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Weiss B, Dikstein R. Unraveling the landscapes and regulation of scanning, leaky scanning, and 48S initiation complex conformations. Cell Rep 2024; 43:114126. [PMID: 38630588 DOI: 10.1016/j.celrep.2024.114126] [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] [Received: 03/02/2023] [Revised: 01/19/2024] [Accepted: 04/02/2024] [Indexed: 04/19/2024] Open
Abstract
Scanning and initiation are critical steps in translation. Here, we utilized translation complex profiling (TCP-seq) to investigate 48S organization and eIF4G1-eIF1 inhibition impact. We provide global views of scanning and leaky scanning, uncovering a central role of eIF4G1-eIF1 in their regulation. We confirm AUG context importance, with non-leaky genes featuring a Kozak context and cytosine at positions -1 and +5. Capturing 48S complexes associated with eIF1, eIF4G1, eIF3, and eIF2 through selective TCP-seq revealed that the eIF3-scanning ribosome is highly vulnerable to eIF4G1-eIF1 inhibition, and eIF1 tends to dissociate upon AUG recognition. Initiation-site footprint analysis revealed a class spanning -12 to +18/19 from the AUG, representing the entire 48S and enriched with eIF2, eIF1, and eIF4G1, indicative of early initiation. Another eIF3-dependent class extends up to +26 and exhibits reduced eIF2 and eIF4G1 association, suggesting a late/alternative initiation complex. Our analysis provides an overview of scanning, initiation, and evidence for conformational rearrangements in vivo.
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Affiliation(s)
- Benjamin Weiss
- Department of Biomolecular Sciences, The Weizmann Institute of Science, Rehovot 76100, Israel.
| | - Rivka Dikstein
- Department of Biomolecular Sciences, The Weizmann Institute of Science, Rehovot 76100, Israel.
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2
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Brito Querido J, Díaz-López I, Ramakrishnan V. The molecular basis of translation initiation and its regulation in eukaryotes. Nat Rev Mol Cell Biol 2024; 25:168-186. [PMID: 38052923 DOI: 10.1038/s41580-023-00624-9] [Citation(s) in RCA: 23] [Impact Index Per Article: 23.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/24/2023] [Indexed: 12/07/2023]
Abstract
The regulation of gene expression is fundamental for life. Whereas the role of transcriptional regulation of gene expression has been studied for several decades, it has been clear over the past two decades that post-transcriptional regulation of gene expression, of which translation regulation is a major part, can be equally important. Translation can be divided into four main stages: initiation, elongation, termination and ribosome recycling. Translation is controlled mainly during its initiation, a process which culminates in a ribosome positioned with an initiator tRNA over the start codon and, thus, ready to begin elongation of the protein chain. mRNA translation has emerged as a powerful tool for the development of innovative therapies, yet the detailed mechanisms underlying the complex process of initiation remain unclear. Recent studies in yeast and mammals have started to shed light on some previously unclear aspects of this process. In this Review, we discuss the current state of knowledge on eukaryotic translation initiation and its regulation in health and disease. Specifically, we focus on recent advances in understanding the processes involved in assembling the 43S pre-initiation complex and its recruitment by the cap-binding complex eukaryotic translation initiation factor 4F (eIF4F) at the 5' end of mRNA. In addition, we discuss recent insights into ribosome scanning along the 5' untranslated region of mRNA and selection of the start codon, which culminates in joining of the 60S large subunit and formation of the 80S initiation complex.
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Affiliation(s)
- Jailson Brito Querido
- MRC Laboratory of Molecular Biology, Cambridge Biomedical Campus, Cambridge, UK
- Department of Biological Chemistry, University of Michigan, Ann Arbor, MI, USA
- Life Sciences Institute, University of Michigan, Ann Arbor, MI, USA
| | - Irene Díaz-López
- MRC Laboratory of Molecular Biology, Cambridge Biomedical Campus, Cambridge, UK
| | - V Ramakrishnan
- MRC Laboratory of Molecular Biology, Cambridge Biomedical Campus, Cambridge, UK.
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3
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Mao Y, Qian SB. Making sense of mRNA translational "noise". Semin Cell Dev Biol 2024; 154:114-122. [PMID: 36925447 PMCID: PMC10500040 DOI: 10.1016/j.semcdb.2023.03.004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2022] [Revised: 03/09/2023] [Accepted: 03/09/2023] [Indexed: 03/15/2023]
Abstract
The importance of translation fidelity has been apparent since the discovery of genetic code. It is commonly believed that translation deviating from the main coding region is to be avoided at all times inside cells. However, ribosome profiling and mass spectrometry have revealed pervasive noncanonical translation. Both the scope and origin of translational "noise" are just beginning to be appreciated. Although largely overlooked, those translational "noises" are associated with a wide range of cellular functions, such as producing unannotated protein products. Furthermore, the dynamic nature of translational "noise" is responsive to stress conditions, highlighting the beneficial effect of translational "noise" in stress adaptation. Mechanistic investigation of translational "noise" will provide better insight into the mechanisms of translational regulation. Ultimately, they are not "noise" at all but represent a signature of cellular activities under pathophysiological conditions. Deciphering translational "noise" holds the therapeutic and diagnostic potential in a wide spectrum of human diseases.
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Affiliation(s)
- Yuanhui Mao
- Division of Nutritional Sciences, Cornell University, Ithaca, NY 14853, USA
| | - Shu-Bing Qian
- Division of Nutritional Sciences, Cornell University, Ithaca, NY 14853, USA.
