1
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Fernandez SG, Ferguson L, Ingolia NT. Ribosome rescue factor PELOTA modulates translation start site choice for C/EBPα protein isoforms. Life Sci Alliance 2024; 7:e202302501. [PMID: 38803235 PMCID: PMC11109482 DOI: 10.26508/lsa.202302501] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2023] [Revised: 04/15/2024] [Accepted: 04/16/2024] [Indexed: 05/29/2024] Open
Abstract
Translation initiation at alternative start sites can dynamically control the synthesis of two or more functionally distinct protein isoforms from a single mRNA. Alternate isoforms of the developmental transcription factor CCAAT/enhancer-binding protein α (C/EBPα) produced from different start sites exert opposing effects during myeloid cell development. This choice between alternative start sites depends on sequence features of the CEBPA transcript, including a regulatory uORF, but the molecular basis is not fully understood. Here, we identify the factors that affect C/EBPα isoform choice using a sensitive and quantitative two-color fluorescent reporter coupled with CRISPRi screening. Our screen uncovered a role of the ribosome rescue factor PELOTA (PELO) in promoting the expression of the longer C/EBPα isoform by directly removing inhibitory unrecycled ribosomes and through indirect effects mediated by the mechanistic target of rapamycin kinase. Our work uncovers further links between ribosome recycling and translation reinitiation that regulate a key transcription factor, with implications for normal hematopoiesis and leukemogenesis.
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Affiliation(s)
- Samantha G Fernandez
- https://ror.org/01an7q238 Department of Molecular and Cell Biology, University of California, Berkeley, CA, USA
| | - Lucas Ferguson
- https://ror.org/01an7q238 Department of Molecular and Cell Biology, University of California, Berkeley, CA, USA
- https://ror.org/01an7q238 Center for Computational Biology and California Institute for Quantitative Biosciences, University of California, Berkeley, CA, USA
| | - Nicholas T Ingolia
- https://ror.org/01an7q238 Department of Molecular and Cell Biology, University of California, Berkeley, CA, USA
- https://ror.org/01an7q238 Center for Computational Biology and California Institute for Quantitative Biosciences, University of California, Berkeley, CA, USA
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2
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Jendruchová K, Gaikwad S, Poncová K, Gunišová S, Valášek LS, Hinnebusch AG. Impacts of yeast Tma20/MCTS1, Tma22/DENR and Tma64/eIF2D on translation reinitiation and ribosome recycling. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.03.06.583729. [PMID: 38903097 PMCID: PMC11188067 DOI: 10.1101/2024.03.06.583729] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/22/2024]
Abstract
Recycling of 40S ribosomal subunits following translation termination, entailing release of deacylated tRNA and dissociation of the empty 40S subunit from mRNA, involves yeast Tma20/Tma22 heterodimer and Tma64, counterparts of mammalian MCTS1/DENR and eIF2D. MCTS1/DENR enhance reinitiation at short upstream open reading frames (uORFs) harboring penultimate codons that confer dependence on these factors in bulk 40S recycling. Tma factors, by contrast, inhibited reinitiation at particular uORFs in extracts; however, their roles at regulatory uORFs in vivo were unknown. We examined effects of eliminating Tma proteins on reinitiation at regulatory uORFs mediating translational control of GCN4 optimized for either promoting (uORF1) or preventing (uORF4) reinitiation. We found that the Tma proteins generally impede reinitiation at native uORF4 and uORF4 variants equipped with various penultimate codons regardless of their Tma-dependence in bulk recycling. The Tma factors have no effect on reinitiation at native uORF1, and equipping uORF1 with Tma-dependent penultimate codons generally did not confer Tma-dependent reinitiation; nor did converting the uORFs to AUG-stop elements. Thus, effects of the Tma proteins vary depending on the reinitiation potential of the uORF and the penultimate codon, but unlike in mammals, are not principally dictated by the Tma-dependence of the codon in bulk 40S recycling.
