1
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Nicchitta CV. An emerging role for the endoplasmic reticulum in stress granule biogenesis. Semin Cell Dev Biol 2024; 156:160-166. [PMID: 36202692 PMCID: PMC10208384 DOI: 10.1016/j.semcdb.2022.09.013] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2022] [Revised: 09/07/2022] [Accepted: 09/26/2022] [Indexed: 11/07/2022]
Abstract
Stress granules (SGs), structurally dynamic, optically resolvable, macromolecular assemblies of mRNAs, RNA binding proteins (RBPs), translation factors, ribosomal subunits, as well as other interacting proteins, assemble in response to cell stress conditions that elicit phosphorylation of eukaryotic initiation factor 2α (eIF2α) and consequently, the inactivation of translation initiation. SG biology is conserved throughout eukaryotes and has recently been linked to the pathological sequelae of neurodegenerative disorders, cancer biology, and viral infection. Substantial insights into mechanisms of SG biogenesis, and more broadly the phenomenon of biological liquid-liquid phase separation (LLPS), have been aided by detailed proteomic and transcriptomic studies as well as in vitro reconstitution approaches. A particularly interesting and largely unexplored element of SG biology is the cell biological context of SG biogenesis, including its subcellular organization and more recently, evidence that the endoplasmic reticulum (ER) membrane may serve important functions in RNA granule biology generally and SG biogenesis specifically. A central role for the ER in SG biogenesis is discussed and a hypothesis linking SG formation on the ER to the trafficking, localization and de novo translation of newly exported mRNAs is presented.
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2
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Marullo R, Rutherford SC, Revuelta MV, Zamponi N, Culjkovic-Kraljacic B, Kotlov N, Di Siervi N, Lara-Garcia J, Allan JN, Ruan J, Furman RR, Chen Z, Shore TB, Phillips AA, Mayer S, Hsu J, van Besien K, Leonard JP, Borden KL, Inghirami G, Martin P, Cerchietti L. XPO1 Enables Adaptive Regulation of mRNA Export Required for Genotoxic Stress Tolerance in Cancer Cells. Cancer Res 2024; 84:101-117. [PMID: 37801604 PMCID: PMC10758694 DOI: 10.1158/0008-5472.can-23-1992] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2023] [Revised: 09/08/2023] [Accepted: 10/03/2023] [Indexed: 10/08/2023]
Abstract
Exportin-1 (XPO1), the main soluble nuclear export receptor in eukaryotic cells, is frequently overexpressed in diffuse large B-cell lymphoma (DLBCL). A selective XPO1 inhibitor, selinexor, received approval as single agent for relapsed or refractory (R/R) DLBCL. Elucidating the mechanisms by which XPO1 overexpression supports cancer cells could facilitate further clinical development of XPO1 inhibitors. We uncovered here that XPO1 overexpression increases tolerance to genotoxic stress, leading to a poor response to chemoimmunotherapy. Upon DNA damage induced by MYC expression or exogenous compounds, XPO1 bound and exported EIF4E and THOC4 carrying DNA damage repair mRNAs, thereby increasing synthesis of DNA damage repair proteins under conditions of increased turnover. Consequently, XPO1 inhibition decreased the capacity of lymphoma cells to repair DNA damage and ultimately resulted in increased cytotoxicity. In a phase I clinical trial conducted in R/R DLBCL, the combination of selinexor with second-line chemoimmunotherapy was tolerated with early indication of efficacy. Overall, this study reveals that XPO1 overexpression plays a critical role in the increased tolerance of cancer cells to DNA damage while providing new insights to optimize the clinical development of XPO1 inhibitors. SIGNIFICANCE XPO1 regulates the dynamic ribonucleoprotein nuclear export in response to genotoxic stress to support tolerance and can be targeted to enhance the sensitivity of cancer cells to endogenous and exogenous DNA damage. See related commentary by Knittel and Reinhardt, p. 3.
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Affiliation(s)
- Rossella Marullo
- Division of Hematology and Oncology, Medicine Department, Weill Cornell Medicine and NewYork-Presbyterian Hospital, New York, New York
| | - Sarah C. Rutherford
- Division of Hematology and Oncology, Medicine Department, Weill Cornell Medicine and NewYork-Presbyterian Hospital, New York, New York
| | - Maria V. Revuelta
- Division of Hematology and Oncology, Medicine Department, Weill Cornell Medicine and NewYork-Presbyterian Hospital, New York, New York
| | - Nahuel Zamponi
- Division of Hematology and Oncology, Medicine Department, Weill Cornell Medicine and NewYork-Presbyterian Hospital, New York, New York
| | - Biljana Culjkovic-Kraljacic
- Institute for Research in Immunology and Cancer and Department of Pathology and Cell Biology, University of Montreal, Montreal, Canada
| | | | - Nicolás Di Siervi
- Division of Hematology and Oncology, Medicine Department, Weill Cornell Medicine and NewYork-Presbyterian Hospital, New York, New York
| | - Juan Lara-Garcia
- Division of Hematology and Oncology, Medicine Department, Weill Cornell Medicine and NewYork-Presbyterian Hospital, New York, New York
| | - John N. Allan
- Division of Hematology and Oncology, Medicine Department, Weill Cornell Medicine and NewYork-Presbyterian Hospital, New York, New York
| | - Jia Ruan
- Division of Hematology and Oncology, Medicine Department, Weill Cornell Medicine and NewYork-Presbyterian Hospital, New York, New York
| | - Richard R. Furman
- Division of Hematology and Oncology, Medicine Department, Weill Cornell Medicine and NewYork-Presbyterian Hospital, New York, New York
| | - Zhengming Chen
- Division of Biostatistics, Population Health Sciences Department, Weill Cornell Medicine, New York, New York
| | - Tsiporah B. Shore
- Division of Hematology and Oncology, Medicine Department, Weill Cornell Medicine and NewYork-Presbyterian Hospital, New York, New York
| | - Adrienne A. Phillips
- Division of Hematology and Oncology, Medicine Department, Weill Cornell Medicine and NewYork-Presbyterian Hospital, New York, New York
| | - Sebastian Mayer
- Division of Hematology and Oncology, Medicine Department, Weill Cornell Medicine and NewYork-Presbyterian Hospital, New York, New York
| | - Jingmei Hsu
- New York University Grossman School of Medicine, New York, New York
| | | | - John P. Leonard
- Division of Hematology and Oncology, Medicine Department, Weill Cornell Medicine and NewYork-Presbyterian Hospital, New York, New York
| | - Katherine L.B. Borden
- Institute for Research in Immunology and Cancer and Department of Pathology and Cell Biology, University of Montreal, Montreal, Canada
| | - Giorgio Inghirami
- Pathology and Laboratory Medicine Department, Weill Cornell Medicine and NewYork-Presbyterian Hospital, New York, New York
| | - Peter Martin
- Division of Hematology and Oncology, Medicine Department, Weill Cornell Medicine and NewYork-Presbyterian Hospital, New York, New York
| | - Leandro Cerchietti
- Division of Hematology and Oncology, Medicine Department, Weill Cornell Medicine and NewYork-Presbyterian Hospital, New York, New York
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Li Y, Ma H, Wu Y, Ma Y, Yang J, Li Y, Yue D, Zhang R, Kong J, Lindsey K, Zhang X, Min L. Single-Cell Transcriptome Atlas and Regulatory Dynamics in Developing Cotton Anthers. Adv Sci (Weinh) 2024; 11:e2304017. [PMID: 37974530 PMCID: PMC10797427 DOI: 10.1002/advs.202304017] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/18/2023] [Revised: 10/08/2023] [Indexed: 11/19/2023]
Abstract
Plant anthers are composed of different specialized cell types with distinct roles in plant reproduction. High temperature (HT) stress causes male sterility, resulting in crop yield reduction. However, the spatial expression atlas and regulatory dynamics during anther development and in response to HT remain largely unknown. Here, the first single-cell transcriptome atlas and chromatin accessibility survey in cotton anther are established, depicting the specific expression and epigenetic landscape of each type of cell in anthers. The reconstruction of meiotic cells, tapetal cells, and middle layer cell developmental trajectories not only identifies novel expressed genes, but also elucidates the precise degradation period of middle layer and reveals a rapid function transition of tapetal cells during the tetrad stage. By applying HT, heterogeneity in HT response is shown among cells of anthers, with tapetal cells responsible for pollen wall synthesis are most sensitive to HT. Specifically, HT shuts down the chromatin accessibility of genes specifically expressed in the tapetal cells responsible for pollen wall synthesis, such as QUARTET 3 (QRT3) and CYTOCHROME P450 703A2 (CYP703A2), resulting in a silent expression of these genes, ultimately leading to abnormal pollen wall and male sterility. Collectively, this study provides substantial information on anthers and provides clues for heat-tolerant crop creation.
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Affiliation(s)
- Yanlong Li
- National Key Laboratory of Crop Genetic Improvement & Hubei Hongshan LaboratoryHuazhong Agricultural UniversityWuhanHubei430070China
| | - Huanhuan Ma
- National Key Laboratory of Crop Genetic Improvement & Hubei Hongshan LaboratoryHuazhong Agricultural UniversityWuhanHubei430070China
| | - Yuanlong Wu
- National Key Laboratory of Crop Genetic Improvement & Hubei Hongshan LaboratoryHuazhong Agricultural UniversityWuhanHubei430070China
| | - Yizan Ma
- National Key Laboratory of Crop Genetic Improvement & Hubei Hongshan LaboratoryHuazhong Agricultural UniversityWuhanHubei430070China
| | - Jing Yang
- National Key Laboratory of Crop Genetic Improvement & Hubei Hongshan LaboratoryHuazhong Agricultural UniversityWuhanHubei430070China
| | - Yawei Li
- National Key Laboratory of Crop Genetic Improvement & Hubei Hongshan LaboratoryHuazhong Agricultural UniversityWuhanHubei430070China
| | - Dandan Yue
- National Key Laboratory of Crop Genetic Improvement & Hubei Hongshan LaboratoryHuazhong Agricultural UniversityWuhanHubei430070China
| | - Rui Zhang
- National Key Laboratory of Crop Genetic Improvement & Hubei Hongshan LaboratoryHuazhong Agricultural UniversityWuhanHubei430070China
| | - Jie Kong
- Institute of Economic CropsXinjiang Academy of Agricultural SciencesXinjiang830091China
| | - Keith Lindsey
- Department of BiosciencesDurham UniversityDurham27710UK
| | - Xianlong Zhang
- National Key Laboratory of Crop Genetic Improvement & Hubei Hongshan LaboratoryHuazhong Agricultural UniversityWuhanHubei430070China
| | - Ling Min
- National Key Laboratory of Crop Genetic Improvement & Hubei Hongshan LaboratoryHuazhong Agricultural UniversityWuhanHubei430070China
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Timcheva K, Dufour S, Touat-Todeschini L, Burnard C, Carpentier MC, Chuffart F, Merret R, Helsmoortel M, Ferré S, Grézy A, Couté Y, Rousseaux S, Khochbin S, Vourc'h C, Bousquet-Antonelli C, Kiernan R, Seigneurin-Berny D, Verdel A. Chromatin-associated YTHDC1 coordinates heat-induced reprogramming of gene expression. Cell Rep 2022; 41:111784. [PMID: 36516773 DOI: 10.1016/j.celrep.2022.111784] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2021] [Revised: 08/01/2022] [Accepted: 11/15/2022] [Indexed: 12/15/2022] Open
Abstract
Heat stress (HS) induces a cellular response leading to profound changes in gene expression. Here, we show that human YTHDC1, a reader of N6-methyladenosine (m6A) RNA modification, mostly associates to the chromatin fraction and that HS induces a redistribution of YTHDC1 across the genome, including to heat-induced heat shock protein (HSP) genes. YTHDC1 binding to m6A-modified HSP transcripts co-transcriptionally promotes expression of HSPs. In parallel, hundreds of the genes enriched in YTHDC1 during HS have their transcripts undergoing YTHDC1- and m6A-dependent intron retention. Later, YTHDC1 concentrates within nuclear stress bodies (nSBs) where it binds to m6A-modified SATIII non-coding RNAs, produced in an HSF1-dependent manner upon HS. These findings reveal that YTHDC1 plays a central role in a chromatin-associated m6A-based reprogramming of gene expression during HS. Furthermore, they support the model where the subsequent and temporary sequestration of YTHDC1 within nSBs calibrates the timing of this YTHDC1-dependent gene expression reprogramming.
