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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] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [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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Farookhi H, Xia X. Differential Selection for Translation Efficiency Shapes Translation Machineries in Bacterial Species. Microorganisms 2024; 12:768. [PMID: 38674712 PMCID: PMC11052298 DOI: 10.3390/microorganisms12040768] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2024] [Revised: 04/01/2024] [Accepted: 04/09/2024] [Indexed: 04/28/2024] Open
Abstract
Different bacterial species have dramatically different generation times, from 20-30 min in Escherichia coli to about two weeks in Mycobacterium leprae. The translation machinery in a cell needs to synthesize all proteins for a new cell in each generation. The three subprocesses of translation, i.e., initiation, elongation, and termination, are expected to be under stronger selection pressure to optimize in short-generation bacteria (SGB) such as Vibrio natriegens than in the long-generation Mycobacterium leprae. The initiation efficiency depends on the start codon decoded by the initiation tRNA, the optimal Shine-Dalgarno (SD) decoded by the anti-SD (aSD) sequence on small subunit rRNA, and the secondary structure that may embed the initiation signals and prevent them from being decoded. The elongation efficiency depends on the tRNA pool and codon usage. The termination efficiency in bacteria depends mainly on the nature of the stop codon and the nucleotide immediately downstream of the stop codon. By contrasting SGB with long-generation bacteria (LGB), we predict (1) SGB to have more ribosome RNA operons to produce ribosomes, and more tRNA genes for carrying amino acids to ribosomes, (2) SGB to have a higher percentage of genes using AUG as the start codon and UAA as the stop codon than LGB, (3) SGB to exhibit better codon and anticodon adaptation than LGB, and (4) SGB to have a weaker secondary structure near the translation initiation signals than LGB. These differences between SGB and LGB should be more pronounced in highly expressed genes than the rest of the genes. We present empirical evidence in support of these predictions.
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Affiliation(s)
- Heba Farookhi
- Department of Biology, University of Ottawa, Ottawa, ON K1N 6N5, Canada;
| | - Xuhua Xia
- Department of Biology, University of Ottawa, Ottawa, ON K1N 6N5, Canada;
- Ottawa Institute of Systems Biology, University of Ottawa, Ottawa, ON K1H 8M5, Canada
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3
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Villa N, Fraser CS. Human eukaryotic initiation factor 4G directly binds the 40S ribosomal subunit to promote efficient translation. J Biol Chem 2024; 300:107242. [PMID: 38569933 PMCID: PMC11063902 DOI: 10.1016/j.jbc.2024.107242] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2023] [Revised: 03/15/2024] [Accepted: 03/19/2024] [Indexed: 04/05/2024] Open
Abstract
Messenger RNA (mRNA) recruitment to the 40S ribosomal subunit is mediated by eukaryotic initiation factor 4F (eIF4F). This complex includes three subunits: eIF4E (m7G cap-binding protein), eIF4A (DEAD-box helicase), and eIF4G. Mammalian eIF4G is a scaffold that coordinates the activities of eIF4E and eIF4A and provides a bridge to connect the mRNA and 40S ribosomal subunit through its interaction with eIF3. While the roles of many eIF4G binding domains are relatively clear, the precise function of RNA binding by eIF4G remains to be elucidated. In this work, we used an eIF4G-dependent translation assay to reveal that the RNA binding domain (eIF4G-RBD; amino acids 682-720) stimulates translation. This stimulating activity is observed when eIF4G is independently tethered to an internal region of the mRNA, suggesting that the eIF4G-RBD promotes translation by a mechanism that is independent of the m7G cap and mRNA tethering. Using a kinetic helicase assay, we show that the eIF4G-RBD has a minimal effect on eIF4A helicase activity, demonstrating that the eIF4G-RBD is not required to coordinate eIF4F-dependent duplex unwinding. Unexpectedly, native gel electrophoresis and fluorescence polarization assays reveal a previously unidentified direct interaction between eIF4G and the 40S subunit. Using binding assays, our data show that this 40S subunit interaction is separate from the previously characterized interaction between eIF4G and eIF3. Thus, our work reveals how eIF4F can bind to the 40S subunit using eIF3-dependent and eIF3-independent binding domains to promote translation initiation.
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Affiliation(s)
- Nancy Villa
- Department of Molecular and Cellular Biology, College of Biological Sciences, University of California, Davis, California, USA
| | - Christopher S Fraser
- Department of Molecular and Cellular Biology, College of Biological Sciences, University of California, Davis, California, USA.
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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 Interdiscip Rev RNA 2024; 15:e1833. [PMID: 38433101 DOI: 10.1002/wrna.1833] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 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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Lee PJ, Soares AR, Sun Y, Fai C, Picciotto MR, Guo JU. Alternative translation initiation produces synaptic organizer proteoforms with distinct localization and functions. bioRxiv 2024:2024.02.16.580719. [PMID: 38405936 PMCID: PMC10888845 DOI: 10.1101/2024.02.16.580719] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/27/2024]
Abstract
While previous studies suggest that many mRNAs contain more than one translation initiation site (TIS), the biological significance of most alternative TISs and their corresponding protein isoforms (proteoforms) remains undetermined. Here we show that alternative translation initiation at a CUG and an AUG TIS in neuronal pentraxin receptor (NPR) mRNA produces two proteoforms, and their relative abundance is regulated by both neuronal activity as well as an adjacent RNA secondary structure. Downstream AUG initiation transforms the N-terminal transmembrane domain into a signal peptide, thereby converting NPR to a secreted factor sufficient to promote synaptic clustering of AMPA-type glutamate receptors. Changing the relative proteoform ratio, but not the overall NPR abundance reduces AMPA receptor in parvalbumin (PV)-positive interneurons and induces changes in learning behaviors in mice. In addition to NPR, N-terminal extensions of C1q-like synaptic organizers, mediated by upstream AUU start codons, anchor these otherwise secreted factors to the membrane. Thus, our results uncovered the plasticity of N-terminal signal sequences regulated by alternative TIS usage as a widespread mechanism to diversify protein localization and functions.
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Affiliation(s)
- Paul Jongseo Lee
- Department of Neuroscience, Yale University School of Medicine, New Haven, CT 06520, USA
- Interdepartmental Neuroscience Program, Yale University, New Haven, CT 06520, USA
| | - Alexa R. Soares
- Department of Psychiatry, Yale University School of Medicine, New Haven, CT 06508, USA
- Interdepartmental Neuroscience Program, Yale University, New Haven, CT 06520, USA
| | - Yu Sun
- Department of Neuroscience, Yale University School of Medicine, New Haven, CT 06520, USA
| | - Caroline Fai
- Department of Psychiatry, Yale University School of Medicine, New Haven, CT 06508, USA
| | - Marina R. Picciotto
- Department of Psychiatry, Yale University School of Medicine, New Haven, CT 06508, USA
- Interdepartmental Neuroscience Program, Yale University, New Haven, CT 06520, USA
| | - Junjie U. Guo
- Department of Neuroscience, Yale University School of Medicine, New Haven, CT 06520, USA
- Interdepartmental Neuroscience Program, Yale University, New Haven, CT 06520, USA
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6
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Rudar M, Suryawan A, Nguyen HV, Chacko SK, Vonderohe C, Stoll B, Burrin DG, Fiorotto ML, Davis TA. Pulsatile Leucine Administration during Continuous Enteral Feeding Enhances Skeletal Muscle Mechanistic Target of Rapamycin Complex 1 Signaling and Protein Synthesis in a Preterm Piglet Model. J Nutr 2024; 154:505-515. [PMID: 38141773 PMCID: PMC10900192 DOI: 10.1016/j.tjnut.2023.12.034] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2023] [Revised: 12/18/2023] [Accepted: 12/19/2023] [Indexed: 12/25/2023] Open
Abstract
BACKGROUND Continuous feeding does not elicit an optimal anabolic response in skeletal muscle but is required for some preterm infants. We reported previously that intermittent intravenous pulses of leucine (Leu; 800 μmol Leu·kg-1·h-1 every 4 h) to continuously fed pigs born at term promoted mechanistic target of rapamycin complex 1 (mTORC1) activation and protein synthesis in skeletal muscle. OBJECTIVES The aim was to determine the extent to which intravenous Leu pulses activate mTORC1 and enhance protein synthesis in the skeletal muscle of continuously fed pigs born preterm. METHODS Pigs delivered 10 d preterm was advanced to full oral feeding >4 d and then assigned to 1 of the following 4 treatments for 28 h: 1) ALA (continuous feeding; pulsed with 800 μmol alanine·kg-1·h-1 every 4 h; n = 8); 2) L1× (continuous feeding; pulsed with 800 μmol Leu·kg-1·h-1 every 4 h; n = 7); 3) L2× (continuous feeding; pulsed with 1600 μmol Leu·kg-1·h-1 every 4 h; n = 8); and 4) INT (intermittent feeding every 4 h; supplied with 800 μmol alanine·kg-1 per feeding; n = 7). Muscle protein synthesis rates were determined with L-[2H5-ring]Phenylalanine. The activation of insulin, amino acid, and translation initiation signaling pathways were assessed by Western blot. RESULTS Peak plasma Leu concentrations were 134% and 420% greater in the L2× compared to the L1× and ALA groups, respectively (P < 0.01). Protein synthesis was greater in the L2× than in the ALA and L1× groups in both the longissimus dorsi and gastrocnemius muscles (P < 0.05) but not different from the INT group (P > 0.10). Amino acid signaling upstream and translation initiation signaling downstream of mTORC1 largely corresponded to the differences in protein synthesis. CONCLUSIONS Intravenous Leu pulses potentiate mTORC1 activity and protein synthesis in the skeletal muscles of continuously fed preterm pigs, but the amount required is greater than in pigs born at term.