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Affiliation(s)
- Kristína Jendruchová
- Laboratory of Regulation of Gene Expression, Institute of Microbiology of the Czech Academy of Sciences, Videnska 1083, 142 20, Prague, the Czech Republic
- Faculty of Science, Charles University, Albertov 6, 128 00 Prague, Czech Republic
| | - Swati Gaikwad
- Divsion of Molecular and Cellular Biology, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, USA
| | - Kristýna Poncová
- Laboratory of Regulation of Gene Expression, Institute of Microbiology of the Czech Academy of Sciences, Videnska 1083, 142 20, Prague, the Czech Republic
| | - Stanislava Gunišová
- Laboratory of Regulation of Gene Expression, Institute of Microbiology of the Czech Academy of Sciences, Videnska 1083, 142 20, Prague, the Czech Republic
| | - Leoš Shivaya Valášek
- Laboratory of Regulation of Gene Expression, Institute of Microbiology of the Czech Academy of Sciences, Videnska 1083, 142 20, Prague, the Czech Republic
| | - Alan G Hinnebusch
- Divsion of Molecular and Cellular Biology, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, USA
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3
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Pacheco M, D’Orazio KN, Lessen LN, Veltri AJ, Neiman Z, Loll-Krippleber R, Brown GW, Green R. Genetic screens in Saccharomyces cerevisiae identify a role for 40S ribosome recycling factors Tma20 and Tma22 in nonsense-mediated decay. G3 (BETHESDA, MD.) 2024; 14:jkad295. [PMID: 38198768 PMCID: PMC10917514 DOI: 10.1093/g3journal/jkad295] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/29/2023] [Revised: 08/29/2023] [Accepted: 12/06/2023] [Indexed: 01/12/2024]
Abstract
The decay of messenger RNA with a premature termination codon by nonsense-mediated decay (NMD) is an important regulatory pathway for eukaryotes and an essential pathway in mammals. NMD is typically triggered by the ribosome terminating at a stop codon that is aberrantly distant from the poly-A tail. Here, we use a fluorescence screen to identify factors involved in NMD in Saccharomyces cerevisiae. In addition to the known NMD factors, including the entire UPF family (UPF1, UPF2, and UPF3), as well as NMD4 and EBS1, we identify factors known to function in posttermination recycling and characterize their contribution to NMD. These observations in S. cerevisiae expand on data in mammals indicating that the 60S recycling factor ABCE1 is important for NMD by showing that perturbations in factors implicated in 40S recycling also correlate with a loss of NMD.
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Affiliation(s)
- Miguel Pacheco
- Department of Molecular Biology and Genetics, Howard Hughes Medical Institute, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Karole N D’Orazio
- Department of Molecular Biology and Genetics, Howard Hughes Medical Institute, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Laura N Lessen
- Department of Molecular Biology and Genetics, Howard Hughes Medical Institute, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Anthony J Veltri
- Department of Molecular Biology and Genetics, Howard Hughes Medical Institute, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Zachary Neiman
- Department of Molecular Biology and Genetics, Howard Hughes Medical Institute, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Raphael Loll-Krippleber
- Department of Biochemistry and Donnelly Centre, University of Toronto, Toronto, ON M5S 3E1, Canada
| | - Grant W Brown
- Department of Biochemistry and Donnelly Centre, University of Toronto, Toronto, ON M5S 3E1, Canada
| | - Rachel Green
- Department of Molecular Biology and Genetics, Howard Hughes Medical Institute, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
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4
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Grove DJ, Russell PJ, Kearse MG. To initiate or not to initiate: A critical assessment of eIF2A, eIF2D, and MCT-1·DENR to deliver initiator tRNA to ribosomes. WILEY INTERDISCIPLINARY REVIEWS. RNA 2024; 15:e1833. [PMID: 38433101 DOI: 10.1002/wrna.1833] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/31/2023] [Revised: 01/15/2024] [Accepted: 01/17/2024] [Indexed: 03/05/2024]
Abstract
Selection of the correct start codon is critical for high-fidelity protein synthesis. In eukaryotes, this is typically governed by a multitude of initiation factors (eIFs), including eIF2·GTP that directly delivers the initiator tRNA (Met-tRNAi Met ) to the P site of the ribosome. However, numerous reports, some dating back to the early 1970s, have described other initiation factors having high affinity for the initiator tRNA and the ability of delivering it to the ribosome, which has provided a foundation for further work demonstrating non-canonical initiation mechanisms using alternative initiation factors. Here we provide a critical analysis of current understanding of eIF2A, eIF2D, and the MCT-1·DENR dimer, the evidence surrounding their ability to initiate translation, their implications in human disease, and lay out important key questions for the field. This article is categorized under: RNA Interactions with Proteins and Other Molecules > RNA-Protein Complexes Translation > Mechanisms Translation > Regulation.
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Affiliation(s)
- Daisy J Grove
- The Ohio State Biochemistry Program, Department of Biological Chemistry, Center for RNA Biology, The Ohio State University, Columbus, Ohio, USA
| | - Paul J Russell
- The Ohio State Biochemistry Program, Department of Biological Chemistry, Center for RNA Biology, The Ohio State University, Columbus, Ohio, USA
- The Cellular, Molecular, Biochemical Sciences Program, Department of Biological Chemistry, Center for RNA Biology, The Ohio State University, Columbus, Ohio, USA
| | - Michael G Kearse
- The Ohio State Biochemistry Program, Department of Biological Chemistry, Center for RNA Biology, The Ohio State University, Columbus, Ohio, USA
- The Cellular, Molecular, Biochemical Sciences Program, Department of Biological Chemistry, Center for RNA Biology, The Ohio State University, Columbus, Ohio, USA
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5
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Boone M, Zappa F. Signaling plasticity in the integrated stress response. Front Cell Dev Biol 2023; 11:1271141. [PMID: 38143923 PMCID: PMC10740175 DOI: 10.3389/fcell.2023.1271141] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2023] [Accepted: 11/29/2023] [Indexed: 12/26/2023] Open
Abstract
The Integrated Stress Response (ISR) is an essential homeostatic signaling network that controls the cell's biosynthetic capacity. Four ISR sensor kinases detect multiple stressors and relay this information to downstream effectors by phosphorylating a common node: the alpha subunit of the eukaryotic initiation factor eIF2. As a result, general protein synthesis is repressed while select transcripts are preferentially translated, thus remodeling the proteome and transcriptome. Mounting evidence supports a view of the ISR as a dynamic signaling network with multiple modulators and feedback regulatory features that vary across cell and tissue types. Here, we discuss updated views on ISR sensor kinase mechanisms, how the subcellular localization of ISR components impacts signaling, and highlight ISR signaling differences across cells and tissues. Finally, we consider crosstalk between the ISR and other signaling pathways as a determinant of cell health.