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4
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Reimão-Pinto MM, Castillo-Hair SM, Seelig G, Schier AF. The regulatory landscape of 5' UTRs in translational control during zebrafish embryogenesis. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.11.23.568470. [PMID: 38045294 PMCID: PMC10690280 DOI: 10.1101/2023.11.23.568470] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/05/2023]
Abstract
The 5' UTRs of mRNAs are critical for translation regulation, but their in vivo regulatory features are poorly characterized. Here, we report the regulatory landscape of 5' UTRs during early zebrafish embryogenesis using a massively parallel reporter assay of 18,154 sequences coupled to polysome profiling. We found that the 5' UTR is sufficient to confer temporal dynamics to translation initiation, and identified 86 motifs enriched in 5' UTRs with distinct ribosome recruitment capabilities. A quantitative deep learning model, DaniO5P, revealed a combined role for 5' UTR length, translation initiation site context, upstream AUGs and sequence motifs on in vivo ribosome recruitment. DaniO5P predicts the activities of 5' UTR isoforms and indicates that modulating 5' UTR length and motif grammar contributes to translation initiation dynamics. This study provides a first quantitative model of 5' UTR-based translation regulation in early vertebrate development and lays the foundation for identifying the underlying molecular effectors. Highlights In vivo MPRA systematically interrogates the regulatory potential of endogenous 5' UTRs The 5' UTR alone is sufficient to regulate the dynamics of ribosome recruitment during early embryogenesis The MPRA identifies 5' UTR cis -regulatory motifs for translation initiation control 5' UTR length, upstream AUGs and motif grammar contribute to the differential regulatory capability of 5' UTR switching isoforms.
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5
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Duncan C, Mata J. Translation-complex profiling of fission yeast cells reveals dynamic rearrangements of scanning ribosomal subunits upon nutritional stress. Nucleic Acids Res 2022; 50:13011-13025. [PMID: 36478272 PMCID: PMC9825154 DOI: 10.1093/nar/gkac1140] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2022] [Revised: 11/09/2022] [Accepted: 11/16/2022] [Indexed: 12/13/2022] Open
Abstract
Control of mRNA translation is key for stress responses. Translation initiation is usually rate-limiting and, in eukaryotes, involves mRNA scanning by the small ribosomal subunit. Despite its importance, many aspects of translation in vivo have not been explored fully, especially at the transcriptome-wide level. A recent method termed translation-complex profiling (TCP-seq) allows transcriptome-wide views of scanning ribosomal subunits. We applied TCP-seq to nutritional stress in the fission yeast Schizosaccharomyces pombe. At initiation sites, we observed multiple complexes resembling those of mammals, and consistent with queuing of scanning subunits. In 5' UTRs, small subunit accumulations were common and may reflect impediments to scanning. A key mediator of stress responses in S. pombe is the Fil1 transcription factor, which is regulated translationally by a poorly-understood mechanism involving upstream Open Reading Frames (uORFs). TCP-seq data of fil1 shows that stress allows scanning subunits to by-pass specific uORFs and reach the fil1 coding sequence. The integration of these observations with reporter assays revealed that fil1 translational control is mediated by a combination of scanning reinitiation-repressive and permissive uORFs, and establishes fil1 as a model for uORF-mediated translational control. Altogether, our transcriptome-wide study reveals general and gene-specific features of translation in a model eukaryote.
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Affiliation(s)
| | - Juan Mata
- To whom correspondence should be addressed. Tel: +44 01223360467;
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6
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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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7
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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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8
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Soukarieh O, Meguerditchian C, Proust C, Aïssi D, Eyries M, Goyenvalle A, Trégouët DA. Common and Rare 5′UTR Variants Altering Upstream Open Reading Frames in Cardiovascular Genomics. Front Cardiovasc Med 2022; 9:841032. [PMID: 35387445 PMCID: PMC8977850 DOI: 10.3389/fcvm.2022.841032] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2021] [Accepted: 02/21/2022] [Indexed: 01/16/2023] Open
Abstract
High-throughput sequencing (HTS) technologies are revolutionizing the research and molecular diagnosis landscape by allowing the exploration of millions of nucleotide sequences at an unprecedented scale. These technologies are of particular interest in the identification of genetic variations contributing to the risk of rare (Mendelian) and common (multifactorial) human diseases. So far, they have led to numerous successes in identifying rare disease-causing mutations in coding regions, but few in non-coding regions that include introns, untranslated (UTR), and intergenic regions. One class of neglected non-coding variations is that of 5′UTR variants that alter upstream open reading frames (upORFs) of the coding sequence (CDS) of a natural protein coding transcript. Following a brief summary of the molecular bases of the origin and functions of upORFs, we will first review known 5′UTR variations altering upORFs and causing rare cardiovascular disorders (CVDs). We will then investigate whether upORF-affecting single nucleotide polymorphisms could be good candidates for explaining association signals detected in the context of genome-wide association studies for common complex CVDs.