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Affiliation(s)
- Marko Rudar
- Department of Animal Sciences, Auburn University, Auburn, AL, United States
| | - Agus Suryawan
- Department of Pediatrics, USDA/Agricultural Research Service, Children's Nutrition Research Center, Baylor College of Medicine, Houston, Texas, United States
| | - Hanh V Nguyen
- Department of Pediatrics, USDA/Agricultural Research Service, Children's Nutrition Research Center, Baylor College of Medicine, Houston, Texas, United States
| | - Shaji K Chacko
- Department of Pediatrics, USDA/Agricultural Research Service, Children's Nutrition Research Center, Baylor College of Medicine, Houston, Texas, United States
| | - Caitlin Vonderohe
- Department of Pediatrics, USDA/Agricultural Research Service, Children's Nutrition Research Center, Baylor College of Medicine, Houston, Texas, United States
| | - Barbara Stoll
- Department of Pediatrics, USDA/Agricultural Research Service, Children's Nutrition Research Center, Baylor College of Medicine, Houston, Texas, United States
| | - Douglas G Burrin
- Department of Pediatrics, USDA/Agricultural Research Service, Children's Nutrition Research Center, Baylor College of Medicine, Houston, Texas, United States
| | - Marta L Fiorotto
- Department of Pediatrics, USDA/Agricultural Research Service, Children's Nutrition Research Center, Baylor College of Medicine, Houston, Texas, United States
| | - Teresa A Davis
- Department of Pediatrics, USDA/Agricultural Research Service, Children's Nutrition Research Center, Baylor College of Medicine, Houston, Texas, United States.
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7
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Ventoso I, Berlanga JJ, Toribio R, Díaz-López I. Translational Control of Alphavirus-Host Interactions: Implications in Viral Evolution, Tropism and Antiviral Response. Viruses 2024; 16:205. [PMID: 38399981 PMCID: PMC10893052 DOI: 10.3390/v16020205] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2023] [Revised: 01/19/2024] [Accepted: 01/24/2024] [Indexed: 02/25/2024] Open
Abstract
Alphaviruses can replicate in arthropods and in many vertebrate species including humankind, but only in vertebrate cells do infections with these viruses result in a strong inhibition of host translation and transcription. Translation shutoff by alphaviruses is a multifactorial process that involves both host- and virus-induced mechanisms, and some of them are not completely understood. Alphavirus genomes contain cis-acting elements (RNA structures and dinucleotide composition) and encode protein activities that promote the translational and transcriptional resistance to type I IFN-induced antiviral effectors. Among them, IFIT1, ZAP and PKR have played a relevant role in alphavirus evolution, since they have promoted the emergence of multiple viral evasion mechanisms at the translational level. In this review, we will discuss how the adaptations of alphaviruses to vertebrate hosts likely involved the acquisition of new features in viral mRNAs and proteins to overcome the effect of type I IFN.
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Affiliation(s)
- Iván Ventoso
- Centro de Biología Molecular “Severo Ochoa” (CSIC-UAM) and Departamento de Biología Molecular, Universidad Autónoma de Madrid (UAM), 28049 Madrid, Spain;
| | - Juan José Berlanga
- Centro de Biología Molecular “Severo Ochoa” (CSIC-UAM) and Departamento de Biología Molecular, Universidad Autónoma de Madrid (UAM), 28049 Madrid, Spain;
| | - René Toribio
- Centro de Biotecnología y Genómica de Plantas, Universidad Politécnica de Madrid-Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria (UPM-INIA), 28049 Madrid, Spain;
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8
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dos Santos JV, Medina JM, Dias Teixeira KL, Agostinho DMJ, Chorev M, Diotallevi A, Galluzzi L, Aktas BH, Gazos Lopes U. Activity of the Di-Substituted Urea-Derived Compound I-17 in Leishmania In Vitro Infections. Pathogens 2024; 13:104. [PMID: 38392842 PMCID: PMC10893125 DOI: 10.3390/pathogens13020104] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2023] [Revised: 01/15/2024] [Accepted: 01/19/2024] [Indexed: 02/25/2024] Open
Abstract
Protein synthesis has been a very rich target for developing drugs to control prokaryotic and eukaryotic pathogens. Despite the development of new drug formulations, treating human cutaneous and visceral Leishmaniasis still needs significant improvements due to the considerable side effects and low adherence associated with the current treatment regimen. In this work, we show that the di-substituted urea-derived compounds I-17 and 3m are effective in inhibiting the promastigote growth of different Leishmania species and reducing the macrophage intracellular load of amastigotes of the Leishmania (L.) amazonensis and L. major species, in addition to exhibiting low macrophage cytotoxicity. We also show a potential immunomodulatory effect of I-17 and 3m in infected macrophages, which exhibited increased expression of inducible Nitric Oxide Synthase (NOS2) and production of Nitric Oxide (NO). Our data indicate that I-17, 3m, and their analogs may be helpful in developing new drugs for treating leishmaniasis.
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Affiliation(s)
- José Vitorino dos Santos
- Laboratory of Molecular Parasitology, Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro (UFRJ), Rio de Janeiro 21941-902, Brazil; (J.V.d.S.); (J.M.M.); (D.M.J.A.)
| | - Jorge Mansur Medina
- Laboratory of Molecular Parasitology, Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro (UFRJ), Rio de Janeiro 21941-902, Brazil; (J.V.d.S.); (J.M.M.); (D.M.J.A.)
| | | | - Daniel Marcos Julio Agostinho
- Laboratory of Molecular Parasitology, Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro (UFRJ), Rio de Janeiro 21941-902, Brazil; (J.V.d.S.); (J.M.M.); (D.M.J.A.)
| | - Michael Chorev
- Division of Hematology, Brigham and Women’s Hospital, Harvard Medical School, Boston, MA 02115, USA;
| | - Aurora Diotallevi
- Department of Biomolecular Sciences, University of Urbino Carlo Bo, 61029 Urbino, Italy; (A.D.)
| | - Luca Galluzzi
- Department of Biomolecular Sciences, University of Urbino Carlo Bo, 61029 Urbino, Italy; (A.D.)
| | - Bertal Huseyin Aktas
- Division of Hematology, Brigham and Women’s Hospital, Harvard Medical School, Boston, MA 02115, USA;
| | - Ulisses Gazos Lopes
- Laboratory of Molecular Parasitology, Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro (UFRJ), Rio de Janeiro 21941-902, Brazil; (J.V.d.S.); (J.M.M.); (D.M.J.A.)
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9
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Fusco F, Pires MC, Lopes APY, Alves VDS, Gonçalves VM. Influence of the mRNA initial region on protein production: a case study using recombinant detoxified pneumolysin as a model. Front Bioeng Biotechnol 2024; 11:1304965. [PMID: 38260740 PMCID: PMC10800503 DOI: 10.3389/fbioe.2023.1304965] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2023] [Accepted: 12/12/2023] [Indexed: 01/24/2024] Open
Abstract
Recombinant proteins are of great importance in modern society, mostly as biopharmaceutical products. However, challenging and complex processes with low production yield are major drawbacks. Normally, the optimization to overcome these obstacles is focused on bioreactor and purification processes, and the biomolecular aspects are neglected, seen as less important. In this work, we present how the 5' mRNA secondary structure region can be relevant for translation and, therefore, protein production. For this, Escherichia coli BL21(DE3) clones, producing recombinant detoxified pneumolysin (PdT) with and without the N-terminal His-tag, were cultivated in 10-L bioreactors. Another version of the pdt gene (version 2) with synonymous changes in the 5'-end nucleotide sequence was also obtained. Protein production, plasmid stability, carbon sources, and acetic acid were quantified during the cultures. Furthermore, in silico mRNA analyses were performed using TIsigner and RNAfold. The results showed that the His-tag presence at the N-terminus generated a minimum 1.5-fold increase in target protein synthesis, which was explained by the in silico mRNA analyses that returned an mRNA secondary structure easier to translate and, therefore, higher protein production than without the His-tag. The pdt gene version 2 showed lower 5' mRNA opening energy than version 1, allowing higher PdT production even without a tag. This work reveals that simple mRNA analyses during heterologous gene design and production steps can help reach high-recombinant protein titers in a shorter time than using only traditional bioprocess optimization strategies.
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Affiliation(s)
- Filipe Fusco
- Laboratory of Vaccine Development, Butantan Institute, Sao Paulo, Brazil
- Interunits Graduate Program in Biotechnology, University of Sao Paulo, Sao Paulo, Brazil
| | - Manuella Cazelato Pires
- Laboratory of Vaccine Development, Butantan Institute, Sao Paulo, Brazil
- Interunits Graduate Program in Biotechnology, University of Sao Paulo, Sao Paulo, Brazil
| | | | - Vítor dos Santos Alves
- Laboratory of Vaccine Development, Butantan Institute, Sao Paulo, Brazil
- Interunits Graduate Program in Biotechnology, University of Sao Paulo, Sao Paulo, Brazil
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10
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Baron N, Purushotham R, Pullaiahgari D, Bose P, Zarivach R, Shapira M. LeishIF4E2 is a cap-binding protein that plays a role in Leishmania cell cycle progression. FASEB J 2024; 38:e23367. [PMID: 38095329 DOI: 10.1096/fj.202301665r] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2023] [Revised: 11/14/2023] [Accepted: 11/27/2023] [Indexed: 12/18/2023]
Abstract
Leishmania encode six paralogs of the cap-binding protein eIF4E and five eIF4G candidates, forming unique complexes. Two cap-binding proteins, LeishIF4E1 and LeishIF4E2, do not bind any identified LeishIF4Gs, thus their roles are intriguing. Here, we combine structural prediction, proteomic analysis, and interaction assays to shed light on LeishIF4E2 function. A nonconserved C-terminal extension was identified through structure prediction and sequence alignment. m7 GTP-binding assays involving both recombinant and transgenic LeishIF4E2 with and without the C-terminal extension revealed that this extension functions as a regulatory gate, modulating the cap-binding activity of LeishIF4E2. The interactomes of the two LeishIF4E2 versions were investigated, highlighting the role of the C-terminal extension in binding to SLBP2. SLBP2 is known to interact with a stem-loop structure in the 3' UTRs of histone mRNAs. Consistent with the predicted inhibitory effect of SLBP2 on histone expression in Xenopus laevis, a hemizygous deletion mutant of LeishIF4E2, exhibited an upregulation of several histones. We therefore propose that LeishIF4E2 is involved in histone expression, possibly through its interaction between SLBP2 and LeishIF4E2, thus affecting cell cycle progression. In addition, cell synchronization showed that LeishIF4E2 expression decreased during the S-phase, when histones are known to be synthesized. Previous studies in T. brucei also highlighted an association between TbEIF4E2 and SLBP2, and further reported on an interaction between TbIF4E2 and S-phase-abundant mRNAs. Our results show that overexpression of LeishIF4E2 correlates with upregulation of cell cycle and chromosome maintenance proteins. Along with its effect on histone expression, we propose that LeishIF4E2 is involved in cell cycle progression.