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Affiliation(s)
- Kalina Timcheva
- RNA, Epigenetics and Stress, Institut pour l'Avancée des Biosciences, CR UGA/Inserm U1209/CNRS UMR5309, Site Santé - Allée des Alpes, 38700 La Tronche, France
| | - Solenne Dufour
- RNA, Epigenetics and Stress, Institut pour l'Avancée des Biosciences, CR UGA/Inserm U1209/CNRS UMR5309, Site Santé - Allée des Alpes, 38700 La Tronche, France
| | - Leila Touat-Todeschini
- RNA, Epigenetics and Stress, Institut pour l'Avancée des Biosciences, CR UGA/Inserm U1209/CNRS UMR5309, Site Santé - Allée des Alpes, 38700 La Tronche, France
| | - Callum Burnard
- Gene Regulation Laboratory, Institut de Génétique Humaine, UMR9002, 141 rue de la Cardonille, 34396 Montpellier, France
| | - Marie-Christine Carpentier
- University Perpignan Via Domitia, LGDP-UMR5096, 58 Av. Paul Alduy, 66860 Perpignan, France; CNRS LGDP-UMR5096, UPVD, 58 Av. Paul Alduy, 66860 Perpignan, France
| | - Florent Chuffart
- Epigenetic Regulations, Institut pour l'Avancée des Biosciences, CR UGA/Inserm U1209/CNRS UMR5309, Site Santé - Allée des Alpes, 38700 La Tronche, France
| | - Rémy Merret
- University Perpignan Via Domitia, LGDP-UMR5096, 58 Av. Paul Alduy, 66860 Perpignan, France; CNRS LGDP-UMR5096, UPVD, 58 Av. Paul Alduy, 66860 Perpignan, France
| | - Marion Helsmoortel
- Gene Regulation Laboratory, Institut de Génétique Humaine, UMR9002, 141 rue de la Cardonille, 34396 Montpellier, France
| | - Sabrina Ferré
- University Grenoble Alpes, Inserm, CEA, UMR BioSanté U1292, CNRS, CEA, FR2048, 38000 Grenoble, France
| | - Aude Grézy
- RNA, Epigenetics and Stress, Institut pour l'Avancée des Biosciences, CR UGA/Inserm U1209/CNRS UMR5309, Site Santé - Allée des Alpes, 38700 La Tronche, France
| | - Yohann Couté
- University Grenoble Alpes, Inserm, CEA, UMR BioSanté U1292, CNRS, CEA, FR2048, 38000 Grenoble, France
| | - Sophie Rousseaux
- Epigenetic Regulations, Institut pour l'Avancée des Biosciences, CR UGA/Inserm U1209/CNRS UMR5309, Site Santé - Allée des Alpes, 38700 La Tronche, France
| | - Saadi Khochbin
- Epigenetic Regulations, Institut pour l'Avancée des Biosciences, CR UGA/Inserm U1209/CNRS UMR5309, Site Santé - Allée des Alpes, 38700 La Tronche, France
| | - Claire Vourc'h
- RNA, Epigenetics and Stress, Institut pour l'Avancée des Biosciences, CR UGA/Inserm U1209/CNRS UMR5309, Site Santé - Allée des Alpes, 38700 La Tronche, France
| | - Cécile Bousquet-Antonelli
- University Perpignan Via Domitia, LGDP-UMR5096, 58 Av. Paul Alduy, 66860 Perpignan, France; CNRS LGDP-UMR5096, UPVD, 58 Av. Paul Alduy, 66860 Perpignan, France
| | - Rosemary Kiernan
- Gene Regulation Laboratory, Institut de Génétique Humaine, UMR9002, 141 rue de la Cardonille, 34396 Montpellier, France
| | - Daphné Seigneurin-Berny
- RNA, Epigenetics and Stress, Institut pour l'Avancée des Biosciences, CR UGA/Inserm U1209/CNRS UMR5309, Site Santé - Allée des Alpes, 38700 La Tronche, France.
| | - André Verdel
- RNA, Epigenetics and Stress, Institut pour l'Avancée des Biosciences, CR UGA/Inserm U1209/CNRS UMR5309, Site Santé - Allée des Alpes, 38700 La Tronche, France.
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5
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Rudzka M, Wróblewska-Ankiewicz P, Majewska K, Hyjek-Składanowska M, Gołębiewski M, Sikora M, Smoliński DJ, Kołowerzo-Lubnau A. Functional nuclear retention of pre-mRNA involving Cajal bodies during meiotic prophase in European larch (Larix decidua). Plant Cell 2022; 34:2404-2423. [PMID: 35294035 PMCID: PMC9134060 DOI: 10.1093/plcell/koac091] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/19/2021] [Accepted: 03/11/2022] [Indexed: 06/14/2023]
Abstract
Gene regulation ensures that the appropriate genes are expressed at the proper time. Nuclear retention of incompletely spliced or mature mRNAs is emerging as a novel, previously underappreciated layer of posttranscriptional regulation. Studies on this phenomenon indicated that it exerts a significant influence on the regulation of gene expression by regulating export and translation delay, which allows the synthesis of specific proteins in response to a stimulus or at strictly controlled time points, for example, during cell differentiation or development. Here, we show that transcription in microsporocytes of European larch (Larix decidua) occurs in a pulsatile manner during prophase of the first meiotic division. Transcriptional activity was then silenced after each pulse. However, the transcripts synthesized were not exported immediately to the cytoplasm but were retained in the nucleoplasm and Cajal bodies (CBs). In contrast to the nucleoplasm, we did not detect mature transcripts in CBs, which only stored nonfully spliced transcripts with retained introns. Notably, the retained introns were spliced at precisely defined times, and fully mature mRNAs were released into the cytoplasm for translation. As similar processes have been observed during spermatogenesis in animals, our results illustrate an evolutionarily conserved mechanism of gene expression regulation during generative cells development in Eukaryota.
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Affiliation(s)
- Magda Rudzka
- Department of Cellular and Molecular Biology, Nicolaus Copernicus University, Torun 87-100, Poland
- Centre for Modern Interdisciplinary Technologies, Nicolaus Copernicus University, Torun 87-100, Poland
| | - Patrycja Wróblewska-Ankiewicz
- Department of Cellular and Molecular Biology, Nicolaus Copernicus University, Torun 87-100, Poland
- Centre for Modern Interdisciplinary Technologies, Nicolaus Copernicus University, Torun 87-100, Poland
| | - Karolina Majewska
- Department of Cellular and Molecular Biology, Nicolaus Copernicus University, Torun 87-100, Poland
- Centre for Modern Interdisciplinary Technologies, Nicolaus Copernicus University, Torun 87-100, Poland
| | | | - Marcin Gołębiewski
- Centre for Modern Interdisciplinary Technologies, Nicolaus Copernicus University, Torun 87-100, Poland
- Department of Plant Physiology and Biotechnology, Nicolaus Copernicus University, Torun 87-100, Poland
| | - Marcin Sikora
- Centre for Modern Interdisciplinary Technologies, Nicolaus Copernicus University, Torun 87-100, Poland
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González-rubio G, Sastre-vergara L, Molina M, Martín H, Fernández-acero T. Substrates of the MAPK Slt2: Shaping Yeast Cell Integrity. J Fungi (Basel) 2022; 8:368. [PMID: 35448599 PMCID: PMC9031059 DOI: 10.3390/jof8040368] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2022] [Revised: 03/30/2022] [Accepted: 03/31/2022] [Indexed: 02/04/2023] Open
Abstract
The cell wall integrity (CWI) MAPK pathway of budding yeast Saccharomyces cerevisiae is specialized in responding to cell wall damage, but ongoing research shows that it participates in many other stressful conditions, suggesting that it has functional diversity. The output of this pathway is mainly driven by the activity of the MAPK Slt2, which regulates important processes for yeast physiology such as fine-tuning of signaling through the CWI and other pathways, transcriptional activation in response to cell wall damage, cell cycle, or determination of the fate of some organelles. To this end, Slt2 precisely phosphorylates protein substrates, modulating their activity, stability, protein interaction, and subcellular localization. Here, after recapitulating the methods that have been employed in the discovery of proteins phosphorylated by Slt2, we review the bona fide substrates of this MAPK and the growing set of candidates still to be confirmed. In the context of the complexity of MAPK signaling regulation, we discuss how Slt2 determines yeast cell integrity through phosphorylation of these substrates. Increasing data from large-scale analyses and the available methodological approaches pave the road to early identification of new Slt2 substrates and functions.
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7
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Carey SB, Bolger TA. Translational control by helicases during cellular stress. Methods Enzymol 2022; 673:103-140. [DOI: 10.1016/bs.mie.2022.03.056] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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Wang C, Barr K, Neutel D, Roy K, Liu Y, Chanfreau GF. Stress-induced inhibition of mRNA export triggers RNase III-mediated decay of the BDF2 mRNA. RNA 2021; 27:1545-1556. [PMID: 34497070 PMCID: PMC8594472 DOI: 10.1261/rna.078880.121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/02/2021] [Accepted: 09/01/2021] [Indexed: 06/13/2023]
Abstract
The expression of bromodomain-containing proteins that regulate chromatin structure and accessibility must be tightly controlled to ensure the appropriate regulation of gene expression. In the yeast S. cerevisiae, Bromodomain Factor 2 (BDF2) expression is extensively regulated post-transcriptionally during stress by RNase III-mediated decay (RMD), which is triggered by cleavage of the BDF2 mRNA in the nucleus by the RNase III homolog Rnt1p. Previous studies have shown that RMD-mediated down-regulation of BDF2 is hyperactivated in osmotic stress conditions, yet the mechanisms driving the enhanced nuclear cleavage of BDF2 RNA under these conditions remain unknown. Here, we show that RMD hyperactivation can be detected in multiple stress conditions that inhibit mRNA export, and that Rnt1p remains primarily localized in the nucleus during salt stress. We show that globally inhibiting mRNA nuclear export by anchoring away mRNA biogenesis or export factors out of the nucleus can recapitulate RMD hyperactivation in the absence of stress. RMD hyperactivation requires Rnt1p nuclear localization but does not depend on the BDF2 gene endogenous promoter, and its efficiency is affected by the structure of the stem-loop cleaved by Rnt1p. Because multiple stress conditions have been shown to mediate global inhibition of mRNA export, our results suggest that the hyperactivation of RMD is primarily the result of the increased nuclear retention of the BDF2 mRNA during stress.
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Affiliation(s)
- Charles Wang
- Department of Chemistry and Biochemistry, UCLA, Los Angeles, California 90095, USA
| | - Keaton Barr
- Department of Chemistry and Biochemistry, UCLA, Los Angeles, California 90095, USA
| | - Dean Neutel
- Department of Chemistry and Biochemistry, UCLA, Los Angeles, California 90095, USA
| | - Kevin Roy
- Department of Chemistry and Biochemistry, UCLA, Los Angeles, California 90095, USA
- Molecular Biology Institute, UCLA, Los Angeles, California 90095, USA
| | - Yanru Liu
- Department of Chemistry and Biochemistry, UCLA, Los Angeles, California 90095, USA
| | - Guillaume F Chanfreau
- Department of Chemistry and Biochemistry, UCLA, Los Angeles, California 90095, USA
- Molecular Biology Institute, UCLA, Los Angeles, California 90095, USA
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9
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Aryanpur PP, Mittelmeier TM, Bolger TA. The RNA helicase Ded1 regulates translation and granule formation during multiple phases of cellular stress responses. Mol Cell Biol 2021;:MCB0024421. [PMID: 34723653 DOI: 10.1128/MCB.00244-21] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Ded1 is a conserved RNA helicase that promotes translation initiation in steady-state conditions. Ded1 has also been shown to regulate translation during cellular stress and affect the dynamics of stress granules (SGs), accumulations of RNA and protein linked to translation repression. To better understand its role in stress responses, we examined Ded1 function in two different models: DED1 overexpression and oxidative stress. DED1 overexpression inhibits growth and promotes the formation of SGs. A ded1 mutant lacking the low-complexity C-terminal region (ded1-ΔCT), which mediates Ded1 oligomerization and interaction with the translation factor eIF4G1, suppressed these phenotypes, consistent with other stresses. During oxidative stress, a ded1-ΔCT mutant was defective in growth and in SG formation compared to wild-type cells, although SGs were increased rather than decreased in these conditions. Unlike stress induced by direct TOR inhibition, the phenotypes in both models were only partially dependent on eIF4G1 interaction, suggesting an additional contribution from Ded1 oligomerization. Furthermore, examination of the growth defects and translational changes during oxidative stress suggested that Ded1 plays a role during recovery from stress. Integrating these disparate results, we propose that Ded1 controls multiple aspects of translation and RNP dynamics in both initial stress responses and during recovery.