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Affiliation(s)
- Omar Soukarieh
- INSERM, Bordeaux Population Health, U1219, Molecular Epidemiology of Vascular and Brain Disorders, University of Bordeaux, Bordeaux, France
- *Correspondence: Omar Soukarieh,
| | - Caroline Meguerditchian
- INSERM, Bordeaux Population Health, U1219, Molecular Epidemiology of Vascular and Brain Disorders, University of Bordeaux, Bordeaux, France
| | - Carole Proust
- INSERM, Bordeaux Population Health, U1219, Molecular Epidemiology of Vascular and Brain Disorders, University of Bordeaux, Bordeaux, France
| | - Dylan Aïssi
- INSERM, Bordeaux Population Health, U1219, Molecular Epidemiology of Vascular and Brain Disorders, University of Bordeaux, Bordeaux, France
| | - Mélanie Eyries
- Department of Genetics, Pitié-Salpêtrière Hospital, Assistance Publique-Hôpitaux de Paris, Sorbonne Université, Paris, France
| | | | - David-Alexandre Trégouët
- INSERM, Bordeaux Population Health, U1219, Molecular Epidemiology of Vascular and Brain Disorders, University of Bordeaux, Bordeaux, France
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9
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Kute PM, Soukarieh O, Tjeldnes H, Trégouët DA, Valen E. Small Open Reading Frames, How to Find Them and Determine Their Function. Front Genet 2022; 12:796060. [PMID: 35154250 PMCID: PMC8831751 DOI: 10.3389/fgene.2021.796060] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2021] [Accepted: 12/30/2021] [Indexed: 12/12/2022] Open
Abstract
Advances in genomics and molecular biology have revealed an abundance of small open reading frames (sORFs) across all types of transcripts. While these sORFs are often assumed to be non-functional, many have been implicated in physiological functions and a significant number of sORFs have been described in human diseases. Thus, sORFs may represent a hidden repository of functional elements that could serve as therapeutic targets. Unlike protein-coding genes, it is not necessarily the encoded peptide of an sORF that enacts its function, sometimes simply the act of translating an sORF might have a regulatory role. Indeed, the most studied sORFs are located in the 5′UTRs of coding transcripts and can have a regulatory impact on the translation of the downstream protein-coding sequence. However, sORFs have also been abundantly identified in non-coding RNAs including lncRNAs, circular RNAs and ribosomal RNAs suggesting that sORFs may be diverse in function. Of the many different experimental methods used to discover sORFs, the most commonly used are ribosome profiling and mass spectrometry. These can confirm interactions between transcripts and ribosomes and the production of a peptide, respectively. Extensions to ribosome profiling, which also capture scanning ribosomes, have further made it possible to see how sORFs impact the translation initiation of mRNAs. While high-throughput techniques have made the identification of sORFs less difficult, defining their function, if any, is typically more challenging. Together, the abundance and potential function of many of these sORFs argues for the necessity of including sORFs in gene annotations and systematically characterizing these to understand their potential functional roles. In this review, we will focus on the high-throughput methods used in the detection and characterization of sORFs and discuss techniques for validation and functional characterization.
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Affiliation(s)
- Preeti Madhav Kute
- Computational Biology Unit, Department of Informatics, University of Bergen, Bergen, Norway
- Sars International Centre for Marine Molecular Biology, University of Bergen, Bergen, Norway
| | - Omar Soukarieh
- Department of Molecular Epidemiology Of Vascular and Brain Disorders, INSERM, BPH, U1219, University of Bordeaux, Bordeaux, France
| | - Håkon Tjeldnes
- Computational Biology Unit, Department of Informatics, University of Bergen, Bergen, Norway
| | - David-Alexandre Trégouët
- Department of Molecular Epidemiology Of Vascular and Brain Disorders, INSERM, BPH, U1219, University of Bordeaux, Bordeaux, France
| | - Eivind Valen
- Computational Biology Unit, Department of Informatics, University of Bergen, Bergen, Norway
- Sars International Centre for Marine Molecular Biology, University of Bergen, Bergen, Norway
- *Correspondence: Eivind Valen,
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10
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Smirnova VV, Shestakova ED, Nogina DS, Mishchenko PA, Prikazchikova TA, Zatsepin TS, Kulakovskiy IV, Shatsky IN, Terenin IM. Ribosomal leaky scanning through a translated uORF requires eIF4G2. Nucleic Acids Res 2022; 50:1111-1127. [PMID: 35018467 PMCID: PMC8789081 DOI: 10.1093/nar/gkab1286] [Citation(s) in RCA: 20] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2021] [Revised: 12/07/2021] [Accepted: 12/18/2021] [Indexed: 11/21/2022] Open
Abstract
eIF4G2 (DAP5 or Nat1) is a homologue of the canonical translation initiation factor eIF4G1 in higher eukaryotes but its function remains poorly understood. Unlike eIF4G1, eIF4G2 does not interact with the cap-binding protein eIF4E and is believed to drive translation under stress when eIF4E activity is impaired. Here, we show that eIF4G2 operates under normal conditions as well and promotes scanning downstream of the eIF4G1-mediated 40S recruitment and cap-proximal scanning. Specifically, eIF4G2 facilitates leaky scanning for a subset of mRNAs. Apparently, eIF4G2 replaces eIF4G1 during scanning of 5′ UTR and the necessity for eIF4G2 only arises when eIF4G1 dissociates from the scanning complex. In particular, this event can occur when the leaky scanning complexes interfere with initiating or elongating 80S ribosomes within a translated uORF. This mechanism is therefore crucial for higher eukaryotes which are known to have long 5′ UTRs with highly frequent uORFs. We suggest that uORFs are not the only obstacle on the way of scanning complexes towards the main start codon, because certain eIF4G2 mRNA targets lack uORF(s). Thus, higher eukaryotes possess two distinct scanning complexes: the principal one that binds mRNA and initiates scanning, and the accessory one that rescues scanning when the former fails.