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Affiliation(s)
- Nofar Baron
- Department of Life Sciences, Ben-Gurion University of the Negev, Beer Sheva, Israel
| | - Rajaram Purushotham
- Department of Life Sciences, Ben-Gurion University of the Negev, Beer Sheva, Israel
| | | | - Priyanka Bose
- Department of Life Sciences, Ben-Gurion University of the Negev, Beer Sheva, Israel
| | - Raz Zarivach
- Department of Life Sciences, Ben-Gurion University of the Negev, Beer Sheva, Israel
| | - Michal Shapira
- Department of Life Sciences, Ben-Gurion University of the Negev, Beer Sheva, Israel
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11
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Barrington CL, Galindo G, Koch AL, Horton ER, Morrison EJ, Tisa S, Stasevich TJ, Rissland OS. Synonymous codon usage regulates translation initiation. Cell Rep 2023; 42:113413. [PMID: 38096059 PMCID: PMC10790568 DOI: 10.1016/j.celrep.2023.113413] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2023] [Revised: 08/30/2023] [Accepted: 10/25/2023] [Indexed: 12/30/2023] Open
Abstract
Nonoptimal synonymous codons repress gene expression, but the underlying mechanisms are poorly understood. We and others have previously shown that nonoptimal codons slow translation elongation speeds and thereby trigger messenger RNA (mRNA) degradation. Nevertheless, transcript levels are often insufficient to explain protein levels, suggesting additional mechanisms by which codon usage regulates gene expression. Using reporters in human and Drosophila cells, we find that transcript levels account for less than half of the variation in protein abundance due to codon usage. This discrepancy is explained by translational differences whereby nonoptimal codons repress translation initiation. Nonoptimal transcripts are also less bound by the translation initiation factors eIF4E and eIF4G1, providing a mechanistic explanation for their reduced initiation rates. Importantly, translational repression can occur without mRNA decay and deadenylation, and it does not depend on the known nonoptimality sensor, CNOT3. Our results reveal a potent mechanism of regulation by codon usage where nonoptimal codons repress further rounds of translation.
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Affiliation(s)
- Chloe L Barrington
- Department of Biochemistry & Molecular Genetics, University of Colorado School of Medicine, Aurora, CO 80045, USA; RNA Bioscience Initiative, University of Colorado School of Medicine, Aurora, CO 80045, USA
| | - Gabriel Galindo
- Department of Biochemistry & Molecular Biology, Colorado State University, Fort Collins, CO 80523, USA
| | - Amanda L Koch
- Department of Biochemistry & Molecular Biology, Colorado State University, Fort Collins, CO 80523, USA
| | - Emma R Horton
- Department of Biochemistry & Molecular Genetics, University of Colorado School of Medicine, Aurora, CO 80045, USA; RNA Bioscience Initiative, University of Colorado School of Medicine, Aurora, CO 80045, USA
| | - Evan J Morrison
- Department of Biochemistry & Molecular Genetics, University of Colorado School of Medicine, Aurora, CO 80045, USA; RNA Bioscience Initiative, University of Colorado School of Medicine, Aurora, CO 80045, USA
| | - Samantha Tisa
- Department of Biochemistry & Molecular Genetics, University of Colorado School of Medicine, Aurora, CO 80045, USA; RNA Bioscience Initiative, University of Colorado School of Medicine, Aurora, CO 80045, USA
| | - Timothy J Stasevich
- Department of Biochemistry & Molecular Biology, Colorado State University, Fort Collins, CO 80523, USA
| | - Olivia S Rissland
- Department of Biochemistry & Molecular Genetics, University of Colorado School of Medicine, Aurora, CO 80045, USA; RNA Bioscience Initiative, University of Colorado School of Medicine, Aurora, CO 80045, USA.
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12
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Hernández G, Vazquez-Pianzola P. eIF4E as a molecular wildcard in metazoans RNA metabolism. Biol Rev Camb Philos Soc 2023; 98:2284-2306. [PMID: 37553111 DOI: 10.1111/brv.13005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2023] [Revised: 07/01/2023] [Accepted: 07/25/2023] [Indexed: 08/10/2023]
Abstract
The evolutionary origin of eukaryotes spurred the transition from prokaryotic-like translation to a more sophisticated, eukaryotic translation. During this process, successive gene duplication of a single, primordial eIF4E gene encoding the mRNA cap-binding protein eukaryotic translation initiation factor 4E (eIF4E) gave rise to a plethora of paralog genes across eukaryotes that underwent further functional diversification in RNA metabolism. The ability to take different roles is due to eIF4E promiscuity in binding many partner proteins, rendering eIF4E a highly versatile and multifunctional player that functions as a molecular wildcard. Thus, in metazoans, eIF4E paralogs are involved in various processes, including messenger RNA (mRNA) processing, export, translation, storage, and decay. Moreover, some paralogs display differential expression in tissues and developmental stages and show variable biochemical properties. In this review, we discuss recent advances shedding light on the functional diversification of eIF4E in metazoans. We emphasise humans and two phylogenetically distant species which have become paradigms for studies on development, namely the fruit fly Drosophila melanogaster and the roundworm Caenorhabditis elegans.
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Affiliation(s)
- Greco Hernández
- mRNA and Cancer Laboratory, Unit of Biomedical Research on Cancer, National Institute of Cancer (Instituto Nacional de Cancerología, INCan), 22 San Fernando Ave., Tlalpan, Mexico City, 14080, Mexico
| | - Paula Vazquez-Pianzola
- Institute of Cell Biology, University of Bern, Baltzerstrasse 4, Berne, 3012, Switzerland
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13
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Sherwood DR, Kenny-Ganzert IW, Balachandar Thendral S. Translational regulation of cell invasion through extracellular matrix-an emerging role for ribosomes. F1000Res 2023; 12:1528. [PMID: 38628976 PMCID: PMC11019292 DOI: 10.12688/f1000research.143519.1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 11/22/2023] [Indexed: 04/19/2024] Open
Abstract
Many developmental and physiological processes require cells to invade and migrate through extracellular matrix barriers. This specialized cellular behavior is also misregulated in many diseases, such as immune disorders and cancer. Cell invasive activity is driven by pro-invasive transcriptional networks that activate the expression of genes encoding numerous different proteins that expand and regulate the cytoskeleton, endomembrane system, cell adhesion, signaling pathways, and metabolic networks. While detailed mechanistic studies have uncovered crucial insights into pro-invasive transcriptional networks and the distinct cell biological attributes of invasive cells, less is known about how invasive cells modulate mRNA translation to meet the robust, dynamic, and unique protein production needs of cell invasion. In this review we outline known modes of translation regulation promoting cell invasion and focus on recent studies revealing elegant mechanisms that expand ribosome biogenesis within invasive cells to meet the increased protein production requirements to invade and migrate through extracellular matrix barriers.
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14
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González-Sánchez AM, Castellanos-Silva EA, Díaz-Figueroa G, Cate JHD. JUN mRNA Translation Regulation is Mediated by Multiple 5' UTR and Start Codon Features. bioRxiv 2023:2023.11.17.567602. [PMID: 38014201 PMCID: PMC10680820 DOI: 10.1101/2023.11.17.567602] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/29/2023]
Abstract
Regulation of mRNA translation by eukaryotic initiation factors (eIFs) is crucial for cell survival. In humans, eIF3 stimulates translation of the JUN mRNA which encodes the transcription factor JUN, an oncogenic transcription factor involved in cell cycle progression, apoptosis, and cell proliferation. Previous studies revealed that eIF3 activates translation of the JUN mRNA by interacting with a stem loop in the 5' untranslated region (5' UTR) and with the 5'-7-methylguanosine cap structure. In addition to its interaction site with eIF3, the JUN 5' UTR is nearly one kilobase in length, and has a high degree of secondary structure, high GC content, and an upstream start codon (uAUG). This motivated us to explore the complexity of JUN mRNA translation regulation in human cells. Here we find that JUN translation is regulated in a sequence and structure-dependent manner in regions adjacent to the eIF3-interacting site in the JUN 5' UTR. Furthermore, we identify contributions of an additional initiation factor, eIF4A, in JUN regulation. We show that enhancing the interaction of eIF4A with JUN by using the compound Rocaglamide A (RocA) represses JUN translation. We also find that both the upstream AUG (uAUG) and the main AUG (mAUG) contribute to JUN translation and that they are conserved throughout vertebrates. Our results reveal additional layers of regulation for JUN translation and show the potential of JUN as a model transcript for understanding multiple interacting modes of translation regulation.
