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Bermudez Y, Hatfield D, Muller M. A Balancing Act: The Viral-Host Battle over RNA Binding Proteins. Viruses 2024; 16:474. [PMID: 38543839 PMCID: PMC10974049 DOI: 10.3390/v16030474] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2023] [Revised: 03/16/2024] [Accepted: 03/18/2024] [Indexed: 04/01/2024] Open
Abstract
A defining feature of a productive viral infection is the co-opting of host cell resources for viral replication. Despite the host repertoire of molecular functions and biological counter measures, viruses still subvert host defenses to take control of cellular factors such as RNA binding proteins (RBPs). RBPs are involved in virtually all steps of mRNA life, forming ribonucleoprotein complexes (mRNPs) in a highly ordered and regulated process to control RNA fate and stability in the cell. As such, the hallmark of the viral takeover of a cell is the reshaping of RNA fate to modulate host gene expression and evade immune responses by altering RBP interactions. Here, we provide an extensive review of work in this area, particularly on the duality of the formation of RNP complexes that can be either pro- or antiviral. Overall, in this review, we highlight the various ways viruses co-opt RBPs to regulate RNA stability and modulate the outcome of infection by gathering novel insights gained from research studies in this field.
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Affiliation(s)
| | | | - Mandy Muller
- Department of Microbiology, University of Massachusetts, Amherst, MA 01003, USA; (Y.B.); (D.H.)
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2
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Feicht J, Jansen RP. The high-density lipoprotein binding protein HDLBP is an unusual RNA-binding protein with multiple roles in cancer and disease. RNA Biol 2024; 21:1-10. [PMID: 38477883 PMCID: PMC10939154 DOI: 10.1080/15476286.2024.2313881] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/29/2024] [Indexed: 03/14/2024] Open
Abstract
The high-density lipoprotein binding protein (HDLBP) is the human member of an evolutionarily conserved family of RNA-binding proteins, the vigilin protein family. These proteins are characterized by 14 or 15 RNA-interacting KH (heterologous nuclear ribonucleoprotein K homology) domains. While mainly present at the cytoplasmic face of the endoplasmic reticulum, HDLBP and its homologs are also found in the cytosol and nucleus. HDLBP is involved in various processes, including translation, chromosome segregation, cholesterol transport and carcinogenesis. Especially, its association with the latter two has attracted specific interest in the HDLBP's molecular role. In this review, we give an overview of some of the functions of the protein as well as introduce its impact on different kinds of cancer, its connection to lipid metabolism and its role in viral infection. We also aim at addressing the possible use of HDLBP as a drug target or biomarker and discuss its future implications.
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Affiliation(s)
- Jonathan Feicht
- Interfaculty Institute of Biochemistry, University of Tuebingen, Tuebingen, Germany
| | - Ralf-Peter Jansen
- Interfaculty Institute of Biochemistry, University of Tuebingen, Tuebingen, Germany
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3
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Oudart M, Avila-Gutierrez K, Moch C, Dossi E, Milior G, Boulay AC, Gaudey M, Moulard J, Lombard B, Loew D, Bemelmans AP, Rouach N, Chapat C, Cohen-Salmon M. The ribosome-associated protein RACK1 represses Kir4.1 translation in astrocytes and influences neuronal activity. Cell Rep 2023; 42:112456. [PMID: 37126448 DOI: 10.1016/j.celrep.2023.112456] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2022] [Revised: 02/10/2023] [Accepted: 04/16/2023] [Indexed: 05/02/2023] Open
Abstract
The regulation of translation in astrocytes, the main glial cells in the brain, remains poorly characterized. We developed a high-throughput proteomics screen for polysome-associated proteins in astrocytes and focused on ribosomal protein receptor of activated protein C kinase 1 (RACK1), a critical factor in translational regulation. In astrocyte somata and perisynaptic astrocytic processes (PAPs), RACK1 preferentially binds to a number of mRNAs, including Kcnj10, encoding the inward-rectifying potassium (K+) channel Kir4.1. By developing an astrocyte-specific, conditional RACK1 knockout mouse model, we show that RACK1 represses production of Kir4.1 in hippocampal astrocytes and PAPs. Upregulation of Kir4.1 in the absence of RACK1 increases astrocytic Kir4.1-mediated K+ currents and volume. It also modifies neuronal activity attenuating burst frequency and duration. Reporter-based assays reveal that RACK1 controls Kcnj10 translation through the transcript's 5' untranslated region. Hence, translational regulation by RACK1 in astrocytes represses Kir4.1 expression and influences neuronal activity.
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Affiliation(s)
- Marc Oudart
- Center for Interdisciplinary Research in Biology, College de France, CNRS, INSERM, Université PSL, Labex Memolife, Paris, France
| | - Katia Avila-Gutierrez
- Center for Interdisciplinary Research in Biology, College de France, CNRS, INSERM, Université PSL, Labex Memolife, Paris, France
| | - Clara Moch
- Laboratoire de Biochimie, Ecole Polytechnique, CNRS, Université Paris-Saclay, Palaiseau, France
| | - Elena Dossi
- Center for Interdisciplinary Research in Biology, College de France, CNRS, INSERM, Université PSL, Labex Memolife, Paris, France
| | - Giampaolo Milior
- Center for Interdisciplinary Research in Biology, College de France, CNRS, INSERM, Université PSL, Labex Memolife, Paris, France
| | - Anne-Cécile Boulay
- Center for Interdisciplinary Research in Biology, College de France, CNRS, INSERM, Université PSL, Labex Memolife, Paris, France
| | - Mathis Gaudey
- Center for Interdisciplinary Research in Biology, College de France, CNRS, INSERM, Université PSL, Labex Memolife, Paris, France
| | - Julien Moulard
- Center for Interdisciplinary Research in Biology, College de France, CNRS, INSERM, Université PSL, Labex Memolife, Paris, France
| | - Bérangère Lombard
- CurieCoreTech Spectrométrie de Masse Protéomique, Institut Curie, University PSL, Paris, France
| | - Damarys Loew
- CurieCoreTech Spectrométrie de Masse Protéomique, Institut Curie, University PSL, Paris, France
| | - Alexis-Pierre Bemelmans
- CEA, Institut de Biologie François Jacob, Molecular Imaging Research Center (MIRCen), CNRS, Université Paris-Sud, Université Paris-Saclay, Fontenay-aux-Roses, France
| | - Nathalie Rouach
- Center for Interdisciplinary Research in Biology, College de France, CNRS, INSERM, Université PSL, Labex Memolife, Paris, France
| | - Clément Chapat
- Laboratoire de Biochimie, Ecole Polytechnique, CNRS, Université Paris-Saclay, Palaiseau, France
| | - Martine Cohen-Salmon
- Center for Interdisciplinary Research in Biology, College de France, CNRS, INSERM, Université PSL, Labex Memolife, Paris, France.
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4
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Hall RA, Wallace EW. Post-transcriptional control of fungal cell wall synthesis. Cell Surf 2022; 8:100074. [PMID: 35097244 PMCID: PMC8783092 DOI: 10.1016/j.tcsw.2022.100074] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2021] [Revised: 01/10/2022] [Accepted: 01/10/2022] [Indexed: 12/21/2022] Open
Abstract
Pathogenic fungi hide from their hosts by camouflage, obscuring immunogenic cell wall components such as beta-glucan with innocuous coverings such as mannoproteins and alpha-glucan that are less readily recognised by the host. Attempts to understand how such processes are regulated have met with varying success. Typically studies focus on understanding the transcriptional response of fungi to either their reservoir environment or the host. However, such approaches do not fully address this research question, due to the layers of post-transcriptional and post-translational regulation that occur within a cell. Although in animals the impact of post-transcriptional and post-translational regulation has been well characterised, our knowledge of these processes in the fungal kingdom is more limited. Mutations in RNA-binding proteins, like Ssd1 and Candida albicans Slr1, affect cell wall composition and fungal virulence indicating that post-transcriptional regulation plays a key role in these processes. Here, we review the current state of knowledge of fungal post-transcriptional regulation, and link this to potential mechanisms of immune evasion by drawing on studies from model yeast and plant pathogenic fungi. We highlight several RNA-binding proteins that regulate cell wall synthesis and could be involved in local translation of cell wall components. Expanding our knowledge on post-transcriptional regulation in human fungal pathogens is essential to fully comprehend fungal virulence strategies and for the design of novel antifungal therapies.
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Affiliation(s)
- Rebecca A. Hall
- Kent Fungal Group, Division of Natural Sciences, School of Biosciences, University of Kent, Canterbury CT2 7NJ, United Kingdom
| | - Edward W.J. Wallace
- Institute for Cell Biology and SynthSys, School of Biological Sciences, University of Edinburgh, EH9 3FF, United Kingdom
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5
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Brugier A, Hafirrassou ML, Pourcelot M, Baldaccini M, Kril V, Couture L, Kümmerer BM, Gallois-Montbrun S, Bonnet-Madin L, Vidalain PO, Delaugerre C, Pfeffer S, Meertens L, Amara A. RACK1 Associates with RNA-Binding Proteins Vigilin and SERBP1 to Facilitate Dengue Virus Replication. J Virol 2022; 96:e0196221. [PMID: 35266803 PMCID: PMC9006918 DOI: 10.1128/jvi.01962-21] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2021] [Accepted: 01/24/2022] [Indexed: 12/11/2022] Open
Abstract
Dengue virus (DENV) is a mosquito-borne flavivirus responsible for dengue disease, a major human health concern for which no effective treatment is available. DENV relies heavily on the host cellular machinery for productive infection. Here, we show that the scaffold protein RACK1, which is part of the DENV replication complex, mediates infection by binding to the 40S ribosomal subunit. Mass spectrometry analysis of RACK1 partners coupled to an RNA interference screen-identified Vigilin and SERBP1 as DENV host-dependency factors. Both are RNA-binding proteins that interact with the DENV genome. Genetic ablation of Vigilin or SERBP1 rendered cells poorly susceptible to DENV, as well as related flaviviruses, by hampering the translation and replication steps. Finally, we established that a Vigilin or SERBP1 mutant lacking RACK1 binding but still interacting with the viral RNA is unable to mediate DENV infection. We propose that RACK1 recruits Vigilin and SERBP1, linking the DENV genome to the translation machinery for efficient infection. IMPORTANCE We recently identified the scaffolding RACK1 protein as an important host-dependency factor for dengue virus (DENV), a positive-stranded RNA virus responsible for the most prevalent mosquito-borne viral disease worldwide. Here, we have performed the first RACK1 interactome in human cells and identified Vigilin and SERBP1 as DENV host-dependency factors. Both are RNA-binding proteins that interact with the DENV RNA to regulate viral replication. Importantly, Vigilin and SERBP1 interact with RACK1 and the DENV viral RNA (vRNA) to mediate viral replication. Overall, our results suggest that RACK1 acts as a binding platform at the surface of the 40S ribosomal subunit to recruit Vigilin and SERBP1, which may therefore function as linkers between the viral RNA and the translation machinery to facilitate infection.