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6
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Ferguson L, Upton HE, Pimentel SC, Mok A, Lareau LF, Collins K, Ingolia NT. Streamlined and sensitive mono- and di-ribosome profiling in yeast and human cells. Nat Methods 2023; 20:1704-1715. [PMID: 37783882 DOI: 10.1038/s41592-023-02028-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2023] [Accepted: 08/23/2023] [Indexed: 10/04/2023]
Abstract
Ribosome profiling has unveiled diverse regulation and perturbations of translation through a transcriptome-wide survey of ribosome occupancy, read out by sequencing of ribosome-protected messenger RNA fragments. Generation of ribosome footprints and their conversion into sequencing libraries is technically demanding and sensitive to biases that distort the representation of physiological ribosome occupancy. We address these challenges by producing ribosome footprints with P1 nuclease rather than RNase I and replacing RNA ligation with ordered two-template relay, a single-tube protocol for sequencing library preparation that incorporates adaptors by reverse transcription. Our streamlined approach reduced sequence bias and enhanced enrichment of ribosome footprints relative to ribosomal RNA. Furthermore, P1 nuclease preserved distinct juxtaposed ribosome complexes informative about yeast and human ribosome fates during translation initiation, stalling and termination. Our optimized methods for mRNA footprint generation and capture provide a richer translatome profile with low input and fewer technical challenges.
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Affiliation(s)
- Lucas Ferguson
- Department of Molecular and Cell Biology, University of California, Berkeley, CA, USA.
- Center for Computational Biology, University of California, Berkeley, CA, USA.
| | - Heather E Upton
- Department of Molecular and Cell Biology, University of California, Berkeley, CA, USA
| | - Sydney C Pimentel
- Department of Molecular and Cell Biology, University of California, Berkeley, CA, USA
| | - Amanda Mok
- Center for Computational Biology, University of California, Berkeley, CA, USA
| | - Liana F Lareau
- Center for Computational Biology, University of California, Berkeley, CA, USA
- Department of Bioengineering, University of California, Berkeley, CA, USA
- California Institute for Quantitative Biosciences, University of California, Berkeley, CA, USA
| | - Kathleen Collins
- Department of Molecular and Cell Biology, University of California, Berkeley, CA, USA.
- California Institute for Quantitative Biosciences, University of California, Berkeley, CA, USA.
| | - Nicholas T Ingolia
- Department of Molecular and Cell Biology, University of California, Berkeley, CA, USA.
- California Institute for Quantitative Biosciences, University of California, Berkeley, CA, USA.
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7
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Sherlock ME, Baquero Galvis L, Vicens Q, Kieft JS, Jagannathan S. Principles, mechanisms, and biological implications of translation termination-reinitiation. RNA (NEW YORK, N.Y.) 2023; 29:865-884. [PMID: 37024263 PMCID: PMC10275272 DOI: 10.1261/rna.079375.122] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/21/2022] [Accepted: 03/28/2023] [Indexed: 06/11/2023]
Abstract
The gene expression pathway from DNA sequence to functional protein is not as straightforward as simple depictions of the central dogma might suggest. Each step is highly regulated, with complex and only partially understood molecular mechanisms at play. Translation is one step where the "one gene-one protein" paradigm breaks down, as often a single mature eukaryotic mRNA leads to more than one protein product. One way this occurs is through translation reinitiation, in which a ribosome starts making protein from one initiation site, translates until it terminates at a stop codon, but then escapes normal recycling steps and subsequently reinitiates at a different downstream site. This process is now recognized as both important and widespread, but we are only beginning to understand the interplay of factors involved in termination, recycling, and initiation that cause reinitiation events. There appear to be several ways to subvert recycling to achieve productive reinitiation, different types of stresses or signals that trigger this process, and the mechanism may depend in part on where the event occurs in the body of an mRNA. This perspective reviews the unique characteristics and mechanisms of reinitiation events, highlights the similarities and differences between three major scenarios of reinitiation, and raises outstanding questions that are promising avenues for future research.