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Adams RL, Wente SR. Dbp5 associates with RNA-bound Mex67 and Nab2 and its localization at the nuclear pore complex is sufficient for mRNP export and cell viability. PLoS Genet 2020; 16:e1009033. [PMID: 33002012 PMCID: PMC7553267 DOI: 10.1371/journal.pgen.1009033] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2020] [Revised: 10/13/2020] [Accepted: 08/06/2020] [Indexed: 01/04/2023] Open
Abstract
In Saccharomyces cerevisiae, the mRNA export receptor Mex67 is recruited to mature nuclear transcripts to mediate mRNA export through the nuclear pore complex (NPC) to the cytoplasm. Mex67 binds transcripts through adaptor proteins such as the poly(A) binding protein Nab2. When a transcript reaches the cytoplasmic face of the NPC, the DEAD-box protein Dbp5 acts to induce a local structural change to release Nab2 and Mex67 in an essential process termed mRNP remodeling. It is unknown how certain proteins (Nab2, Mex67) are released during Dbp5-mediated mRNP remodeling, whereas others remain associated. Here, we demonstrate that Dbp5 associates in close proximity with Mex67 and Nab2 in a cellular complex. Further, fusion of Dbp5 to Nup159 anchors Dbp5 at the cytoplasmic face of the NPC and is sufficient for cell viability. Thus, we speculate that the essential role of Dbp5 in remodeling exporting mRNPs requires its localization to the NPC and is separable from other subcellular functions of Dbp5. This work supports a model where the diverse nuclear, cytoplasmic and NPC functions of Dbp5 in the mRNA lifecycle are not interdependent and that Dbp5 is locally recruited through complex protein-protein interactions to select regions of transcripts for specific removal of transport proteins at the NPC.
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Affiliation(s)
- Rebecca L. Adams
- Department of Cell and Developmental Biology, Vanderbilt University School of Medicine, Nashville, Tennessee, United States of America
| | - Susan R. Wente
- Department of Cell and Developmental Biology, Vanderbilt University School of Medicine, Nashville, Tennessee, United States of America
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11
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Zarnack K, Balasubramanian S, Gantier MP, Kunetsky V, Kracht M, Schmitz ML, Sträßer K. Dynamic mRNP Remodeling in Response to Internal and External Stimuli. Biomolecules 2020; 10:biom10091310. [PMID: 32932892 PMCID: PMC7565591 DOI: 10.3390/biom10091310] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2020] [Revised: 09/02/2020] [Accepted: 09/08/2020] [Indexed: 02/06/2023] Open
Abstract
Signal transduction and the regulation of gene expression are fundamental processes in every cell. RNA-binding proteins (RBPs) play a key role in the post-transcriptional modulation of gene expression in response to both internal and external stimuli. However, how signaling pathways regulate the assembly of RBPs with mRNAs remains largely unknown. Here, we summarize observations showing that the formation and composition of messenger ribonucleoprotein particles (mRNPs) is dynamically remodeled in space and time by specific signaling cascades and the resulting post-translational modifications. The integration of signaling events with gene expression is key to the rapid adaptation of cells to environmental changes and stress. Only a combined approach analyzing the signal transduction pathways and the changes in post-transcriptional gene expression they cause will unravel the mechanisms coordinating these important cellular processes.
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Affiliation(s)
- Kathi Zarnack
- Buchmann Institute for Molecular Life Sciences, Goethe University Frankfurt, 60438 Frankfurt a.M., Germany;
| | | | - Michael P. Gantier
- Centre for Innate Immunity and Infectious Diseases, Hudson Institute of Medical Research, Clayton, VIC 3168, Australia;
- Department of Molecular and Translational Science, Monash University, Clayton, VIC 3800, Australia
| | - Vladislav Kunetsky
- Institute of Biochemistry, FB08, Justus Liebig University, 35392 Giessen, Germany;
| | - Michael Kracht
- Rudolf Buchheim Institute of Pharmacology, FB11, Justus Liebig University, 35392 Giessen, Germany;
| | - M. Lienhard Schmitz
- Institute of Biochemistry, FB11, Justus Liebig University, 35392 Giessen, Germany;
| | - Katja Sträßer
- Institute of Biochemistry, FB08, Justus Liebig University, 35392 Giessen, Germany;
- Correspondence:
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12
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Haas R, Horev G, Lipkin E, Kesten I, Portnoy M, Buhnik-Rosenblau K, Soller M, Kashi Y. Mapping Ethanol Tolerance in Budding Yeast Reveals High Genetic Variation in a Wild Isolate. Front Genet 2019; 10:998. [PMID: 31824552 PMCID: PMC6879558 DOI: 10.3389/fgene.2019.00998] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2019] [Accepted: 09/18/2019] [Indexed: 01/08/2023] Open
Abstract
Ethanol tolerance, a polygenic trait of the yeast Saccharomyces cerevisiae, is the primary factor determining industrial bioethanol productivity. Until now, genomic elements affecting ethanol tolerance have been mapped only at low resolution, hindering their identification. Here, we explore the genetic architecture of ethanol tolerance, in the F6 generation of an Advanced Intercrossed Line (AIL) mapping population between two phylogenetically distinct, but phenotypically similar, S. cerevisiae strains (a common laboratory strain and a wild strain isolated from nature). Under ethanol stress, 51 quantitative trait loci (QTLs) affecting growth and 96 QTLs affecting survival, most of them novel, were identified, with high resolution, in some cases to single genes, using a High-Resolution Mapping Package of methodologies that provided high power and high resolution. We confirmed our results experimentally by showing the effects of the novel mapped genes: MOG1, MGS1, and YJR154W. The mapped QTLs explained 34% of phenotypic variation for growth and 72% for survival. High statistical power provided by our analysis allowed detection of many loci with small, but mappable effects, uncovering a novel “quasi-infinitesimal” genetic architecture. These results are striking demonstration of tremendous amounts of hidden genetic variation exposed in crosses between phylogenetically separated strains with similar phenotypes; as opposed to the more common design where strains with distinct phenotypes are crossed. Our findings suggest that ethanol tolerance is under natural evolutionary fitness-selection for an optimum phenotype that would tend to eliminate alleles of large effect. The study provides a platform for development of superior ethanol-tolerant strains using genome editing or selection.
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Affiliation(s)
- Roni Haas
- Faculty of Biotechnology and Food Engineering, Technion, Haifa, Israel
| | - Guy Horev
- Lorey I. Lokey Interdisciplinary Center for Life Sciences and Engineering, Technion-Israel Institute of Technology, Haifa, Israel
| | - Ehud Lipkin
- Department of Genetics, Silberman Life Sciences Institute, The Hebrew University of Edmond Safra Campus, Jerusalem, Israel
| | - Inbar Kesten
- Faculty of Biotechnology and Food Engineering, Technion, Haifa, Israel
| | - Maya Portnoy
- Faculty of Biotechnology and Food Engineering, Technion, Haifa, Israel
| | | | - Morris Soller
- Department of Genetics, Silberman Life Sciences Institute, The Hebrew University of Edmond Safra Campus, Jerusalem, Israel
| | - Yechezkel Kashi
- Faculty of Biotechnology and Food Engineering, Technion, Haifa, Israel
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13
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Martín-Expósito M, Gas ME, Mohamad N, Nuño-Cabanes C, Tejada-Colón A, Pascual-García P, de la Fuente L, Chaves-Arquero B, Merran J, Corden J, Conesa A, Pérez-Cañadillas JM, Bravo J, Rodríguez-Navarro S. Mip6 binds directly to the Mex67 UBA domain to maintain low levels of Msn2/4 stress-dependent mRNAs. EMBO Rep 2019; 20:e47964. [PMID: 31680439 DOI: 10.15252/embr.201947964] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2019] [Revised: 08/30/2019] [Accepted: 09/11/2019] [Indexed: 11/09/2022] Open
Abstract
RNA-binding proteins (RBPs) participate in all steps of gene expression, underscoring their potential as regulators of RNA homeostasis. We structurally and functionally characterize Mip6, a four-RNA recognition motif (RRM)-containing RBP, as a functional and physical interactor of the export factor Mex67. Mip6-RRM4 directly interacts with the ubiquitin-associated (UBA) domain of Mex67 through a loop containing tryptophan 442. Mip6 shuttles between the nucleus and the cytoplasm in a Mex67-dependent manner and concentrates in cytoplasmic foci under stress. Photoactivatable ribonucleoside-enhanced crosslinking and immunoprecipitation experiments show preferential binding of Mip6 to mRNAs regulated by the stress-response Msn2/4 transcription factors. Consistent with this binding, MIP6 deletion affects their export and expression levels. Additionally, Mip6 interacts physically and/or functionally with proteins with a role in mRNA metabolism and transcription such as Rrp6, Xrn1, Sgf73, and Rpb1. These results reveal a novel role for Mip6 in the homeostasis of Msn2/4-dependent transcripts through its direct interaction with the Mex67 UBA domain.
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Affiliation(s)
- Manuel Martín-Expósito
- Gene Expression and RNA Metabolism Laboratory, Instituto de Biomedicina de Valencia (CSIC), Valencia, Spain.,Gene Expression and RNA Metabolism Laboratory, Centro de Investigación Príncipe Felipe (CIPF), Valencia, Spain
| | - Maria-Eugenia Gas
- Gene Expression and RNA Metabolism Laboratory, Centro de Investigación Príncipe Felipe (CIPF), Valencia, Spain
| | - Nada Mohamad
- Signal Transduction Laboratory, Instituto de Biomedicina de Valencia (CSIC), Valencia, Spain
| | - Carme Nuño-Cabanes
- Gene Expression and RNA Metabolism Laboratory, Instituto de Biomedicina de Valencia (CSIC), Valencia, Spain.,Gene Expression and RNA Metabolism Laboratory, Centro de Investigación Príncipe Felipe (CIPF), Valencia, Spain
| | - Ana Tejada-Colón
- Gene Expression and RNA Metabolism Laboratory, Instituto de Biomedicina de Valencia (CSIC), Valencia, Spain
| | - Pau Pascual-García
- Gene Expression and RNA Metabolism Laboratory, Centro de Investigación Príncipe Felipe (CIPF), Valencia, Spain
| | - Lorena de la Fuente
- Genomics of Gene Expression Laboratory, Centro de Investigación Príncipe Felipe (CIPF), Valencia, Spain
| | - Belén Chaves-Arquero
- Department of Biological Physical Chemistry, Institute of Physical-Chemistry "Rocasolano" (CSIC), Madrid, Spain
| | - Jonathan Merran
- Department of Molecular Biology and Genetics, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Jeffry Corden
- Department of Molecular Biology and Genetics, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Ana Conesa
- Genetics Institute, University of Florida, Gainesville, FL, USA.,Microbiology and Cell Science Department, Institute for Food and Agricultural Research, University of Florida, Gainesville, FL, USA
| | | | - Jerónimo Bravo
- Signal Transduction Laboratory, Instituto de Biomedicina de Valencia (CSIC), Valencia, Spain
| | - Susana Rodríguez-Navarro
- Gene Expression and RNA Metabolism Laboratory, Instituto de Biomedicina de Valencia (CSIC), Valencia, Spain.,Gene Expression and RNA Metabolism Laboratory, Centro de Investigación Príncipe Felipe (CIPF), Valencia, Spain
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14
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Jean-Baptiste K, McFaline-Figueroa JL, Alexandre CM, Dorrity MW, Saunders L, Bubb KL, Trapnell C, Fields S, Queitsch C, Cuperus JT. Dynamics of Gene Expression in Single Root Cells of Arabidopsis thaliana. Plant Cell 2019. [PMID: 30923229 DOI: 10.1101/448514] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/16/2023]
Abstract
Single cell RNA sequencing can yield high-resolution cell-type-specific expression signatures that reveal new cell types and the developmental trajectories of cell lineages. Here, we apply this approach to Arabidopsis (Arabidopsis thaliana) root cells to capture gene expression in 3,121 root cells. We analyze these data with Monocle 3, which orders single cell transcriptomes in an unsupervised manner and uses machine learning to reconstruct single cell developmental trajectories along pseudotime. We identify hundreds of genes with cell-type-specific expression, with pseudotime analysis of several cell lineages revealing both known and novel genes that are expressed along a developmental trajectory. We identify transcription factor motifs that are enriched in early and late cells, together with the corresponding candidate transcription factors that likely drive the observed expression patterns. We assess and interpret changes in total RNA expression along developmental trajectories and show that trajectory branch points mark developmental decisions. Finally, by applying heat stress to whole seedlings, we address the longstanding question of possible heterogeneity among cell types in the response to an abiotic stress. Although the response of canonical heat-shock genes dominates expression across cell types, subtle but significant differences in other genes can be detected among cell types. Taken together, our results demonstrate that single cell transcriptomics holds promise for studying plant development and plant physiology with unprecedented resolution.