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Affiliation(s)
- Alexis Brugier
- Université de Paris, INSERM U944, CNRS 7212, Biology of Emerging Viruses Team, Institut de Recherche Saint-Louis, Hôpital Saint-Louis, Paris, France
| | - Mohamed Lamine Hafirrassou
- Université de Paris, INSERM U944, CNRS 7212, Biology of Emerging Viruses Team, Institut de Recherche Saint-Louis, Hôpital Saint-Louis, Paris, France
| | - Marie Pourcelot
- Université de Paris, INSERM U944, CNRS 7212, Biology of Emerging Viruses Team, Institut de Recherche Saint-Louis, Hôpital Saint-Louis, Paris, France
| | - Morgane Baldaccini
- Université de Strasbourg, Architecture et Réactivité de l’ARN, Institut de Biologie Moléculaire et Cellulaire du CNRS, Strasbourg, France
| | - Vasiliya Kril
- Université de Paris, INSERM U944, CNRS 7212, Biology of Emerging Viruses Team, Institut de Recherche Saint-Louis, Hôpital Saint-Louis, Paris, France
| | - Laurine Couture
- Université de Paris, INSERM U944, CNRS 7212, Biology of Emerging Viruses Team, Institut de Recherche Saint-Louis, Hôpital Saint-Louis, Paris, France
| | - Beate M. Kümmerer
- Institute of Virology, Medical Faculty, University of Bonn, Bonn, Germany
| | | | - Lucie Bonnet-Madin
- Université de Paris, INSERM U944, CNRS 7212, Biology of Emerging Viruses Team, Institut de Recherche Saint-Louis, Hôpital Saint-Louis, Paris, France
| | - Pierre-Olivier Vidalain
- Centre International de Recherche en Infectiologie, Team Viral Infection, Metabolism and Immunity, INSERM U1111, CNRS UMR5308, ENS de Lyon, Université Claude Bernard Lyon 1, Lyon, France
| | - Constance Delaugerre
- Université de Paris, INSERM U944, CNRS 7212, Biology of Emerging Viruses Team, Institut de Recherche Saint-Louis, Hôpital Saint-Louis, Paris, France
- Laboratoire de Virologie et Département des Maladies Infectieuses, Hôpital Saint-Louis, Assistance Publique–Hôpitaux de Paris, Paris, France
| | - Sébastien Pfeffer
- Université de Strasbourg, Architecture et Réactivité de l’ARN, Institut de Biologie Moléculaire et Cellulaire du CNRS, Strasbourg, France
| | - Laurent Meertens
- Université de Paris, INSERM U944, CNRS 7212, Biology of Emerging Viruses Team, Institut de Recherche Saint-Louis, Hôpital Saint-Louis, Paris, France
| | - Ali Amara
- Université de Paris, INSERM U944, CNRS 7212, Biology of Emerging Viruses Team, Institut de Recherche Saint-Louis, Hôpital Saint-Louis, Paris, France
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6
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Multi-omics analysis of glucose-mediated signaling by a moonlighting Gβ protein Asc1/RACK1. PLoS Genet 2021; 17:e1009640. [PMID: 34214075 PMCID: PMC8282090 DOI: 10.1371/journal.pgen.1009640] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2021] [Revised: 07/15/2021] [Accepted: 06/02/2021] [Indexed: 12/31/2022] Open
Abstract
Heterotrimeric G proteins were originally discovered through efforts to understand the effects of hormones, such as glucagon and epinephrine, on glucose metabolism. On the other hand, many cellular metabolites, including glucose, serve as ligands for G protein-coupled receptors. Here we investigate the consequences of glucose-mediated receptor signaling, and in particular the role of a Gα subunit Gpa2 and a non-canonical Gβ subunit, known as Asc1 in yeast and RACK1 in animals. Asc1/RACK1 is of particular interest because it has multiple, seemingly unrelated, functions in the cell. The existence of such “moonlighting” operations has complicated the determination of phenotype from genotype. Through a comparative analysis of individual gene deletion mutants, and by integrating transcriptomics and metabolomics measurements, we have determined the relative contributions of the Gα and Gβ protein subunits to glucose-initiated processes in yeast. We determined that Gpa2 is primarily involved in regulating carbohydrate metabolism while Asc1 is primarily involved in amino acid metabolism. Both proteins are involved in regulating purine metabolism. Of the two subunits, Gpa2 regulates a greater number of gene transcripts and was particularly important in determining the amplitude of response to glucose addition. We conclude that the two G protein subunits regulate distinct but complementary processes downstream of the glucose-sensing receptor, as well as processes that lead ultimately to changes in cell growth and metabolism. Despite the societal importance of glucose fermentation in yeast, the mechanisms by which these cells detect and respond to glucose have remained obscure. Glucose detection requires a cell surface receptor coupled to a G protein that is comprised of two subunits, rather than the more typical heterotrimer: an α subunit Gpa2 and the β subunit Asc1 (or RACK1 in humans). Asc1/RACK1 also serves as a subunit of the ribosome, where it regulates the synthesis of proteins involved in glucose fermentation. This manuscript uses global metabolomics and transcriptomics to demonstrate the distinct roles of each G protein subunit in transmitting the glucose signal. Whereas Gpa2 is primarily involved in the metabolism of carbohydrates, Asc1/RACK1 contributes to production of amino acids necessary for protein synthesis and cell division. These findings reveal the initial steps of glucose signaling and several unique and complementary functions of the G protein subunits. More broadly, the integrated approach used here is likely to guide efforts to determine the topology of complex G protein and metabolic signaling networks in humans.
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7
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Shaheen F, Stephany-Brassesco I, Kelly BL. Dynamic modulation of Leishmania cytochrome c oxidase subunit IV (LmCOX4) expression in response to mammalian temperature. Mol Biochem Parasitol 2021; 244:111391. [PMID: 34144085 DOI: 10.1016/j.molbiopara.2021.111391] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2021] [Revised: 06/10/2021] [Accepted: 06/11/2021] [Indexed: 10/21/2022]
Abstract
The Leishmania LACK antigen is a ribosome-associated protein that facilitates expression of mitochondrial cytochrome c oxidase subunit IV (LmCOX4) to support parasite mitochondrial fitness and virulence within the vertebrate host. To further examine the relationship between LACK, its putative ribosome binding motif and LmCOX4, we compared the kinetics of LmCOX4 expression following temperature elevation in wildtype LACK (LACK WT) and LACK-putative ribosome-binding mutant (LACKDDE) L. major. We found that, after initial exposure to mammalian temperature, LmCOX4 levels became undetectable in LACKDDE L. major and also, surprisingly, in wild type (WT) control strains. Upon sustained exposure to mammalian temperature, LmCOX4 expression returned in WT control strains only. The initial loss of LmCOX4 in WT L. major was substantially reversed by treatment with the proteasome inhibitor MG132. Our findings indicate that initial loss of LmCOX4 under mammalian conditions is dependent upon proteasome degradation and LmCOX4 re-expression is dependent upon LACK possessing a WT putative ribosome binding motif.
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Affiliation(s)
- Farhana Shaheen
- Department of Microbiology, Immunology and Parasitology, Louisiana State University Health Sciences Center, New Orleans, LA, USA
| | - Isabel Stephany-Brassesco
- Department of Microbiology, Immunology and Parasitology, Louisiana State University Health Sciences Center, New Orleans, LA, USA
| | - Ben L Kelly
- Department of Microbiology, Immunology and Parasitology, Louisiana State University Health Sciences Center, New Orleans, LA, USA.
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8
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Martínez-Fernández V, Cuevas-Bermúdez A, Gutiérrez-Santiago F, Garrido-Godino AI, Rodríguez-Galán O, Jordán-Pla A, Lois S, Triviño JC, de la Cruz J, Navarro F. Prefoldin-like Bud27 influences the transcription of ribosomal components and ribosome biogenesis in Saccharomyces cerevisiae. RNA (NEW YORK, N.Y.) 2020; 26:1360-1379. [PMID: 32503921 PMCID: PMC7491330 DOI: 10.1261/rna.075507.120] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/26/2020] [Accepted: 05/28/2020] [Indexed: 05/08/2023]
Abstract
Understanding the functional connection that occurs for the three nuclear RNA polymerases to synthesize ribosome components during the ribosome biogenesis process has been the focal point of extensive research. To preserve correct homeostasis on the production of ribosomal components, cells might require the existence of proteins that target a common subunit of these RNA polymerases to impact their respective activities. This work describes how the yeast prefoldin-like Bud27 protein, which physically interacts with the Rpb5 common subunit of the three RNA polymerases, is able to modulate the transcription mediated by the RNA polymerase I, likely by influencing transcription elongation, the transcription of the RNA polymerase III, and the processing of ribosomal RNA. Bud27 also regulates both RNA polymerase II-dependent transcription of ribosomal proteins and ribosome biogenesis regulon genes, likely by occupying their DNA ORFs, and the processing of the corresponding mRNAs. With RNA polymerase II, this association occurs in a transcription rate-dependent manner. Our data also indicate that Bud27 inactivation alters the phosphorylation kinetics of ribosomal protein S6, a readout of TORC1 activity. We conclude that Bud27 impacts the homeostasis of the ribosome biogenesis process by regulating the activity of the three RNA polymerases and, in this way, the synthesis of ribosomal components. This quite likely occurs through a functional connection of Bud27 with the TOR signaling pathway.
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Affiliation(s)
- Verónica Martínez-Fernández
- Departamento de Biología Experimental-Genética, Universidad de Jaén, Paraje de las Lagunillas, s/n, E-23071, Jaén, Spain
| | - Abel Cuevas-Bermúdez
- Departamento de Biología Experimental-Genética, Universidad de Jaén, Paraje de las Lagunillas, s/n, E-23071, Jaén, Spain
| | - Francisco Gutiérrez-Santiago
- Departamento de Biología Experimental-Genética, Universidad de Jaén, Paraje de las Lagunillas, s/n, E-23071, Jaén, Spain
| | - Ana I Garrido-Godino
- Departamento de Biología Experimental-Genética, Universidad de Jaén, Paraje de las Lagunillas, s/n, E-23071, Jaén, Spain
| | - Olga Rodríguez-Galán
- Instituto de Biomedicina de Sevilla (IBiS), Hospital Universitario Virgen del Rocío/CSIC/Universidad de Sevilla, E-41013 Seville, Spain
- Departamento de Genética, Universidad de Sevilla, E-41012 Seville, Spain
| | - Antonio Jordán-Pla
- ERI Biotecmed, Facultad de Biológicas, Universitat de València, E-46100 Burjassot, Valencia, Spain
| | - Sergio Lois
- Sistemas Genómicos. Ronda de Guglielmo Marconi, 6, 46980 Paterna, Valencia, Spain
| | - Juan C Triviño
- Sistemas Genómicos. Ronda de Guglielmo Marconi, 6, 46980 Paterna, Valencia, Spain
| | - Jesús de la Cruz
- Instituto de Biomedicina de Sevilla (IBiS), Hospital Universitario Virgen del Rocío/CSIC/Universidad de Sevilla, E-41013 Seville, Spain
- Departamento de Genética, Universidad de Sevilla, E-41012 Seville, Spain
| | - Francisco Navarro
- Departamento de Biología Experimental-Genética, Universidad de Jaén, Paraje de las Lagunillas, s/n, E-23071, Jaén, Spain
- Centro de Estudios Avanzados en Aceite de Oliva y Olivar, Universidad de Jaén, Paraje de las Lagunillas, s/n, E-23071, Jaén, Spain
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9
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Manchalu S, Mittal N, Spang A, Jansen RP. Local translation of yeast ERG4 mRNA at the endoplasmic reticulum requires the brefeldin A resistance protein Bfr1. RNA (NEW YORK, N.Y.) 2019; 25:1661-1672. [PMID: 31455610 PMCID: PMC6859859 DOI: 10.1261/rna.072017.119] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/20/2019] [Accepted: 08/20/2019] [Indexed: 05/13/2023]
Abstract
Brefeldin A resistance factor 1 (Bfr1p) is a nonessential RNA-binding protein and multicopy suppressor of brefeldin A sensitivity in Saccharomyces cerevisiae Deletion of BFR1 leads to multiple defects, including altered cell shape and size, change in ploidy, induction of P-bodies and chromosomal missegregation. Bfr1p has been shown to associate with polysomes, binds to several hundred mRNAs, and can target some of them to P-bodies. Although this implies a role of Bfr1p in translational control of mRNAs, its molecular function remains elusive. In the present study, we show that mutations in RNA-binding residues of Bfr1p impede its RNA-dependent colocalization with ER, yet do not mimic the known cellular defects seen upon BFR1 deletion. However, a Bfr1 RNA-binding mutant is impaired in binding to ERG4 mRNA, which encodes an enzyme required for the final step of ergosterol biosynthesis. Consistently, bfr1Δ strains show a strong reduction in Erg4p protein levels, most likely because of degradation of misfolded Erg4p. Polysome profiling of bfr1Δ or bfr1 mutant strains reveals a strong shift of ERG4 mRNA to polysomes, consistent with a function of Bfr1p in elongation or increased ribosome loading. Collectively, our data reveal that Bfr1 has at least two separable functions: one in RNA binding and cotranslational protein translocation into the ER and one in ploidy control or chromosome segregation.
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Affiliation(s)
- Srinivas Manchalu
- Interfaculty Institute of Biochemistry, University of Tübingen, Tübingen 72076, Germany
| | - Nitish Mittal
- Biozentrum, University of Basel, Basel 4056, Switzerland
| | - Anne Spang
- Biozentrum, University of Basel, Basel 4056, Switzerland
| | - Ralf-Peter Jansen
- Interfaculty Institute of Biochemistry, University of Tübingen, Tübingen 72076, Germany
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10
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Schmitt K, Valerius O. yRACK1/Asc1 proxiOMICs-Towards Illuminating Ships Passing in the Night. Cells 2019; 8:cells8111384. [PMID: 31689955 PMCID: PMC6912217 DOI: 10.3390/cells8111384] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2019] [Revised: 10/25/2019] [Accepted: 10/29/2019] [Indexed: 02/01/2023] Open
Abstract
Diverse signals and stress factors regulate the activity and homeostasis of ribosomes in all cells. The Saccharomyces cerevisiae protein Asc1/yRACK1 occupies an exposed site at the head region of the 40S ribosomal subunit (hr40S) and represents a central hub for signaling pathways. Asc1 strongly affects protein phosphorylation and is involved in quality control pathways induced by translation elongation arrest. Therefore, it is important to understand the dynamics of protein formations in the Asc1 microenvironment at the hr40S. We made use of the in vivo protein-proximity labeling technique Biotin IDentification (BioID). Unbiased proxiOMICs from two adjacent perspectives identified nucleocytoplasmic shuttling mRNA-binding proteins, the deubiquitinase complex Ubp3-Bre5, as well as the ubiquitin E3 ligase Hel2 as neighbors of Asc1. We observed Asc1-dependency of hr40S localization of mRNA-binding proteins and the Ubp3 co-factor Bre5. Hel2 and Ubp3-Bre5 are described to balance the mono-ubiquitination of Rps3 (uS3) during ribosome quality control. Here, we show that the absence of Asc1 resulted in massive exposure and accessibility of the C-terminal tail of its ribosomal neighbor Rps3 (uS3). Asc1 and some of its direct neighbors together might form a ribosomal decision tree that is tightly connected to close-by signaling modules.
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Affiliation(s)
- Kerstin Schmitt
- Department of Molecular Microbiology and Genetics, Institute of Microbiology and Genetics, Göttingen Center for Molecular Biosciences (GZMB), Georg-August-University Göttingen, 37077 Göttingen, Germany.
| | - Oliver Valerius
- Department of Molecular Microbiology and Genetics, Institute of Microbiology and Genetics, Göttingen Center for Molecular Biosciences (GZMB), Georg-August-University Göttingen, 37077 Göttingen, Germany.