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Affiliation(s)
- Madeline E Sherlock
- Department of Biochemistry and Molecular Genetics, University of Colorado Anschutz Medical Campus, Aurora, Colorado 80045, USA
| | - Laura Baquero Galvis
- Department of Biochemistry and Molecular Genetics, University of Colorado Anschutz Medical Campus, Aurora, Colorado 80045, USA
| | - Quentin Vicens
- Department of Biochemistry and Molecular Genetics, University of Colorado Anschutz Medical Campus, Aurora, Colorado 80045, USA
- RNA Bioscience Initiative, University of Colorado Anschutz Medical Campus, Aurora, Colorado 80045, USA
| | - Jeffrey S Kieft
- Department of Biochemistry and Molecular Genetics, University of Colorado Anschutz Medical Campus, Aurora, Colorado 80045, USA
- RNA Bioscience Initiative, University of Colorado Anschutz Medical Campus, Aurora, Colorado 80045, USA
| | - Sujatha Jagannathan
- Department of Biochemistry and Molecular Genetics, University of Colorado Anschutz Medical Campus, Aurora, Colorado 80045, USA
- RNA Bioscience Initiative, University of Colorado Anschutz Medical Campus, Aurora, Colorado 80045, USA
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8
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Boyle EA, Her HL, Mueller JR, Naritomi JT, Nguyen GG, Yeo GW. Skipper analysis of eCLIP datasets enables sensitive detection of constrained translation factor binding sites. CELL GENOMICS 2023; 3:100317. [PMID: 37388912 PMCID: PMC10300551 DOI: 10.1016/j.xgen.2023.100317] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/20/2022] [Revised: 02/17/2023] [Accepted: 04/06/2023] [Indexed: 07/01/2023]
Abstract
Technology for crosslinking and immunoprecipitation (CLIP) followed by sequencing (CLIP-seq) has identified the transcriptomic targets of hundreds of RNA-binding proteins in cells. To increase the power of existing and future CLIP-seq datasets, we introduce Skipper, an end-to-end workflow that converts unprocessed reads into annotated binding sites using an improved statistical framework. Compared with existing methods, Skipper on average calls 210%-320% more transcriptomic binding sites and sometimes >1,000% more sites, providing deeper insight into post-transcriptional gene regulation. Skipper also calls binding to annotated repetitive elements and identifies bound elements for 99% of enhanced CLIP experiments. We perform nine translation factor enhanced CLIPs and apply Skipper to learn determinants of translation factor occupancy, including transcript region, sequence, and subcellular localization. Furthermore, we observe depletion of genetic variation in occupied sites and nominate transcripts subject to selective constraint because of translation factor occupancy. Skipper offers fast, easy, customizable, and state-of-the-art analysis of CLIP-seq data.
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Affiliation(s)
- Evan A. Boyle
- Department of Cellular and Molecular Medicine, Institute for Genomic Medicine, UCSD Stem Cell Program, University of California San Diego, La Jolla, CA 92093, USA
| | - Hsuan-Lin Her
- Department of Cellular and Molecular Medicine, Institute for Genomic Medicine, UCSD Stem Cell Program, University of California San Diego, La Jolla, CA 92093, USA
| | - Jasmine R. Mueller
- Department of Cellular and Molecular Medicine, Institute for Genomic Medicine, UCSD Stem Cell Program, University of California San Diego, La Jolla, CA 92093, USA
| | - Jack T. Naritomi
- Department of Cellular and Molecular Medicine, Institute for Genomic Medicine, UCSD Stem Cell Program, University of California San Diego, La Jolla, CA 92093, USA
| | - Grady G. Nguyen
- Department of Cellular and Molecular Medicine, Institute for Genomic Medicine, UCSD Stem Cell Program, University of California San Diego, La Jolla, CA 92093, USA
| | - Gene W. Yeo
- Department of Cellular and Molecular Medicine, Institute for Genomic Medicine, UCSD Stem Cell Program, University of California San Diego, La Jolla, CA 92093, USA
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9
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Ikeuchi K, Ivic N, Buschauer R, Cheng J, Fröhlich T, Matsuo Y, Berninghausen O, Inada T, Becker T, Beckmann R. Molecular basis for recognition and deubiquitination of 40S ribosomes by Otu2. Nat Commun 2023; 14:2730. [PMID: 37169754 PMCID: PMC10175282 DOI: 10.1038/s41467-023-38161-w] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2021] [Accepted: 04/19/2023] [Indexed: 05/13/2023] Open
Abstract
In actively translating 80S ribosomes the ribosomal protein eS7 of the 40S subunit is monoubiquitinated by the E3 ligase Not4 and deubiquitinated by Otu2 upon ribosomal subunit recycling. Despite its importance for translation efficiency the exact role and structural basis for this translational reset is poorly understood. Here, structural analysis by cryo-electron microscopy of native and reconstituted Otu2-bound ribosomal complexes reveals that Otu2 engages 40S subunits mainly between ribosome recycling and initiation stages. Otu2 binds to several sites on the intersubunit surface of the 40S that are not occupied by any other 40S-binding factors. This binding mode explains the discrimination against 80S ribosomes via the largely helical N-terminal domain of Otu2 as well as the specificity for mono-ubiquitinated eS7 on 40S. Collectively, this study reveals mechanistic insights into the Otu2-driven deubiquitination steps for translational reset during ribosome recycling/(re)initiation.