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Affiliation(s)
- Ken Jean-Baptiste
- Department of Genome Sciences, University of Washington, Seattle, Washington 98195
| | | | - Cristina M Alexandre
- Department of Genome Sciences, University of Washington, Seattle, Washington 98195
| | - Michael W Dorrity
- Department of Genome Sciences, University of Washington, Seattle, Washington 98195
| | - Lauren Saunders
- Department of Genome Sciences, University of Washington, Seattle, Washington 98195
| | - Kerry L Bubb
- Department of Genome Sciences, University of Washington, Seattle, Washington 98195
| | - Cole Trapnell
- Department of Genome Sciences, University of Washington, Seattle, Washington 98195
| | - Stanley Fields
- Department of Genome Sciences, University of Washington, Seattle, Washington 98195
- Department of Medicine, University of Washington, Seattle, Washington 98195
| | - Christine Queitsch
- Department of Genome Sciences, University of Washington, Seattle, Washington 98195
| | - Josh T Cuperus
- Department of Genome Sciences, University of Washington, Seattle, Washington 98195
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15
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Mizuno Y, Ohtsu M, Shibata Y, Tanaka A, Camagna M, Ojika M, Mori H, Sato I, Chiba S, Kawakita K, Takemoto D. Nicotiana benthamiana RanBP1-1 Is Involved in the Induction of Disease Resistance via Regulation of Nuclear-Cytoplasmic Transport of Small GTPase Ran. Front Plant Sci 2019; 10:222. [PMID: 30906303 PMCID: PMC6418045 DOI: 10.3389/fpls.2019.00222] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/03/2018] [Accepted: 02/08/2019] [Indexed: 06/07/2023]
Abstract
Plant cells enhance the tolerances to abiotic and biotic stresses via recognition of the stress, activation and nuclear import of signaling factors, up-regulation of defense genes, nuclear export of mRNA and translation of defense proteins. Nuclear pore-mediated transports should play critical roles in these processes, however, the regulatory mechanisms of nuclear-cytoplasmic transport during stress responses are largely unknown. In this study, a regulator of nuclear export of RNA and proteins, NbRanBP1-1 (Ran-binding protein1-1), was identified as an essential gene for the resistance of Nicotiana benthamiana to potato blight pathogen Phytophthora infestans. NbRanBP1-1-silenced plants showed delayed accumulation of capsidiol, a sesquiterpenoid phytoalexin, in response to elicitor treatment, and reduced resistance to P. infestans. Abnormal accumulation of mRNA was observed in NbRanBP1-1-silenced plants, indicating that NbRanBP1-1 is involved in the nuclear export of mRNA. In NbRanBP1-1-silenced plants, elicitor-induced expression of defense genes, NbEAS and NbWIPK, was not affected in the early stage of defense induction, but the accumulation of NbWIPK protein was reduced. Nuclear export of the small G-protein NbRan1a was activated during the induction of plant defense, whereas this process was compromised in NbRanBP1-1-silenced plants. Silencing of genes encoding the nuclear pore proteins, Nup75 and Nup160, also caused abnormal nuclear accumulation of mRNA, defects in the nuclear export of NbRan1a, and reduced production of capsidiol, resulting in decreased resistance to P. infestans. These results suggest that nuclear export of NbRan is a key event for defense induction in N. benthamiana, and both RanBP1-1 and nucleoporins play important roles in the process.
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16
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Zhang K, Daigle JG, Cunningham KM, Coyne AN, Ruan K, Grima JC, Bowen KE, Wadhwa H, Yang P, Rigo F, Taylor JP, Gitler AD, Rothstein JD, Lloyd TE. Stress Granule Assembly Disrupts Nucleocytoplasmic Transport. Cell 2018; 173:958-971.e17. [PMID: 29628143 DOI: 10.1016/j.cell.2018.03.025] [Citation(s) in RCA: 238] [Impact Index Per Article: 39.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2017] [Revised: 01/08/2018] [Accepted: 03/06/2018] [Indexed: 01/21/2023]
Abstract
Defects in nucleocytoplasmic transport have been identified as a key pathogenic event in amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD) mediated by a GGGGCC hexanucleotide repeat expansion in C9ORF72, the most common genetic cause of ALS/FTD. Furthermore, nucleocytoplasmic transport disruption has also been implicated in other neurodegenerative diseases with protein aggregation, suggesting a shared mechanism by which protein stress disrupts nucleocytoplasmic transport. Here, we show that cellular stress disrupts nucleocytoplasmic transport by localizing critical nucleocytoplasmic transport factors into stress granules, RNA/protein complexes that play a crucial role in ALS pathogenesis. Importantly, inhibiting stress granule assembly, such as by knocking down Ataxin-2, suppresses nucleocytoplasmic transport defects as well as neurodegeneration in C9ORF72-mediated ALS/FTD. Our findings identify a link between stress granule assembly and nucleocytoplasmic transport, two fundamental cellular processes implicated in the pathogenesis of C9ORF72-mediated ALS/FTD and other neurodegenerative diseases.
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Affiliation(s)
- Ke Zhang
- Department of Neurology, School of Medicine, Johns Hopkins University, Baltimore, MD 21205, USA; Brain Science Institute, School of Medicine, Johns Hopkins University, Baltimore, MD 21205, USA
| | - J Gavin Daigle
- Department of Neurology, School of Medicine, Johns Hopkins University, Baltimore, MD 21205, USA; Brain Science Institute, School of Medicine, Johns Hopkins University, Baltimore, MD 21205, USA
| | - Kathleen M Cunningham
- Cellular and Molecular Medicine Program, School of Medicine, Johns Hopkins University, Baltimore, MD 21205, USA
| | - Alyssa N Coyne
- Department of Neurology, School of Medicine, Johns Hopkins University, Baltimore, MD 21205, USA; Brain Science Institute, School of Medicine, Johns Hopkins University, Baltimore, MD 21205, USA
| | - Kai Ruan
- Department of Neurology, School of Medicine, Johns Hopkins University, Baltimore, MD 21205, USA
| | - Jonathan C Grima
- Brain Science Institute, School of Medicine, Johns Hopkins University, Baltimore, MD 21205, USA; Solomon H. Snyder Department of Neuroscience, School of Medicine, Johns Hopkins University, Baltimore, MD 21205, USA
| | - Kelly E Bowen
- Department of Neurology, School of Medicine, Johns Hopkins University, Baltimore, MD 21205, USA; Brain Science Institute, School of Medicine, Johns Hopkins University, Baltimore, MD 21205, USA
| | - Harsh Wadhwa
- Department of Neurology, School of Medicine, Johns Hopkins University, Baltimore, MD 21205, USA
| | - Peiguo Yang
- Department of Cell and Molecular Biology, St. Jude Children's Research Hospital, Memphis, TN 38105, USA
| | - Frank Rigo
- Ionis Pharmaceuticals, Carlsbad, CA 92010, USA
| | - J Paul Taylor
- Department of Cell and Molecular Biology, St. Jude Children's Research Hospital, Memphis, TN 38105, USA; Department of Cell and Molecular Biology, Howard Hughes Medical Institute, St. Jude Children's Research Hospital, Memphis, TN 38105, USA
| | - Aaron D Gitler
- Department of Genetics, Stanford University, School of Medicine, Stanford, CA 94305, USA
| | - Jeffrey D Rothstein
- Department of Neurology, School of Medicine, Johns Hopkins University, Baltimore, MD 21205, USA; Brain Science Institute, School of Medicine, Johns Hopkins University, Baltimore, MD 21205, USA; Cellular and Molecular Medicine Program, School of Medicine, Johns Hopkins University, Baltimore, MD 21205, USA; Solomon H. Snyder Department of Neuroscience, School of Medicine, Johns Hopkins University, Baltimore, MD 21205, USA.
| | - Thomas E Lloyd
- Department of Neurology, School of Medicine, Johns Hopkins University, Baltimore, MD 21205, USA; Cellular and Molecular Medicine Program, School of Medicine, Johns Hopkins University, Baltimore, MD 21205, USA; Solomon H. Snyder Department of Neuroscience, School of Medicine, Johns Hopkins University, Baltimore, MD 21205, USA.
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17
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Zander G, Krebber H. Quick or quality? How mRNA escapes nuclear quality control during stress. RNA Biol 2017; 14:1642-1648. [PMID: 28708448 PMCID: PMC5731798 DOI: 10.1080/15476286.2017.1345835] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2017] [Revised: 06/19/2017] [Accepted: 06/20/2017] [Indexed: 10/19/2022] Open
Abstract
Understanding the mechanisms for mRNA production under normal conditions and in response to cytotoxic stresses has been subject of numerous studies for several decades. The shutdown of canonical mRNA transcription, export and translation is required to have enough free resources for the immediate production of heat shock proteins that act as chaperones to sustain cellular processes. In recent work we uncovered a simple mechanism, in which the export block of regular mRNAs and a fast export of heat shock mRNAs is achieved by deactivation of the nuclear mRNA quality control mediated by the guard proteins. In this point of view we combine long known data with recently gathered information that support this novel model, in which cells omit quality control of stress responsive transcripts to ensure survival.
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Affiliation(s)
- Gesa Zander
- Abteilung für Molekulare Genetik, Institut für Mikrobiologie und Genetik, Göttinger Zentrum für Molekulare Biowissenschaften (GZMB), Georg-August Universität Göttingen, Göttingen, Germany
| | - Heike Krebber
- Abteilung für Molekulare Genetik, Institut für Mikrobiologie und Genetik, Göttinger Zentrum für Molekulare Biowissenschaften (GZMB), Georg-August Universität Göttingen, Göttingen, Germany
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18
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Adams RL, Mason AC, Glass L, Aditi, Wente SR. Nup42 and IP 6 coordinate Gle1 stimulation of Dbp5/DDX19B for mRNA export in yeast and human cells. Traffic 2017; 18:776-790. [PMID: 28869701 DOI: 10.1111/tra.12526] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2017] [Revised: 08/30/2017] [Accepted: 08/30/2017] [Indexed: 11/30/2022]
Abstract
The mRNA lifecycle is driven through spatiotemporal changes in the protein composition of mRNA particles (mRNPs) that are triggered by RNA-dependent DEAD-box protein (Dbp) ATPases. As mRNPs exit the nuclear pore complex (NPC) in Saccharomyces cerevisiae, this remodeling occurs through activation of Dbp5 by inositol hexakisphosphate (IP6 )-bound Gle1. At the NPC, Gle1 also binds Nup42, but Nup42's molecular function is unclear. Here we employ the power of structure-function analysis in S. cerevisiae and human (h) cells, and find that the high-affinity Nup42-Gle1 interaction is integral to Dbp5 (hDDX19B) activation and efficient mRNA export. The Nup42 carboxy-terminal domain (CTD) binds Gle1/hGle1B at an interface distinct from the Gle1-Dbp5/hDDX19B interaction site. A nup42-CTD/gle1-CTD/Dbp5 trimeric complex forms in the presence of IP6 . Deletion of NUP42 abrogates Gle1-Dbp5 interaction, and disruption of the Nup42 or IP6 binding interfaces on Gle1/hGle1B leads to defective mRNA export in S. cerevisiae and human cells. In vitro, Nup42-CTD and IP6 stimulate Gle1/hGle1B activation of Dbp5 and DDX19B recombinant proteins in similar, nonadditive manners, demonstrating complete functional conservation between humans and S. cerevisiae. Together, a highly conserved mechanism governs spatial coordination of mRNP remodeling during export. This has implications for understanding human disease mutations that perturb the Nup42-hGle1B interaction.
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Affiliation(s)
- Rebecca L Adams
- Department of Cell and Developmental Biology, Vanderbilt University School of Medicine, Nashville, Tennessee
| | - Aaron C Mason
- Department of Cell and Developmental Biology, Vanderbilt University School of Medicine, Nashville, Tennessee
| | - Laura Glass
- Department of Cell and Developmental Biology, Vanderbilt University School of Medicine, Nashville, Tennessee
| | - Aditi
- Department of Cell and Developmental Biology, Vanderbilt University School of Medicine, Nashville, Tennessee
| | - Susan R Wente
- Department of Cell and Developmental Biology, Vanderbilt University School of Medicine, Nashville, Tennessee
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19
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Shan P, Fan G, Sun L, Liu J, Wang W, Hu C, Zhang X, Zhai Q, Song X, Cao L, Cui Y, Zhang S, Wang C. SIRT1 Functions as a Negative Regulator of Eukaryotic Poly(A)RNA Transport. Curr Biol 2017; 27:2271-2284.e5. [PMID: 28756945 DOI: 10.1016/j.cub.2017.06.040] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2016] [Revised: 05/04/2017] [Accepted: 06/15/2017] [Indexed: 10/19/2022]
Abstract
Most eukaryotic mRNAs are polyadenylated in the nucleus, and the poly(A)-tail is required for efficient mRNA export and translation. However, mechanisms governing mRNA transport remain unclear. Here, we report that the nicotinamide adenine dinucleotide (NAD)-dependent deacetylase SIRT1 acts as an energy sensor and negatively regulates poly(A)RNA transport via deacetylating a poly(A)-binding protein, PABP1. Upon energy starvation, SIRT1 interacts with and deacetylates PABP1 and deactivates its poly(A)RNA binding, leading to nuclear accumulation of PABP1 and poly(A)RNA and thus facilitating eukaryotic cells to attenuate protein synthesis and energy consumption to adapt to energy stress. Moreover, AMPK-directed SIRT1 phosphorylation is required for energy starvation-induced PABP1-SIRT1 association, PABP1 deacetylation, and poly(A)RNA nuclear retention. In addition, the SIRT1-PABP1 association is not specific to energy starvation but represents a common stress response. These observations provide insights into dynamic modulation of eukaryotic mRNA transport and translation, suggesting that the poly(A)-tail also provides a basis for eukaryotes to effectively shut down mature mRNA transport and thereby tailor protein synthesis to maintain energy homeostasis under stress conditions.