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Affiliation(s)
| | - Eimy A Castellanos-Silva
- University of California, Davis, Department of Biochemistry and Molecular Biology, Davis, CA, USA
| | - Gabriela Díaz-Figueroa
- University of California, Berkeley, Department of Molecular and Cell Biology, Berkeley, CA, USA
| | - Jamie H D Cate
- University of California, Berkeley, Department of Molecular and Cell Biology, Berkeley, CA, USA
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15
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Pugsley L, Naineni SK, Amiri M, Yanagiya A, Cencic R, Sonenberg N, Pelletier J. C8ORF88: A Novel eIF4E-Binding Protein. Genes (Basel) 2023; 14:2076. [PMID: 38003019 PMCID: PMC10670996 DOI: 10.3390/genes14112076] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2023] [Revised: 11/03/2023] [Accepted: 11/09/2023] [Indexed: 11/26/2023] Open
Abstract
Translation initiation in eukaryotes is regulated at several steps, one of which involves the availability of the cap binding protein to participate in cap-dependent protein synthesis. Binding of eIF4E to translational repressors (eIF4E-binding proteins [4E-BPs]) suppresses translation and is used by cells to link extra- and intracellular cues to protein synthetic rates. The best studied of these interactions involves repression of translation by 4E-BP1 upon inhibition of the PI3K/mTOR signaling pathway. Herein, we characterize a novel 4E-BP, C8ORF88, whose expression is predominantly restricted to early spermatids. C8ORF88:eIF4E interaction is dependent on the canonical eIF4E binding motif (4E-BM) present in other 4E-BPs. Whereas 4E-BP1:eIF4E interaction is dependent on the phosphorylation of 4E-BP1, these sites are not conserved in C8ORF88 indicating a different mode of regulation.
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Affiliation(s)
- Lauren Pugsley
- Department of Biochemistry, McGill University, Montreal, QC H3G 1Y6, Canada; (L.P.); (S.K.N.); (M.A.); (N.S.)
| | - Sai Kiran Naineni
- Department of Biochemistry, McGill University, Montreal, QC H3G 1Y6, Canada; (L.P.); (S.K.N.); (M.A.); (N.S.)
| | - Mehdi Amiri
- Department of Biochemistry, McGill University, Montreal, QC H3G 1Y6, Canada; (L.P.); (S.K.N.); (M.A.); (N.S.)
| | | | - Regina Cencic
- Department of Biochemistry, McGill University, Montreal, QC H3G 1Y6, Canada; (L.P.); (S.K.N.); (M.A.); (N.S.)
| | - Nahum Sonenberg
- Department of Biochemistry, McGill University, Montreal, QC H3G 1Y6, Canada; (L.P.); (S.K.N.); (M.A.); (N.S.)
- Rosalind and Morris Goodman Cancer Institute, McGill University, Montreal, QC H3A 1A3, Canada
| | - Jerry Pelletier
- Department of Biochemistry, McGill University, Montreal, QC H3G 1Y6, Canada; (L.P.); (S.K.N.); (M.A.); (N.S.)
- Rosalind and Morris Goodman Cancer Institute, McGill University, Montreal, QC H3A 1A3, Canada
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16
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Cyran AM, Kleinegger F, Nass N, Naumann M, Haybaeck J, Arens C. Inhibition of EIF2α Dephosphorylation Decreases Cell Viability and Synergizes with Standard-of-Care Chemotherapeutics in Head and Neck Squamous Cell Carcinoma. Cancers (Basel) 2023; 15:5350. [PMID: 38001610 PMCID: PMC10670742 DOI: 10.3390/cancers15225350] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2023] [Revised: 10/27/2023] [Accepted: 11/01/2023] [Indexed: 11/26/2023] Open
Abstract
Drug resistance is a common cause of therapy failure in head and neck squamous cell carcinoma (HNSCC). One approach to tackling it is by targeting fundamental cellular processes, such as translation. The eukaryotic translation initiation factor 2α (EIF2α) is a key player in canonical translation initiation and integrates diverse stress signals; when phosphorylated, it curbs global protein synthesis. This study evaluates EIF2α expression and phosphorylation in HNSCC. A small-molecule inhibitor of EIF2α dephosphorylation, salubrinal, was tested in vitro, followed by viability assays, flow cytometry, and immunoblot analyses. Patient-derived 3D tumor spheres (PD3DS) were cultured with salubrinal and their viability assessed. Lastly, salubrinal was evaluated with standard-of-care chemotherapeutics. Our analysis of RNA and proteomics data shows elevated EIF2α expression in HNSCC. Immunohistochemical staining reveals increasing EIF2α abundance from premalignant lesions to invasive and metastatic carcinoma. In immunoblots from intraoperative samples, EIF2α expression and steady-state phosphorylation are higher in HNSCC than in neighboring normal tissue. Inhibition of EIF2α dephosphorylation decreases HNSCC cell viability and clonogenic survival and impairs the G1/S transition. Salubrinal also decreases the viability of PD3DS and acts synergistically with cisplatin, 5-fluorouracil, bleomycin, and proteasome inhibitors. Our results indicate that pharmacological inhibition of EIF2α dephosphorylation is a potential therapeutic strategy for HNSCC.
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Affiliation(s)
- Anna M. Cyran
- Legorreta Cancer Center, Department of Pathology and Laboratory Medicine, Brown University, Providence, RI 02906, USA
- Department of Otorhinolaryngology, Head and Neck Surgery, Otto-von-Guericke University, 39120 Magdeburg, Germany
| | - Florian Kleinegger
- Diagnostic & Research Center for Molecular Biomedicine, Institute of Pathology, Medical University of Graz, 8010 Graz, Austria (J.H.)
| | - Norbert Nass
- Institute of Pathology, University Hospital Brandenburg, Brandenburg Medical School Theodor Fontane, 14770 Brandenburg an der Havel, Germany;
| | - Michael Naumann
- Institute of Experimental Internal Medicine, Otto von Guericke University, 39120 Magdeburg, Germany;
| | - Johannes Haybaeck
- Diagnostic & Research Center for Molecular Biomedicine, Institute of Pathology, Medical University of Graz, 8010 Graz, Austria (J.H.)
| | - Christoph Arens
- Department of Otorhinolaryngology, Head and Neck Surgery, Giessen and Marburg University Hospitals, Campus Giessen, 35392 Giessen, Germany;
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17
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Kamada Y, Ando R, Izawa S, Matsuura A. Yeast Tor complex 1 phosphorylates eIF4E-binding protein, Caf20. Genes Cells 2023; 28:789-799. [PMID: 37700444 DOI: 10.1111/gtc.13067] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2023] [Revised: 08/24/2023] [Accepted: 08/29/2023] [Indexed: 09/14/2023]
Abstract
Tor complex 1 (TORC1), a master regulator of cell growth, is an evolutionarily conserved protein kinase within eukaryotic organisms. To control cell growth, TORC1 governs translational processes by phosphorylating its substrate proteins in response to cellular nutritional cues. Mammalian TORC1 (mTORC1) assumes the responsibility of phosphorylating the eukaryotic translation initiation factor 4E (eIF4E)-binding protein 1 (4E-BP1) to regulate its interaction with eIF4E. The budding yeast Saccharomyces cerevisiae possesses a pair of 4E-BP genes, CAF20 and EAP1. However, the extent to which the TORC1-4E-BP axis regulates translational initiation in yeast remains uncertain. In this study, we demonstrated the influence of TORC1 on the phosphorylation status of Caf20 in vivo, as well as the direct phosphorylation of Caf20 by TORC1 in vitro. Furthermore, we found the TORC1-dependent recruitment of Caf20 to the 80S ribosome. Consequently, our study proposes a plausible involvement of yeast's 4E-BP in the efficacy of translation initiation, an aspect under the control of TORC1.
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Affiliation(s)
- Yoshiaki Kamada
- National Institute for Basic Biology, Okazaki, Japan
- Graduate University for Advanced Studies (SOKENDAI), Hayama, Kanagawa, Japan
| | - Ryoko Ando
- Department of Applied Biology, Graduate School of Science and Technology, Kyoto Institute of Technology, Kyoto, Japan
| | - Shingo Izawa
- Department of Applied Biology, Graduate School of Science and Technology, Kyoto Institute of Technology, Kyoto, Japan
| | - Akira Matsuura
- Department of Biology, Graduate School of Science, Chiba University, Chiba, Japan
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18
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Jiang J, Zhang L, Zou J, Liu J, Yang J, Jiang Q, Duan P, Jiang B. Phosphorylated S6K1 and 4E-BP1 play different roles in constitutively active Rheb-mediated retinal ganglion cell survival and axon regeneration after optic nerve injury. Neural Regen Res 2023; 18:2526-2534. [PMID: 37282486 PMCID: PMC10360084 DOI: 10.4103/1673-5374.371372] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/08/2023] Open
Abstract
Ras homolog enriched in brain (Rheb) is a small GTPase that activates mammalian target of rapamycin complex 1 (mTORC1). Previous studies have shown that constitutively active Rheb can enhance the regeneration of sensory axons after spinal cord injury by activating downstream effectors of mTOR. S6K1 and 4E-BP1 are important downstream effectors of mTORC1. In this study, we investigated the role of Rheb/mTOR and its downstream effectors S6K1 and 4E-BP1 in the protection of retinal ganglion cells. We transfected an optic nerve crush mouse model with adeno-associated viral 2-mediated constitutively active Rheb and observed the effects on retinal ganglion cell survival and axon regeneration. We found that overexpression of constitutively active Rheb promoted survival of retinal ganglion cells in the acute (14 days) and chronic (21 and 42 days) stages of injury. We also found that either co-expression of the dominant-negative S6K1 mutant or the constitutively active 4E-BP1 mutant together with constitutively active Rheb markedly inhibited axon regeneration of retinal ganglion cells. This suggests that mTORC1-mediated S6K1 activation and 4E-BP1 inhibition were necessary components for constitutively active Rheb-induced axon regeneration. However, only S6K1 activation, but not 4E-BP1 knockdown, induced axon regeneration when applied alone. Furthermore, S6K1 activation promoted the survival of retinal ganglion cells at 14 days post-injury, whereas 4E-BP1 knockdown unexpectedly slightly decreased the survival of retinal ganglion cells at 14 days post-injury. Overexpression of constitutively active 4E-BP1 increased the survival of retinal ganglion cells at 14 days post-injury. Likewise, co-expressing constitutively active Rheb and constitutively active 4E-BP1 markedly increased the survival of retinal ganglion cells compared with overexpression of constitutively active Rheb alone at 14 days post-injury. These findings indicate that functional 4E-BP1 and S6K1 are neuroprotective and that 4E-BP1 may exert protective effects through a pathway at least partially independent of Rheb/mTOR. Together, our results show that constitutively active Rheb promotes the survival of retinal ganglion cells and axon regeneration through modulating S6K1 and 4E-BP1 activity. Phosphorylated S6K1 and 4E-BP1 promote axon regeneration but play an antagonistic role in the survival of retinal ganglion cells.