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Affiliation(s)
- Victoria V Smirnova
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow 119234, Russia
| | - Ekaterina D Shestakova
- Faculty of Bioengineering and Bioinformatics, Lomonosov Moscow State University, Moscow 119234, Russia
| | - Daria S Nogina
- Faculty of Bioengineering and Bioinformatics, Lomonosov Moscow State University, Moscow 119234, Russia
| | - Polina A Mishchenko
- Faculty of Bioengineering and Bioinformatics, Lomonosov Moscow State University, Moscow 119234, Russia
| | | | - Timofei S Zatsepin
- Skolkovo Institute of Science and Technology, Skolkovo, Moscow 121205, Russia.,Chemistry Department, Lomonosov Moscow State University, Moscow 119991, Russia
| | - Ivan V Kulakovskiy
- Center for Precision Genome Editing and Genetic Technologies for Biomedicine, Engelhardt Institute of Molecular Biology, Russian Academy of Sciences, Moscow 119991, Russia.,Institute of Protein Research, Russian Academy of Sciences, Pushchino 142290, Russia.,Vavilov Institute of General Genetics, Russian Academy of Sciences, Moscow 119991, Russia
| | - Ivan N Shatsky
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow 119234, Russia
| | - Ilya M Terenin
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow 119234, Russia.,Sirius University of Science and Technology, Sochi, Olimpiyskiy ave. b.1, 354349, Russia
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11
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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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12
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Gu Y, Mao Y, Jia L, Dong L, Qian SB. Bi-directional ribosome scanning controls the stringency of start codon selection. Nat Commun 2021; 12:6604. [PMID: 34782646 PMCID: PMC8593136 DOI: 10.1038/s41467-021-26923-3] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2021] [Accepted: 10/28/2021] [Indexed: 11/29/2022] Open
Abstract
The fidelity of start codon recognition by ribosomes is paramount during protein synthesis. The current knowledge of eukaryotic translation initiation implies unidirectional 5'→3' migration of the pre-initiation complex (PIC) along the 5' UTR. In probing translation initiation from ultra-short 5' UTR, we report that an AUG triplet near the 5' end can be selected via PIC backsliding. Bi-directional ribosome scanning is supported by competitive selection of closely spaced AUG codons and recognition of two initiation sites flanking an internal ribosome entry site. Transcriptome-wide PIC profiling reveals footprints with an oscillation pattern near the 5' end and start codons. Depleting the RNA helicase eIF4A leads to reduced PIC oscillations and impaired selection of 5' end start codons. Enhancing the ATPase activity of eIF4A promotes nonlinear PIC scanning and stimulates upstream translation initiation. The helicase-mediated PIC conformational switch may provide an operational mechanism that unifies ribosome recruitment, scanning, and start codon selection.
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Affiliation(s)
- Yifei Gu
- Division of Nutritional Sciences, Cornell University, Ithaca, NY, 14853, USA
| | - Yuanhui Mao
- Division of Nutritional Sciences, Cornell University, Ithaca, NY, 14853, USA
| | - Longfei Jia
- Division of Nutritional Sciences, Cornell University, Ithaca, NY, 14853, USA
| | - Leiming Dong
- Division of Nutritional Sciences, Cornell University, Ithaca, NY, 14853, USA
| | - Shu-Bing Qian
- Division of Nutritional Sciences, Cornell University, Ithaca, NY, 14853, USA.
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13
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Andreev DE, Smirnova VV, Shatsky IN. Modifications of Ribosome Profiling that Provide New Data on the Translation Regulation. BIOCHEMISTRY (MOSCOW) 2021; 86:1095-1106. [PMID: 34565313 DOI: 10.1134/s0006297921090054] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Ribosome profiling (riboseq) has opened the possibilities for the genome-wide studies of translation in all living organisms. This method is based on deep sequencing of mRNA fragments protected by the ribosomes from hydrolysis by ribonucleases, the so-called ribosomal footprints (RFPs). Ribosomal profiling together with RNA sequencing allows not only to identify with a reasonable accuracy translated reading frames in the transcriptome, but also to track changes in gene expression in response to various stimuli. Notably, ribosomal profiling in its classical version has certain limitations. The size of the selected mRNA fragments is 25-35 nts, while RFPs of other sizes are usually omitted from analysis. Also, ribosomal profiling "averages" the data from all ribosomes and does not allow to study specific ribosomal complexes associated with particular translation factors. However, recently developed modifications of ribosomal profiling provide answers to a number of questions. Thus, it has become possible to analyze not only elongating, but also scanning and reinitiating ribosomes, to study events associated with the collision of ribosomes during mRNA translation, to discover new ways of cotranslational assembly of multisubunit protein complexes during translation, and to selectively isolate ribosomal complexes associated with certain protein factors. New data obtained using these modified approaches provide a better understanding of the mechanisms of translation regulation and the functional roles of translational apparatus components.
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Affiliation(s)
- Dmitry E Andreev
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, 119992, Russia.,Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry of the Russian Academy of Sciences, Moscow, 117997, Russia
| | - Viktoriya V Smirnova
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, 119992, Russia
| | - Ivan N Shatsky
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, 119992, Russia.
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14
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Auparakkitanon S, Wilairat P. Universal scanning-free initiation of eukaryote protein translation-a new normal. Biomol Concepts 2021; 12:129-131. [PMID: 34496168 DOI: 10.1515/bmc-2021-0014] [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: 07/11/2021] [Accepted: 08/18/2021] [Indexed: 11/15/2022] Open
Abstract
A unique feature of eukaryote initiation of protein translation is a so-called scanning of 5'-untranslated region (5'-UTR) by a ribosome initiation complex to enable bound Met-tRNAi access to the initiation codon located further downstream. Here, we propose a universal scanning-free translation initiation model that is independent of 5'-UTR length and applicable to both 5'-m7G (capped) and uncapped mRNAs.
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Affiliation(s)
- Saranya Auparakkitanon
- Department of Pathology, Faculty of Medicine Ramathibodi Hospital, Mahidol University, Rama 6 Road, Bangkok 10400, Thailand
| | - Prapon Wilairat
- Department of Biochemistry, Faculty of Science, Mahidol University, Rama 6 Road, Bangkok 10400, Thailand
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15
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Ichihara K, Matsumoto A, Nishida H, Kito Y, Shimizu H, Shichino Y, Iwasaki S, Imami K, Ishihama Y, Nakayama KI. Combinatorial analysis of translation dynamics reveals eIF2 dependence of translation initiation at near-cognate codons. Nucleic Acids Res 2021; 49:7298-7317. [PMID: 34226921 PMCID: PMC8287933 DOI: 10.1093/nar/gkab549] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2021] [Revised: 06/08/2021] [Accepted: 06/11/2021] [Indexed: 02/05/2023] Open
Abstract
Although ribosome-profiling and translation initiation sequencing (TI-seq) analyses have identified many noncanonical initiation codons, the precise detection of translation initiation sites (TISs) remains a challenge, mainly because of experimental artifacts of such analyses. Here, we describe a new method, TISCA (TIS detection by translation Complex Analysis), for the accurate identification of TISs. TISCA proved to be more reliable for TIS detection compared with existing tools, and it identified a substantial number of near-cognate codons in Kozak-like sequence contexts. Analysis of proteomics data revealed the presence of methionine at the NH2-terminus of most proteins derived from near-cognate initiation codons. Although eukaryotic initiation factor 2 (eIF2), eIF2A and eIF2D have previously been shown to contribute to translation initiation at near-cognate codons, we found that most noncanonical initiation events are most probably dependent on eIF2, consistent with the initial amino acid being methionine. Comprehensive identification of TISs by TISCA should facilitate characterization of the mechanism of noncanonical initiation.