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Affiliation(s)
- Peipei Shan
- Institute of Translational Medicine, Shanghai General Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 201620, China
| | - Guangjian Fan
- Institute of Translational Medicine, Shanghai General Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 201620, China
| | - Lianhui Sun
- Institute of Translational Medicine, Shanghai General Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 201620, China
| | - Jinqin Liu
- Shanghai Key Laboratory of Regulatory Biology, Institute of Biomedical Sciences, East China Normal University, Shanghai 200241, China
| | - Weifang Wang
- Shanghai Key Laboratory of Regulatory Biology, Institute of Biomedical Sciences, East China Normal University, Shanghai 200241, China
| | - Chen Hu
- Department of Oncology, Karmanos Cancer Institute, Wayne State University School of Medicine, 4100 John R, Detroit, MI 48201, USA
| | - Xiaohong Zhang
- Department of Oncology, Karmanos Cancer Institute, Wayne State University School of Medicine, 4100 John R, Detroit, MI 48201, USA
| | - Qiwei Zhai
- Key Laboratory of Nutrition and Metabolism, Institute for Nutritional Sciences, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200031, China
| | - Xiaoyu Song
- Key Laboratory of Medical Cell Biology, College of Translational Medicine, China Medical University, Shengyang 110000, China
| | - Liu Cao
- Key Laboratory of Medical Cell Biology, College of Translational Medicine, China Medical University, Shengyang 110000, China
| | - Yongping Cui
- Key Laboratory of Cellular Physiology Ministry of Education, Shanxi Medical University, Shanxi 030001, China
| | - Shengping Zhang
- Institute of Translational Medicine, Shanghai General Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 201620, China.
| | - Chuangui Wang
- Institute of Translational Medicine, Shanghai General Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 201620, China; Department of Ophthalmology, Shanghai General Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 201620, China; Shanghai Key Laboratory of Fundus Diseases, 100 Haining Road, Shanghai 200080, China.
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20
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Yang Y, Wang W, Chu Z, Zhu JK, Zhang H. Roles of Nuclear Pores and Nucleo-cytoplasmic Trafficking in Plant Stress Responses. Front Plant Sci 2017; 8:574. [PMID: 28446921 PMCID: PMC5388774 DOI: 10.3389/fpls.2017.00574] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/02/2017] [Accepted: 03/30/2017] [Indexed: 05/29/2023]
Abstract
The nuclear pore complex (NPC) is a large protein complex that controls the exchange of components between the nucleus and the cytoplasm. In plants, the NPC family components play critical roles not only in essential growth and developmental processes, but also in plant responses to various environmental stress conditions. The involvement of NPC components in plant stress responses is mainly attributed to different mechanisms including control of mRNA/protein nucleo-cytoplasmic trafficking and transcriptional gene regulation. This mini review summarizes current knowledge of the NPC-mediated plant stress responses and provides an overview of the underlying molecular mechanisms.
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Affiliation(s)
- Yu Yang
- Shanghai Center for Plant Stress Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of SciencesShanghai, China
| | - Wei Wang
- Shanghai Key Laboratory of Plant Functional Genomics and Resources, Shanghai Chenshan Botanical GardenShanghai, China
- Shanghai Chenshan Plant Science Research Center, Chinese Academy of SciencesShanghai, China
| | - Zhaoqing Chu
- Shanghai Key Laboratory of Plant Functional Genomics and Resources, Shanghai Chenshan Botanical GardenShanghai, China
- Shanghai Chenshan Plant Science Research Center, Chinese Academy of SciencesShanghai, China
| | - Jian-Kang Zhu
- Shanghai Center for Plant Stress Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of SciencesShanghai, China
- Department of Horticulture and Landscape Architecture, Purdue University, West LafayetteIN, USA
| | - Huiming Zhang
- Shanghai Center for Plant Stress Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of SciencesShanghai, China
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21
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Ariyachet C, Beißel C, Li X, Lorrey S, Mackenzie O, Martin PM, O'Brien K, Pholcharee T, Sim S, Krebber H, McBride AE. Post-translational modification directs nuclear and hyphal tip localization of Candida albicans mRNA-binding protein Slr1. Mol Microbiol 2017; 104:499-519. [PMID: 28187496 PMCID: PMC5405739 DOI: 10.1111/mmi.13643] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/06/2017] [Indexed: 12/21/2022]
Abstract
The morphological transition of the opportunistic fungal pathogen Candida albicans from budding to hyphal growth has been implicated in its ability to cause disease in animal models. Absence of SR‐like RNA‐binding protein Slr1 slows hyphal formation and decreases virulence in a systemic candidiasis model, suggesting a role for post‐transcriptional regulation in these processes. SR (serine–arginine)‐rich proteins influence multiple steps in mRNA metabolism and their localization and function are frequently controlled by modification. We now demonstrate that Slr1 binds to polyadenylated RNA and that its intracellular localization is modulated by phosphorylation and methylation. Wildtype Slr1‐GFP is predominantly nuclear, but also co‐fractionates with translating ribosomes. The non‐phosphorylatable slr1‐6SA‐GFP protein, in which six serines in SR/RS clusters are substituted with alanines, primarily localizes to the cytoplasm in budding cells. Intriguingly, hyphal cells display a slr1‐6SA‐GFP focus at the tip near the Spitzenkörper, a vesicular structure involved in molecular trafficking to the tip. The presence of slr1‐6SA‐GFP hyphal tip foci is reduced in the absence of the mRNA‐transport protein She3, suggesting that unphosphorylated Slr1 associates with mRNA–protein complexes transported to the tip. The impact of SLR1 deletion on hyphal formation and function thus may be partially due to a role in hyphal mRNA transport.
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Affiliation(s)
| | - Christian Beißel
- Abteilung für Molekulare Genetik, Institut für Mikrobiologie und Genetik, Göttinger Zentrum für Molekulare Biowissenschaften, Georg-August Universität Göttingen, Göttingen, Germany
| | - Xiang Li
- Biology Department, Bowdoin College, Brunswick, ME, 04011, USA
| | - Selena Lorrey
- Biology Department, Bowdoin College, Brunswick, ME, 04011, USA
| | | | | | | | | | - Sue Sim
- Biology Department, Bowdoin College, Brunswick, ME, 04011, USA
| | - Heike Krebber
- Abteilung für Molekulare Genetik, Institut für Mikrobiologie und Genetik, Göttinger Zentrum für Molekulare Biowissenschaften, Georg-August Universität Göttingen, Göttingen, Germany
| | - Anne E McBride
- Biology Department, Bowdoin College, Brunswick, ME, 04011, USA
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22
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Masser AE, Kandasamy G, Kaimal JM, Andréasson C. Luciferase NanoLuc as a reporter for gene expression and protein levels in Saccharomyces cerevisiae. Yeast 2016; 33:191-200. [PMID: 26860732 PMCID: PMC5069653 DOI: 10.1002/yea.3155] [Citation(s) in RCA: 44] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2015] [Revised: 01/13/2016] [Accepted: 01/29/2016] [Indexed: 11/30/2022] Open
Abstract
Reporter proteins are essential tools in the study of biological processes and are employed to monitor changes in gene expression and protein levels. Luciferases are reporter proteins that enable rapid and highly sensitive detection with an outstanding dynamic range. Here we evaluated the usefulness of the 19 kDa luciferase NanoLuc (Nluc), derived from the deep sea shrimp Oplophorus gracilirostris, as a reporter protein in yeast. Cassettes with codon‐optimized genes expressing yeast Nluc (yNluc) or its destabilized derivative yNlucPEST have been assembled in the context of the dominant drug resistance marker kanMX. The reporter proteins do not impair the growth of yeast cells and exhibit half‐lives of 40 and 5 min, respectively. The commercial substrate Nano‐Glo® is compatible with detection of yNluc bioluminescence in < 50 cells. Using the unstable yNlucPEST to report on the rapid and transient expression of a heat‐shock promoter (PCYC1–HSE), we found a close match between the intensity of the bioluminescent signal and mRNA levels during both induction and decay. We demonstrated that the bioluminescence of yNluc fused to the C‐terminus of a temperature‐sensitive protein reports on its protein levels. In conclusion, yNluc and yNlucPEST are valuable new reporter proteins suitable for experiments with yeast using standard commercial substrate. © 2016 The Authors. Yeast published by John Wiley & Sons Ltd.
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Affiliation(s)
- Anna E Masser
- Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm University, Sweden
| | - Ganapathi Kandasamy
- Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm University, Sweden
| | | | - Claes Andréasson
- Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm University, Sweden
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23
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Sloan KE, Gleizes PE, Bohnsack MT. Nucleocytoplasmic Transport of RNAs and RNA-Protein Complexes. J Mol Biol 2015; 428:2040-59. [PMID: 26434509 DOI: 10.1016/j.jmb.2015.09.023] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2015] [Revised: 09/26/2015] [Accepted: 09/28/2015] [Indexed: 12/15/2022]
Abstract
RNAs and ribonucleoprotein complexes (RNPs) play key roles in mediating and regulating gene expression. In eukaryotes, most RNAs are transcribed, processed and assembled with proteins in the nucleus and then either function in the cytoplasm or also undergo a cytoplasmic phase in their biogenesis. This compartmentalization ensures that sequential steps in gene expression and RNP production are performed in the correct order and it allows important quality control mechanisms that prevent the involvement of aberrant RNAs/RNPs in these cellular pathways. The selective exchange of RNAs/RNPs between the nucleus and cytoplasm is enabled by nuclear pore complexes, which function as gateways between these compartments. RNA/RNP transport is facilitated by a range of nuclear transport receptors and adaptors, which are specifically recruited to their cargos and mediate interactions with nucleoporins to allow directional translocation through nuclear pore complexes. While some transport factors are only responsible for the export/import of a certain class of RNA/RNP, others are multifunctional and, in the case of large RNPs, several export factors appear to work together to bring about export. Recent structural studies have revealed aspects of the mechanisms employed by transport receptors to enable specific cargo recognition, and genome-wide approaches have provided the first insights into the diverse composition of pre-mRNPs during export. Furthermore, the regulation of RNA/RNP export is emerging as an important means to modulate gene expression under stress conditions and in disease.
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Affiliation(s)
- Katherine E Sloan
- Institute for Molecular Biology, Goettingen University Medical Department, 37073 Goettingen, Germany
| | - Pierre-Emmanuel Gleizes
- Laboratoire de Biologie Moléculaire Eucaryote, UMR 5099, Université de Toulouse-Paul Sabatier, CNRS, Toulouse, France
| | - Markus T Bohnsack
- Institute for Molecular Biology, Goettingen University Medical Department, 37073 Goettingen, Germany; Goettingen Centre for Molecular Biosciences, Georg-August-University, 37075 Goettingen, Germany.
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24
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Abstract
Post-transcriptional regulation of RNA facilitates the fine-tuning of gene expression. It occurs through multiple pathways that include the nuclear processing of mRNA and its precursors, mRNA silencing, regulation of mRNA decay, and regulation of translation. Poly(ADP-ribose) polymerases (PARPs), enzymes that modify target proteins with ADP-ribose, play important roles in many of the RNA regulatory pathways through multiple mechanisms. For example, RNA-binding PARPs can target specific transcripts for regulation, ADP-ribosylation of RNA-regulatory proteins can alter their localization, activity or RNA-binding, and non-covalent interactions of RNA-binding proteins with poly(ADP-ribose) can affect their function. In addition to regulating RNA during non-stress conditions, PARPs mediate RNA regulation during cellular stress conditions that are critical for the proper execution of a stress response. In this review, we summarize the current knowledge regarding PARP-dependent regulation of RNAs, and describe how by modulating RNA processing, translation and decay, PARPs impact multiple processes in the cell.
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Affiliation(s)
- Florian J Bock
- Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, 500 Main Street, Cambridge, MA 02139, USA
| | - Tanya T Todorova
- Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, 500 Main Street, Cambridge, MA 02139, USA; Department of Biology, Massachusetts Institute of Technology, 500 Main Street, Cambridge, MA 02139, USA
| | - Paul Chang
- Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, 500 Main Street, Cambridge, MA 02139, USA; Department of Biology, Massachusetts Institute of Technology, 500 Main Street, Cambridge, MA 02139, USA.
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25
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Bonnet A, Palancade B. Regulation of mRNA trafficking by nuclear pore complexes. Genes (Basel) 2014; 5:767-91. [PMID: 25184662 PMCID: PMC4198930 DOI: 10.3390/genes5030767] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2014] [Revised: 08/25/2014] [Accepted: 08/26/2014] [Indexed: 11/17/2022] Open
Abstract
Over the last two decades, multiple studies have explored the mechanisms governing mRNA export out of the nucleus, a crucial step in eukaryotic gene expression. During transcription and processing, mRNAs are assembled into messenger ribonucleoparticles (mRNPs). mRNPs are then exported through nuclear pore complexes (NPCs), which are large multiprotein assemblies made of several copies of a limited number of nucleoporins. A considerable effort has been put into the dissection of mRNA export through NPCs at both cellular and molecular levels, revealing the conserved contributions of a subset of nucleoporins in this process, from yeast to vertebrates. Several reports have also demonstrated the ability of NPCs to sort out properly-processed mRNPs for entry into the nuclear export pathway. Importantly, changes in mRNA export have been associated with post-translational modifications of nucleoporins or changes in NPC composition, depending on cell cycle progression, development or exposure to stress. How NPC modifications also impact on cellular mRNA export in disease situations, notably upon viral infection, is discussed.