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Affiliation(s)
- Jikuan Jiang
- Department of Ophthalmology, Second Xiangya Hospital, Central South University; Hunan Clinical Research Center of Ophthalmic Disease, Changsha, Hunan Province, China
| | - Lusi Zhang
- Department of Ophthalmology, Second Xiangya Hospital, Central South University; Hunan Clinical Research Center of Ophthalmic Disease, Changsha, Hunan Province, China
| | - Jingling Zou
- Department of Ophthalmology, Second Xiangya Hospital, Central South University; Hunan Clinical Research Center of Ophthalmic Disease, Changsha, Hunan Province, China
| | - Jingyuan Liu
- Department of Ophthalmology, Second Xiangya Hospital, Central South University; Hunan Clinical Research Center of Ophthalmic Disease, Changsha, Hunan Province, China
| | - Jia Yang
- Department of Ophthalmology, Second Xiangya Hospital, Central South University; Hunan Clinical Research Center of Ophthalmic Disease, Changsha, Hunan Province, China
| | - Qian Jiang
- Department of Ophthalmology, Second Xiangya Hospital, Central South University; Hunan Clinical Research Center of Ophthalmic Disease, Changsha, Hunan Province, China
| | - Peiyun Duan
- Department of Ophthalmology, Second Xiangya Hospital, Central South University; Hunan Clinical Research Center of Ophthalmic Disease, Changsha, Hunan Province, China
| | - Bing Jiang
- Department of Ophthalmology, Second Xiangya Hospital, Central South University; Hunan Clinical Research Center of Ophthalmic Disease, Changsha, Hunan Province, China
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19
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Ruggiero V, Fagioli C, de Pretis S, Di Carlo V, Landsberger N, Zacchetti D. Complex CDKL5 translational regulation and its potential role in CDKL5 deficiency disorder. Front Cell Neurosci 2023; 17:1231493. [PMID: 37964795 PMCID: PMC10642286 DOI: 10.3389/fncel.2023.1231493] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2023] [Accepted: 10/10/2023] [Indexed: 11/16/2023] Open
Abstract
CDKL5 is a kinase with relevant functions in correct neuronal development and in the shaping of synapses. A decrease in its expression or activity leads to a severe neurodevelopmental condition known as CDKL5 deficiency disorder (CDD). CDD arises from CDKL5 mutations that lie in the coding region of the gene. However, the identification of a SNP in the CDKL5 5'UTR in a patient with symptoms consistent with CDD, together with the complexity of the CDKL5 transcript leader, points toward a relevant translational regulation of CDKL5 expression with important consequences in physiological processes as well as in the pathogenesis of CDD. We performed a bioinformatics and molecular analysis of the 5'UTR of CDKL5 to identify translational regulatory features. We propose an important role for structural cis-acting elements, with the involvement of the eukaryotic translational initiation factor eIF4B. By evaluating both cap-dependent and cap-independent translation initiation, we suggest the presence of an IRES supporting the translation of CDKL5 mRNA and propose a pathogenic effect of the C>T -189 SNP in decreasing the translation of the downstream protein.
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Affiliation(s)
- Valeria Ruggiero
- Vita-Salute San Raffaele University, Milan, Italy
- Division of Neuroscience, IRCCS San Raffaele Scientific Institute, Milan, Italy
| | - Claudio Fagioli
- Vita-Salute San Raffaele University, Milan, Italy
- Division of Neuroscience, IRCCS San Raffaele Scientific Institute, Milan, Italy
| | - Stefano de Pretis
- Vita-Salute San Raffaele University, Milan, Italy
- Division of Neuroscience, IRCCS San Raffaele Scientific Institute, Milan, Italy
| | - Valerio Di Carlo
- Department of Medical Biotechnology and Translational Medicine, University of Milan, Segrate, Italy
| | - Nicoletta Landsberger
- Division of Neuroscience, IRCCS San Raffaele Scientific Institute, Milan, Italy
- Department of Medical Biotechnology and Translational Medicine, University of Milan, Segrate, Italy
| | - Daniele Zacchetti
- Vita-Salute San Raffaele University, Milan, Italy
- Division of Neuroscience, IRCCS San Raffaele Scientific Institute, Milan, Italy
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20
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Li Q, Liu X, Xu Y, Lu Z, Jiang S, Yao Y. Translation of paired box 6 (PAX6) mRNA is IRES-mediated and inhibited by cymarin in breast cancer cells. Genes Genet Syst 2023; 98:161-169. [PMID: 37793815 DOI: 10.1266/ggs.23-00039] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/06/2023] Open
Abstract
Paired box 6 (PAX6) is a member of the PAX family and plays an essential role in cancer cell cycle progression, colony formation, proliferation and invasion. Its expression is upregulated in many cancers including breast cancer, but the process of PAX6 mRNA translation has rarely been studied. We found that PAX6 translation level increased in MCF-7 breast cancer cells treated with the chemotherapeutic drug adriamycin (ADM), which might be attributable to internal ribosome entry site (IRES)-mediated translation. By modifying a bicistronic luciferase plasmid that is widely used to examine IRES activity, we found that the 469-base 5'-UTR of PAX6 mRNA contains an IRES element and that core IRES activity is located between nucleotides 159 and 333. Moreover, PAX6 IRES activity was induced during ADM treatment, which may be the main reason for the elevated level of PAX6 protein. We also found that cymarin, a cardiac glycoside, acts as an inhibitor of PAX6 protein expression by impairing its IRES-mediated translation. Furthermore, MCF-7 cell proliferation was suppressed during treatment with cymarin. These results provide novel insights into the translation mechanism of PAX6 in breast cancer cells and suggest that cymarin is a promising candidate for the treatment of breast cancer via targeting the expression of PAX6.
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Affiliation(s)
- Qi Li
- Wuxi Maternity and Child Health Care Hospital, Wuxi School of Medicine, Jiangnan University
| | - Xiao Liu
- Wuxi Maternity and Child Health Care Hospital, Wuxi School of Medicine, Jiangnan University
| | - Yun Xu
- Wuxi Maternity and Child Health Care Hospital, Wuxi School of Medicine, Jiangnan University
| | - Zihong Lu
- Wuxi Maternity and Child Health Care Hospital, Wuxi School of Medicine, Jiangnan University
| | - Sunmin Jiang
- Wuxi Maternity and Child Health Care Hospital, Wuxi School of Medicine, Jiangnan University
| | - Ying Yao
- Wuxi Maternity and Child Health Care Hospital, Wuxi School of Medicine, Jiangnan University
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21
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Kershaw CJ, Nelson MG, Castelli LM, Jennings MD, Lui J, Talavera D, Grant CM, Pavitt GD, Hubbard SJ, Ashe MP. Translation factor and RNA binding protein mRNA interactomes support broader RNA regulons for posttranscriptional control. J Biol Chem 2023; 299:105195. [PMID: 37633333 PMCID: PMC10562868 DOI: 10.1016/j.jbc.2023.105195] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2023] [Revised: 08/18/2023] [Accepted: 08/20/2023] [Indexed: 08/28/2023] Open
Abstract
The regulation of translation provides a rapid and direct mechanism to modulate the cellular proteome. In eukaryotes, an established model for the recruitment of ribosomes to mRNA depends upon a set of conserved translation initiation factors. Nevertheless, how cells orchestrate and define the selection of individual mRNAs for translation, as opposed to other potential cytosolic fates, is poorly understood. We have previously found significant variation in the interaction between individual mRNAs and an array of translation initiation factors. Indeed, mRNAs can be separated into different classes based upon these interactions to provide a framework for understanding different modes of translation initiation. Here, we extend this approach to include new mRNA interaction profiles for additional proteins involved in shaping the cytoplasmic fate of mRNAs. This work defines a set of seven mRNA clusters, based on their interaction profiles with 12 factors involved in translation and/or RNA binding. The mRNA clusters share both physical and functional characteristics to provide a rationale for the interaction profiles. Moreover, a comparison with mRNA interaction profiles from a host of RNA binding proteins suggests that there are defined patterns in the interactions of functionally related mRNAs. Therefore, this work defines global cytoplasmic mRNA binding modules that likely coordinate the synthesis of functionally related proteins.
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Affiliation(s)
- Christopher J Kershaw
- Division of Molecular and Cellular Function, School of Biological Sciences, The University of Manchester, Manchester, UK
| | - Michael G Nelson
- Division of Molecular and Cellular Function, School of Biological Sciences, The University of Manchester, Manchester, UK
| | - Lydia M Castelli
- Division of Molecular and Cellular Function, School of Biological Sciences, The University of Manchester, Manchester, UK
| | - Martin D Jennings
- Division of Molecular and Cellular Function, School of Biological Sciences, The University of Manchester, Manchester, UK
| | - Jennifer Lui
- Division of Molecular and Cellular Function, School of Biological Sciences, The University of Manchester, Manchester, UK
| | - David Talavera
- Division of Cardiovascular Sciences, School of Medical Sciences, The University of Manchester, Manchester, UK
| | - Chris M Grant
- Division of Molecular and Cellular Function, School of Biological Sciences, The University of Manchester, Manchester, UK
| | - Graham D Pavitt
- Division of Molecular and Cellular Function, School of Biological Sciences, The University of Manchester, Manchester, UK.
| | - Simon J Hubbard
- Division of Molecular and Cellular Function, School of Biological Sciences, The University of Manchester, Manchester, UK.
| | - Mark P Ashe
- Division of Molecular and Cellular Function, School of Biological Sciences, The University of Manchester, Manchester, UK.