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11
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Nürenberg-Goloub E, Tampé R. Ribosome recycling in mRNA translation, quality control, and homeostasis. Biol Chem 2019; 401:47-61. [DOI: 10.1515/hsz-2019-0279] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2019] [Accepted: 10/22/2019] [Indexed: 02/07/2023]
Abstract
Abstract
Protein biosynthesis is a conserved process, essential for life. Ongoing research for four decades has revealed the structural basis and mechanistic details of most protein biosynthesis steps. Numerous pathways and their regulation have recently been added to the translation system describing protein quality control and messenger ribonucleic acid (mRNA) surveillance, ribosome-associated protein folding and post-translational modification as well as human disorders associated with mRNA and ribosome homeostasis. Thus, translation constitutes a key regulatory process placing the ribosome as a central hub at the crossover of numerous cellular pathways. Here, we describe the role of ribosome recycling by ATP-binding cassette sub-family E member 1 (ABCE1) as a crucial regulatory step controlling the biogenesis of functional proteins and the degradation of aberrant nascent chains in quality control processes.
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Affiliation(s)
- Elina Nürenberg-Goloub
- Institute of Biochemistry, Biocenter, Goethe University Frankfurt , Max-von-Laue-Str. 9 , D-60438 Frankfurt/Main , Germany
| | - Robert Tampé
- Institute of Biochemistry, Biocenter, Goethe University Frankfurt , Max-von-Laue-Str. 9 , D-60438 Frankfurt/Main , Germany
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12
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Johnson AG, Lapointe CP, Wang J, Corsepius NC, Choi J, Fuchs G, Puglisi JD. RACK1 on and off the ribosome. RNA (NEW YORK, N.Y.) 2019; 25:881-895. [PMID: 31023766 PMCID: PMC6573788 DOI: 10.1261/rna.071217.119] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/12/2019] [Accepted: 04/21/2019] [Indexed: 05/17/2023]
Abstract
Receptor for activated C kinase 1 (RACK1) is a eukaryote-specific ribosomal protein (RP) implicated in diverse biological functions. To engineer ribosomes for specific fluorescent labeling, we selected RACK1 as a target given its location on the small ribosomal subunit and other properties. However, prior results suggested that RACK1 has roles both on and off the ribosome, and such an exchange might be related to its various cellular functions and hinder our ability to use RACK1 as a stable fluorescent tag for the ribosome. In addition, the kinetics of spontaneous exchange of RACK1 or any RP from a mature ribosome in vitro remain unclear. To address these issues, we engineered fluorescently labeled human ribosomes via RACK1, and applied bulk and single-molecule biochemical analyses to track RACK1 on and off the human ribosome. Our results demonstrate that, despite its cellular nonessentiality from yeast to humans, RACK1 readily reassociates with the ribosome, displays limited conformational dynamics, and remains stably bound to the ribosome for hours in vitro. This work sheds insight into the biochemical basis of RPs exchange on and off a mature ribosome and provides tools for single-molecule analysis of human translation.
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Affiliation(s)
- Alex G Johnson
- Department of Structural Biology, Stanford University School of Medicine, Stanford, California 94305, USA
- Department of Chemical and Systems Biology, Stanford University School of Medicine, Stanford, California 94305, USA
| | - Christopher P Lapointe
- Department of Structural Biology, Stanford University School of Medicine, Stanford, California 94305, USA
| | - Jinfan Wang
- Department of Structural Biology, Stanford University School of Medicine, Stanford, California 94305, USA
| | - Nicholas C Corsepius
- Department of Structural Biology, Stanford University School of Medicine, Stanford, California 94305, USA
| | - Junhong Choi
- Department of Structural Biology, Stanford University School of Medicine, Stanford, California 94305, USA
- Department of Applied Physics, Stanford University, Stanford, California 94305, USA
| | - Gabriele Fuchs
- The RNA Institute, Department of Biological Sciences, University of Albany, Albany, New York 12222, USA
| | - Joseph D Puglisi
- Department of Structural Biology, Stanford University School of Medicine, Stanford, California 94305, USA
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13
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Stahl T, Hümmer S, Ehrenfeuchter N, Mittal N, Fucile G, Spang A. Asymmetric distribution of glucose transporter mRNA provides a growth advantage in yeast. EMBO J 2019; 38:e100373. [PMID: 30910878 PMCID: PMC6517814 DOI: 10.15252/embj.2018100373] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2018] [Revised: 02/21/2019] [Accepted: 02/27/2019] [Indexed: 01/09/2023] Open
Abstract
Asymmetric localization of mRNA is important for cell fate decisions in eukaryotes and provides the means for localized protein synthesis in a variety of cell types. Here, we show that hexose transporter mRNAs are retained in the mother cell of S. cerevisiae until metaphase-anaphase transition (MAT) and then are released into the bud. The retained mRNA was translationally less active but bound to ribosomes before MAT Importantly, when cells were shifted from starvation to glucose-rich conditions, HXT2 mRNA, but none of the other HXT mRNAs, was enriched in the bud after MAT This enrichment was dependent on the Ras/cAMP/PKA pathway, the APC ortholog Kar9, and nuclear segregation into the bud. Competition experiments between strains that only expressed one hexose transporter at a time revealed that HXT2 only cells grow faster than their counterparts when released from starvation. Therefore, asymmetric distribution of HXT2 mRNA provides a growth advantage for daughters, who are better prepared for nutritional changes in the environment. Our data provide evidence that asymmetric mRNA localization is an important factor in determining cellular fitness.
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Affiliation(s)
- Timo Stahl
- Biozentrum, University of Basel, Basel, Switzerland
| | | | | | | | - Geoffrey Fucile
- SIB Swiss Institute of Bioinformatics, sciCORE Computing Center, University of Basel, Basel, Switzerland
| | - Anne Spang
- Biozentrum, University of Basel, Basel, Switzerland
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14
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RACK1 Specifically Regulates Translation through Its Binding to Ribosomes. Mol Cell Biol 2018; 38:MCB.00230-18. [PMID: 30201806 PMCID: PMC6234289 DOI: 10.1128/mcb.00230-18] [Citation(s) in RCA: 39] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2018] [Accepted: 08/26/2018] [Indexed: 12/22/2022] Open
Abstract
The translational capability of ribosomes deprived of specific nonfundamental ribosomal proteins may be altered. Physiological mechanisms are scanty, and it is unclear whether free ribosomal proteins can cross talk with the signaling machinery. The translational capability of ribosomes deprived of specific nonfundamental ribosomal proteins may be altered. Physiological mechanisms are scanty, and it is unclear whether free ribosomal proteins can cross talk with the signaling machinery. RACK1 (receptor for activated C kinase 1) is a highly conserved scaffold protein, located on the 40S subunit near the mRNA exit channel. RACK1 is involved in a variety of intracellular contexts, both on and off the ribosomes, acting as a receptor for proteins in signaling, such as the protein kinase C (PKC) family. Here we show that the binding of RACK1 to ribosomes is essential for full translation of capped mRNAs and efficient recruitment of eukaryotic initiation factor 4E (eIF4E). In vitro, when RACK1 is partially depleted, supplementing the ribosome machinery with wild-type RACK1 restores the translational capability, whereas the addition of a RACK1 mutant that is unable to bind ribosomes does not. Outside the ribosome, RACK1 has a reduced half-life. By accumulating in living cells, free RACK1 exerts an inhibitory phenotype, impairing cell cycle progression and repressing global translation. Here we present RACK1 binding to ribosomes as a crucial way to regulate translation, possibly through interaction with known partners on or off the ribosome that are involved in signaling.
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15
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Ergüden B. Dhh1 is a member of the SESA network. Yeast 2018; 36:99-105. [PMID: 30346046 DOI: 10.1002/yea.3363] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2018] [Revised: 10/10/2018] [Accepted: 10/16/2018] [Indexed: 11/09/2022] Open
Abstract
The correct separation of chromosomes during mitosis is necessary to prevent genetic instability and aneuploidy, which are responsible for cancer and other diseases, and it depends on proper centrosome duplication. In a recent study, we found that Smy2 can suppress the essential role of Mps2 in the insertion of yeast centrosome into the nuclear membrane by interacting with Eap1, Scp160, and Asc1 and designated this network as SESA (Smy2, Eap1, Scp160, Asc1). Detailed analysis showed that the SESA network is part of a mechanism which regulates translation of POM34 mRNA. Thus, SESA is a system that suppresses spindle pole body duplication defects by repressing the translation of POM34 mRNA. In this study, we performed a genome-wide screening in order to identify new members of the SESA network and confirmed Dhh1 as a putative member. Dhh1 is a cytoplasmic DEAD-box helicase known to regulate translation. Therefore, we hypothesized that Dhh1 is responsible for the highly selective inhibition of POM34 mRNA by SESA.
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Affiliation(s)
- Bengü Ergüden
- Department of Bioengineering, Gebze Technical University, Kocaeli, Turkey
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16
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Crawford RA, Pavitt GD. Translational regulation in response to stress in Saccharomyces cerevisiae. Yeast 2018; 36:5-21. [PMID: 30019452 PMCID: PMC6492140 DOI: 10.1002/yea.3349] [Citation(s) in RCA: 51] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2018] [Revised: 06/08/2018] [Accepted: 06/25/2018] [Indexed: 12/19/2022] Open
Abstract
The budding yeast Saccharomyces cerevisiae must dynamically alter the composition of its proteome in order to respond to diverse stresses. The reprogramming of gene expression during stress typically involves initial global repression of protein synthesis, accompanied by the activation of stress‐responsive mRNAs through both translational and transcriptional responses. The ability of specific mRNAs to counter the global translational repression is therefore crucial to the overall response to stress. Here we summarize the major repressive mechanisms and discuss mechanisms of translational activation in response to different stresses in S. cerevisiae. Taken together, a wide range of studies indicate that multiple elements act in concert to bring about appropriate translational responses. These include regulatory elements within mRNAs, altered mRNA interactions with RNA‐binding proteins and the specialization of ribosomes that each contribute towards regulating protein expression to suit the changing environmental conditions.
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Affiliation(s)
- Robert A Crawford
- Division of Molecular and Cellular Function, School of Biological Sciences, Faculty of Biology, Medicine and Health, Manchester Academic Health Science Centre, The University of Manchester, Michael Smith Building, Dover Street, Manchester, M13 9PT, UK
| | - Graham D Pavitt
- Division of Molecular and Cellular Function, School of Biological Sciences, Faculty of Biology, Medicine and Health, Manchester Academic Health Science Centre, The University of Manchester, Michael Smith Building, Dover Street, Manchester, M13 9PT, UK
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17
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The RNA-Binding Protein Scp160p Facilitates Aggregation of Many Endogenous Q/N-Rich Proteins. Cell Rep 2018; 24:20-26. [DOI: 10.1016/j.celrep.2018.06.015] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2017] [Revised: 04/18/2018] [Accepted: 06/01/2018] [Indexed: 01/05/2023] Open
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18
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Costello JL, Kershaw CJ, Castelli LM, Talavera D, Rowe W, Sims PFG, Ashe MP, Grant CM, Hubbard SJ, Pavitt GD. Dynamic changes in eIF4F-mRNA interactions revealed by global analyses of environmental stress responses. Genome Biol 2017; 18:201. [PMID: 29078784 PMCID: PMC5660459 DOI: 10.1186/s13059-017-1338-4] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2017] [Accepted: 10/13/2017] [Indexed: 11/29/2022] Open
Abstract
Background Translation factors eIF4E and eIF4G form eIF4F, which interacts with the messenger RNA (mRNA) 5′ cap to promote ribosome recruitment and translation initiation. Variations in the association of eIF4F with individual mRNAs likely contribute to differences in translation initiation frequencies between mRNAs. As translation initiation is globally reprogrammed by environmental stresses, we were interested in determining whether eIF4F interactions with individual mRNAs are reprogrammed and how this may contribute to global environmental stress responses. Results Using a tagged-factor protein capture and RNA-sequencing (RNA-seq) approach, we have assessed how mRNA associations with eIF4E, eIF4G1 and eIF4G2 change globally in response to three defined stresses that each cause a rapid attenuation of protein synthesis: oxidative stress induced by hydrogen peroxide and nutrient stresses caused by amino acid or glucose withdrawal. We find that acute stress leads to dynamic and unexpected changes in eIF4F–mRNA interactions that are shared among each factor and across the stresses imposed. eIF4F–mRNA interactions stabilised by stress are predominantly associated with translational repression, while more actively initiating mRNAs become relatively depleted for eIF4F. Simultaneously, other mRNAs are insulated from these stress-induced changes in eIF4F association. Conclusion Dynamic eIF4F–mRNA interaction changes are part of a coordinated early translational control response shared across environmental stresses. Our data are compatible with a model where multiple mRNA closed-loop complexes form with differing stability. Hence, unexpectedly, in the absence of other stabilising factors, rapid translation initiation on mRNAs correlates with less stable eIF4F interactions. Electronic supplementary material The online version of this article (doi:10.1186/s13059-017-1338-4) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Joseph L Costello
- Division of Molecular and Cellular Function, School of Biological Sciences, Faculty of Biology Medicine and Health, Manchester Academic Health Science Centre, The University of Manchester, Manchester, M13 9PT, UK.,Present address: Biosciences, College of Life and Environmental Sciences, Geoffrey Pope Building, University of Exeter, Stocker Road, Exeter, EX4 4QD, UK
| | - Christopher J Kershaw
- Division of Molecular and Cellular Function, School of Biological Sciences, Faculty of Biology Medicine and Health, Manchester Academic Health Science Centre, The University of Manchester, Manchester, M13 9PT, UK
| | - Lydia M Castelli
- Division of Molecular and Cellular Function, School of Biological Sciences, Faculty of Biology Medicine and Health, Manchester Academic Health Science Centre, The University of Manchester, Manchester, M13 9PT, UK.,Present address: Sheffield Institute for Translational Neuroscience, The University of Sheffield, 385a Glossop Road, Sheffield, S10 2HQ, UK
| | - David Talavera
- Division of Cardiovascular Sciences, School of Medicine, Faculty of Biology Medicine and Health, Manchester Academic Health Science Centre, The University of Manchester, Manchester, M13 9PT, UK
| | - William Rowe
- Division of Molecular and Cellular Function, School of Biological Sciences, Faculty of Biology Medicine and Health, Manchester Academic Health Science Centre, The University of Manchester, Manchester, M13 9PT, UK.,Present address: Department of Chemistry, Loughborough University, Epinal Way, Loughborough, Leicestershire, LE11 3TU, UK
| | - Paul F G Sims
- Manchester Institute of Biotechnology (MIB), The University of Manchester, 131 Princess Street, Manchester, M1 7DN, UK
| | - Mark P Ashe
- Division of Molecular and Cellular Function, School of Biological Sciences, Faculty of Biology Medicine and Health, Manchester Academic Health Science Centre, The University of Manchester, Manchester, M13 9PT, UK
| | - Christopher M Grant
- Division of Molecular and Cellular Function, School of Biological Sciences, Faculty of Biology Medicine and Health, Manchester Academic Health Science Centre, The University of Manchester, Manchester, M13 9PT, UK
| | - Simon J Hubbard
- Division of Evolution and Genomic Sciences, School of Biological Sciences, Faculty of Biology Medicine and Health, Manchester Academic Health Science Centre, The University of Manchester, Manchester, M13 9PT, UK
| | - Graham D Pavitt
- Division of Molecular and Cellular Function, School of Biological Sciences, Faculty of Biology Medicine and Health, Manchester Academic Health Science Centre, The University of Manchester, Manchester, M13 9PT, UK.