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Affiliation(s)
- Amandine Bonnet
- Institut Jacques Monod, CNRS, UMR 7592, University Paris Diderot, Sorbonne Paris Cité, Paris F-75205, France.
| | - Benoit Palancade
- Institut Jacques Monod, CNRS, UMR 7592, University Paris Diderot, Sorbonne Paris Cité, Paris F-75205, France.
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26
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27
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Shalgi R, Hurt JA, Lindquist S, Burge CB. Widespread inhibition of posttranscriptional splicing shapes the cellular transcriptome following heat shock. Cell Rep 2014; 7:1362-1370. [PMID: 24857664 DOI: 10.1016/j.celrep.2014.04.044] [Citation(s) in RCA: 132] [Impact Index Per Article: 13.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2014] [Revised: 03/13/2014] [Accepted: 04/21/2014] [Indexed: 10/25/2022] Open
Abstract
During heat shock and other proteotoxic stresses, cells regulate multiple steps in gene expression in order to globally repress protein synthesis and selectively upregulate stress response proteins. Splicing of several mRNAs is known to be inhibited during heat stress, often meditated by SRp38, but the extent and specificity of this effect have remained unclear. Here, we examined splicing regulation genome-wide during heat shock in mouse fibroblasts. We observed widespread retention of introns in transcripts from ∼1,700 genes, which were enriched for tRNA synthetase, nuclear pore, and spliceosome functions. Transcripts with retained introns were largely nuclear and untranslated. However, a group of 580+ genes biased for oxidation reduction and protein folding functions continued to be efficiently spliced. Interestingly, these unaffected transcripts are mostly cotranscriptionally spliced under both normal and stress conditions, whereas splicing-inhibited transcripts are mostly spliced posttranscriptionally. Altogether, our data demonstrate widespread repression of splicing in the mammalian heat stress response, disproportionately affecting posttranscriptionally spliced genes.
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Affiliation(s)
- Reut Shalgi
- Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02142, USA
| | - Jessica A Hurt
- Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02142, USA
| | - Susan Lindquist
- Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02142, USA; Whitehead Institute for Biomedical Research, Massachusetts Institute of Technology, Cambridge, MA 02142, USA; Howard Hughes Medical Institute, Massachusetts Institute of Technology, Cambridge, MA 02142, USA
| | - Christopher B Burge
- Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02142, USA; Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, MA 02142, USA.
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28
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Abstract
Release of properly processed and assembled mRNPs from the actively transcribing genes, movement of the mRNPs through the interchromatin and interaction with the Nuclear Pore Complexes, leading to cytoplasmic export, are essential steps of eukaryotic gene expression. Here, we review these intranuclear gene expression steps.
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Affiliation(s)
- Petra Björk
- Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm University, SE-106 91 Stockholm, Sweden.
| | - Lars Wieslander
- Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm University, SE-106 91 Stockholm, Sweden.
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29
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Kelly S, Kramer S, Schwede A, Maini PK, Gull K, Carrington M. Genome organization is a major component of gene expression control in response to stress and during the cell division cycle in trypanosomes. Open Biol 2013; 2:120033. [PMID: 22724062 PMCID: PMC3376733 DOI: 10.1098/rsob.120033] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2012] [Accepted: 03/14/2012] [Indexed: 01/16/2023] Open
Abstract
The trypanosome genome is characterized by RNA polymerase II-driven polycistronic transcription of protein-coding genes. Ten to hundreds of genes are co-transcribed from a single promoter; thus, selective regulation of individual genes via initiation is impossible. However, selective responses to external stimuli occur and post-transcriptional mechanisms are thought to account for all temporal gene expression patterns. We show that genes encoding mRNAs that are differentially regulated during the heat-shock response are selectively positioned in polycistronic transcription units; downregulated genes are close to transcription initiation sites and upregulated genes are distant. We demonstrate that the position of a reporter gene within a transcription unit is sufficient to reproduce this effect. Analysis of gene ontology annotations reveals that positional bias is not restricted to stress-response genes and that there is a genome-wide organization based on proximity to transcription initiation sites. Furthermore, we show that the relative abundance of mRNAs at different time points in the cell division cycle is dependent on the location of the corresponding genes to transcription initiation sites. This work provides evidence that the genome in trypanosomes is organized to facilitate co-coordinated temporal control of gene expression in the absence of selective promoters.
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Affiliation(s)
- S Kelly
- Department of Plant Sciences, University of Oxford, South Parks Road, Oxford OX1 3RB, UK.
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30
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Natalizio BJ, Wente SR. Postage for the messenger: designating routes for nuclear mRNA export. Trends Cell Biol 2013; 23:365-73. [PMID: 23583578 DOI: 10.1016/j.tcb.2013.03.006] [Citation(s) in RCA: 82] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2013] [Revised: 03/12/2013] [Accepted: 03/14/2013] [Indexed: 01/22/2023]
Abstract
Transcription of mRNA occurs in the nucleus, making the translocation of mRNA across the nuclear envelope (NE) boundary a critical determinant of proper gene expression and cell survival. A major mRNA export route occurs via the NXF1-dependent pathway through the nuclear pore complexes (NPCs) embedded in the NE. However, recent findings have discovered new evidence supporting the existence of multiple mechanisms for crossing the NE, including both NPC-mediated and NE budding-mediated pathways. An analysis of the trans-acting factors and cis components that define these pathways reveals shared elements as well as mechanistic differences. We review here the current understanding of the mechanisms that characterize each pathway and highlight the determinants that influence mRNA transport fate.
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Affiliation(s)
- Barbara J Natalizio
- Department of Cell and Developmental Biology, Vanderbilt University School of Medicine, Nashville, TN 37323, USA
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31
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Dostalova A, Käser S, Cristodero M, Schimanski B. The nuclear mRNA export receptor Mex67-Mtr2 ofTrypanosoma bruceicontains a unique and essential zinc finger motif. Mol Microbiol 2013; 88:728-39. [DOI: 10.1111/mmi.12217] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/25/2013] [Indexed: 11/28/2022]
Affiliation(s)
| | | | | | - Bernd Schimanski
- Institute of Cell Biology; University of Bern; Bern; Switzerland
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32
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Chen Q, Fang Y, Zhao H, Zhang G, Jin Y. Transcriptional analysis of Saccharomyces cerevisiae during high-temperature fermentation. ANN MICROBIOL 2013. [DOI: 10.1007/s13213-013-0606-0] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022] Open
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33
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Kramer S, Bannerman-Chukualim B, Ellis L, Boulden EA, Kelly S, Field MC, Carrington M. Differential localization of the two T. brucei poly(A) binding proteins to the nucleus and RNP granules suggests binding to distinct mRNA pools. PLoS One 2013; 8:e54004. [PMID: 23382864 PMCID: PMC3559699 DOI: 10.1371/journal.pone.0054004] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2012] [Accepted: 12/06/2012] [Indexed: 12/30/2022] Open
Abstract
The number of paralogs of proteins involved in translation initiation is larger in trypanosomes than in yeasts or many metazoan and includes two poly(A) binding proteins, PABP1 and PABP2, and four eIF4E variants. In many cases, the paralogs are individually essential and are thus unlikely to have redundant functions although, as yet, distinct functions of different isoforms have not been determined. Here, trypanosome PABP1 and PABP2 have been further characterised. PABP1 and PABP2 diverged subsequent to the differentiation of the Kinetoplastae lineage, supporting the existence of specific aspects of translation initiation regulation. PABP1 and PABP2 exhibit major differences in intracellular localization and distribution on polysome fractionation under various conditions that interfere with mRNA metabolism. Most striking are differences in localization to the four known types of inducible RNP granules. Moreover, only PABP2 but not PABP1 can accumulate in the nucleus. Taken together, these observations indicate that PABP1 and PABP2 likely associate with distinct populations of mRNAs. The differences in localization to inducible RNP granules also apply to paralogs of components of the eIF4F complex: eIF4E1 showed similar localization pattern to PABP2, whereas the localisation of eIF4E4 and eIF4G3 resembled that of PABP1. The grouping of translation initiation as either colocalizing with PABP1 or with PABP2 can be used to complement interaction studies to further define the translation initiation complexes in kinetoplastids.
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Affiliation(s)
- Susanne Kramer
- Department of Biochemistry, University of Cambridge, Cambridge, United Kingdom
| | | | - Louise Ellis
- Department of Biochemistry, University of Cambridge, Cambridge, United Kingdom
| | | | - Steve Kelly
- Department of Plant Sciences, University of Oxford, and Oxford Centre for Integrative Systems Biology, Department of Biochemistry, University of Oxford, Oxford, United Kingdom
| | - Mark C. Field
- Department of Pathology, University of Cambridge, Cambridge, United Kingdom
| | - Mark Carrington
- Department of Biochemistry, University of Cambridge, Cambridge, United Kingdom
- * E-mail:
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34
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Verghese J, Abrams J, Wang Y, Morano KA. Biology of the heat shock response and protein chaperones: budding yeast (Saccharomyces cerevisiae) as a model system. Microbiol Mol Biol Rev 2012; 76:115-58. [PMID: 22688810 DOI: 10.1128/MMBR.05018-11] [Citation(s) in RCA: 362] [Impact Index Per Article: 30.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
The eukaryotic heat shock response is an ancient and highly conserved transcriptional program that results in the immediate synthesis of a battery of cytoprotective genes in the presence of thermal and other environmental stresses. Many of these genes encode molecular chaperones, powerful protein remodelers with the capacity to shield, fold, or unfold substrates in a context-dependent manner. The budding yeast Saccharomyces cerevisiae continues to be an invaluable model for driving the discovery of regulatory features of this fundamental stress response. In addition, budding yeast has been an outstanding model system to elucidate the cell biology of protein chaperones and their organization into functional networks. In this review, we evaluate our understanding of the multifaceted response to heat shock. In addition, the chaperone complement of the cytosol is compared to those of mitochondria and the endoplasmic reticulum, organelles with their own unique protein homeostasis milieus. Finally, we examine recent advances in the understanding of the roles of protein chaperones and the heat shock response in pathogenic fungi, which is being accelerated by the wealth of information gained for budding yeast.
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35
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Abstract
Several lines of evidence have shown that, besides its traditional function in ribosome biogenesis, the nucleolus is also involved in regulating other cellular processes such as mRNA metabolism, and that it also plays an important role as a sensor and coordinator of the stress response. We have recently shown that a subset of RNA Binding Proteins and the poly(A)+ RNA are accumulated into the Trypanosoma cruzi nucleolus after inducing transcription inhibition with Actinomycin D. In this study, we investigated the behaviour of the T. cruzi mRNA population in parasites subjected to severe heat shock, an environmental stress that also decreases the rate of RNA synthesis. We found that the bulk of poly(A)+ RNA is reversibly accumulated into the nucleolus when exposing T. cruzi epimastigote forms to severe heat shock. However, the Hsp70 mRNA was able to bypass such nucleolar accumulation. Together, these data reinforce the idea about the involvement of the T. cruzi nucleolus in mRNA metabolism during an environmental stress response. Interestingly, T. brucei procyclic forms did not induce nucleolar accumulation of poly(A)+ RNA under such stress condition, suggesting that different trypanosomatids have adopted different responses to deal with the same stress conditions.
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Affiliation(s)
- Ezequiel Názer
- Instituto de Investigaciones Biotecnológicas - UNSAM-CONICET, San Martín, Provincia de Buenos Aires, Argentina
| | - Ramiro E. Verdún
- Leonard M. Miller School of Medicine, University of Miami, Miami, Florida, United States of America
| | - Daniel O. Sánchez
- Instituto de Investigaciones Biotecnológicas - UNSAM-CONICET, San Martín, Provincia de Buenos Aires, Argentina
- * E-mail:
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36
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Abstract
For most eukaryotic organisms, including Saccharomyces cerevisiae, the rapid inhibition of protein synthesis forms part of a response to stress. In order to balance the changing conditions, precise stress-specific alterations to the cell's proteome are required. Therefore, in the background of a global down-regulation in protein synthesis, specific proteins are induced. Given the level of plasticity required to enable stress-specific alterations of this kind, it is surprising that the mechanisms of translational regulation are not more diverse. In the present review, we summarize the impact of stress on translation initiation, highlighting both the similarities and distinctions between various stress responses. Finally, we speculate as to how yeast cells generate stress-responsive programmes of protein production when regulation is focused on the same steps in the translation pathway.