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22
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Chen X, An Y, Tan M, Xie D, Liu L, Xu B. Biological functions and research progress of eIF4E. Front Oncol 2023; 13:1076855. [PMID: 37601696 PMCID: PMC10435865 DOI: 10.3389/fonc.2023.1076855] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2022] [Accepted: 01/30/2023] [Indexed: 08/22/2023] Open
Abstract
The eukaryotic translation initiation factor eIF4E can specifically bind to the cap structure of an mRNA 5' end, mainly regulating translation initiation and preferentially enhancing the translation of carcinogenesis related mRNAs. The expression of eIF4E is closely related to a variety of malignant tumors. In tumor cells, eIF4E activity is abnormally increased, which stimulates cell growth, metastasis and translation of related proteins. The main factors affecting eIF4E activity include intranuclear regulation, phosphorylation of 4EBPs, and phosphorylation and sumoylation of eIF4E. In this review, we summarize the biological functions and the research progress of eIF4E, the main influencing factors of eIF4E activity, and the recent progress of drugs targeting eIF4E, in the hope of providing new insights for the treatment of multiple malignancies and development of targeted drugs.
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Affiliation(s)
- Xiaocong Chen
- Department of Clinical Medicine, Fenyang College of Shanxi Medical University, Fenyang, China
| | - Yang An
- Department of Clinical Medicine, Fenyang College of Shanxi Medical University, Fenyang, China
| | - Mengsi Tan
- Department of Clinical Medicine, Fenyang College of Shanxi Medical University, Fenyang, China
| | - Dongrui Xie
- Department of Clinical Medicine, Fenyang College of Shanxi Medical University, Fenyang, China
| | - Ling Liu
- Department of Medical Laboratory Science, Fenyang College of Shanxi Medical University, Fenyang, China
- Key Laboratory of Lvliang for Clinical Molecular Diagnostics, Fenyang, China
- Department of Clinical Laboratory, Fenyang Hospital of Shanxi Province, Fenyang, China
| | - Benjin Xu
- Department of Medical Laboratory Science, Fenyang College of Shanxi Medical University, Fenyang, China
- Key Laboratory of Lvliang for Clinical Molecular Diagnostics, Fenyang, China
- Department of Clinical Laboratory, Fenyang Hospital of Shanxi Province, Fenyang, China
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23
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Wek RC, Anthony TG, Staschke KA. Surviving and Adapting to Stress: Translational Control and the Integrated Stress Response. Antioxid Redox Signal 2023; 39:351-373. [PMID: 36943285 PMCID: PMC10443206 DOI: 10.1089/ars.2022.0123] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/16/2022] [Revised: 02/16/2023] [Accepted: 02/20/2023] [Indexed: 03/23/2023]
Abstract
Significance: Organisms adapt to changing environments by engaging cellular stress response pathways that serve to restore proteostasis and enhance survival. A primary adaptive mechanism is the integrated stress response (ISR), which features phosphorylation of the α subunit of eukaryotic translation initiation factor 2 (eIF2). Four eIF2α kinases respond to different stresses, enabling cells to rapidly control translation to optimize management of resources and reprogram gene expression for stress adaptation. Phosphorylation of eIF2 blocks its guanine nucleotide exchange factor, eIF2B, thus lowering the levels of eIF2 bound to GTP that is required to deliver initiator transfer RNA (tRNA) to ribosomes. While bulk messenger RNA (mRNA) translation can be sharply lowered by heightened phosphorylation of eIF2α, there are other gene transcripts whose translation is unchanged or preferentially translated. Among the preferentially translated genes is ATF4, which directs transcription of adaptive genes in the ISR. Recent Advances and Critical Issues: This review focuses on how eIF2α kinases function as first responders of stress, the mechanisms by which eIF2α phosphorylation and other stress signals regulate the exchange activity of eIF2B, and the processes by which the ISR triggers differential mRNA translation. To illustrate the synergy between stress pathways, we describe the mechanisms and functional significance of communication between the ISR and another key regulator of translation, mammalian/mechanistic target of rapamycin complex 1 (mTORC1), during acute and chronic amino acid insufficiency. Finally, we discuss the pathological conditions that stem from aberrant regulation of the ISR, as well as therapeutic strategies targeting the ISR to alleviate disease. Future Directions: Important topics for future ISR research are strategies for modulating this stress pathway in disease conditions and drug development, molecular processes for differential translation and the coordinate regulation of GCN2 and other stress pathways during physiological and pathological conditions. Antioxid. Redox Signal. 39, 351-373.
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Affiliation(s)
- Ronald C. Wek
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, Indiana, USA
- Indiana University Melvin and Bren Simon Comprehensive Cancer Center, Indianapolis, Indiana, USA
| | - Tracy G. Anthony
- Department of Nutritional Sciences, Rutgers University, New Brunswick, New Jersey, USA
| | - Kirk A. Staschke
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, Indiana, USA
- Indiana University Melvin and Bren Simon Comprehensive Cancer Center, Indianapolis, Indiana, USA
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Miścicka A, Lu K, Abaeva IS, Pestova TV, Hellen CUT. Initiation of translation on nedicistrovirus and related intergenic region IRESs by their factor-independent binding to the P site of 80S ribosomes. RNA 2023; 29:1051-1068. [PMID: 37041031 DOI: 10.1261/rna.079599.123] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/17/2023] [Accepted: 03/27/2023] [Indexed: 06/18/2023]
Abstract
Initiation of translation on many viral mRNAs occurs by noncanonical mechanisms that involve 5' end-independent binding of ribosomes to an internal ribosome entry site (IRES). The ∼190-nt-long intergenic region (IGR) IRES of dicistroviruses such as cricket paralysis virus (CrPV) initiates translation without Met-tRNAi Met or initiation factors. Advances in metagenomics have revealed numerous dicistrovirus-like genomes with shorter, structurally distinct IGRs, such as nedicistrovirus (NediV) and Antarctic picorna-like virus 1 (APLV1). Like canonical IGR IRESs, the ∼165-nt-long NediV-like IGRs comprise three domains, but they lack key canonical motifs, including L1.1a/L1.1b loops (which bind to the L1 stalk of the ribosomal 60S subunit) and the apex of stem-loop V (SLV) (which binds to the head of the 40S subunit). Domain 2 consists of a compact, highly conserved pseudoknot (PKIII) that contains a UACUA loop motif and a protruding CrPV-like stem--loop SLIV. In vitro reconstitution experiments showed that NediV-like IRESs initiate translation from a non-AUG codon and form elongation-competent 80S ribosomal complexes in the absence of initiation factors and Met-tRNAi Met Unlike canonical IGR IRESs, NediV-like IRESs bind directly to the peptidyl (P) site of ribosomes leaving the aminoacyl (A) site accessible for decoding. The related structures of NediV-like IRESs and their common mechanism of action indicate that they exemplify a distinct class of IGR IRES.
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Affiliation(s)
- Anna Miścicka
- Department of Cell Biology, SUNY Downstate Health Sciences University, Brooklyn, New York 11203, USA
| | - Kristen Lu
- Department of Cell Biology, SUNY Downstate Health Sciences University, Brooklyn, New York 11203, USA
| | - Irina S Abaeva
- Department of Cell Biology, SUNY Downstate Health Sciences University, Brooklyn, New York 11203, USA
| | - Tatyana V Pestova
- Department of Cell Biology, SUNY Downstate Health Sciences University, Brooklyn, New York 11203, USA
| | - Christopher U T Hellen
- Department of Cell Biology, SUNY Downstate Health Sciences University, Brooklyn, New York 11203, USA
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25
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Alard A, Katsara O, Rios-Fuller T, Parra CDL, Ozerdem U, Ernlund A, Schneider RJ. Breast cancer cell mesenchymal transition and metastasis directed by DAP5/eIF3d-mediated selective mRNA translation. Cell Rep 2023; 42:112646. [PMID: 37314929 PMCID: PMC10895648 DOI: 10.1016/j.celrep.2023.112646] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2021] [Revised: 04/24/2023] [Accepted: 05/30/2023] [Indexed: 06/16/2023] Open
Abstract
Cancer cell plasticity enables cell survival in harsh physiological environments and fate transitions such as the epithelial-to-mesenchymal transition (EMT) that underlies invasion and metastasis. Using genome-wide transcriptomic and translatomic studies, an alternate mechanism of cap-dependent mRNA translation by the DAP5/eIF3d complex is shown to be essential for metastasis, EMT, and tumor directed angiogenesis. DAP5/eIF3d carries out selective translation of mRNAs encoding EMT transcription factors and regulators, cell migration integrins, metalloproteinases, and cell survival and angiogenesis factors. DAP5 is overexpressed in metastatic human breast cancers associated with poor metastasis-free survival. In human and murine breast cancer animal models, DAP5 is not required for primary tumor growth but is essential for EMT, cell migration, invasion, metastasis, angiogenesis, and resistance to anoikis. Thus, cancer cell mRNA translation involves two cap-dependent mRNA translation mechanisms, eIF4E/mTORC1 and DAP5/eIF3d. These findings highlight a surprising level of plasticity in mRNA translation during cancer progression and metastasis.
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Affiliation(s)
- Amandine Alard
- Department of Microbiology, NYU School of Medicine, New York, NY 10016, USA
| | - Olga Katsara
- Department of Microbiology, NYU School of Medicine, New York, NY 10016, USA
| | | | | | - Ugur Ozerdem
- Department of Pathology, NYU School of Medicine, New York, NY 10016, USA
| | - Amanda Ernlund
- Department of Microbiology, NYU School of Medicine, New York, NY 10016, USA
| | - Robert J Schneider
- Department of Microbiology, NYU School of Medicine, New York, NY 10016, USA
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26
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O'Sullivan MH, Fraser CS. Monitoring RNA restructuring in a human cell-free extract reveals eIF4A-dependent and eIF4A-independent unwinding activity. J Biol Chem 2023:104936. [PMID: 37331603 PMCID: PMC10362145 DOI: 10.1016/j.jbc.2023.104936] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2022] [Revised: 06/12/2023] [Accepted: 06/14/2023] [Indexed: 06/20/2023] Open
Abstract
The canonical DEAD-box helicase, eIF4A, unwinds 5' UTR secondary structures to promote mRNA translation initiation. Growing evidence has indicated that other helicases, such as DHX29 and DDX3/ded1p, also function to promote the scanning of the 40S subunit on highly structured mRNAs. It is unknown how the relative contributions of eIF4A and other helicases regulate duplex unwinding on an mRNA to promote initiation. Here, we have adapted a real-time fluorescent duplex unwinding assay to monitor precisely helicase activity in the 5' UTR of a reporter mRNA that can be translated in a cell-free extract in parallel. We monitored the rate of 5' UTR-dependent duplex unwinding in the absence or presence of an eIF4A inhibitor (Hippuristanol), a dominant negative eIF4A (eIF4A-R362Q), or a mutant eIF4E (eIF4E-W73L) that can bind the m7G cap but not eIF4G. Our experiments reveal that the duplex unwinding activity in the cell-free extract is roughly evenly split between eIF4A-dependent and eIF4A-independent mechanisms. Importantly, we show that the robust eIF4A-independent duplex unwinding is not sufficient for translation. We also show that the m7G cap structure, and not the poly(A) tail, is the primary mRNA modification responsible for promoting duplex unwinding in our cell-free extract system. Overall, the fluorescent duplex unwinding assay provides a precise method to investigate how eIF4A-dependent and eIF4A-independent helicase activity regulates translation initiation in cell-free extracts. We anticipate that potential small molecule inhibitors could be tested for helicase inhibition using this duplex unwinding assay.