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Affiliation(s)
- Ken Ikeuchi
- Department of Biochemistry, Gene Center, Feodor-Lynen-Str. 25, University of Munich, 81377, Munich, Germany
| | - Nives Ivic
- Division of Physical Chemistry, Rudjer Boskovic Institute, Bijenicka cesta 54, 10000, Zagreb, Croatia
| | - Robert Buschauer
- Department of Biochemistry, Gene Center, Feodor-Lynen-Str. 25, University of Munich, 81377, Munich, Germany
| | - Jingdong Cheng
- Department of Biochemistry, Gene Center, Feodor-Lynen-Str. 25, University of Munich, 81377, Munich, Germany
- Institutes of biomedical science, Shanghai Key Laboratory of Medical Epigenetics, International Co-laboratory of Medical Epigenetics and Metabolism (Ministry of Science and Technology), Fudan university, Dong'an Road 131, 200032, Shanghai, China
| | - Thomas Fröhlich
- LAFUGA, Laboratory for Functional Genome Analysis, Gene Center, Feodor-Lynen-Str. 25, University of Munich, 81377, Munich, Germany
| | - Yoshitaka Matsuo
- Division of RNA and Gene Regulation, Institute of Medical Science, The University of Tokyo, Minato-ku, 108-8639, Japan
| | - Otto Berninghausen
- Department of Biochemistry, Gene Center, Feodor-Lynen-Str. 25, University of Munich, 81377, Munich, Germany
| | - Toshifumi Inada
- Division of RNA and Gene Regulation, Institute of Medical Science, The University of Tokyo, Minato-ku, 108-8639, Japan
| | - Thomas Becker
- Department of Biochemistry, Gene Center, Feodor-Lynen-Str. 25, University of Munich, 81377, Munich, Germany.
| | - Roland Beckmann
- Department of Biochemistry, Gene Center, Feodor-Lynen-Str. 25, University of Munich, 81377, Munich, Germany.
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10
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Zhang D, Zhu L, Wang F, Li P, Wang Y, Gao Y. Molecular mechanisms of eukaryotic translation fidelity and their associations with diseases. Int J Biol Macromol 2023; 242:124680. [PMID: 37141965 DOI: 10.1016/j.ijbiomac.2023.124680] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2023] [Accepted: 04/27/2023] [Indexed: 05/06/2023]
Abstract
Converting genetic information into functional proteins is a complex, multi-step process, with each step being tightly regulated to ensure the accuracy of translation, which is critical to cellular health. In recent years, advances in modern biotechnology, especially the development of cryo-electron microscopy and single-molecule techniques, have enabled a clearer understanding of the mechanisms of protein translation fidelity. Although there are many studies on the regulation of protein translation in prokaryotes, and the basic elements of translation are highly conserved in prokaryotes and eukaryotes, there are still great differences in the specific regulatory mechanisms. This review describes how eukaryotic ribosomes and translation factors regulate protein translation and ensure translation accuracy. However, a certain frequency of translation errors does occur in translation, so we describe diseases that arise when the rate of translation errors reaches or exceeds a threshold of cellular tolerance.
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Affiliation(s)
- Dejiu Zhang
- Institute for Translational Medicine, The Affiliated Hospital of Qingdao University, College of Medicine, Qingdao University, Qingdao, China
| | - Lei Zhu
- College of Basic Medical, Qingdao Binhai University, Qingdao, China
| | - Fei Wang
- Institute for Translational Medicine, The Affiliated Hospital of Qingdao University, College of Medicine, Qingdao University, Qingdao, China
| | - Peifeng Li
- Institute for Translational Medicine, The Affiliated Hospital of Qingdao University, College of Medicine, Qingdao University, Qingdao, China
| | - Yin Wang
- Institute for Translational Medicine, The Affiliated Hospital of Qingdao University, College of Medicine, Qingdao University, Qingdao, China.
| | - Yanyan Gao
- Institute for Translational Medicine, The Affiliated Hospital of Qingdao University, College of Medicine, Qingdao University, Qingdao, China.