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19
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Opitz N, Schmitt K, Hofer-Pretz V, Neumann B, Krebber H, Braus GH, Valerius O. Capturing the Asc1p/ Receptor for Activated C Kinase 1 (RACK1) Microenvironment at the Head Region of the 40S Ribosome with Quantitative BioID in Yeast. Mol Cell Proteomics 2017; 16:2199-2218. [PMID: 28982715 DOI: 10.1074/mcp.m116.066654] [Citation(s) in RCA: 51] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2016] [Revised: 09/29/2017] [Indexed: 12/13/2022] Open
Abstract
The Asc1 protein of Saccharomyces cerevisiae is a scaffold protein at the head region of ribosomal 40S that links mRNA translation to cellular signaling. In this study, proteins that colocalize with Asc1p were identified with proximity-dependent Biotin IDentification (BioID), an in vivo labeling technique described here for the first time for yeast. Biotinylated Asc1p-birA*-proximal proteins were identified and quantitatively verified against controls applying SILAC and mass spectrometry. The mRNA-binding proteins Sro9p and Gis2p appeared together with Scp160p, each providing ribosomes with nuclear transcripts. The cap-binding protein eIF4E (Cdc33p) and the eIF3/a-subunit (Rpg1p) were identified reflecting the encounter of proteins involved in the initiation of mRNA translation at the head region of ribosomal 40S. Unexpectedly, a protein involved in ribosome preservation (the clamping factor Stm1p), the deubiquitylation complex Ubp3p-Bre5p, the RNA polymerase II degradation factor 1 (Def1p), and transcription factors (Spt5p, Mbf1p) colocalize with Asc1p in exponentially growing cells. For Asc1R38D, K40Ep, a variant considered to be deficient in binding to ribosomes, BioID revealed its predominant ribosome localization. Glucose depletion replaced most of the Asc1p colocalizing proteins for additional ribosomal proteins, suggesting a ribosome aggregation process during early nutrient limitation, possibly concomitant with ribosomal subunit clamping. Overall, the characterization of the Asc1p microenvironment with BioID confirmed and substantiated our recent findings that the β-propeller broadly contributes to signal transduction influencing phosphorylation of colocalizing proteins (e.g. of Bre5p), and by that might affect nuclear gene transcription and the fate of ribosomes.
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Affiliation(s)
- Nadine Opitz
- From the ‡Department of Molecular Microbiology and Genetics, Institute of Microbiology and Genetics, Göttingen Center for Molecular Biosciences (GZMB), Georg-August-University Göttingen, 37077 Göttingen, Germany
| | - Kerstin Schmitt
- From the ‡Department of Molecular Microbiology and Genetics, Institute of Microbiology and Genetics, Göttingen Center for Molecular Biosciences (GZMB), Georg-August-University Göttingen, 37077 Göttingen, Germany
| | - Verena Hofer-Pretz
- From the ‡Department of Molecular Microbiology and Genetics, Institute of Microbiology and Genetics, Göttingen Center for Molecular Biosciences (GZMB), Georg-August-University Göttingen, 37077 Göttingen, Germany
| | - Bettina Neumann
- §Department of Molecular Genetics, Institute of Microbiology and Genetics, GZMB, Georg-August-University Göttingen, 37077 Göttingen, Germany
| | - Heike Krebber
- §Department of Molecular Genetics, Institute of Microbiology and Genetics, GZMB, Georg-August-University Göttingen, 37077 Göttingen, Germany
| | - Gerhard H Braus
- From the ‡Department of Molecular Microbiology and Genetics, Institute of Microbiology and Genetics, Göttingen Center for Molecular Biosciences (GZMB), Georg-August-University Göttingen, 37077 Göttingen, Germany
| | - Oliver Valerius
- From the ‡Department of Molecular Microbiology and Genetics, Institute of Microbiology and Genetics, Göttingen Center for Molecular Biosciences (GZMB), Georg-August-University Göttingen, 37077 Göttingen, Germany;
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20
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Cheng MH, Jansen RP. A jack of all trades: the RNA-binding protein vigilin. WILEY INTERDISCIPLINARY REVIEWS-RNA 2017; 8. [PMID: 28975734 DOI: 10.1002/wrna.1448] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/31/2017] [Revised: 07/21/2017] [Accepted: 08/17/2017] [Indexed: 12/25/2022]
Abstract
The vigilin family of proteins is evolutionarily conserved from yeast to humans and characterized by the proteins' 14 or 15 hnRNP K homology (KH) domains, typically associated with RNA-binding. Vigilin is the largest RNA-binding protein (RBP) in the KH domain-containing family and one of the largest RBP known to date. Since its identification 30 years ago, vigilin has been shown to bind over 700 mRNAs and has been associated with cancer progression and cardiovascular disease. We provide a brief historic overview of vigilin research and outline the proteins' different functions, focusing on maintenance of genome ploidy, heterochromatin formation, RNA export, as well as regulation of translation, mRNA transport, and mRNA stability. The multitude of associated functions is reflected by the large number of identified interaction partners, ranging from tRNAs, mRNAs, ribosomes and ribosome-associated proteins, to histone methyltransferases and DNA-dependent protein kinases. Most of these partners bind to vigilin's carboxyterminus, and the two most C-terminal KH domains of the protein, KH13 and KH14, represent the main mRNA-binding interface. Since the nuclear functions of vigilins in particular are not conserved, we outline a model for the basal functions of vigilins, as well as those which were acquired during the transition from unicellular organisms to metazoa. WIREs RNA 2017, 8:e1448. doi: 10.1002/wrna.1448 For further resources related to this article, please visit the WIREs website.
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Affiliation(s)
- Matthew Hk Cheng
- International Max Planck Research School, Tuebingen, Germany.,Interfaculty Institute of Biochemistry, Tuebingen, Germany
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21
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Nielsen MH, Flygaard RK, Jenner LB. Structural analysis of ribosomal RACK1 and its role in translational control. Cell Signal 2017; 35:272-281. [PMID: 28161490 DOI: 10.1016/j.cellsig.2017.01.026] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2017] [Accepted: 01/31/2017] [Indexed: 12/28/2022]
Abstract
Receptor for Activated C-Kinase 1 (RACK1) belongs to the WD40 family of proteins, known to act as scaffolding proteins in interaction networks. Accordingly, RACK1 is found to have numerous interacting partners ranging from kinases and signaling proteins to membrane bound receptors and ion channels. Interestingly, RACK1 has also been identified as a ribosomal protein present in all eukaryotic ribosomes. Structures of eukaryotic ribosomes have shown RACK1 to be located at the back of the head of the small ribosomal subunit. This suggests that RACK1 could act as a ribosomal scaffolding protein recruiting regulators of translation to the ribosome, and several studies have in fact found RACK1 to play a role in regulation of translation. To fully understand the role of RACK1 we need to understand whether the many reported interaction partners of RACK1 bind to free or ribosomal RACK1. In this review we provide a structural analysis of ribosome-bound RACK1 to provide a basis for answering this fundamental question. Our analysis shows that RACK1 is tightly bound to the ribosome through highly conserved and specific interactions confirming RACK1 as an integral ribosomal protein. Furthermore, we have analyzed whether reported binding sites for RACK1 interacting partners with a proposed role in translational control are accessible on ribosomal RACK1. Our analysis shows that most of the interaction partners with putative regulatory functions have binding sites that are available on ribosomal RACK1, supporting the role of RACK1 as a ribosomal signaling hub. We also discuss the possible role for RACK1 in recruitment of ribosomes to focal adhesion sites and regulation of local translation during cell spreading and migration.
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Affiliation(s)
- Maja Holch Nielsen
- Department of Molecular Biology and Genetics, Gustav Wieds Vej 10C, DK-8000 Aarhus C, Aarhus University, Denmark
| | - Rasmus Kock Flygaard
- Department of Molecular Biology and Genetics, Gustav Wieds Vej 10C, DK-8000 Aarhus C, Aarhus University, Denmark
| | - Lasse Bohl Jenner
- Department of Molecular Biology and Genetics, Gustav Wieds Vej 10C, DK-8000 Aarhus C, Aarhus University, Denmark
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22
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Asc1p/RACK1 Connects Ribosomes to Eukaryotic Phosphosignaling. Mol Cell Biol 2017; 37:MCB.00279-16. [PMID: 27821475 DOI: 10.1128/mcb.00279-16] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2016] [Accepted: 10/24/2016] [Indexed: 02/07/2023] Open
Abstract
WD40 repeat proteins fold into characteristic β-propeller structures and control signaling circuits during cellular adaptation processes within eukaryotes. The RACK1 protein of Saccharomyces cerevisiae, Asc1p, consists exclusively of a single seven-bladed β-propeller that operates from the ribosomal base at the head region of the 40S subunit. Here we show that the R38D K40E ribosomal binding-compromised variant (Asc1DEp) is severely destabilized through mutation of phosphosite T143 to a dephosphorylation-mimicking alanine, probably through proteasomal degradation, leading to asc1- phenotypes. Phosphosite Y250 contributes to resistance to translational inhibitors but does not influence Asc1DEp stability. Beyond its own phosphorylation at T143, Y250, and other sites, Asc1p heavily influences the phosphorylation of as many as 90 proteins at 120 sites. Many of these proteins are regulators of fundamental processes ranging from mRNA translation to protein transport and turnover, cytoskeleton organization, and cellular signaling. Our data expose Asc1p/RACK1 as a key factor in phosphosignaling and manifest it as a control point at the head of the ribosomal 40S subunit itself regulated through posttranslational modification.
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23
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Receptor for Activated C-Kinase 1 (PfRACK1) is required for Plasmodium falciparum intra-erythrocytic proliferation. Mol Biochem Parasitol 2016; 211:62-66. [PMID: 27732881 DOI: 10.1016/j.molbiopara.2016.10.002] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2016] [Revised: 10/05/2016] [Accepted: 10/08/2016] [Indexed: 11/24/2022]
Abstract
Emerging resistance to current anti-malarials necessitates a more detailed understanding of the biological processes of Plasmodium falciparum proliferation, thus allowing identification of new drug targets. The well-conserved protein Receptor for Activated C-Kinase 1 (RACK1) was originally identified in mammalian cells as an anchoring protein for protein kinase C (PKC) and has since been shown to be important for cell migration, cytokinesis, transcription, epigenetics, and protein translation. The P. falciparum ortholog, PfRACK1, is expressed in blood stages of the parasite and is diffusely localized in the parasite cytoplasm. Using a destabilizing domain to allow inducible knockdown of the endogenous protein level, we evaluated the requirement for PfRACK1 during blood-stage replication. Following destabilization, the parasites demonstrate a nearly complete growth arrest at the trophozoite stage. The essential nature of PfRACK1 suggests that the protein itself or the pathways regulated by the protein are potential targets for novel anti-malarial therapeutics.
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24
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Mobin MB, Gerstberger S, Teupser D, Campana B, Charisse K, Heim MH, Manoharan M, Tuschl T, Stoffel M. The RNA-binding protein vigilin regulates VLDL secretion through modulation of Apob mRNA translation. Nat Commun 2016; 7:12848. [PMID: 27665711 PMCID: PMC5052685 DOI: 10.1038/ncomms12848] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2016] [Accepted: 08/01/2016] [Indexed: 01/07/2023] Open
Abstract
The liver is essential for the synthesis of plasma proteins and integration of lipid metabolism. While the role of transcriptional networks in these processes is increasingly understood, less is known about post-transcriptional control of gene expression by RNA-binding proteins (RBPs). Here, we show that the RBP vigilin is upregulated in livers of obese mice and in patients with fatty liver disease. By using in vivo, biochemical and genomic approaches, we demonstrate that vigilin controls very-low-density lipoprotein (VLDL) secretion through the modulation of apolipoproteinB/Apob mRNA translation. Crosslinking studies reveal that vigilin binds to CU-rich regions in the mRNA coding sequence of Apob and other proatherogenic secreted proteins, including apolipoproteinC-III/Apoc3 and fibronectin/Fn1. Consequently, hepatic vigilin knockdown decreases VLDL/low-density lipoprotein (LDL) levels and formation of atherosclerotic plaques in Ldlr−/− mice. These studies uncover a role for vigilin as a key regulator of hepatic Apob translation and demonstrate the therapeutic potential of inhibiting vigilin for cardiovascular diseases. RNA-binding proteins (RBP) are an emerging group of post-translational regulators. Here the authors show that the RBP vigilin regulates translation of mRNA encoding for proatherogenic proteins—apoB, apoC-III and fibronectin—representing a potential therapeutic target in cardiovascular diseases.
