TOR nutrient-sensing pathway and have only a rudimentary amino acid starvation-sensing eukaryotic initiation factor 2α (eIF2α) stress response. Isoleucine deprivation results in GCN2-mediated phosphorylation of eIF2α, but kinase-knockout clones still are able to hibernate and recover, indicating that this pathway does not directly promote survival during isoleucine starvation. We conclude that P. falciparum, in the absence of canonical eukaryotic nutrient stress-response pathways, can cope with an inconsistent bloodstream amino acid supply by hibernating and waiting for more nutrient to be provided.
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47
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Carvalho ND, Jørgensen TR, Arentshorst M, Nitsche BM, van den Hondel CA, Archer DB, Ram AF. Genome-wide expression analysis upon constitutive activation of the HacA bZIP transcription factor in Aspergillus niger reveals a coordinated cellular response to counteract ER stress. BMC Genomics 2012; 13:350. [PMID: 22846479 PMCID: PMC3472299 DOI: 10.1186/1471-2164-13-350] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2012] [Accepted: 07/09/2012] [Indexed: 01/07/2023] Open
Abstract
Background HacA/Xbp1 is a conserved bZIP transcription factor in eukaryotic cells which regulates gene expression in response to various forms of secretion stress and as part of secretory cell differentiation. In the present study, we replaced the endogenous hacA gene of an Aspergillus niger strain with a gene encoding a constitutively active form of the HacA transcription factor (HacACA). The impact of constitutive HacA activity during exponential growth was explored in bioreactor controlled cultures using transcriptomic analysis to identify affected genes and processes. Results Transcription profiles for the wild-type strain (HacAWT) and the HacACA strain were obtained using Affymetrix GeneChip analysis of three replicate batch cultures of each strain. In addition to the well known HacA targets such as the ER resident foldases and chaperones, GO enrichment analysis revealed up-regulation of genes involved in protein glycosylation, phospholipid biosynthesis, intracellular protein transport, exocytosis and protein complex assembly in the HacACA mutant. Biological processes over-represented in the down-regulated genes include those belonging to central metabolic pathways, translation and transcription. A remarkable transcriptional response in the HacACA strain was the down-regulation of the AmyR transcription factor and its target genes. Conclusions The results indicate that the constitutive activation of the HacA leads to a coordinated regulation of the folding and secretion capacity of the cell, but with consequences on growth and fungal physiology to reduce secretion stress.
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Affiliation(s)
- Neuza Dsp Carvalho
- Institute of Biology Leiden, Leiden University, Molecular Microbiology and Biotechnology, BE Leiden, The Netherlands
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48
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Thompson SR. So you want to know if your message has an IRES? WILEY INTERDISCIPLINARY REVIEWS-RNA 2012; 3:697-705. [PMID: 22733589 DOI: 10.1002/wrna.1129] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Transcriptional regulation of gene expression has been widely studied. More recently, there has been increasing appreciation of the role that translational regulation plays in gene expression, resulting in a number of new fields engaging in translational studies. Regulation of protein synthesis is critical for cell growth, development, and survival, and is primarily controlled at the initiation step. Eukaryotic cells utilize multiple mechanisms to initiate translation, depending on cell stress, growth conditions, viral infection, or the sequences present in the mRNA. While the vast majority of mRNAs are translated in a cap-dependent manner, an important subset of mRNAs uses an alternative mechanism, whereby ribosomes are recruited internally to the message to initiate cap-independent translation. Some of these mRNAs contain an internal ribosome entry site (IRES) located in the 5' untranslated region (UTR). However, establishing that an RNA element is a functional IRES requires a number of carefully executed experiments with specific controls. This review will clearly explain the required experiments, and the pros and cons of various assays, used to determine whether (or not) an RNA element functions as an IRES to promote initiation of translation. We hope that demystifying the accepted methods for assaying IRES activity will open the study of this important mechanism to the broader community.
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Affiliation(s)
- Sunnie R Thompson
- Department of Microbiology, University of Alabama at Birmingham, Birmingham, AL, USA.