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Affiliation(s)
- Kazuya Ichihara
- Department of Molecular and Cellular Biology, Medical Institute of Bioregulation, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka, Fukuoka 812-8582, Japan
| | - Akinobu Matsumoto
- Department of Molecular and Cellular Biology, Medical Institute of Bioregulation, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka, Fukuoka 812-8582, Japan
| | - Hiroshi Nishida
- Department of Molecular and Cellular Bioanalysis, Graduate School of Pharmaceutical Sciences, Kyoto University, Sakyo-ku, Kyoto 606-8501, Japan
| | - Yuki Kito
- Department of Molecular and Cellular Biology, Medical Institute of Bioregulation, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka, Fukuoka 812-8582, Japan
| | - Hideyuki Shimizu
- Department of Molecular and Cellular Biology, Medical Institute of Bioregulation, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka, Fukuoka 812-8582, Japan
| | - Yuichi Shichino
- RNA Systems Biochemistry Laboratory, RIKEN Cluster for Pioneering Research, Wako, Saitama 351-0198, Japan
| | - Shintaro Iwasaki
- RNA Systems Biochemistry Laboratory, RIKEN Cluster for Pioneering Research, Wako, Saitama 351-0198, Japan.,Department of Computational Biology and Medical Sciences, Graduate School of Frontier Sciences, The University of Tokyo, Kashiwa, Chiba 277-8561, Japan.,AMED-CREST, Japan Agency for Medical Research and Development, Wako, Saitama 351-0198, Japan
| | - Koshi Imami
- Department of Molecular and Cellular Bioanalysis, Graduate School of Pharmaceutical Sciences, Kyoto University, Sakyo-ku, Kyoto 606-8501, Japan
| | - Yasushi Ishihama
- Department of Molecular and Cellular Bioanalysis, Graduate School of Pharmaceutical Sciences, Kyoto University, Sakyo-ku, Kyoto 606-8501, Japan
| | - Keiichi I Nakayama
- Department of Molecular and Cellular Biology, Medical Institute of Bioregulation, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka, Fukuoka 812-8582, Japan
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16
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Tjeldnes H, Labun K, Torres Cleuren Y, Chyżyńska K, Świrski M, Valen E. ORFik: a comprehensive R toolkit for the analysis of translation. BMC Bioinformatics 2021; 22:336. [PMID: 34147079 PMCID: PMC8214792 DOI: 10.1186/s12859-021-04254-w] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2021] [Accepted: 06/09/2021] [Indexed: 12/13/2022] Open
Abstract
BACKGROUND With the rapid growth in the use of high-throughput methods for characterizing translation and the continued expansion of multi-omics, there is a need for back-end functions and streamlined tools for processing, analyzing, and characterizing data produced by these assays. RESULTS Here, we introduce ORFik, a user-friendly R/Bioconductor API and toolbox for studying translation and its regulation. It extends GenomicRanges from the genome to the transcriptome and implements a framework that integrates data from several sources. ORFik streamlines the steps to process, analyze, and visualize the different steps of translation with a particular focus on initiation and elongation. It accepts high-throughput sequencing data from ribosome profiling to quantify ribosome elongation or RCP-seq/TCP-seq to also quantify ribosome scanning. In addition, ORFik can use CAGE data to accurately determine 5'UTRs and RNA-seq for determining translation relative to RNA abundance. ORFik supports and calculates over 30 different translation-related features and metrics from the literature and can annotate translated regions such as proteins or upstream open reading frames (uORFs). As a use-case, we demonstrate using ORFik to rapidly annotate the dynamics of 5' UTRs across different tissues, detect their uORFs, and characterize their scanning and translation in the downstream protein-coding regions. CONCLUSION In summary, ORFik introduces hundreds of tested, documented and optimized methods. ORFik is designed to be easily customizable, enabling users to create complete workflows from raw data to publication-ready figures for several types of sequencing data. Finally, by improving speed and scope of many core Bioconductor functions, ORFik offers enhancement benefiting the entire Bioconductor environment. AVAILABILITY http://bioconductor.org/packages/ORFik .
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Affiliation(s)
- Håkon Tjeldnes
- Computational Biology Unit, Department of Informatics, University of Bergen, Bergen, Norway
| | - Kornel Labun
- Computational Biology Unit, Department of Informatics, University of Bergen, Bergen, Norway
| | - Yamila Torres Cleuren
- Computational Biology Unit, Department of Informatics, University of Bergen, Bergen, Norway.,Sars International Centre for Marine Molecular Biology, University of Bergen, Bergen, Norway
| | - Katarzyna Chyżyńska
- Computational Biology Unit, Department of Informatics, University of Bergen, Bergen, Norway
| | - Michał Świrski
- Institute of Genetics and Biotechnology, Faculty of Biology, University of Warsaw, Warsaw, Poland
| | - Eivind Valen
- Computational Biology Unit, Department of Informatics, University of Bergen, Bergen, Norway. .,Sars International Centre for Marine Molecular Biology, University of Bergen, Bergen, Norway.