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Affiliation(s)
- Mehrpouya B Mobin
- Institute of Molecular Health Sciences, ETH Zurich, Otto-Stern Weg 7, 8093 Zurich, Switzerland
| | - Stefanie Gerstberger
- Howard Hughes Medical Institute, The Rockefeller University, 1230 York Avenue, New York, New York 10065, USA
| | - Daniel Teupser
- Institute of Laboratory Medicine, Ludwig-Maximilians-University Munich, Marchioninistr. 15, 81377 Munich, Germany
| | - Benedetta Campana
- Department of Biomedicine and Clinic for Gastroenterology and Hepatology, University Hospital Basel, Hebelstrasse 20, 4031 Basel, Switzerland
| | - Klaus Charisse
- Alnylam Pharmaceuticals, 300 Third Street, Cambridge, Massachusetts 02142, USA
| | - Markus H Heim
- Department of Biomedicine and Clinic for Gastroenterology and Hepatology, University Hospital Basel, Hebelstrasse 20, 4031 Basel, Switzerland
| | - Muthiah Manoharan
- Alnylam Pharmaceuticals, 300 Third Street, Cambridge, Massachusetts 02142, USA
| | - Thomas Tuschl
- Howard Hughes Medical Institute, The Rockefeller University, 1230 York Avenue, New York, New York 10065, USA
| | - Markus Stoffel
- Institute of Molecular Health Sciences, ETH Zurich, Otto-Stern Weg 7, 8093 Zurich, Switzerland
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25
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Thompson MK, Rojas-Duran MF, Gangaramani P, Gilbert WV. The ribosomal protein Asc1/RACK1 is required for efficient translation of short mRNAs. eLife 2016; 5. [PMID: 27117520 PMCID: PMC4848094 DOI: 10.7554/elife.11154] [Citation(s) in RCA: 83] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2015] [Accepted: 03/21/2016] [Indexed: 02/06/2023] Open
Abstract
Translation is a core cellular process carried out by a highly conserved macromolecular machine, the ribosome. There has been remarkable evolutionary adaptation of this machine through the addition of eukaryote-specific ribosomal proteins whose individual effects on ribosome function are largely unknown. Here we show that eukaryote-specific Asc1/RACK1 is required for efficient translation of mRNAs with short open reading frames that show greater than average translational efficiency in diverse eukaryotes. ASC1 mutants in S. cerevisiae display compromised translation of specific functional groups, including cytoplasmic and mitochondrial ribosomal proteins, and display cellular phenotypes consistent with their gene-specific translation defects. Asc1-sensitive mRNAs are preferentially associated with the translational ‘closed loop’ complex comprised of eIF4E, eIF4G, and Pab1, and depletion of eIF4G mimics the translational defects of ASC1 mutants. Together our results reveal a role for Asc1/RACK1 in a length-dependent initiation mechanism optimized for efficient translation of genes with important housekeeping functions. DOI:http://dx.doi.org/10.7554/eLife.11154.001 Ribosomes are structures within cells that are responsible for making proteins. Molecules called messenger RNAs (or mRNAs), which contain genetic information derived from the DNA of a gene, pass through ribosomes that then “translate” that information to build proteins. Although all living cells contain ribosomes, the protein building blocks that make up the structure of the ribosome are not the same in all species. Furthermore, the exact roles that each building block plays during translation are not known. The ribosomes of plants, animals, and budding yeast contain the same protein, known as Asc1 in budding yeast and RACK1 in plants and animals. Thompson et al. have now explored the role of Asc1 in yeast cells by measuring translation in the absence of Asc1 using a technique called ribosome footprint profiling. This analysis revealed that cells lacking Asc1 translate fewer short mRNA molecules than normal cells. Short mRNAs encode small proteins that tend to play important ‘housekeeping’ roles in the cell — by forming the structural building blocks of ribosomes, for example. It has been observed previously that short mRNAs are translated at a higher rate than longer mRNAs on average, although the reasons behind this bias are still mysterious. The findings of Thompson et al. suggest that the ribosome itself may discriminate between short and long mRNAs and that the Asc1 protein is involved in calibrating the ribosome’s preference for short mRNAs. Cells need differing amounts of small proteins in different growth conditions. It will therefore be interesting to investigate whether mRNA length discrimination can be regulated by Asc1 and/or other components of the ribosome to tune gene expression to the environment. DOI:http://dx.doi.org/10.7554/eLife.11154.002
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Affiliation(s)
- Mary K Thompson
- Department of Biology, Massachusetts Institute of Technology, Cambridge, United States
| | - Maria F Rojas-Duran
- Department of Biology, Massachusetts Institute of Technology, Cambridge, United States
| | - Paritosh Gangaramani
- Department of Biology, Massachusetts Institute of Technology, Cambridge, United States
| | - Wendy V Gilbert
- Department of Biology, Massachusetts Institute of Technology, Cambridge, United States
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Shi Z, Barna M. Translating the genome in time and space: specialized ribosomes, RNA regulons, and RNA-binding proteins. Annu Rev Cell Dev Biol 2015; 31:31-54. [PMID: 26443190 DOI: 10.1146/annurev-cellbio-100814-125346] [Citation(s) in RCA: 143] [Impact Index Per Article: 15.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
A central question in cell and developmental biology is how the information encoded in the genome is differentially interpreted to generate a diverse array of cell types. A growing body of research on posttranscriptional gene regulation is revealing that both global protein synthesis rates and the translation of specific mRNAs are highly specialized in different cell types. How this exquisite translational regulation is achieved is the focus of this review. Two levels of regulation are discussed: the translation machinery and cis-acting elements within mRNAs. Recent evidence shows that the ribosome itself directs how the genome is translated in time and space and reveals surprising functional specificity in individual components of the core translation machinery. We are also just beginning to appreciate the rich regulatory information embedded in the untranslated regions of mRNAs, which direct the selective translation of transcripts. These hidden RNA regulons may interface with a myriad of RNA-binding proteins and specialized translation machinery to provide an additional layer of regulation to how transcripts are spatiotemporally expressed. Understanding this largely unexplored world of translational codes hardwired in the core translation machinery is an exciting new research frontier fundamental to our understanding of gene regulation, organismal development, and evolution.
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Affiliation(s)
- Zhen Shi
- Department of Developmental Biology and Department of Genetics, Stanford University, Stanford, California 94305;
| | - Maria Barna
- Department of Developmental Biology and Department of Genetics, Stanford University, Stanford, California 94305;
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A Gβ protein and the TupA Co-Regulator Bind to Protein Kinase A Tpk2 to Act as Antagonistic Molecular Switches of Fungal Morphological Changes. PLoS One 2015; 10:e0136866. [PMID: 26334875 PMCID: PMC4559445 DOI: 10.1371/journal.pone.0136866] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2015] [Accepted: 08/09/2015] [Indexed: 11/19/2022] Open
Abstract
The human pathogenic fungus Paracoccidioides brasiliensis (Pb) undergoes a morphological transition from a saprobic mycelium to pathogenic yeast that is controlled by the cAMP-signaling pathway. There is a change in the expression of the Gβ-protein PbGpb1, which interacts with adenylate cyclase, during this morphological transition. We exploited the fact that the cAMP-signaling pathway of Saccharomyces cerevisiae does not include a Gβ-protein to probe the functional role of PbGpb1. We present data that indicates that PbGpb1 and the transcriptional regulator PbTupA both bind to the PKA protein PbTpk2. PbTPK2 was able to complement a TPK2Δ strain of S. cerevisiae, XPY5a/α, which was defective in pseudohyphal growth. Whilst PbGPB1 had no effect on the parent S. cerevisiae strain, MLY61a/α, it repressed the filamentous growth of XPY5a/α transformed with PbTPK2, behaviour that correlated with a reduced expression of the floculin FLO11. In vitro, PbGpb1 reduced the kinase activity of PbTpk2, suggesting that inhibition of PbTpk2 by PbGpb1 reduces the level of expression of Flo11, antagonizing the filamentous growth of the cells. In contrast, expressing the co-regulator PbTUPA in XPY5a/α cells transformed with PbTPK2, but not untransformed cells, induced hyperfilamentous growth, which could be antagonized by co-transforming the cells with PbGPB1. PbTUPA was unable to induce the hyperfilamentous growth of a FLO8Δ strain, suggesting that PbTupA functions in conjunction with the transcription factor Flo8 to control Flo11 expression. Our data indicates that P. brasiliensis PbGpb1 and PbTupA, both of which have WD/β-propeller structures, bind to PbTpk2 to act as antagonistic molecular switches of cell morphology, with PbTupA and PbGpb1 inducing and repressing filamentous growth, respectively. Our findings define a potential mechanism for controlling the morphological switch that underpins the virulence of dimorphic fungi.
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Wolf AS, Grayhack EJ. Asc1, homolog of human RACK1, prevents frameshifting in yeast by ribosomes stalled at CGA codon repeats. RNA (NEW YORK, N.Y.) 2015; 21:935-45. [PMID: 25792604 PMCID: PMC4408800 DOI: 10.1261/rna.049080.114] [Citation(s) in RCA: 57] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/21/2014] [Accepted: 01/14/2015] [Indexed: 05/09/2023]
Abstract
Quality control systems monitor and stop translation at some ribosomal stalls, but it is unknown if halting translation at such stalls actually prevents synthesis of abnormal polypeptides. In yeast, ribosome stalling occurs at Arg CGA codon repeats, with even two consecutive CGA codons able to reduce translation by up to 50%. The conserved eukaryotic Asc1 protein limits translation through internal Arg CGA codon repeats. We show that, in the absence of Asc1 protein, ribosomes continue translating at CGA codons, but undergo substantial frameshifting with dramatically higher levels of frameshifting occurring with additional repeats of CGA codons. Frameshifting depends upon the slow or inefficient decoding of these codons, since frameshifting is suppressed by increased expression of the native tRNA(Arg(ICG)) that decodes CGA codons by wobble decoding. Moreover, the extent of frameshifting is modulated by the position of the CGA codon repeat relative to the translation start site. Thus, translation fidelity depends upon Asc1-mediated quality control.
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Affiliation(s)
- Andrew S Wolf
- Department of Biochemistry and Biophysics, School of Medicine and Dentistry, University of Rochester, Rochester, New York 14642, USA
| | - Elizabeth J Grayhack
- Department of Biochemistry and Biophysics, School of Medicine and Dentistry, University of Rochester, Rochester, New York 14642, USA Center for RNA Biology, University of Rochester, Rochester, New York 14642, USA
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The yeast La related protein Slf1p is a key activator of translation during the oxidative stress response. PLoS Genet 2015; 11:e1004903. [PMID: 25569619 PMCID: PMC4287443 DOI: 10.1371/journal.pgen.1004903] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2014] [Accepted: 11/19/2014] [Indexed: 12/22/2022] Open
Abstract
The mechanisms by which RNA-binding proteins control the translation of subsets of mRNAs are not yet clear. Slf1p and Sro9p are atypical-La motif containing proteins which are members of a superfamily of RNA-binding proteins conserved in eukaryotes. RIP-Seq analysis of these two yeast proteins identified overlapping and distinct sets of mRNA targets, including highly translated mRNAs such as those encoding ribosomal proteins. In paralell, transcriptome analysis of slf1Δ and sro9Δ mutant strains indicated altered gene expression in similar functional classes of mRNAs following loss of each factor. The loss of SLF1 had a greater impact on the transcriptome, and in particular, revealed changes in genes involved in the oxidative stress response. slf1Δ cells are more sensitive to oxidants and RIP-Seq analysis of oxidatively stressed cells enriched Slf1p targets encoding antioxidants and other proteins required for oxidant tolerance. To quantify these effects at the protein level, we used label-free mass spectrometry to compare the proteomes of wild-type and slf1Δ strains following oxidative stress. This analysis identified several proteins which are normally induced in response to hydrogen peroxide, but where this increase is attenuated in the slf1Δ mutant. Importantly, a significant number of the mRNAs encoding these targets were also identified as Slf1p-mRNA targets. We show that Slf1p remains associated with the few translating ribosomes following hydrogen peroxide stress and that Slf1p co-immunoprecipitates ribosomes and members of the eIF4E/eIF4G/Pab1p ‘closed loop’ complex suggesting that Slf1p interacts with actively translated mRNAs following stress. Finally, mutational analysis of SLF1 revealed a novel ribosome interacting domain in Slf1p, independent of its RNA binding La-motif. Together, our results indicate that Slf1p mediates a translational response to oxidative stress via mRNA-specific translational control. All organisms must respond to changes in their external environment such as exposure to different stresses. The availability of genome sequences and post-genomic technologies has enabled the analysis of these adaptive responses at the molecular level in terms of altered gene expression profiles. However, relatively few studies have focused on how cells regulate the translation of mRNA into protein in response to stress, despite its fundamental role in gene expression pathways. In this study, we show that a previously identified RNA-binding protein called Slf1p plays a major role in mRNA-specific regulation of translation during oxidative stress conditions and is necessary to promote the translation of stress-responsive mRNAs. This protein is a member of the so-called “La-related” family of proteins that have not been well characterized, although they are conserved throughout evolution. Exposure to oxidants is known to cause a general down-regulation of protein synthesis, although many stress response proteins are able to overcome this inhibition and increase their protein levels following stress by as yet unknown mechanisms. Our experiments offer one possible explanation, as they show that Slf1p plays a critical role in enhancing translation of many of these proteins, including many that are necessary for the cellular stress response.