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49
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Kim Guisbert KS, Zhang Y, Flatow J, Hurtado S, Staley JP, Lin S, Sontheimer EJ. Meiosis-induced alterations in transcript architecture and noncoding RNA expression in S. cerevisiae. RNA (NEW YORK, N.Y.) 2012; 18:1142-53. [PMID: 22539527 PMCID: PMC3358637 DOI: 10.1261/rna.030510.111] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/02/2023]
Abstract
Changes in transcript architecture can have powerful effects on protein expression. Regulation of the transcriptome is often dramatically revealed during dynamic conditions such as development. To examine changes in transcript architecture we analyzed the expression and transcript boundaries of protein-coding and noncoding RNAs over the developmental process of meiosis in Saccharomyces cerevisiae. Custom-designed, high-resolution tiling arrays were used to define the time-resolved transcriptome of cells undergoing meiosis and sporulation. These arrays were specifically designed for the S. cerevisiae strain SK1 that sporulates with high efficiency and synchrony. In addition, new methods were created to define transcript boundaries and to identify dynamic changes in transcript expression and architecture over time. Of 8407 total segments, 699 (8.3%) were identified by our algorithm as regions containing potential transcript architecture changes. Our analyses reveal extensive changes to both the coding and noncoding transcriptome, including altered 5' ends, 3' ends, and splice sites. Additionally, 3910 (46.5%) unannotated expressed segments were identified. Interestingly, subsets of unannotated RNAs are located across from introns (anti-introns) or across from the junction between two genes (anti-intergenic junctions). Many of these unannotated RNAs are abundant and exhibit sporulation-specific changes in expression patterns. All work, including heat maps of the tiling array, annotation for the SK1 strain, and phastCONS conservation analysis, is available at http://groups.molbiosci.northwestern.edu/sontheimer/sk1meiosis.php. Our high-resolution transcriptome analyses reveal that coding and noncoding transcript architectures are exceptionally dynamic in S. cerevisiae and suggest a vast array of novel transcriptional and post-transcriptional control mechanisms that are activated upon meiosis and sporulation.
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Affiliation(s)
- Karen S. Kim Guisbert
- Department of Molecular Biosciences, Northwestern University, Evanston, Illinois 60208, USA
| | - Yong Zhang
- Department of Ecology and Evolution, University of Chicago, Chicago, Illinois 60637, USA
| | - Jared Flatow
- Robert H. Lurie Comprehensive Cancer Center, Feinberg School of Medicine, Northwestern University, Chicago, Illinois 60611, USA
| | - Sara Hurtado
- Department of Molecular Biosciences, Northwestern University, Evanston, Illinois 60208, USA
| | - Jonathan P. Staley
- Department of Molecular Genetics and Cell Biology, University of Chicago, Chicago, Illinois 60637, USA
| | - Simon Lin
- Robert H. Lurie Comprehensive Cancer Center, Feinberg School of Medicine, Northwestern University, Chicago, Illinois 60611, USA
| | - Erik J. Sontheimer
- Department of Molecular Biosciences, Northwestern University, Evanston, Illinois 60208, USA
- Corresponding author.E-mail .
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50
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The alpha subunit of eukaryotic initiation factor 2B (eIF2B) is required for eIF2-mediated translational suppression of vesicular stomatitis virus. J Virol 2011; 85:9716-25. [PMID: 21795329 DOI: 10.1128/jvi.05146-11] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
Eukaryotic translation initiation factor 2B (eIF2B) is a heteropentameric guanine nucleotide exchange factor that converts protein synthesis initiation factor 2 (eIF2) from a GDP-bound form to the active eIF2-GTP complex. Cellular stress can repress translation initiation by activating kinases capable of phosphorylating the alpha subunit of eIF2 (eIF2α), which sequesters eIF2B to prevent exchange activity. Previously, we demonstrated that tumor cells are sensitive to viral replication, possibly due to the occurrence of defects in eIF2B that overcome the inhibitory effects of eIF2α phosphorylation. To extend this analysis, we have investigated the importance of eIF2Bα function and report that this subunit can functionally substitute for its counterpart, GCN3, in yeast. In addition, a variant of mammalian eIF2Bα harboring a point mutation (T41A) was able overcome translational inhibition invoked by amino acid depravation, which activates Saccharomyces cerevisiae GCN2 to phosphorylate the yeast eIF2α homolog SUI2. Significantly, we also demonstrate that the loss of eIF2Bα, or the expression of the T41A variant in mammalian cells, is sufficient to neutralize the consequences of eIF2α phosphorylation and render normal cells susceptible to virus infection. Our data emphasize the importance of eIF2Bα in mediating the eIF2 kinase translation-inhibitory activity and may provide insight into the complex nature of viral oncolysis.
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