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17
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Jürgens L, Manske F, Hubert E, Kischka T, Flötotto L, Klaas O, Shabardina V, Schliemann C, Makalowski W, Wethmar K. Somatic Functional Deletions of Upstream Open Reading Frame-Associated Initiation and Termination Codons in Human Cancer. Biomedicines 2021; 9:biomedicines9060618. [PMID: 34072580 PMCID: PMC8227997 DOI: 10.3390/biomedicines9060618] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2021] [Revised: 05/22/2021] [Accepted: 05/27/2021] [Indexed: 11/16/2022] Open
Abstract
Upstream open reading frame (uORF)-mediated translational control has emerged as an important regulatory mechanism in human health and disease. However, a systematic search for cancer-associated somatic uORF mutations has not been performed. Here, we analyzed the genetic variability at canonical (uAUG) and alternative translational initiation sites (aTISs), as well as the associated upstream termination codons (uStops) in 3394 whole-exome-sequencing datasets from patient samples of breast, colon, lung, prostate, and skin cancer and of acute myeloid leukemia, provided by The Cancer Genome Atlas research network. We found that 66.5% of patient samples were affected by at least one of 5277 recurrent uORF-associated somatic single nucleotide variants altering 446 uAUG, 347 uStop, and 4733 aTIS codons. While twelve uORF variants were detected in all entities, 17 variants occurred in all five types of solid cancer analyzed here. Highest frequencies of individual somatic variants in the TLSs of NBPF20 and CHCHD2 reached 10.1% among LAML and 8.1% among skin cancer patients, respectively. Functional evaluation by dual luciferase reporter assays identified 19 uORF variants causing significant translational deregulation of the associated main coding sequence, ranging from 1.73-fold induction for an AUG.1 > UUG variant in SETD4 to 0.006-fold repression for a CUG.6 > GUG variant in HLA-DRB1. These data suggest that somatic uORF mutations are highly prevalent in human malignancies and that defective translational regulation of protein expression may contribute to the onset or progression of cancer.
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Affiliation(s)
- Lara Jürgens
- Department of Medicine A, Hematology, Oncology, Hemostaseology and Pneumology, University Hospital Münster, 48149 Münster, Germany; (L.J.); (E.H.); (L.F.); (O.K.); (C.S.)
| | - Felix Manske
- Faculty of Medicine, Institute of Bioinformatics, University of Münster, 48149 Münster, Germany; (F.M.); (T.K.); (W.M.)
| | - Elvira Hubert
- Department of Medicine A, Hematology, Oncology, Hemostaseology and Pneumology, University Hospital Münster, 48149 Münster, Germany; (L.J.); (E.H.); (L.F.); (O.K.); (C.S.)
| | - Tabea Kischka
- Faculty of Medicine, Institute of Bioinformatics, University of Münster, 48149 Münster, Germany; (F.M.); (T.K.); (W.M.)
| | - Lea Flötotto
- Department of Medicine A, Hematology, Oncology, Hemostaseology and Pneumology, University Hospital Münster, 48149 Münster, Germany; (L.J.); (E.H.); (L.F.); (O.K.); (C.S.)
| | - Oliver Klaas
- Department of Medicine A, Hematology, Oncology, Hemostaseology and Pneumology, University Hospital Münster, 48149 Münster, Germany; (L.J.); (E.H.); (L.F.); (O.K.); (C.S.)
| | - Victoria Shabardina
- Institute of Evolutionary Biology, CSIC-Unversitat Pompeu Frabra, 08002 Barcelona, Spain;
| | - Christoph Schliemann
- Department of Medicine A, Hematology, Oncology, Hemostaseology and Pneumology, University Hospital Münster, 48149 Münster, Germany; (L.J.); (E.H.); (L.F.); (O.K.); (C.S.)
| | - Wojciech Makalowski
- Faculty of Medicine, Institute of Bioinformatics, University of Münster, 48149 Münster, Germany; (F.M.); (T.K.); (W.M.)
| | - Klaus Wethmar
- Department of Medicine A, Hematology, Oncology, Hemostaseology and Pneumology, University Hospital Münster, 48149 Münster, Germany; (L.J.); (E.H.); (L.F.); (O.K.); (C.S.)
- Correspondence: ; Tel.: +49-251-8347587; Fax: +49-251-8347588
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18
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Young DJ, Meydan S, Guydosh NR. 40S ribosome profiling reveals distinct roles for Tma20/Tma22 (MCT-1/DENR) and Tma64 (eIF2D) in 40S subunit recycling. Nat Commun 2021; 12:2976. [PMID: 34016977 PMCID: PMC8137927 DOI: 10.1038/s41467-021-23223-8] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2020] [Accepted: 04/14/2021] [Indexed: 12/21/2022] Open
Abstract
The recycling of ribosomes at stop codons for use in further rounds of translation is critical for efficient protein synthesis. Removal of the 60S subunit is catalyzed by the ATPase Rli1 (ABCE1) while removal of the 40S is thought to require Tma64 (eIF2D), Tma20 (MCT-1), and Tma22 (DENR). However, it remains unclear how these Tma proteins cause 40S removal and control reinitiation of downstream translation. Here we used a 40S ribosome footprinting strategy to directly observe intermediate steps of ribosome recycling in cells. Deletion of the genes encoding these Tma proteins resulted in broad accumulation of unrecycled 40S subunits at stop codons, directly establishing their role in 40S recycling. Furthermore, the Tma20/Tma22 heterodimer was responsible for a majority of 40S recycling events while Tma64 played a minor role. Introduction of an autism-associated mutation into TMA22 resulted in a loss of 40S recycling activity, linking ribosome recycling and neurological disease.
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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, MD, USA
| | - Sezen Meydan
- Laboratory of Biochemistry and Genetics, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD, USA
- Postdoctoral Research Associate Training Program, National Institute of General Medical Sciences, National Institutes of Health, Bethesda, MD, USA
| | - Nicholas R Guydosh
- Laboratory of Biochemistry and Genetics, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD, USA.