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11
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Rehfeld F, Eitson JL, Ohlson MB, Chang TC, Schoggins JW, Mendell JT. CRISPR screening reveals a dependency on ribosome recycling for efficient SARS-CoV-2 programmed ribosomal frameshifting and viral replication. Cell Rep 2023; 42:112076. [PMID: 36753415 PMCID: PMC9884621 DOI: 10.1016/j.celrep.2023.112076] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2022] [Revised: 11/21/2022] [Accepted: 01/23/2023] [Indexed: 01/31/2023] Open
Abstract
During translation of the genomic RNA of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the causative virus in the COVID-19 pandemic, host ribosomes undergo programmed ribosomal frameshifting (PRF) at a conserved structural element. Although PRF is essential for coronavirus replication, host factors that regulate this process have not yet been identified. Here we perform genome-wide CRISPR-Cas9 knockout screens to identify regulators of SARS-CoV-2 PRF. These screens reveal that loss of ribosome recycling factors markedly decreases frameshifting efficiency and impairs SARS-CoV-2 viral replication. Mutational studies support a model wherein efficient removal of ribosomal subunits at the ORF1a stop codon is required for frameshifting of trailing ribosomes. This dependency upon ribosome recycling is not observed with other non-pathogenic human betacoronaviruses and is likely due to the unique position of the ORF1a stop codon in the SARS clade of coronaviruses. These findings therefore uncover host factors that support efficient SARS-CoV-2 translation and replication.
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Affiliation(s)
- Frederick Rehfeld
- Department of Molecular Biology, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Jennifer L Eitson
- Department of Microbiology, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Maikke B Ohlson
- Department of Microbiology, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Tsung-Cheng Chang
- Department of Molecular Biology, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - John W Schoggins
- Department of Microbiology, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Joshua T Mendell
- Department of Molecular Biology, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA; Harold C. Simmons Comprehensive Cancer Center, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA; Hamon Center for Regenerative Science and Medicine, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA; Howard Hughes Medical Institute, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA.
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12
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Embree CM, Abu-Alhasan R, Singh G. Features and factors that dictate if terminating ribosomes cause or counteract nonsense-mediated mRNA decay. J Biol Chem 2022; 298:102592. [PMID: 36244451 PMCID: PMC9661723 DOI: 10.1016/j.jbc.2022.102592] [Citation(s) in RCA: 21] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2022] [Revised: 10/07/2022] [Accepted: 10/10/2022] [Indexed: 11/13/2022] Open
Abstract
Nonsense-mediated mRNA decay (NMD) is a quality control pathway in eukaryotes that continuously monitors mRNA transcripts to ensure truncated polypeptides are not produced. The expression of many normal mRNAs that encode full-length polypeptides is also regulated by this pathway. Such transcript surveillance by NMD is intimately linked to translation termination. When a ribosome terminates translation at a normal termination codon, NMD is not activated, and mRNA can undergo repeated rounds of translation. On the other hand, when translation termination is deemed abnormal, such as that on a premature termination codon, it leads to a series of poorly understood events involving the NMD pathway, which destabilizes the transcript. In this review, we summarize our current understanding of how the NMD machinery interfaces with the translation termination factors to initiate NMD. We also discuss a variety of cis-acting sequence contexts and trans-acting factors that can cause readthrough, ribosome reinitiation, or ribosome frameshifting at stop codons predicted to induce NMD. These alternative outcomes can lead to the ribosome translating downstream of such stop codons and hence the transcript escaping NMD. NMD escape via these mechanisms can have wide-ranging implications on human health, from being exploited by viruses to hijack host cell systems to being harnessed as potential therapeutic possibilities to treat genetic diseases.
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Affiliation(s)
- Caleb M Embree
- Department of Molecular Genetics, The Ohio State University, Columbus, Ohio, USA; Center for RNA Biology, The Ohio State University, Columbus, Ohio USA
| | - Rabab Abu-Alhasan
- Department of Molecular Genetics, The Ohio State University, Columbus, Ohio, USA; Center for RNA Biology, The Ohio State University, Columbus, Ohio USA
| | - Guramrit Singh
- Department of Molecular Genetics, The Ohio State University, Columbus, Ohio, USA; Center for RNA Biology, The Ohio State University, Columbus, Ohio USA.
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13
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Bottorff TA, Park H, Geballe AP, Subramaniam AR. Translational buffering by ribosome stalling in upstream open reading frames. PLoS Genet 2022; 18:e1010460. [PMID: 36315596 PMCID: PMC9648851 DOI: 10.1371/journal.pgen.1010460] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2022] [Revised: 11/10/2022] [Accepted: 10/04/2022] [Indexed: 11/05/2022] Open
Abstract
Upstream open reading frames (uORFs) are present in over half of all human mRNAs. uORFs can potently regulate the translation of downstream open reading frames through several mechanisms: siphoning away scanning ribosomes, regulating re-initiation, and allowing interactions between scanning and elongating ribosomes. However, the consequences of these different mechanisms for the regulation of protein expression remain incompletely understood. Here, we performed systematic measurements on the uORF-containing 5' UTR of the cytomegaloviral UL4 mRNA to test alternative models of uORF-mediated regulation in human cells. We find that a terminal diproline-dependent elongating ribosome stall in the UL4 uORF prevents decreases in main ORF protein expression when ribosome loading onto the mRNA is reduced. This uORF-mediated buffering is insensitive to the location of the ribosome stall along the uORF. Computational kinetic modeling based on our measurements suggests that scanning ribosomes dissociate rather than queue when they collide with stalled elongating ribosomes within the UL4 uORF. We identify several human uORFs that repress main ORF protein expression via a similar terminal diproline motif. We propose that ribosome stalls in uORFs provide a general mechanism for buffering against reductions in main ORF translation during stress and developmental transitions.