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Gandin V, Senft D, Topisirovic I, Ronai ZA. RACK1 Function in Cell Motility and Protein Synthesis. Genes Cancer 2014; 4:369-77. [PMID: 24349634 DOI: 10.1177/1947601913486348] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
The receptor for activated C kinase 1 (RACK1) serves as an adaptor for a number of proteins along the MAPK, protein kinase C, and Src signaling pathways. The abundance and near ubiquitous expression of RACK1 reflect its role in coordinating signaling molecules for many critical biological processes, from mRNA translation to cell motility to cell survival and death. Complete deficiency of Rack1 is embryonic lethal, but the recent development of genetic Rack1 hypomorphic mice has highlighted the central role that RACK1 plays in cell movement and protein synthesis. This review focuses on the importance of RACK1 in these processes and places the recent work in the larger context of understanding RACK1 function.
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Affiliation(s)
- Valentina Gandin
- Lady Davis Institute for Medical Research, Sir Mortimer B. Davis Jewish General Hospital, Montréal, QC, Canada ; Department of Oncology, McGill University, Montréal, QC, Canada
| | - Daniela Senft
- Signal Transduction Program, Cancer Center, Sanford-Burnham Medical Research Institute, La Jolla, CA, USA
| | - Ivan Topisirovic
- Lady Davis Institute for Medical Research, Sir Mortimer B. Davis Jewish General Hospital, Montréal, QC, Canada ; Department of Oncology, McGill University, Montréal, QC, Canada
| | - Ze'ev A Ronai
- Signal Transduction Program, Cancer Center, Sanford-Burnham Medical Research Institute, La Jolla, CA, USA
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Wong W, Bai XC, Brown A, Fernandez IS, Hanssen E, Condron M, Tan YH, Baum J, Scheres SHW. Cryo-EM structure of the Plasmodium falciparum 80S ribosome bound to the anti-protozoan drug emetine. eLife 2014; 3. [PMID: 24913268 PMCID: PMC4086275 DOI: 10.7554/elife.03080] [Citation(s) in RCA: 220] [Impact Index Per Article: 22.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2014] [Accepted: 06/06/2014] [Indexed: 12/17/2022] Open
Abstract
Malaria inflicts an enormous burden on global human health. The emergence of parasite resistance to front-line drugs has prompted a renewed focus on the repositioning of clinically approved drugs as potential anti-malarial therapies. Antibiotics that inhibit protein translation are promising candidates for repositioning. We have solved the cryo-EM structure of the cytoplasmic ribosome from the human malaria parasite, Plasmodium falciparum, in complex with emetine at 3.2 Å resolution. Emetine is an anti-protozoan drug used in the treatment of ameobiasis that also displays potent anti-malarial activity. Emetine interacts with the E-site of the ribosomal small subunit and shares a similar binding site with the antibiotic pactamycin, thereby delivering its therapeutic effect by blocking mRNA/tRNA translocation. As the first cryo-EM structure that visualizes an antibiotic bound to any ribosome at atomic resolution, this establishes cryo-EM as a powerful tool for screening and guiding the design of drugs that target parasite translation machinery. DOI:http://dx.doi.org/10.7554/eLife.03080.001 Each year, malaria kills more than 600,000 people, mostly children younger than 5 years old. Humans who have been bitten by mosquitoes infected with malaria-causing parasites become ill as the parasites rapidly multiply in blood cells. Although there are several drugs that are currently used to treat malaria, the parasites are rapidly developing resistance to them, setting off an urgent hunt for new malaria drugs. Developing new antimalarial medications from scratch is likely to take decades—too long to combat the current public health threat posed by emerging strains of drug-resistant parasites. To speed up the process, scientists are investigating whether drugs developed for other illnesses may also act as therapies for malaria, either when used alone or in combination with existing malaria drugs. Certain antibiotics—including one called emetine—have already shown promise as antimalarial drugs. These antibiotics prevent the parasites from multiplying by interfering with the ribosome—the part of a cell that builds new proteins. However, humans become ill after taking emetine for long periods because it also blocks the production of human proteins. Tweaking emetine so that it acts only against the production of parasite proteins would make it a safer malaria treatment. To do this, scientists must first map the precise interactions between the drug and the ribosomes in parasites. Wong et al. have now used a technique called cryo-electron microscopy to examine the ribosome of the most virulent form of malaria parasite. This technique uses very cold temperatures to rapidly freeze molecules, allowing scientists to look at molecular-level details without distorting the structure of the molecule—a problem sometimes encountered in other techniques. The images of the parasitic ribosome taken by Wong, Bai, Brown et al. show that emetine binds to the end of the ribosome where the instructions for how to assemble amino acids into a protein are copied from strands of RNA. In addition, the images revealed features of the parasitic ribosome that are not found in the human form. Drug makers could exploit these features to improve emetine so that it more specifically targets the production of proteins by the parasite and is less toxic to humans. DOI:http://dx.doi.org/10.7554/eLife.03080.002
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Affiliation(s)
- Wilson Wong
- Division of Infection and Immunity, Walter and Eliza Hall Institute of Medical Research, Melbourne, Australia
| | - Xiao-chen Bai
- Structural Studies, Medical Research Council Laboratory of Molecular Biology, Cambridge, United Kingdom
| | - Alan Brown
- Structural Studies, Medical Research Council Laboratory of Molecular Biology, Cambridge, United Kingdom
| | - Israel S Fernandez
- Structural Studies, Medical Research Council Laboratory of Molecular Biology, Cambridge, United Kingdom
| | - Eric Hanssen
- Electron Microscopy Unit, Bio21 Molecular Science and Biotechnology Institute, University of Melbourne, Melbourne, Australia
| | - Melanie Condron
- Division of Infection and Immunity, Walter and Eliza Hall Institute of Medical Research, Melbourne, Australia
| | - Yan Hong Tan
- Division of Infection and Immunity, Walter and Eliza Hall Institute of Medical Research, Melbourne, Australia
| | - Jake Baum
- Division of Infection and Immunity, Walter and Eliza Hall Institute of Medical Research, Melbourne, Australia
| | - Sjors H W Scheres
- Structural Studies, Medical Research Council Laboratory of Molecular Biology, Cambridge, United Kingdom
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RACK1, a versatile hub in cancer. Oncogene 2014; 34:1890-8. [PMID: 24882575 DOI: 10.1038/onc.2014.127] [Citation(s) in RCA: 130] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2014] [Revised: 04/07/2014] [Accepted: 04/10/2014] [Indexed: 01/15/2023]
Abstract
RACK1 is a highly conserved intracellular adaptor protein with significant homology to Gβ and was originally identified as the anchoring protein for activated protein kinase C. In the past 20 years, the number of binding partners and validated cellular functions for RACK1 has increased, which facilitates clarification of its involvement in different biological events. In this review, we will focus on its role in cancer, summarizing its aberrant expression, pro- or anti-oncogenic effects and the underlying mechanisms in various cancers.
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Tarnowski K, Fituch K, Szczepanowski RH, Dadlez M, Kaus-Drobek M. Patterns of structural dynamics in RACK1 protein retained throughout evolution: a hydrogen-deuterium exchange study of three orthologs. Protein Sci 2014; 23:639-51. [PMID: 24591271 DOI: 10.1002/pro.2448] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2014] [Revised: 02/25/2014] [Accepted: 02/26/2014] [Indexed: 12/15/2022]
Abstract
RACK1 is a member of the WD repeat family of proteins and is involved in multiple fundamental cellular processes. An intriguing feature of RACK1 is its ability to interact with at least 80 different protein partners. Thus, the structural features enabling such interactomic flexibility are of great interest. Several previous studies of the crystal structures of RACK1 orthologs described its detailed architecture and confirmed predictions that RACK1 adopts a seven-bladed β-propeller fold. However, this did not explain its ability to bind to multiple partners. We performed hydrogen-deuterium (H-D) exchange mass spectrometry on three orthologs of RACK1 (human, yeast, and plant) to obtain insights into the dynamic properties of RACK1 in solution. All three variants retained similar patterns of deuterium uptake, with some pronounced differences that can be attributed to RACK1's divergent biological functions. In all cases, the most rigid structural elements were confined to B-C turns and, to some extent, strands B and C, while the remaining regions retained much flexibility. We also compared the average rate constants for H-D exchange in different regions of RACK1 and found that amide protons in some regions exchanged at least 1000-fold faster than in others. We conclude that its evolutionarily retained structural architecture might have allowed RACK1 to accommodate multiple molecular partners. This was exemplified by our additional analysis of yeast RACK1 dimer, which showed stabilization, as well as destabilization, of several interface regions upon dimer formation.
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Affiliation(s)
- Krzysztof Tarnowski
- Institute of Biochemistry and Biophysics Department, Polish Academy of Science, 02-106, Warsaw, Poland
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Yang WL, Wei L, Huang WQ, Li R, Shen WY, Liu JY, Xu JM, Li B, Qin Y. Vigilin is overexpressed in hepatocellular carcinoma and is required for HCC cell proliferation and tumor growth. Oncol Rep 2014; 31:2328-34. [PMID: 24676454 DOI: 10.3892/or.2014.3111] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2014] [Accepted: 03/05/2014] [Indexed: 02/05/2023] Open
Abstract
Vigilin contains multiple KH domains and is an evolutionarily conserved RNA-binding protein from yeast to the human. Its reported roles in human carcinogenesis are controversial in different types of human cancers. To obtain the specific expression profiles of vigilin in human hepatocellular carcinomas (HCCs), we examined vigilin protein levels in normal human liver, liver cirrhosis, adjacent non-tumor liver and HCC tumor tissues as well as in several HCC cell lines. We discovered that vigilin expression increased progressively from the liver cirrhosis tissue to adjacent non-tumor liver tissue and then to HCC tumor cells. Vigilin protein was also overexpressed in all three HCC cell lines examined, HepG2, BEL7402 and SMMC7721, when compared with the vigilin expression level in the L-02 human embryonic hepatocyte cell line. We further investigated the impact of vigilin knockdown on HCC cell proliferation, survival, motility, tumor growth and sensitivity to chemotherapy. We found that knockdown of vigilin in the BEL7402 HCC cells significantly inhibited their proliferation, colony formation and migration, but largely enhanced the cisplatin treatment-induced growth inhibition of these cells in culture. We also found that vigilin knockdown effectively inhibited the growth of BEL7402 cell-derived xenograft tumors in nude mice by decreasing the proliferation and increasing the apoptosis of the BEL7402 HCC cells. Taken together, these results suggest that progressively upregulated vigilin may serve as a molecular risk marker for HCC development, and targeting vigilin may help to inhibit HCC cell growth, survival and migration.
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Affiliation(s)
- Wen Li Yang
- Department of Biochemistry and Molecular Biology, School of Preclinical and Forensic Medicine, West China Medical Center, Sichuan University, Chengdu, Sichuan 610041, P.R. China
| | - Ling Wei
- Department of Biochemistry and Molecular Biology, School of Preclinical and Forensic Medicine, West China Medical Center, Sichuan University, Chengdu, Sichuan 610041, P.R. China
| | - Wen Qing Huang
- Department of Biochemistry and Molecular Biology, School of Preclinical and Forensic Medicine, West China Medical Center, Sichuan University, Chengdu, Sichuan 610041, P.R. China
| | - Ran Li
- Department of Biochemistry and Molecular Biology, School of Preclinical and Forensic Medicine, West China Medical Center, Sichuan University, Chengdu, Sichuan 610041, P.R. China
| | - Wen Yan Shen
- Department of Biochemistry and Molecular Biology, School of Preclinical and Forensic Medicine, West China Medical Center, Sichuan University, Chengdu, Sichuan 610041, P.R. China
| | - Jian Yu Liu
- Department of Biochemistry and Molecular Biology, School of Preclinical and Forensic Medicine, West China Medical Center, Sichuan University, Chengdu, Sichuan 610041, P.R. China
| | - Jian Ming Xu
- Institute for Cancer Medicine, Luzhou Medical College, Luzhou, Sichuan 646000, P.R. China
| | - Bo Li
- Department of General Surgery, West China Hospital, Sichuan University, Chengdu, Sichuan 610041, P.R. China
| | - Yang Qin
- Department of Biochemistry and Molecular Biology, School of Preclinical and Forensic Medicine, West China Medical Center, Sichuan University, Chengdu, Sichuan 610041, P.R. China
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Rossi D, Kuroshu R, Zanelli CF, Valentini SR. eIF5A and EF-P: two unique translation factors are now traveling the same road. WILEY INTERDISCIPLINARY REVIEWS. RNA 2014; 5:209-22. [PMID: 24402910 DOI: 10.1002/wrna.1211] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/01/2013] [Revised: 11/01/2013] [Accepted: 11/06/2013] [Indexed: 11/09/2022]
Abstract
Translational control is extremely important in all organisms, and some of its aspects are highly conserved among all primary kingdoms, such as those related to the translation elongation step. The previously classified translation initiation factor 5A (eIF5A) and its bacterial homologue elongation factor P (EF-P) were discovered in the late 70's and have recently been the object of many studies. eIF5A and EF-P are the only cellular proteins that undergo hypusination and lysinylation, respectively, both of which are unique posttranslational modifications. Herein, we review all the important discoveries related to the biochemical and functional characterization of these factors, highlighting the implication of eIF5A in translation elongation instead of initiation. The findings that eIF5A and EF-P are important for specific cellular processes and play a role in the relief of ribosome stalling caused by specific amino acid sequences, such as those containing prolines reinforce the hypothesis that these factors are involved in specialized translation. Although there are some divergences between these unique factors, recent studies have clarified that they act similarly during protein synthesis. Further studies may reveal their precise mechanism of ribosome activity modulation as well as the mRNA targets that require eIF5A and EF-P for their proper translation.