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19
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Gerovac M, Vogel J, Smirnov A. The World of Stable Ribonucleoproteins and Its Mapping With Grad-Seq and Related Approaches. Front Mol Biosci 2021; 8:661448. [PMID: 33898526 PMCID: PMC8058203 DOI: 10.3389/fmolb.2021.661448] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2021] [Accepted: 03/04/2021] [Indexed: 12/13/2022] Open
Abstract
Macromolecular complexes of proteins and RNAs are essential building blocks of cells. These stable supramolecular particles can be viewed as minimal biochemical units whose structural organization, i.e., the way the RNA and the protein interact with each other, is directly linked to their biological function. Whether those are dynamic regulatory ribonucleoproteins (RNPs) or integrated molecular machines involved in gene expression, the comprehensive knowledge of these units is critical to our understanding of key molecular mechanisms and cell physiology phenomena. Such is the goal of diverse complexomic approaches and in particular of the recently developed gradient profiling by sequencing (Grad-seq). By separating cellular protein and RNA complexes on a density gradient and quantifying their distributions genome-wide by mass spectrometry and deep sequencing, Grad-seq charts global landscapes of native macromolecular assemblies. In this review, we propose a function-based ontology of stable RNPs and discuss how Grad-seq and related approaches transformed our perspective of bacterial and eukaryotic ribonucleoproteins by guiding the discovery of new RNA-binding proteins and unusual classes of noncoding RNAs. We highlight some methodological aspects and developments that permit to further boost the power of this technique and to look for exciting new biology in understudied and challenging biological models.
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Affiliation(s)
- Milan Gerovac
- Institute of Molecular Infection Biology (IMIB), University of Würzburg, Würzburg, Germany
| | - Jörg Vogel
- Institute of Molecular Infection Biology (IMIB), University of Würzburg, Würzburg, Germany
- Helmholtz Institute for RNA-based Infection Research (HIRI), Helmholtz Centre for Infection Research (HZI), Würzburg, Germany
| | - Alexandre Smirnov
- UMR 7156—Génétique Moléculaire, Génomique, Microbiologie (GMGM), University of Strasbourg, CNRS, Strasbourg, France
- University of Strasbourg Institute for Advanced Study (USIAS), Strasbourg, France
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20
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Ho JJD, Man JHS, Schatz JH, Marsden PA. Translational remodeling by RNA-binding proteins and noncoding RNAs. WILEY INTERDISCIPLINARY REVIEWS-RNA 2021; 12:e1647. [PMID: 33694288 DOI: 10.1002/wrna.1647] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/21/2020] [Revised: 02/09/2021] [Accepted: 02/10/2021] [Indexed: 12/14/2022]
Abstract
Responsible for generating the proteome that controls phenotype, translation is the ultimate convergence point for myriad upstream signals that influence gene expression. System-wide adaptive translational reprogramming has recently emerged as a pillar of cellular adaptation. As classic regulators of mRNA stability and translation efficiency, foundational studies established the concept of collaboration and competition between RNA-binding proteins (RBPs) and noncoding RNAs (ncRNAs) on individual mRNAs. Fresh conceptual innovations now highlight stress-activated, evolutionarily conserved RBP networks and ncRNAs that increase the translation efficiency of populations of transcripts encoding proteins that participate in a common cellular process. The discovery of post-transcriptional functions for long noncoding RNAs (lncRNAs) was particularly intriguing given their cell-type-specificity and historical definition as nuclear-functioning epigenetic regulators. The convergence of RBPs, lncRNAs, and microRNAs on functionally related mRNAs to enable adaptive protein synthesis is a newer biological paradigm that highlights their role as "translatome (protein output) remodelers" and reinvigorates the paradigm of "RNA operons." Together, these concepts modernize our understanding of cellular stress adaptation and strategies for therapeutic development. This article is categorized under: RNA Interactions with Proteins and Other Molecules > Protein-RNA Interactions: Functional Implications Translation > Translation Regulation Regulatory RNAs/RNAi/Riboswitches > Regulatory RNAs.
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Affiliation(s)
- J J David Ho
- Sylvester Comprehensive Cancer Center, Miller School of Medicine, University of Miami, Miami, Florida, USA.,Division of Hematology, Department of Medicine, Miller School of Medicine, University of Miami, Miami, Florida, USA
| | - Jeffrey H S Man
- Keenan Research Centre, Li Ka Shing Knowledge Institute, St. Michael's Hospital, Toronto, Ontario, Canada.,Department of Medicine, University of Toronto, Toronto, Ontario, Canada.,Department of Respirology, University Health Network, Latner Thoracic Research Laboratories, University of Toronto, Toronto, Ontario, Canada
| | - Jonathan H Schatz
- Sylvester Comprehensive Cancer Center, Miller School of Medicine, University of Miami, Miami, Florida, USA.,Division of Hematology, Department of Medicine, Miller School of Medicine, University of Miami, Miami, Florida, USA
| | - Philip A Marsden
- Keenan Research Centre, Li Ka Shing Knowledge Institute, St. Michael's Hospital, Toronto, Ontario, Canada.,Department of Medicine, University of Toronto, Toronto, Ontario, Canada
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21
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Lapointe CP, Grosely R, Johnson AG, Wang J, Fernández IS, Puglisi JD. Dynamic competition between SARS-CoV-2 NSP1 and mRNA on the human ribosome inhibits translation initiation. Proc Natl Acad Sci U S A 2021; 118:e2017715118. [PMID: 33479166 PMCID: PMC8017934 DOI: 10.1073/pnas.2017715118] [Citation(s) in RCA: 116] [Impact Index Per Article: 38.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is a beta-CoV that recently emerged as a human pathogen and is the causative agent of the COVID-19 pandemic. A molecular framework of how the virus manipulates host cellular machinery to facilitate infection remains unclear. Here, we focus on SARS-CoV-2 NSP1, which is proposed to be a virulence factor that inhibits protein synthesis by directly binding the human ribosome. We demonstrate biochemically that NSP1 inhibits translation of model human and SARS-CoV-2 messenger RNAs (mRNAs). NSP1 specifically binds to the small (40S) ribosomal subunit, which is required for translation inhibition. Using single-molecule fluorescence assays to monitor NSP1-40S subunit binding in real time, we determine that eukaryotic translation initiation factors (eIFs) allosterically modulate the interaction of NSP1 with ribosomal preinitiation complexes in the absence of mRNA. We further elucidate that NSP1 competes with RNA segments downstream of the start codon to bind the 40S subunit and that the protein is unable to associate rapidly with 80S ribosomes assembled on an mRNA. Collectively, our findings support a model where NSP1 proteins from viruses in at least two subgenera of beta-CoVs associate with the open head conformation of the 40S subunit to inhibit an early step of translation, by preventing accommodation of mRNA within the entry channel.