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37
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Abstract
All organisms are able to modulate gene expression in response to internal and external stimuli. Trypanosomes represent a group that diverged early during the radiation of eukaryotes and do not utilise regulated initiation of transcription by RNA polymerase II. Here, the mechanisms present in trypanosomes to alter gene expression in response to stress and change of host environment are discussed and contrasted with those operating in yeast and cultured mammalian cells.
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Affiliation(s)
- Angela Schwede
- Department of Biochemistry, University of Cambridge, Tennis Court Road, Cambridge, CB2 1QW UK
| | - Susanne Kramer
- Department of Biochemistry, University of Cambridge, Tennis Court Road, Cambridge, CB2 1QW UK
| | - Mark Carrington
- Department of Biochemistry, University of Cambridge, Tennis Court Road, Cambridge, CB2 1QW UK
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38
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Kamo K, Takabatake A, Inoue Y, Izawa S. Temperature dependent N-glycosylation of plasma membrane heat shock protein Hsp30p in Saccharomyces cerevisiae. Biochem Biophys Res Commun 2012; 420:119-23. [DOI: 10.1016/j.bbrc.2012.02.126] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2012] [Accepted: 02/22/2012] [Indexed: 11/18/2022]
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39
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Lavut A, Raveh D. Sequestration of highly expressed mRNAs in cytoplasmic granules, P-bodies, and stress granules enhances cell viability. PLoS Genet 2012; 8:e1002527. [PMID: 22383896 PMCID: PMC3285586 DOI: 10.1371/journal.pgen.1002527] [Citation(s) in RCA: 72] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2011] [Accepted: 12/21/2011] [Indexed: 02/07/2023] Open
Abstract
Transcriptome analyses indicate that a core 10%–15% of the yeast genome is modulated by a variety of different stresses. However, not all the induced genes undergo translation, and null mutants of many induced genes do not show elevated sensitivity to the particular stress. Elucidation of the RNA lifecycle reveals accumulation of non-translating mRNAs in cytoplasmic granules, P-bodies, and stress granules for future regulation. P-bodies contain enzymes for mRNA degradation; under stress conditions mRNAs may be transferred to stress granules for storage and return to translation. Protein degradation by the ubiquitin-proteasome system is elevated by stress; and here we analyzed the steady state levels, decay, and subcellular localization of the mRNA of the gene encoding the F-box protein, UFO1, that is induced by stress. Using the MS2L mRNA reporter system UFO1 mRNA was observed in granules that colocalized with P-bodies and stress granules. These P-bodies stored diverse mRNAs. Granules of two mRNAs transported prior to translation, ASH1-MS2L and OXA1-MS2L, docked with P-bodies. HSP12 mRNA that gave rise to highly elevated protein levels was not observed in granules under these stress conditions. ecd3, pat1 double mutants that are defective in P-body formation were sensitive to mRNAs expressed ectopically from strong promoters. These highly expressed mRNAs showed elevated translation compared with wild-type cells, and the viability of the mutants was strongly reduced. ecd3, pat1 mutants also exhibited increased sensitivity to different stresses. Our interpretation is that sequestration of highly expressed mRNAs in P-bodies is essential for viability. Storage of mRNAs for future regulation may contribute to the discrepancy between the steady state levels of many stress-induced mRNAs and their proteins. Sorting of mRNAs for future translation or decay by individual cells could generate potentially different phenotypes in a genetically identical population and enhance its ability to withstand stress. 10%–15% of the yeast genome is modulated by stress; however, there is a discrepancy between the genes that are upregulated and the sensitivity of the null mutants of those genes to the stress. The question is: what happens to these highly expressed mRNAs? mRNAs have a complex lifecycle and non-translating mRNAs can be stored in cytoplasmic granules, processing P-bodies, and stress granules for decay or future translation, respectively. UFO1 encodes a component of the regulated protein degradation system, and its transcription is elevated by stress; however, the deletion mutants do not show enhanced sensitivity. UFO1 mRNA is stored in P-bodies and stress granules. Storage of mRNAs may contribute to the discrepancy between the steady state levels of stress-induced mRNAs and their proteins. To test this hypothesis, we expressed high levels of mRNA in cells unable to form P-bodies. We found that translation of these mRNAs was 3–8 fold higher than in wild-type cells. Furthermore high level expression of mRNA affected the viability of the mutants. The ability to store mRNAs for future translation or decay would generate different phenotypes in a genetically identical population and enhance its ability to withstand stress.
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Affiliation(s)
- Anna Lavut
- Department of Life Sciences, Ben Gurion University of the Negev, Beersheba, Israel
| | - Dina Raveh
- Department of Life Sciences, Ben Gurion University of the Negev, Beersheba, Israel
- * E-mail:
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40
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Abstract
Rapid expression of the survival gene, inducible heat shock protein 70 (hsp70), is critical for mounting cytoprotection against severe cellular stress, like elevated temperature. Hsp70 protein chaperones the refolding of heat-denatured peptides to minimize proteolytic degradation as a part of an eukaryotically conserved phenomenon referred to as the heat shock response. The physiologic stress associated with exercise, which can include elevated temperature, mechanical damage, hypoxia, lowered pH, and reactive oxygen species generation, may promote protein unfolding, leading to hsp70 gene expression in skeletal myofibers. Although the pre-transcriptional activation of hsp70 gene expression has been thoroughly reviewed, discussion of downstream hsp70 gene regulation is less extensive. The purpose of this brief review was to examine all levels of hsp70 gene regulation in response to heat stress and exercise with a special focus on skeletal myofibers where data are available. In general, while heat stress represses bulk gene expression, hsp70 mRNA expression is enhanced. Post-transcriptionally, intronless hsp70 mRNA circumvents a host of decay pathways, as well as heat stress-repressed pre-mRNA splicing and nuclear export. Pre-translationally, hsp70 mRNA is excluded from stress granules and preferentially translated during heat stress-repressed global cap-dependent translation. Post-translationally, nascent Hsp70 protein is thermodynamically stable at elevated temperatures, allowing for the commencement of chaperoning activity early after synthesis to attenuate the heat shock response and protect against subsequent injury. This review demonstrates that hsp70 mRNA expression is closely coupled with functional protein translation.
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Affiliation(s)
- Jordan Thomas Silver
- School of Kinesiology, Faculty of Health Sciences, The University of Western Ontario, London, ON Canada N6A 3K7
| | - Earl G. Noble
- School of Kinesiology, Faculty of Health Sciences, The University of Western Ontario, London, ON Canada N6A 3K7
- Lawson Health Research Institute, The University of Western Ontario, London, ON Canada N6A 3K7
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41
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Abstract
Translocation of transport complexes across the nuclear envelope is mediated by nucleoporins, proteins of the nuclear pore complex that contain phenylalanine-glycine (FG) repeats as a characteristic binding motif for transport receptors. CRM1 (exportin 1), the major export receptor, forms trimeric complexes with RanGTP and proteins containing nuclear export sequences (NESs). We analyzed the role of the nucleoporin-like protein 1, NLP1 (also known as hCG1 and NUPL2) in CRM1-dependent nuclear transport. NLP1, which contains many FG repeats, localizes to the nuclear envelope and could also be mobile within the nucleus. It promotes the formation of complexes containing CRM1 and RanGTP, with or without NES-containing cargo proteins, that can be dissociated by RanBP1 and/or the cytoplasmic nucleoporin Nup214. The FG repeats of NLP1 do not play a major role in CRM1 binding. Overexpression of NLP1 promotes CRM1-dependent export of certain cargos, whereas its depletion by small interfering RNAs leads to reduced export rates. Thus, NLP1 functions as an accessory factor in CRM1-dependent nuclear protein export.
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Affiliation(s)
- Inga Waldmann
- Department of Biochemistry I, Faculty of Medicine, Georg-August-University of Göttingen, Göttingen, Germany
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42
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Abstract
A common need for microbial cells is the ability to respond to potentially toxic environmental insults. Here we review the progress in understanding the response of the yeast Saccharomyces cerevisiae to two important environmental stresses: heat shock and oxidative stress. Both of these stresses are fundamental challenges that microbes of all types will experience. The study of these environmental stress responses in S. cerevisiae has illuminated many of the features now viewed as central to our understanding of eukaryotic cell biology. Transcriptional activation plays an important role in driving the multifaceted reaction to elevated temperature and levels of reactive oxygen species. Advances provided by the development of whole genome analyses have led to an appreciation of the global reorganization of gene expression and its integration between different stress regimens. While the precise nature of the signal eliciting the heat shock response remains elusive, recent progress in the understanding of induction of the oxidative stress response is summarized here. Although these stress conditions represent ancient challenges to S. cerevisiae and other microbes, much remains to be learned about the mechanisms dedicated to dealing with these environmental parameters.
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Lee MV, Topper SE, Hubler SL, Hose J, Wenger CD, Coon JJ, Gasch AP. A dynamic model of proteome changes reveals new roles for transcript alteration in yeast. Mol Syst Biol 2011; 7:514. [PMID: 21772262 PMCID: PMC3159980 DOI: 10.1038/msb.2011.48] [Citation(s) in RCA: 218] [Impact Index Per Article: 16.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2010] [Accepted: 06/15/2011] [Indexed: 12/20/2022] Open
Abstract
By characterizing dynamic changes in yeast protein abundance following osmotic shock, this study shows that the correlation between protein and mRNA differs for transcripts that increase versus decrease in abundance, and reveals physiological reasons for these differences. The correlation between protein and mRNA change is very high at transcripts that increase in abundance, but negligible at reduced transcripts following NaCl shock. Modeling and experimental data suggest that reducing levels of high-abundance transcripts helps to direct translational machinery to newly made transcripts. The transient burst of transcript increase serves to accelerate changes in protein abundance. Post-transcriptional regulation of protein abundance is pervasive, although most of the variance in protein change is explained by changes in mRNA abundance.
Natural microenvironments change rapidly, and living creatures must respond quickly and efficiently to thrive within this flux. At all cellular levels—signaling, transcription, translation, metabolism, cell growth, and division—the response is dynamic and coordinated. Some aspects of this response, such as dynamic changes of the transcriptome, are well understood. But other aspects, like the response of the proteome, have remained obscured primarily because of previous limitations in technology. Without coordinated time-course data, it has remained impossible to correctly characterize the correlations and dependencies between these two essential levels of cell biology. This work presents an extended picture of the coordinated response of the transcriptome and proteome as cells respond to an abrupt environmental change. To assay proteomic dynamics, we developed a strategy for large-scale, multiplexed quantitation using isobaric tags and high mass accuracy mass spectrometry. This sensitive yet efficient platform allows for the expedient collection of quantitative time-course proteomic data at six time points, sufficiently reproducible to permit meaningful interpretation of variation across biological replicates. Time-course transcriptome data were generated from paired biological samples, allowing us to examine the relationships between changes in mRNA and protein for each gene in terms of direction and intensity, as well as the characteristics of the temporal profiles for each gene. It was immediately obvious that a single measure of correlation across the entire data set was a meaningless metric. We therefore analyzed relationships between mRNA and protein for different subsets of data. In response to osmotic shock, hundreds of transcripts are highly induced, and their temporal pattern reveals a transient peak of maximal induction, which resolves into a new elevated level as cells acclimate (Figure 2). For this group of genes, there is extremely high correlation between peak mRNA change and protein change (R2∼0.8). But the dynamics of the molecules differ: while mRNA levels transiently overshoot their final levels, proteins gradually rise in abundance toward their new, elevated state. We observed, however, that a measure of efficiency connects the two profiles. The time it takes for a protein to acclimate to its new state correlates with the magnitude of the excess mRNA induction. Thus, the cell imparts an urgency to protein induction by transiently producing excess transcript. The most surprising result, however, involves transcripts that decrease in abundance. In response to osmotic shock, the cell transiently reduces over 600 transcripts, many of which are among the most highly expressed in unstressed cells. But protein levels for these genes remain, for the most part, almost completely unchanged. The stark absence of protein repression is independent of basal protein abundance, independent of reported protein half-lives, reproducible across biological replicates, and validated by quantitative western blots. Furthermore, since we do detect a handful of proteins whose abundance is significantly reduced, our technology is capable of identifying protein loss. Thus, we conclude that transcript reduction serves another purpose besides reducing protein levels. To explore alternate interpretations of the consequence of transcriptional repression, we devised a mass-action kinetic model, which describes protein changes based on mRNA dynamics in the context of transient changes in the rates of cell division. The model successfully recapitulated the observed data, allowing us to alter modeling parameters to test various hypotheses. In response to osmotic shock, overall rates of translation temporarily decrease and cell growth transiently arrests before resuming at a slower rate. We reasoned that mRNA reduction might lower the rate of new protein synthesis, but that retarded production is balanced by reduced cell division. We explored both aspects of this logic with our model. As expected, removing cell division from our model led to a calculated decrease of protein levels, indicating that reduced growth is necessary for maintaining protein levels. However, when we computationally held mRNA levels stable and calculated protein levels in the absence of mRNA repression, we did not find the expected increase in protein abundance. We then considered the possibility that one function of the regulated repression of these highly abundant transcripts was to liberate proteins essential for translation, such as ribosomes or translation initiation factors. To explore this, we examined a mutant lacking the Dot6p/Tod6p transcriptional repressors, which fails to properly repress ∼250 genes in response to osmotic shock. In the wild type, the mRNA for a Dot6p/Tod6p target (ARX1) decreased seven-fold, and the remaining transcript was generally unassociated with poly-ribosomes. In the mutant, however, the mRNA levels were reduced only two-fold, while the remaining transcript continued to bind ribosomes. Therefore, failure to reduce transcript levels led to a persistent association with poly-ribosomes, thereby consuming translational machinery. Our hypothesis is, therefore, that widespread changes in the transcriptome promote efficient translation of new proteins. Transcript increase serves to increase abundance of the encoded proteins, while reduction of some of the most abundant and highly translated mRNAs supports this project by liberating translational capacity. While it is not clear what factors are the limiting elements, it is clear that a full picture of cellular biology requires exploring the dynamics of the cellular response. The transcriptome and proteome change dynamically as cells respond to environmental stress; however, prior proteomic studies reported poor correlation between mRNA and protein, rendering their relationships unclear. To address this, we combined high mass accuracy mass spectrometry with isobaric tagging to quantify dynamic changes in ∼2500 Saccharomyces cerevisiae proteins, in biological triplicate and with paired mRNA samples, as cells acclimated to high osmolarity. Surprisingly, while transcript induction correlated extremely well with protein increase, transcript reduction produced little to no change in the corresponding proteins. We constructed a mathematical model of dynamic protein changes and propose that the lack of protein reduction is explained by cell-division arrest, while transcript reduction supports redistribution of translational machinery. Furthermore, the transient ‘burst' of mRNA induction after stress serves to accelerate change in the corresponding protein levels. We identified several classes of post-transcriptional regulation, but show that most of the variance in protein changes is explained by mRNA. Our results present a picture of the coordinated physiological responses at the levels of mRNA, protein, protein-synthetic capacity, and cellular growth.