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Affiliation(s)
- Danuza Rossi
- Department of Biological Sciences, School of Pharmaceutical Sciences, Univ Estadual Paulista (UNESP), Araraquara, SP, Brazil
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Weidner J, Wang C, Prescianotto-Baschong C, Estrada AF, Spang A. The polysome-associated proteins Scp160 and Bfr1 prevent P body formation under normal growth conditions. J Cell Sci 2014; 127:1992-2004. [PMID: 24569876 DOI: 10.1242/jcs.142083] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
Numerous mRNAs are degraded in processing bodies (P bodies) in Saccharomyces cerevisiae. In logarithmically growing cells, only 0-1 P bodies per cell are detectable. However, the number and appearance of P bodies change once the cell encounters stress. Here, we show that the polysome-associated mRNA-binding protein Scp160 interacts with P body components, such as the decapping protein Dcp2 and the scaffold protein Pat1, presumably, on polysomes. Loss of either Scp160 or its interaction partner Bfr1 caused the formation of Dcp2-positive structures. These Dcp2-positive foci contained mRNA, because their formation was inhibited by the presence of cycloheximide. In addition, Scp160 was required for proper P body formation because only a subset of bona fide P body components could assemble into the Dcp2-positive foci in Δscp160 cells. In either Δbfr1 or Δscp160 cells, P body formation was uncoupled from translational attenuation as the polysome profile remained unchanged. Collectively, our data suggest that Bfr1 and Scp160 prevent P body formation under normal growth conditions.
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Affiliation(s)
- Julie Weidner
- Growth & Development, Biozentrum, University of Basel, Klingelbergstrasse 70, 4056 Basel, Switzerland
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Gachomo EW, Jimenez-Lopez JC, Baptiste LJ, Kotchoni SO. GIGANTUS1 (GTS1), a member of Transducin/WD40 protein superfamily, controls seed germination, growth and biomass accumulation through ribosome-biogenesis protein interactions in Arabidopsis thaliana. BMC PLANT BIOLOGY 2014; 14:37. [PMID: 24467952 PMCID: PMC3914372 DOI: 10.1186/1471-2229-14-37] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/30/2013] [Accepted: 01/24/2014] [Indexed: 05/06/2023]
Abstract
BACKGROUND WD40 domains have been found in a plethora of eukaryotic proteins, acting as scaffolding molecules assisting proper activity of other proteins, and are involved in multi-cellular processes. They comprise several stretches of 44-60 amino acid residues often terminating with a WD di-peptide. They act as a site of protein-protein interactions or multi-interacting platforms, driving the assembly of protein complexes or as mediators of transient interplay among other proteins. In Arabidopsis, members of WD40 protein superfamily are known as key regulators of plant-specific events, biologically playing important roles in development and also during stress signaling. RESULTS Using reverse genetic and protein modeling approaches, we characterize GIGANTUS1 (GTS1), a new member of WD40 repeat protein in Arabidopsis thaliana and provide evidence of its role in controlling plant growth development. GTS1 is highly expressed during embryo development and negatively regulates seed germination, biomass yield and growth improvement in plants. Structural modeling analysis suggests that GTS1 folds into a β-propeller with seven pseudo symmetrically arranged blades around a central axis. Molecular docking analysis shows that GTS1 physically interacts with two ribosomal protein partners, a component of ribosome Nop16, and a ribosome-biogenesis factor L19e through β-propeller blade 4 to regulate cell growth development. CONCLUSIONS Our results indicate that GTS1 might function in plant developmental processes by regulating ribosomal structural features, activities and biogenesis in plant cells. Our results suggest that GIGANTUS1 might be a promising target to engineer transgenic plants with higher biomass and improved growth development for plant-based bioenergy production.
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Affiliation(s)
- Emma W Gachomo
- Department of Biology, Rutgers University, 315 Penn St., Camden, NJ 08102, USA
- Center for Computational and Integrative Biology (CCIB), Rutgers University, 315 Penn St., Camden, NJ 08102, USA
| | - Jose C Jimenez-Lopez
- The UWA Institute of Agriculture, The University of Western Australia, 35 Stirling Highway, Crawley, Perth, WA 6009, Australia
- Department of Biochemistry, Cell and Molecular Biology of Plants, Estación Experimental del Zaidín, High Council for Scientific Research (CSIC), Profesor Albareda 1, Granada E-18008, Spain
| | - Lyla Jno Baptiste
- Department of Biology, Rutgers University, 315 Penn St., Camden, NJ 08102, USA
| | - Simeon O Kotchoni
- Department of Biology, Rutgers University, 315 Penn St., Camden, NJ 08102, USA
- Center for Computational and Integrative Biology (CCIB), Rutgers University, 315 Penn St., Camden, NJ 08102, USA
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Hirschmann WD, Westendorf H, Mayer A, Cannarozzi G, Cramer P, Jansen RP. Scp160p is required for translational efficiency of codon-optimized mRNAs in yeast. Nucleic Acids Res 2014; 42:4043-55. [PMID: 24445806 PMCID: PMC3973333 DOI: 10.1093/nar/gkt1392] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
The budding yeast multi-K homology domain RNA-binding protein Scp160p binds to >1000 messenger RNAs (mRNAs) and polyribosomes, and its mammalian homolog vigilin binds transfer RNAs (tRNAs) and translation elongation factor EF1alpha. Despite its implication in translation, studies on Scp160p's molecular function are lacking to date. We applied translational profiling approaches and demonstrate that the association of a specific subset of mRNAs with ribosomes or heavy polysomes depends on Scp160p. Interaction of Scp160p with these mRNAs requires the conserved K homology domains 13 and 14. Transfer RNA pairing index analysis of Scp160p target mRNAs indicates a high degree of consecutive use of iso-decoding codons. As shown for one target mRNA encoding the glycoprotein Pry3p, Scp160p depletion results in translational downregulation but increased association with polysomes, suggesting that it is required for efficient translation elongation. Depletion of Scp160p also decreased the relative abundance of ribosome-associated tRNAs whose codons show low potential for autocorrelation on mRNAs. Conversely, tRNAs with highly autocorrelated codons in mRNAs are less impaired. Our data indicate that Scp160p might increase the efficiency of tRNA recharge, or prevent diffusion of discharged tRNAs, both of which were also proposed to be the likely basis for the translational fitness effect of tRNA pairing.
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Affiliation(s)
- Wolf D Hirschmann
- Interfaculty Institute for Biochemistry, Universität Tübingen, Hoppe-Seyler-Strasse 4, D-72076 Tübingen, Germany, Gene Center Munich and Department of Biochemistry, LMU München, Feodor-Lynen-Str. 25, D-81377 Munich, Germany, Institute of Plant Sciences, University of Bern, Altenbergrain 21, CH-3013 Bern, Switzerland and Department of Molecular Biology, Max Planck Institute for Biophysical Chemistry, Am Fassberg 11, D-37077 Göttingen, Germany
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Depuydt G, Xie F, Petyuk VA, Shanmugam N, Smolders A, Dhondt I, Brewer HM, Camp DG, Smith RD, Braeckman BP. Reduced insulin/insulin-like growth factor-1 signaling and dietary restriction inhibit translation but preserve muscle mass in Caenorhabditis elegans. Mol Cell Proteomics 2013; 12:3624-39. [PMID: 24002365 PMCID: PMC3861712 DOI: 10.1074/mcp.m113.027383] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
Reduced signaling through the C. elegans insulin/insulin-like growth factor-1-like tyrosine kinase receptor daf-2 and dietary restriction via bacterial dilution are two well-characterized lifespan-extending interventions that operate in parallel or through (partially) independent mechanisms. Using accurate mass and time tag LC-MS/MS quantitative proteomics, we detected that the abundance of a large number of ribosomal subunits is decreased in response to dietary restriction, as well as in the daf-2(e1370) insulin/insulin-like growth factor-1-receptor mutant. In addition, general protein synthesis levels in these long-lived worms are repressed. Surprisingly, ribosomal transcript levels were not correlated to actual protein abundance, suggesting that post-transcriptional regulation determines ribosome content. Proteomics also revealed the increased presence of many structural muscle cell components in long-lived worms, which appeared to result from the prioritized preservation of muscle cell volume in nutrient-poor conditions or low insulin-like signaling. Activation of DAF-16, but not diet restriction, stimulates mRNA expression of muscle-related genes to prevent muscle atrophy. Important daf-2-specific proteome changes include overexpression of aerobic metabolism enzymes and general activation of stress-responsive and immune defense systems, whereas the increased abundance of many protein subunits of the proteasome core complex is a dietary-restriction-specific characteristic.
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Affiliation(s)
- Geert Depuydt
- Biology Department, Ghent University, Proeftuinstraat 86 N1, B-9000 Ghent, Belgium
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40
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Tarumoto Y, Kanoh J, Ishikawa F. Receptor for activated C-kinase (RACK1) homolog Cpc2 facilitates the general amino acid control response through Gcn2 kinase in fission yeast. J Biol Chem 2013; 288:19260-8. [PMID: 23671279 DOI: 10.1074/jbc.m112.445270] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
General amino acid control (GAAC) is crucial for sensing and adaptation to nutrient availability. Amino acid starvation activates protein kinase Gcn2, which plays a central role in the GAAC response by phosphorylating the α-subunit of eukaryotic initiation factor 2 (eIF2α), leading to the translational switch to stimulate selective expression of stress-responsive genes. We report here that in fission yeast Schizosaccharomyces pombe, Cpc2, a homolog of mammalian receptor for activated C-kinase (RACK1), is important for the GAAC response. Deletion of S. pombe cpc2 impairs the amino acid starvation-induced phosphorylation of eIF2α and the expression of amino acid biosynthesis genes, thereby rendering cells severely sensitive to amino acid limitation. Unlike the Saccharomyces cerevisiae Cpc2 ortholog, which normally suppresses the GAAC response, our findings suggest that S. pombe Cpc2 promotes the GAAC response. We also found that S. pombe Cpc2 is required for starvation-induced Gcn2 autophosphorylation, which is essential for Gcn2 function. These results indicate that S. pombe Cpc2 facilitates the GAAC response through the regulation of Gcn2 activation and provide a novel insight for the regulatory function of RACK1 on Gcn2-mediated GAAC response.
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Affiliation(s)
- Yusuke Tarumoto
- Department of Gene Mechanisms, Graduate School of Biostudies, Kyoto University, Yoshida-Konoe-cho, Sakyo-ku, Kyoto 606-8501, Japan
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Volta V, Beugnet A, Gallo S, Magri L, Brina D, Pesce E, Calamita P, Sanvito F, Biffo S. RACK1 depletion in a mouse model causes lethality, pigmentation deficits and reduction in protein synthesis efficiency. Cell Mol Life Sci 2013; 70:1439-50. [PMID: 23212600 PMCID: PMC11113757 DOI: 10.1007/s00018-012-1215-y] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2012] [Revised: 11/02/2012] [Accepted: 11/08/2012] [Indexed: 10/27/2022]
Abstract
The receptor for activated C-kinase 1 (RACK1) is a conserved structural protein of 40S ribosomes. Strikingly, deletion of RACK1 in yeast homolog Asc1 is not lethal. Mammalian RACK1 also interacts with many nonribosomal proteins, hinting at several extraribosomal functions. A knockout mouse for RACK1 has not previously been described. We produced the first RACK1 mutant mouse, in which both alleles of RACK1 gene are defective in RACK1 expression (ΔF/ΔF), in a pure C57 Black/6 background. In a sample of 287 pups, we observed no ΔF/ΔF mice (72 expected). Dissection and genotyping of embryos at various stages showed that lethality occurs at gastrulation. Heterozygotes (ΔF/+) have skin pigmentation defects with a white belly spot and hypopigmented tail and paws. ΔF/+ have a transient growth deficit (shown by measuring pup size at P11). The pigmentation deficit is partly reverted by p53 deletion, whereas the lethality is not. ΔF/+ livers have mild accumulation of inactive 80S ribosomal subunits by polysomal profile analysis. In ΔF/+ fibroblasts, protein synthesis response to extracellular and pharmacological stimuli is reduced. These results highlight the role of RACK1 as a ribosomal protein converging signaling to the translational apparatus.