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Affiliation(s)
- Christopher P Lapointe
- Department of Structural Biology, Stanford University School of Medicine, Stanford, CA 94305
| | - Rosslyn Grosely
- Department of Structural Biology, Stanford University School of Medicine, Stanford, CA 94305
| | - Alex G Johnson
- Department of Structural Biology, Stanford University School of Medicine, Stanford, CA 94305
- Department of Chemical and Systems Biology, Stanford University School of Medicine, Stanford, CA 94305
| | - Jinfan Wang
- Department of Structural Biology, Stanford University School of Medicine, Stanford, CA 94305
| | - Israel S Fernández
- Department of Biochemistry and Molecular Biophysics, Columbia University, New York City, NY 10032
| | - Joseph D Puglisi
- Department of Structural Biology, Stanford University School of Medicine, Stanford, CA 94305;
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22
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Skariah G, Todd PK. Translational control in aging and neurodegeneration. WILEY INTERDISCIPLINARY REVIEWS-RNA 2020; 12:e1628. [PMID: 32954679 DOI: 10.1002/wrna.1628] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/22/2020] [Revised: 08/19/2020] [Accepted: 09/07/2020] [Indexed: 12/13/2022]
Abstract
Protein metabolism plays central roles in age-related decline and neurodegeneration. While a large body of research has explored age-related changes in protein degradation, alterations in the efficiency and fidelity of protein synthesis with aging are less well understood. Age-associated changes occur in both the protein synthetic machinery (ribosomal proteins and rRNA) and within regulatory factors controlling translation. At the same time, many of the interventions that prolong lifespan do so in part by pre-emptively decreasing protein synthesis rates to allow better harmonization to age-related declines in protein catabolism. Here we review the roles of translation regulation in aging, with a specific focus on factors implicated in age-related neurodegeneration. We discuss how emerging technologies such as ribosome profiling and superior mass spectrometric approaches are illuminating age-dependent mRNA-specific changes in translation rates across tissues to reveal a critical interplay between catabolic and anabolic pathways that likely contribute to functional decline. These new findings point to nodes in posttranscriptional gene regulation that both contribute to aging and offer targets for therapy. This article is categorized under: Translation > Translation Regulation Translation > Ribosome Biogenesis Translation > Translation Mechanisms.
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Affiliation(s)
- Geena Skariah
- Department of Neurology, University of Michigan, Ann Arbor, Michigan, USA
| | - Peter K Todd
- Department of Neurology, University of Michigan, Ann Arbor, Michigan, USA
- Ann Arbor VA Healthcare System, Department of Veterans Affairs, Ann Arbor, Michigan, USA
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23
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DENR promotes translation reinitiation via ribosome recycling to drive expression of oncogenes including ATF4. Nat Commun 2020; 11:4676. [PMID: 32938922 PMCID: PMC7494916 DOI: 10.1038/s41467-020-18452-2] [Citation(s) in RCA: 46] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2019] [Accepted: 08/14/2020] [Indexed: 12/19/2022] Open
Abstract
Translation efficiency varies considerably between different mRNAs, thereby impacting protein expression. Translation of the stress response master-regulator ATF4 increases upon stress, but the molecular mechanisms are not well understood. We discover here that translation factors DENR, MCTS1 and eIF2D are required to induce ATF4 translation upon stress by promoting translation reinitiation in the ATF4 5'UTR. We find DENR and MCTS1 are only needed for reinitiation after upstream Open Reading Frames (uORFs) containing certain penultimate codons, perhaps because DENR•MCTS1 are needed to evict only certain tRNAs from post-termination 40S ribosomes. This provides a model for how DENR and MCTS1 promote translation reinitiation. Cancer cells, which are exposed to many stresses, require ATF4 for survival and proliferation. We find a strong correlation between DENR•MCTS1 expression and ATF4 activity across cancers. Furthermore, additional oncogenes including a-Raf, c-Raf and Cdk4 have long uORFs and are translated in a DENR•MCTS1 dependent manner.
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24
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Slobodin B, Dikstein R. So close, no matter how far: multiple paths connecting transcription to mRNA translation in eukaryotes. EMBO Rep 2020; 21:e50799. [PMID: 32803873 PMCID: PMC7507372 DOI: 10.15252/embr.202050799] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2020] [Revised: 06/22/2020] [Accepted: 07/23/2020] [Indexed: 12/15/2022] Open
Abstract
Transcription of DNA into mRNA and translation of mRNA into proteins are two major processes underlying gene expression. Due to the distinct molecular mechanisms, timings, and locales of action, these processes are mainly considered to be independent. During the last two decades, however, multiple factors and elements were shown to coordinate transcription and translation, suggesting an intricate level of synchronization. This review discusses the molecular mechanisms that impact both processes in eukaryotic cells of different origins. The emerging global picture suggests evolutionarily conserved regulation and coordination between transcription and mRNA translation, indicating the importance of this phenomenon for the fine-tuning of gene expression and the adjustment to constantly changing conditions.
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Affiliation(s)
- Boris Slobodin
- Department of Biomolecular SciencesThe Weizmann Institute of ScienceRehovotIsrael
| | - Rivka Dikstein
- Department of Biomolecular SciencesThe Weizmann Institute of ScienceRehovotIsrael
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