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Affiliation(s)
- M Violet Lee
- Department of Chemistry, University of Wisconsin-Madison, Madison, WI, USA
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44
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Abstract
Localization of messenger RNA (mRNA) is a process used by eukaryotes to control the spatio-temporal expression of proteins involved in cellular motility, asymmetric cell division, or polarized cell growth. A better understanding of this process relies on methods to detect specifically the position of an mRNA in fixed or living cells. This chapter presents methods to visualize mRNA in both fixed and living yeast Saccharomyces cerevisiae. In fixed cells, position of mRNAs can be assessed by using Fluorescent In Situ Hybridization (FISH) that consists of the hybridization of fluorescent probes that target a specific transcript in situ. In living cells, dynamics of mRNAs can be monitored using a bipartite system composed of MS2 stem-loops inserted in the mRNA of interest. These stem-loops are recognized specifically by the MS2 RNA-binding protein, fused to a fluorescent protein. In vivo association between the reporter (fluorescent MS2 protein) and the MS2-tagged mRNA reconstitutes active fluorescent ribonucleoparticles that can be followed by live cell imaging. Detailed protocols for the realization of these methods are provided and several technical considerations are discussed. Together, these methods provide very robust tools to determine the intracellular position and dynamics of your mRNA of interest in yeast.
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Affiliation(s)
- Franck Gallardo
- Département de Biochimie, Université de Montréal, Montréal, QC, Canada
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45
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Powrie EA, Zenklusen D, Singer RH. A nucleoporin, Nup60p, affects the nuclear and cytoplasmic localization of ASH1 mRNA in S. cerevisiae. RNA 2011; 17:134-144. [PMID: 21036941 PMCID: PMC3004054 DOI: 10.1261/rna.1210411] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/06/2008] [Accepted: 09/27/2010] [Indexed: 05/30/2023]
Abstract
The biogenesis of a localization-competent mRNP begins in the nucleus. It is thought that the coordinated action of nuclear and cytoplasmic components of the localization machinery is required for the efficient export and subsequent subcellular localization of these mRNAs in the cytoplasm. Using quantitative poly(A)(+) and transcript-specific fluorescent in situ hybridization, we analyzed different nonessential nucleoporins and nuclear pore-associated proteins for their potential role in mRNA export and localization. We found that Nup60p, a nuclear pore protein located on the nucleoplasmic side of the nuclear pore complex, was required for the mRNA localization pathway. In a Δnup60 background, localized mRNAs were preferentially retained within the nucleus compared to nonlocalized transcripts. However, the export block was only partial and some transcripts could still reach the cytoplasm. Importantly, downstream processes were also affected. Localization of ASH1 and IST2 mRNAs to the bud was impaired in the Δnup60 background, suggesting that the assembly of a localization competent mRNP ("locasome") was inhibited when NUP60 was deleted. These results demonstrate transcript specificity of a nuclear mRNA retention defect and identify a specific nucleoporin as a functional component of the localization pathway in budding yeast.
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Affiliation(s)
- Erin A Powrie
- Department of Cell Biology, Albert Einstein College of Medicine, Bronx, New York 10461, USA
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46
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Komarova TV, Schwartz AM, Frolova OY, Zvereva AS, Gleba YY, Citovsky V, Dorokhov YL. Pol II-directed short RNAs suppress the nuclear export of mRNA. Plant Mol Biol 2010; 74:591-603. [PMID: 20953971 DOI: 10.1007/s11103-010-9700-x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/26/2010] [Accepted: 09/28/2010] [Indexed: 05/30/2023]
Abstract
The synthesis and subsequent nuclear export of non-coding RNA (ncRNA) directed by RNA polymerase (Pol) II is very sensitive to abiotic and biotic external stimuli including pathogen challenges. To assess whether stress-induced ncRNAs may suppress the nuclear export of mRNA, we exploited the ability of Agrobacterium tumefaciens to co-deliver Pol I, II and III promoter-based vectors for the transcription of short (s) ncRNAs, GFP mRNA or genomic RNA of plant viruses (Tobacco mosaic virus, TMV; or Potato virus X, PVX) into the nucleus of Nicotiana benthamiana cells. We showed that, in contrast to Pol I- and Pol III-derived sncRNAs, all tested Pol II-derived sncRNAs (U6 RNA, tRNA or artificial RNAs) resulted in decreased expression of GFP and host mRNA. The level of this inhibitory effect depended on the non-coding transcript length and promoter strength. Short coding RNA (scRNA) can also compete with mRNA for nuclear export. We showed that scRNA, an artificial 117-nt short sequence encoding Elastin-Like peptide element tandems with FLAG sequence (ELF) and the 318-nt N. benthamiana antimicrobial peptide thionin (defensin) gene efficiently decreased GFP expression. The stress-induced export of Pol II-derived sncRNA and scRNA into the cytoplasm via the mRNA export pathway may block nucleocytoplasmic traffic including the export of mRNA responsible for antivirus protection. Consistent with this model, we observed that Pol II-derived sncRNAs as well as scRNA, thionin and ELF strongly enhanced the cytoplasmic reproduction of TMV and PVX RNA.
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Affiliation(s)
- Tatiana V Komarova
- A. N. Belozersky Institute of Physico-Chemical Biology, Moscow State University, Leninsky Gory 1, Laboratory Building A, 119992, Moscow, Russia
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Carmody SR, Tran EJ, Apponi LH, Corbett AH, Wente SR. The mitogen-activated protein kinase Slt2 regulates nuclear retention of non-heat shock mRNAs during heat shock-induced stress. Mol Cell Biol 2010; 30:5168-79. [PMID: 20823268 DOI: 10.1128/MCB.00735-10] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Cellular adaptation to environmental stress conditions requires rapid and specific changes in gene expression. During heat shock, most polyadenylated mRNAs are retained in the nucleus, whereas the export of heat shock-induced mRNAs is allowed. Although essential mRNA export factors are known, the precise mechanism for regulating transport is not fully understood. Here we find that during heat shock in Saccharomyces cerevisiae, the mRNA-binding protein Nab2 is phosphorylated on threonine 178 and serine 180 by the mitogen-activated protein (MAP) kinase Slt2/Mpk1. Slt2 is required for nuclear poly(A(+)) mRNA accumulation upon heat shock, and thermotolerance is decreased in a nup42 nab2-T178A/S180A mutant. Coincident with phosphorylation, Nab2 and Yra1 colocalize in nuclear foci with Mlp1, a protein involved in mRNA retention. Nab2 nuclear focus formation and Nab2 phosphorylation are independent, suggesting that heat shock induces multiple cellular alterations that impinge upon transport efficiency. Under normal conditions, we find that the mRNA export receptor Mex67 and Nab2 directly interact. However, upon heat shock stress, Mex67 does not localize to the Mlp1 nuclear foci, and its association with Nab2 complexes is reduced. These results reveal a novel mechanism by which the MAP kinase Slt2 and Mlp1 control mRNA export factors during heat shock stress.
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Dossani ZY, Weirich CS, Erzberger JP, Berger JM, Weis K. Structure of the C-terminus of the mRNA export factor Dbp5 reveals the interaction surface for the ATPase activator Gle1. Proc Natl Acad Sci U S A 2009; 106:16251-6. [PMID: 19805289 DOI: 10.1073/pnas.0902251106] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
The DExD/H-box RNA-dependent ATPase Dbp5 plays an essential role in the nuclear export of mRNA. Dbp5 localizes to the nuclear pore complex, where its ATPase activity is stimulated by Gle1 and its coactivator inositol hexakisphosphate. Here, we present the crystal structure of the C-terminal domain of Dbp5, refined to 1.8 A. The structure reveals a RecA-like fold that contains two defining characteristics not present in other structurally characterized DExD/H-box proteins: a C-terminal alpha-helix and a loop connecting beta5 and alpha4, both of which are composed of conserved and unique elements in the Dbp5 primary sequence. Using structure-guided mutagenesis, we have identified several charged surface residues that, when mutated, weaken the binding of Gle1 and inhibit the ability of Gle1 to stimulate Dbp5's ATPase activity. In vivo analysis of the same mutations reveals that those mutants displaying the weakest ATPase stimulation in vitro are also unable to support yeast growth. Analysis of the correlation between the in vitro and in vivo data indicates that a threshold level of Dbp5 ATPase activity is required for cellular mRNA export that is not met by the unstimulated enzyme, suggesting a possible mechanism by which Dbp5's activity can be modulated to regulate mRNA export.
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Katahira J, Inoue H, Hurt E, Yoneda Y. Adaptor Aly and co-adaptor Thoc5 function in the Tap-p15-mediated nuclear export of HSP70 mRNA. EMBO J 2009; 28:556-67. [PMID: 19165146 DOI: 10.1038/emboj.2009.5] [Citation(s) in RCA: 122] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2008] [Accepted: 01/05/2009] [Indexed: 11/08/2022] Open
Abstract
In metazoans, nuclear export of bulk mRNA is mediated by Tap-p15, a conserved heterodimeric export receptor that cooperates with adaptor RNA-binding proteins. In this article, we show that Thoc5, a subunit of the mammalian TREX complex, binds to a distinct surface on the middle (Ntf2-like) domain of Tap. Notably, adaptor protein Aly and Thoc5 can simultaneously bind to non-overlapping binding sites on Tap-p15. In vivo, Thoc5 was not required for bulk mRNA export. However, nuclear export of HSP70 mRNA depends on both Thoc5 and Aly. Consistent with a function as a specific export adaptor, Thoc5 exhibits in vitro RNA-binding activity and is associated with HSP70 mRNPs in vivo as a component of the stable THO complex. Thus, through the combinatorial use of an adaptor (e.g., Aly) and co-adapter (e.g., Thoc5), Tap-p15 could function as an export receptor for different classes of mRNAs.
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50
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Abstract
Nucleic acids are substrates for different types of damage, but little is known about the fate of damaged RNAs. We addressed the existence of an RNA-damage response in yeast. The decay kinetics of GAL1p-driven mRNAs revealed a dose-dependent mRNA stabilization upon UV-irradiation that was not observed after heat or saline shocks, or during nitrogen starvation. UV-induced mRNA stabilization did not depend on DNA repair, damage checkpoint or mRNA degradation machineries. Notably, fluorescent in situ hybridization revealed that after UV-irradiation, polyadenylated mRNA accumulated in cytoplasmic foci that increased in size with time. In situ colocalization showed that these foci are not processing-bodies, eIF4E-, eIF4G-, and Pab1-containing bodies, stress granules, autophagy vesicles, or part of the secretory or endocytic pathways. These results point to the existence of a specific eukaryotic RNA-damage response, which leads to new polyadenylated mRNA-containing granules (UV-induced mRNA granules; UVGs). We propose that potentially damaged mRNAs, which may be deleterious to the cell, are temporarily stored in UVG granules to safeguard cell viability.
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Affiliation(s)
- Hélène Gaillard
- Departamento de Genética, Facultad de Biología, Universidad de Sevilla, Centro Andaluz de Biología Molecular and Medicina Regenativa CABIMER, 41092 Sevilla, Spain
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