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Affiliation(s)
- Ty A. Bottorff
- Basic Sciences Division and Computational Biology Program of the Public Health Sciences Division, Fred Hutchinson Cancer Center, Seattle, Washington, United States of America
- Biological Physics, Structure and Design Graduate Program, University of Washington, Seattle, Washington, United States of America
| | - Heungwon Park
- Basic Sciences Division and Computational Biology Program of the Public Health Sciences Division, Fred Hutchinson Cancer Center, Seattle, Washington, United States of America
| | - Adam P. Geballe
- Human Biology and Clinical Research Divisions, Fred Hutchinson Cancer Center, Seattle, Washington, United States of America
| | - Arvind Rasi Subramaniam
- Basic Sciences Division and Computational Biology Program of the Public Health Sciences Division, Fred Hutchinson Cancer Center, Seattle, Washington, United States of America
- Biological Physics, Structure and Design Graduate Program, University of Washington, Seattle, Washington, United States of America
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14
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Ichihara K, Nakayama KI, Matsumoto A. Identification of unannotated coding sequences and their physiological functions. J Biochem 2022; 173:237-242. [PMID: 35959549 DOI: 10.1093/jb/mvac064] [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: 06/21/2022] [Accepted: 08/05/2022] [Indexed: 11/12/2022] Open
Abstract
Most protein-coding sequences (CDSs) are predicted sequences based on criteria such as a size sufficient to encode a product of at least 100 amino acids and with translation starting at an AUG initiation codon. However, recent studies based on ribosome profiling and mass spectrometry have shown that several RNAs annotated as long noncoding RNAs (lncRNAs) are actually translated to generate polypeptides of fewer than 100 amino acids, and that many proteins are translated from near-cognate initiation codons such as CUG and GUG. Furthermore, studies of genetically engineered mouse models have revealed that such polypeptides and proteins contribute to diverse physiological processes. In this review, we describe the latest methods for the identification of unannotated CDSs and provide examples of their physiological functions.
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Affiliation(s)
- Kazuya Ichihara
- Division of Cell Biology, Medical Institute of Bioregulation, Kyushu University, Fukuoka, Fukuoka 819-0395, Japan
| | - Keiichi I Nakayama
- Division of Cell Biology, Medical Institute of Bioregulation, Kyushu University, Fukuoka, Fukuoka 819-0395, Japan
| | - Akinobu Matsumoto
- Division of Cell Biology, Medical Institute of Bioregulation, Kyushu University, Fukuoka, Fukuoka 819-0395, Japan
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15
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Selective footprinting of 40S and 80S ribosome subpopulations (Sel-TCP-seq) to study translation and its control. Nat Protoc 2022; 17:2139-2187. [DOI: 10.1038/s41596-022-00708-4] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2021] [Accepted: 04/01/2022] [Indexed: 11/08/2022]
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16
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Young DJ, Guydosh NR. Rebirth of the translational machinery: The importance of recycling ribosomes. Bioessays 2022; 44:e2100269. [PMID: 35147231 PMCID: PMC9270684 DOI: 10.1002/bies.202100269] [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: 11/10/2021] [Revised: 01/26/2022] [Accepted: 01/27/2022] [Indexed: 11/10/2022]
Abstract
Translation of the genetic code occurs in a cycle where ribosomes engage mRNAs, synthesize protein, and then disengage in order to repeat the process again. The final part of this process-ribosome recycling, where ribosomes dissociate from mRNAs-involves a complex molecular choreography of specific protein factors to remove the large and small subunits of the ribosome in a coordinated fashion. Errors in this process can lead to the accumulation of ribosomes at stop codons or translation of downstream open reading frames (ORFs). Ribosome recycling is also critical when a ribosome stalls during the elongation phase of translation and must be rescued to allow continued translation of the mRNA. Here we discuss the molecular interactions that drive ribosome recycling, and their regulation in the cell. We also examine the consequences of inefficient recycling with regards to disease, and its functional roles in synthesis of novel peptides, regulation of gene expression, and control of mRNA-associated proteins. Alterations in ribosome recycling efficiency have the potential to impact many cellular functions but additional work is needed to understand how this regulatory power is utilized.