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Affiliation(s)
- Mattie H O'Sullivan
- Department of Molecular and Cellular Biology, College of Biological Sciences, University of California, Davis, CA 95616
| | - Christopher S Fraser
- Department of Molecular and Cellular Biology, College of Biological Sciences, University of California, Davis, CA 95616.
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27
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Kito Y, Matsumoto A, Ichihara K, Shiraishi C, Tang R, Hatano A, Matsumoto M, Han P, Iwasaki S, Nakayama KI. The ASC-1 complex promotes translation initiation by scanning ribosomes. EMBO J 2023; 42:e112869. [PMID: 37092320 PMCID: PMC10267693 DOI: 10.15252/embj.2022112869] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2022] [Revised: 03/18/2023] [Accepted: 03/27/2023] [Indexed: 04/25/2023] Open
Abstract
Translation initiates when the eIF4F complex binds the 5' mRNA cap, followed by 5' untranslated region scanning for the start codon by scanning ribosomes. Here, we demonstrate that the ASC-1 complex (ASCC), which was previously shown to promote the dissociation of colliding 80S ribosomes, associates with scanning ribosomes to regulate translation initiation. Selective translation complex profiling (TCP-seq) analysis revealed that ASCC3, a helicase domain-containing subunit of ASCC, localizes predominantly to the 5' untranslated region of mRNAs. Ribo-seq, TCP-seq, and luciferase reporter analyses showed that ASCC3 knockdown impairs 43S preinitiation complex loading and scanning dynamics, thereby reducing translation efficiency. Whereas eIF4A, an RNA helicase in the eIF4F complex, is important for global translation, ASCC was found to regulate the scanning process for a specific subset of transcripts. Our results have thus revealed that ASCC is required not only for dissociation of colliding 80S ribosomes but also for efficient translation initiation by scanning ribosomes at a subset of transcripts.
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Affiliation(s)
- Yuki Kito
- Division of Cell Biology, Medical Institute of BioregulationKyushu UniversityFukuokaJapan
| | - Akinobu Matsumoto
- Division of Cell Biology, Medical Institute of BioregulationKyushu UniversityFukuokaJapan
| | - Kazuya Ichihara
- Division of Cell Biology, Medical Institute of BioregulationKyushu UniversityFukuokaJapan
| | - Chisa Shiraishi
- Division of Cell Biology, Medical Institute of BioregulationKyushu UniversityFukuokaJapan
| | - Ronghao Tang
- Division of Cell Biology, Medical Institute of BioregulationKyushu UniversityFukuokaJapan
| | - Atsushi Hatano
- Department of Omics and Systems BiologyGraduate School of Medical and Dental Sciences, Niigata UniversityNiigataJapan
| | - Masaki Matsumoto
- Department of Omics and Systems BiologyGraduate School of Medical and Dental Sciences, Niigata UniversityNiigataJapan
| | - Peixun Han
- RNA Systems Biochemistry LaboratoryRIKEN Cluster for Pioneering ResearchWakoJapan
- Department of Computational Biology and Medical Sciences, Graduate School of Frontier SciencesThe University of TokyoKashiwaJapan
| | - Shintaro Iwasaki
- RNA Systems Biochemistry LaboratoryRIKEN Cluster for Pioneering ResearchWakoJapan
- Department of Computational Biology and Medical Sciences, Graduate School of Frontier SciencesThe University of TokyoKashiwaJapan
| | - Keiichi I Nakayama
- Division of Cell Biology, Medical Institute of BioregulationKyushu UniversityFukuokaJapan
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28
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Wu C, Liu D, Zhang L, Wang J, Ding Y, Sun Z, Wang W. 5'-tiRNA-Gln inhibits hepatocellular carcinoma progression by repressing translation through the interaction with eukaryotic initiation factor 4A-I. Front Med 2023; 17:476-492. [PMID: 36973570 DOI: 10.1007/s11684-022-0966-6] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2022] [Accepted: 10/01/2022] [Indexed: 03/29/2023]
Abstract
tRNA-derived small RNAs (tsRNAs) are novel non-coding RNAs that are involved in the occurrence and progression of diverse diseases. However, their exact presence and function in hepatocellular carcinoma (HCC) remain unclear. Here, differentially expressed tsRNAs in HCC were profiled. A novel tsRNA, tRNAGln-TTG derived 5'-tiRNA-Gln, is significantly downregulated, and its expression level is correlated with progression in patients. In HCC cells, 5'-tiRNA-Gln overexpression impaired the proliferation, migration, and invasion in vitro and in vivo, while 5'-tiRNA-Gln knockdown yielded opposite results. 5'-tiRNA-Gln exerted its function by binding eukaryotic initiation factor 4A-I (EIF4A1), which unwinds complex RNA secondary structures during translation initiation, causing the partial inhibition of translation. The suppressed downregulated proteins include ARAF, MEK1/2 and STAT3, causing the impaired signaling pathway related to HCC progression. Furthermore, based on the construction of a mutant 5'-tiRNA-Gln, the sequence of forming intramolecular G-quadruplex structure is crucial for 5'-tiRNA-Gln to strongly bind EIF4A1 and repress translation. Clinically, 5'-tiRNA-Gln expression level is negatively correlated with ARAF, MEK1/2, and STAT3 in HCC tissues. Collectively, these findings reveal that 5'-tiRJNA-Gln interacts with EIF4A1 to reduce related mRNA binding through the intramolecular G-quadruplex structure, and this process partially inhibits translation and HCC progression.
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Affiliation(s)
- Chengdong Wu
- Department of Hepatobiliary and Pancreatic Surgery, The Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, 310009, China
- Key Laboratory of Precision Diagnosis and Treatment for Hepatobiliary and Pancreatic Tumor of Zhejiang Province, Hangzhou, 310009, China
- Research Center of Diagnosis and Treatment Technology for Hepatocellular Carcinoma of Zhejiang Province, Hangzhou, 310009, China
- Clinical Medicine Innovation Center of Precision Diagnosis and Treatment for Hepatobiliary and Pancreatic Disease of Zhejiang University, Hangzhou, 310009, China
- Clinical Research Center of Hepatobiliary and Pancreatic Diseases of Zhejiang Province, Hangzhou, 310009, China
- Cancer Center, Zhejiang University, Hangzhou, 310009, China
| | - Dekai Liu
- Department of Hepatobiliary and Pancreatic Surgery, The Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, 310009, China
- Key Laboratory of Precision Diagnosis and Treatment for Hepatobiliary and Pancreatic Tumor of Zhejiang Province, Hangzhou, 310009, China
- Research Center of Diagnosis and Treatment Technology for Hepatocellular Carcinoma of Zhejiang Province, Hangzhou, 310009, China
- Clinical Medicine Innovation Center of Precision Diagnosis and Treatment for Hepatobiliary and Pancreatic Disease of Zhejiang University, Hangzhou, 310009, China
- Clinical Research Center of Hepatobiliary and Pancreatic Diseases of Zhejiang Province, Hangzhou, 310009, China
- Cancer Center, Zhejiang University, Hangzhou, 310009, China
| | - Lufei Zhang
- Department of Hepatobiliary and Pancreatic Surgery, The Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, 310009, China
- Key Laboratory of Precision Diagnosis and Treatment for Hepatobiliary and Pancreatic Tumor of Zhejiang Province, Hangzhou, 310009, China
- Research Center of Diagnosis and Treatment Technology for Hepatocellular Carcinoma of Zhejiang Province, Hangzhou, 310009, China
- Clinical Medicine Innovation Center of Precision Diagnosis and Treatment for Hepatobiliary and Pancreatic Disease of Zhejiang University, Hangzhou, 310009, China
- Clinical Research Center of Hepatobiliary and Pancreatic Diseases of Zhejiang Province, Hangzhou, 310009, China
- Cancer Center, Zhejiang University, Hangzhou, 310009, China
| | - Jingjie Wang
- Department of Hepatobiliary and Pancreatic Surgery, The Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, 310009, China
- Key Laboratory of Precision Diagnosis and Treatment for Hepatobiliary and Pancreatic Tumor of Zhejiang Province, Hangzhou, 310009, China
- Research Center of Diagnosis and Treatment Technology for Hepatocellular Carcinoma of Zhejiang Province, Hangzhou, 310009, China
- Clinical Medicine Innovation Center of Precision Diagnosis and Treatment for Hepatobiliary and Pancreatic Disease of Zhejiang University, Hangzhou, 310009, China
- Clinical Research Center of Hepatobiliary and Pancreatic Diseases of Zhejiang Province, Hangzhou, 310009, China
- Cancer Center, Zhejiang University, Hangzhou, 310009, China
| | - Yuan Ding
- Department of Hepatobiliary and Pancreatic Surgery, The Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, 310009, China
- Key Laboratory of Precision Diagnosis and Treatment for Hepatobiliary and Pancreatic Tumor of Zhejiang Province, Hangzhou, 310009, China
- Research Center of Diagnosis and Treatment Technology for Hepatocellular Carcinoma of Zhejiang Province, Hangzhou, 310009, China
- Clinical Medicine Innovation Center of Precision Diagnosis and Treatment for Hepatobiliary and Pancreatic Disease of Zhejiang University, Hangzhou, 310009, China
- Clinical Research Center of Hepatobiliary and Pancreatic Diseases of Zhejiang Province, Hangzhou, 310009, China
- Cancer Center, Zhejiang University, Hangzhou, 310009, China
| | - Zhongquan Sun
- Department of Hepatobiliary and Pancreatic Surgery, The Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, 310009, China
- Key Laboratory of Precision Diagnosis and Treatment for Hepatobiliary and Pancreatic Tumor of Zhejiang Province, Hangzhou, 310009, China
- Research Center of Diagnosis and Treatment Technology for Hepatocellular Carcinoma of Zhejiang Province, Hangzhou, 310009, China
- Clinical Medicine Innovation Center of Precision Diagnosis and Treatment for Hepatobiliary and Pancreatic Disease of Zhejiang University, Hangzhou, 310009, China
- Clinical Research Center of Hepatobiliary and Pancreatic Diseases of Zhejiang Province, Hangzhou, 310009, China
- Cancer Center, Zhejiang University, Hangzhou, 310009, China
| | - Weilin Wang
- Department of Hepatobiliary and Pancreatic Surgery, The Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, 310009, China.