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Affiliation(s)
- Viviana Volta
- Laboratory of Molecular Histology and Cell Growth, Division of Oncology, San Raffaele Scientific Institute, Via Olgettina 58, 20132 Milan, Italy
| | - Anne Beugnet
- Laboratory of Molecular Histology and Cell Growth, Division of Oncology, San Raffaele Scientific Institute, Via Olgettina 58, 20132 Milan, Italy
| | - Simone Gallo
- Laboratory of Molecular Histology and Cell Growth, Division of Oncology, San Raffaele Scientific Institute, Via Olgettina 58, 20132 Milan, Italy
| | - Laura Magri
- Laboratory of Molecular Histology and Cell Growth, Division of Oncology, San Raffaele Scientific Institute, Via Olgettina 58, 20132 Milan, Italy
| | - Daniela Brina
- Laboratory of Molecular Histology and Cell Growth, Division of Oncology, San Raffaele Scientific Institute, Via Olgettina 58, 20132 Milan, Italy
| | - Elisa Pesce
- Laboratory of Molecular Histology and Cell Growth, Division of Oncology, San Raffaele Scientific Institute, Via Olgettina 58, 20132 Milan, Italy
- Environmental and Life Science Department (DISAV), University of Eastern Piedmont, Alessandria, Italy
| | - Piera Calamita
- Laboratory of Molecular Histology and Cell Growth, Division of Oncology, San Raffaele Scientific Institute, Via Olgettina 58, 20132 Milan, Italy
| | - Francesca Sanvito
- Department of Pathology, San Raffaele Scientific Institute, Milan, Italy
| | - Stefano Biffo
- Laboratory of Molecular Histology and Cell Growth, Division of Oncology, San Raffaele Scientific Institute, Via Olgettina 58, 20132 Milan, Italy
- Environmental and Life Science Department (DISAV), University of Eastern Piedmont, Alessandria, Italy
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42
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Molecular cloning and expression analysis of a new WD40 repeat protein gene in upland cotton. Biologia (Bratisl) 2012. [DOI: 10.2478/s11756-012-0103-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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43
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Rachfall N, Schmitt K, Bandau S, Smolinski N, Ehrenreich A, Valerius O, Braus GH. RACK1/Asc1p, a ribosomal node in cellular signaling. Mol Cell Proteomics 2012; 12:87-105. [PMID: 23071099 DOI: 10.1074/mcp.m112.017277] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
RACK1/Asc1p and its essential orthologues in higher eukaryotes, such as RACK1 in metazoa, are involved in several distinct cellular signaling processes. The implications of a total deletion have never been assessed in a comprehensive manner. This study reveals the major cellular processes affected in a Saccharomyces cerevisiae Δasc1 deletion background via de novo proteome and transcriptome analysis, as well as subsequent phenotypical characterizations. The deletion of ASC1 reduces iron uptake and causes nitrosative stress, both known indicators for hypoxia, which manifests in a shift of energy metabolism from respiration to fermentation in the Δasc1 strain. Asc1p further impacts cellular metabolism through its regulative role in the MAP kinase signal transduction pathways of invasive/filamentous growth and cell wall integrity. In the Δasc1 mutant strain, aberrations from the expected cellular response, mediated by these pathways, can be observed and are linked to changes in protein abundances of pathway-targeted transcription factors. Evidence of the translational regulation of such transcription factors suggests that ribosomal Asc1p is involved in signal transduction pathways and controls the biosynthesis of the respective final transcriptional regulators.
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Affiliation(s)
- Nicole Rachfall
- Institute of Microbiology and Genetics, Georg-August Universität, D-37077 Göttingen, Germany
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44
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Ruan Y, Sun L, Hao Y, Wang L, Xu J, Zhang W, Xie J, Guo L, Zhou L, Yun X, Zhu H, Shen A, Gu J. Ribosomal RACK1 promotes chemoresistance and growth in human hepatocellular carcinoma. J Clin Invest 2012; 122:2554-66. [PMID: 22653060 DOI: 10.1172/jci58488] [Citation(s) in RCA: 106] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2011] [Accepted: 04/24/2012] [Indexed: 01/14/2023] Open
Abstract
Coordinated translation initiation is coupled with cell cycle progression and cell growth, whereas excessive ribosome biogenesis and translation initiation often lead to tumor transformation and survival. Hepatocellular carcinoma (HCC) is among the most common and aggressive cancers worldwide and generally displays inherently high resistance to chemotherapeutic drugs. We found that RACK1, the receptor for activated C-kinase 1, was highly expressed in normal liver and frequently upregulated in HCC. Aberrant expression of RACK1 contributed to in vitro chemoresistance as well as in vivo tumor growth of HCC. These effects depended on ribosome localization of RACK1. Ribosomal RACK1 coupled with PKCβII to promote the phosphorylation of eukaryotic initiation factor 4E (eIF4E), which led to preferential translation of the potent factors involved in growth and survival. Inhibition of PKCβII or depletion of eIF4E abolished RACK1-mediated chemotherapy resistance of HCC in vitro. Our results imply that RACK1 may function as an internal factor involved in the growth and survival of HCC and suggest that targeting RACK1 may be an efficacious strategy for HCC treatment.
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Affiliation(s)
- Yuanyuan Ruan
- Key Laboratory of Glycoconjugate Research, Ministry of Public Health, Shanghai Medical College of Fudan University, Shanghai, People’s Republic of China
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45
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Xue S, Barna M. Specialized ribosomes: a new frontier in gene regulation and organismal biology. Nat Rev Mol Cell Biol 2012; 13:355-69. [PMID: 22617470 DOI: 10.1038/nrm3359] [Citation(s) in RCA: 485] [Impact Index Per Article: 40.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Historically, the ribosome has been viewed as a complex ribozyme with constitutive rather than intrinsic regulatory capacity in mRNA translation. However, emerging studies reveal that ribosome activity may be highly regulated. Heterogeneity in ribosome composition resulting from differential expression and post-translational modifications of ribosomal proteins, ribosomal RNA (rRNA) diversity and the activity of ribosome-associated factors may generate 'specialized ribosomes' that have a substantial impact on how the genomic template is translated into functional proteins. Moreover, constitutive components of the ribosome may also exert more specialized activities by virtue of their interactions with specific mRNA regulatory elements such as internal ribosome entry sites (IRESs) or upstream open reading frames (uORFs). Here we discuss the hypothesis that intrinsic regulation by the ribosome acts to selectively translate subsets of mRNAs harbouring unique cis-regulatory elements, thereby introducing an additional level of regulation in gene expression and the life of an organism.
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Affiliation(s)
- Shifeng Xue
- Department of Biochemistry and Biophysics, Cardiovascular Research Institute, University of California, San Francisco, CA 94158, USA
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46
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RACK1 research - ships passing in the night? FEBS Lett 2012; 586:2787-9. [PMID: 22580388 DOI: 10.1016/j.febslet.2012.04.048] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2012] [Revised: 04/23/2012] [Accepted: 04/24/2012] [Indexed: 01/09/2023]
Abstract
It should not be surprising that a protein with a name like RACK1 - short for receptor for activated C kinase 1 - is found in a variety of signaling complexes. Its alternative name, the splendidly unmemorable GNB2L1 - short for guanine nucleotide-binding protein subunit beta-2-like 1 - should reinforce this link to signaling complexes. There are currently over 400 publications listed in PubMed mentioning RACK1/GNB2L1 in the abstract, so it is certainly an actively studied protein with much involvement in different aspects of cell regulation being reported. RACK1 binds to the 40S ribosomal subunit, suggesting it links cell regulation and translation. It is also a target of intracellular parasites. And yet does this protein have the profile that it should? And why are there two kinds of RACK1 researcher who do not seem to communicate well?
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47
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Gelin-Licht R, Paliwal S, Conlon P, Levchenko A, Gerst JE. Scp160-dependent mRNA trafficking mediates pheromone gradient sensing and chemotropism in yeast. Cell Rep 2012; 1:483-94. [PMID: 22832273 DOI: 10.1016/j.celrep.2012.03.004] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2011] [Revised: 03/12/2012] [Accepted: 03/15/2012] [Indexed: 01/09/2023] Open
Abstract
mRNAs encoding polarity and secretion factors (POLs) target the incipient bud site in yeast for localized translation during division. In pheromone-treated cells we now find that these mRNAs are also localized to the yeast-mating projection (shmoo) tip. However, in contrast to the budding program, neither the She2 nor She3 proteins are involved. Instead, the Scp160 RNA-binding protein binds POL and mating pathway mRNAs and regulates their spatial distribution in a Myo4- and cortical ER-dependent fashion. RNA binding by Scp160 is stimulated by activation of Gpa1, the G protein α subunit regulated by the pheromone receptor, and is required for pheromone gradient sensing, as well as subsequent chemotropic growth and cell-cell mating. These effects are incurred independently of obvious changes in translation; thus, mRNA trafficking is required for chemotropism and completion of the mating program. This is, to our knowledge, the first demonstration of ligand-activated RNA targeting in the development of a simple eukaryote.
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Affiliation(s)
- Rita Gelin-Licht
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 76100, Israel
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48
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Lupo J, Conti A, Sueur C, Coly PA, Couté Y, Hunziker W, Burmeister WP, Germi R, Manet E, Gruffat H, Morand P, Boyer V. Identification of new interacting partners of the shuttling protein ubinuclein (Ubn-1). Exp Cell Res 2012; 318:509-20. [PMID: 22245583 DOI: 10.1016/j.yexcr.2011.12.020] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2011] [Revised: 12/21/2011] [Accepted: 12/24/2011] [Indexed: 10/14/2022]
Abstract
We have previously characterized ubinuclein (Ubn-1) as a NACos (Nuclear and Adherent junction Complex components) protein which interacts with viral or cellular transcription factors and the tight junction (TJ) protein ZO-1. The purpose of the present study was to get more insights on the binding partners of Ubn-1, notably those present in the epithelial junctions. Using an in vivo assay of fluorescent protein-complementation assay (PCA), we demonstrated that the N-terminal domains of the Ubn-1 and ZO-1 proteins triggered a functional interaction inside the cell. Indeed, expression of both complementary fragments of venus fused to the N-terminal parts of Ubn-1 and ZO-1 was able to reconstitute a fluorescent venus protein. Furthermore, nuclear expression of the chimeric Ubn-1 triggered nuclear localization of the chimeric ZO-1. We could localize this interaction to the PDZ2 domain of ZO-1 using an in vitro pull-down assay. More precisely, a 184-amino acid region (from amino acids 39 to 223) at the N-terminal region of Ubn-1 was responsible for the interaction with the PDZ2 domain of ZO-1. Co-imunoprecipitation and confocal microscopy experiments also revealed the tight junction protein cingulin as a new interacting partner of Ubn-1. A proteomic approach based on mass spectrometry analysis (MS) was then undertaken to identify further binding partners of GST-Ubn-1 fusion protein in different subcellular fractions of human epithelial HT29 cells. LYRIC (Lysine-rich CEACAM1-associated protein) and RACK-1 (receptor for activated C-kinase) proteins were validated as bona fide interacting partners of Ubn-1. Altogether, these results suggest that Ubn-1 is a scaffold protein influencing protein subcellular localization and is involved in several processes such as cell-cell contact signalling or modulation of gene activity.
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Affiliation(s)
- Julien Lupo
- Unit of Virus Host Cell Interactions, UMI 3265 UJF-EMBL-CNRS, 6 rue Jules Horowitz, BP 181, F-38042 Grenoble Cedex 9, France
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Adams DR, Ron D, Kiely PA. RACK1, A multifaceted scaffolding protein: Structure and function. Cell Commun Signal 2011; 9:22. [PMID: 21978545 PMCID: PMC3195729 DOI: 10.1186/1478-811x-9-22] [Citation(s) in RCA: 330] [Impact Index Per Article: 25.4] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2011] [Accepted: 10/06/2011] [Indexed: 12/17/2022] Open
Abstract
The Receptor for Activated C Kinase 1 (RACK1) is a member of the tryptophan-aspartate repeat (WD-repeat) family of proteins and shares significant homology to the β subunit of G-proteins (Gβ). RACK1 adopts a seven-bladed β-propeller structure which facilitates protein binding. RACK1 has a significant role to play in shuttling proteins around the cell, anchoring proteins at particular locations and in stabilising protein activity. It interacts with the ribosomal machinery, with several cell surface receptors and with proteins in the nucleus. As a result, RACK1 is a key mediator of various pathways and contributes to numerous aspects of cellular function. Here, we discuss RACK1 gene and structure and its role in specific signaling pathways, and address how posttranslational modifications facilitate subcellular location and translocation of RACK1. This review condenses several recent studies suggesting a role for RACK1 in physiological processes such as development, cell migration, central nervous system (CN) function and circadian rhythm as well as reviewing the role of RACK1 in disease.
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Affiliation(s)
- David R Adams
- Department of Life Sciences, and Materials and Surface Science Institute, University of Limerick, Limerick, Ireland.
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Wang L, Berndt P, Xia X, Kahnt J, Kahmann R. A seven-WD40 protein related to human RACK1 regulates mating and virulence in Ustilago maydis. Mol Microbiol 2011; 81:1484-98. [PMID: 21815950 DOI: 10.1111/j.1365-2958.2011.07783.x] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
In mammalian cells RACK1 serves as a scaffold protein that has a role in integrating inputs from different signalling pathways and affects translation through association with ribosomes. Ustilago maydis contains a seven-WD40 repeat motif protein designated Rak1, which shows 68% identity to RACK1 and 51% identity to Asc1p of Saccharomyces cerevisiae. An asc1 mutant could be complemented by introduction of U. maydis rak1. The deletion of rak1 affected cell growth, cell wall integrity and specifically attenuated cell fusion. This latter defect was caused by reduced expression of prf1 encoding the regulator for pheromone (mfa) and pheromone-receptor genes. Rak1 interacts with a variety of ribosomal proteins and microarray analysis revealed that the deletion of rak1 led to severely reduced expression of rop1, a transcriptional activator of prf1. The constitutive expression of rop1 could rescue the defect of mfa1 expression as well as conjugation tube formation in response to pheromone induction in the rak1 mutant. Moreover, a solopathogenic rak1 mutant failed to respond to plant-derived stimuli, resulting in attenuated filamentation and pathogenicity. This could be partially rescued by constitutive expression of the b heterodimer. These data suggest that rak1 is a regulator of rop1 expression with additional roles after cell fusion.
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Affiliation(s)
- Lei Wang
- Max Planck Institute for Terrestrial Microbiology, Karl-von-Frisch-Strasse 10, D-35043 Marburg, Germany
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