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Affiliation(s)
- David J Young
- Laboratory of Biochemistry and Genetics, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland, USA
| | - Nicholas R Guydosh
- Laboratory of Biochemistry and Genetics, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland, USA
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17
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Shirokikh NE. Translation complex stabilization on messenger RNA and footprint profiling to study the RNA responses and dynamics of protein biosynthesis in the cells. Crit Rev Biochem Mol Biol 2021; 57:261-304. [PMID: 34852690 DOI: 10.1080/10409238.2021.2006599] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
During protein biosynthesis, ribosomes bind to messenger (m)RNA, locate its protein-coding information, and translate the nucleotide triplets sequentially as codons into the corresponding sequence of amino acids, forming proteins. Non-coding mRNA features, such as 5' and 3' untranslated regions (UTRs), start sites or stop codons of different efficiency, stretches of slower or faster code and nascent polypeptide interactions can alter the translation rates transcript-wise. Most of the homeostatic and signal response pathways of the cells converge on individual mRNA control, as well as alter the global translation output. Among the multitude of approaches to study translational control, one of the most powerful is to infer the locations of translational complexes on mRNA based on the mRNA fragments protected by these complexes from endonucleolytic hydrolysis, or footprints. Translation complex profiling by high-throughput sequencing of the footprints allows to quantify the transcript-wise, as well as global, alterations of translation, and uncover the underlying control mechanisms by attributing footprint locations and sizes to different configurations of the translational complexes. The accuracy of all footprint profiling approaches critically depends on the fidelity of footprint generation and many methods have emerged to preserve certain or multiple configurations of the translational complexes, often in challenging biological material. In this review, a systematic summary of approaches to stabilize translational complexes on mRNA for footprinting is presented and major findings are discussed. Future directions of translation footprint profiling are outlined, focusing on the fidelity and accuracy of inference of the native in vivo translation complex distribution on mRNA.
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Affiliation(s)
- Nikolay E Shirokikh
- Division of Genome Sciences and Cancer, The John Curtin School of Medical Research, The Australian National University, Canberra, Australia
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18
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Coupled protein synthesis and ribosome-guided piRNA processing on mRNAs. Nat Commun 2021; 12:5970. [PMID: 34645830 PMCID: PMC8514520 DOI: 10.1038/s41467-021-26233-8] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2021] [Accepted: 09/17/2021] [Indexed: 12/16/2022] Open
Abstract
PIWI-interacting small RNAs (piRNAs) protect the germline genome and are essential for fertility. piRNAs originate from transposable element (TE) RNAs, long non-coding RNAs, or 3´ untranslated regions (3´UTRs) of protein-coding messenger genes, with the last being the least characterized of the three piRNA classes. Here, we demonstrate that the precursors of 3´UTR piRNAs are full-length mRNAs and that post-termination 80S ribosomes guide piRNA production on 3´UTRs in mice and chickens. At the pachytene stage, when other co-translational RNA surveillance pathways are sequestered, piRNA biogenesis degrades mRNAs right after pioneer rounds of translation and fine-tunes protein production from mRNAs. Although 3´UTR piRNA precursor mRNAs code for distinct proteins in mice and chickens, they all harbor embedded TEs and produce piRNAs that cleave TEs. Altogether, we discover a function of the piRNA pathway in fine-tuning protein production and reveal a conserved piRNA biogenesis mechanism that recognizes translating RNAs in amniotes.
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Park J, Park J, Lee J, Lim C. The trinity of ribosome-associated quality control and stress signaling for proteostasis and neuronal physiology. BMB Rep 2021. [PMID: 34488933 PMCID: PMC8505234 DOI: 10.5483/bmbrep.2021.54.9.097] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Translating ribosomes accompany co-translational regulation of nascent polypeptide chains, including subcellular targeting, protein folding, and covalent modifications. Ribosome-associated quality control (RQC) is a co-translational surveillance mechanism triggered by ribosomal collisions, an indication of atypical translation. The ribosome-associated E3 ligase ZNF598 ubiquitinates small subunit proteins at the stalled ribosomes. A series of RQC factors are then recruited to dissociate and triage aberrant translation intermediates. Regulatory ribosomal stalling may occur on endogenous transcripts for quality gene expression, whereas ribosomal collisions are more globally induced by ribotoxic stressors such as translation inhibitors, ribotoxins, and UV radiation. The latter are sensed by ribosome-associated kinases GCN2 and ZAKα, activating integrated stress response (ISR) and ribotoxic stress response (RSR), respectively. Hierarchical crosstalks among RQC, ISR, and RSR pathways are readily detectable since the collided ribosome is their common substrate for activation. Given the strong implications of RQC factors in neuronal physiology and neurological disorders, the interplay between RQC and ribosome-associated stress signaling may sustain proteostasis, adaptively determine cell fate, and contribute to neural pathogenesis. The elucidation of underlying molecular principles in relevant human diseases should thus provide unexplored therapeutic opportunities.
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Affiliation(s)
- Jumin Park
- Department of Biological Sciences, Ulsan National Institute of Science and Technology, Ulsan 44919, Korea
| | - Jongmin Park
- Department of Biological Sciences, Ulsan National Institute of Science and Technology, Ulsan 44919, Korea
| | - Jongbin Lee
- Department of Biological Sciences, Ulsan National Institute of Science and Technology, Ulsan 44919, Korea
| | - Chunghun Lim
- Department of Biological Sciences, Ulsan National Institute of Science and Technology, Ulsan 44919, Korea
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