- Key Laboratory of Precision Diagnosis and Treatment for Hepatobiliary and Pancreatic Tumor of Zhejiang Province, Hangzhou, 310009, China.
- Research Center of Diagnosis and Treatment Technology for Hepatocellular Carcinoma of Zhejiang Province, Hangzhou, 310009, China.
- Clinical Medicine Innovation Center of Precision Diagnosis and Treatment for Hepatobiliary and Pancreatic Disease of Zhejiang University, Hangzhou, 310009, China.
- Clinical Research Center of Hepatobiliary and Pancreatic Diseases of Zhejiang Province, Hangzhou, 310009, China.
- Cancer Center, Zhejiang University, Hangzhou, 310009, China.
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29
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Ghosh A, Bharmal MHM, Ghaleb AM, Nandana V, Schrader JM. Initiator AUGs Are Discriminated from Elongator AUGs Predominantly through mRNA Accessibility in C. crescentus. J Bacteriol 2023; 205:e0042022. [PMID: 37092987 PMCID: PMC10210977 DOI: 10.1128/jb.00420-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2022] [Accepted: 03/27/2023] [Indexed: 04/25/2023] Open
Abstract
The initiation of translation in bacteria is thought to occur upon base pairing between the Shine-Dalgarno (SD) site in the mRNA and the anti-SD site in the rRNA. However, in many bacterial species, such as Caulobacter crescentus, a minority of mRNAs have SD sites. To examine the functional importance of SD sites in C. crescentus, we analyzed the transcriptome and found that more SD sites exist in the coding sequence than in the preceding start codons. To examine the function of SD sites in initiation, we designed a series of mutants with altered ribosome accessibility and SD content in translation initiation regions (TIRs) and in elongator AUG regions (EARs). A lack of mRNA structure content is required for initiation in TIRs, and, when introduced into EARs, can stimulate initiation, thereby suggesting that low mRNA structure content is a major feature that is required for initiation. SD sites appear to stimulate initiation in TIRs, which generally lack structure content, but SD sites only stimulate initiation in EARs if RNA secondary structures are destabilized. Taken together, these results suggest that the difference in secondary structure between TIRs and EARs directs ribosomes to start codons where SD base pairing can tune the efficiency of initiation, but SDs in EARs do not stimulate initiation, as they are blocked by stable secondary structures. This highlights the importance of studying translation initiation mechanisms in diverse bacterial species. IMPORTANCE Start codon selection is an essential process that is thought to occur via the base pairing of the rRNA to the SD site in the mRNA. This model is based on studies in E. coli, yet whole-genome sequencing revealed that SD sites are absent at start codons in many species. By examining the transcriptome of C. crescentus, we found more SD-AUG pairs in the CDS of mRNAs than preceding start codons, yet these internal sites do not initiate. Instead, start codon regions have lower mRNA secondary structure content than do internal SD-AUG regions. Therefore, we find that start codon selection is not controlled by the presence of SD sites, which tune initiation efficiency, but by lower mRNA structure content surrounding the start codon.
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Affiliation(s)
- Aishwarya Ghosh
- Department of Biological Sciences, Wayne State University, Detroit, Michigan, USA
| | | | - Amar M. Ghaleb
- Department of Biological Sciences, Wayne State University, Detroit, Michigan, USA
| | - Vidhyadhar Nandana
- Department of Biological Sciences, Wayne State University, Detroit, Michigan, USA
| | - Jared M. Schrader
- Department of Biological Sciences, Wayne State University, Detroit, Michigan, USA
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Layana C, Vilardo ES, Corujo G, Hernández G, Rivera-Pomar R. Drosophila Me31B is a Dual eIF4E-Interacting Protein. J Mol Biol 2023; 435:167949. [PMID: 36638908 DOI: 10.1016/j.jmb.2023.167949] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2021] [Revised: 12/14/2022] [Accepted: 01/03/2023] [Indexed: 01/12/2023]
Abstract
Eukaryotic translation initiation factor 4E (eIF4E) is a key factor involved in different aspects of mRNA metabolism. Drosophila melanogaster genome encodes eight eIF4E isoforms, and the canonical isoform eIF4E-1 is a ubiquitous protein that plays a key role in mRNA translation. eIF4E-3 is specifically expressed in testis and controls translation during spermatogenesis. In eukaryotic cells, translational control and mRNA decay is highly regulated in different cytoplasmic ribonucleoprotein foci, which include the processing bodies (PBs). In this study, we show that Drosophila eIF4E-1 and eIF4E-3 occur in PBs along the DEAD-box RNA helicase Me31B. We show that Me31B interacts with eIF4E-1 and eIF4E-3 by means of yeast two-hybrid system, FRET in D. melanogaster S2 cells and coimmunoprecipitation in testis. Truncation and point mutations of Me31B proteins show two eIF4E-binding sites located in different protein domains. Residues Y401-L407 (at the carboxy-terminus) are essential for interaction with eIF4E-1, whereas residues F63-L70 (at the amino-terminus) are critical for interaction with eIF4E-3. The residue W117 in eIF4E-1 and the homolog position F103 in eIF4E-3 are necessary for Me31B-eIF4E interaction suggesting that the change of tryptophan to phenylalanine provides specificity. Me31B represents a novel type of eIF4E-interacting protein with dual and specific interaction domains that might be recognized by different eIF4E isoforms in different tissues, adding complexity to the control of gene expression in eukaryotes.
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Affiliation(s)
- Carla Layana
- Centro Regional de Estudios Genómicos, Facultad de Ciencias Exactas, Universidad Nacional de La Plata, Boulevard 120 N° 1459, 1900 La Plata, Argentina.
| | - Emiliano Salvador Vilardo
- Centro Regional de Estudios Genómicos, Facultad de Ciencias Exactas, Universidad Nacional de La Plata, Boulevard 120 N° 1459, 1900 La Plata, Argentina
| | - Gonzalo Corujo
- Centro Regional de Estudios Genómicos, Facultad de Ciencias Exactas, Universidad Nacional de La Plata, Boulevard 120 N° 1459, 1900 La Plata, Argentina
| | - Greco Hernández
- Translation and Cancer Laboratory, Unit of Biomedical Research on Cancer, National Institute of Cancer (Instituto Nacional de Cancerología, INCan), 22 San Fernando Ave., Tlalpan, 14080 Mexico City, Mexico
| | - Rolando Rivera-Pomar
- Centro Regional de Estudios Genómicos, Facultad de Ciencias Exactas, Universidad Nacional de La Plata, Boulevard 120 N° 1459, 1900 La Plata, Argentina; Centro de Investigación y Transferencia del Noroeste de Buenos Aires (CITNOBA) - Centro de Bioinvestigaciones, Universidad Nacional del Noroeste de Buenos Aires, Av. Presidente Frondizi Km 4, 2700 Pergamino, Argentina; Molecular Developmental Biology Emeritus Group, Max Planck Institute for Multidisciplinary Sciences, Am Fassberg 11, 37077 Göttingen, Germany
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31
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Christie M, Igreja C. eIF4E-homologous protein (4EHP): a multifarious cap-binding protein. FEBS J 2023; 290:266-285. [PMID: 34758096 DOI: 10.1111/febs.16275] [Citation(s) in RCA: 10] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2021] [Revised: 10/29/2021] [Accepted: 11/09/2021] [Indexed: 02/05/2023]
Abstract
The cap-binding protein 4EHP/eIF4E2 has been a recent object of interest in the field of post-transcriptional gene regulation and translational control. From ribosome-associated quality control, to RNA decay and microRNA-mediated gene silencing, this member of the eIF4E protein family regulates gene expression through numerous pathways. Low in abundance but ubiquitously expressed, 4EHP interacts with different binding partners to form multiple protein complexes that regulate translation in a variety of biological contexts. Documented functions of 4EHP primarily relate to its role as a translational repressor, but recent findings indicate that it might also participate in the activation of translation in specific settings. In this review, we discuss the known functions, properties and mechanisms that involve 4EHP in the control of gene expression. We also discuss our current understanding of how 4EHP processes are regulated in eukaryotic cells, and the diseases implicated with dysregulation of 4EHP-mediated translational control.
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Affiliation(s)
- Mary Christie
- School of Life and Environmental Sciences, The University of Sydney, NSW, Australia
| | - Cátia Igreja
- Department for Integrative Evolutionary Biology, Max Planck Institute for Developmental Biology, Tübingen, Germany
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32
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Chen F, Cocaign-Bousquet M, Girbal L, Nouaille S. 5'UTR sequences influence protein levels in Escherichia coli by regulating translation initiation and mRNA stability. Front Microbiol 2022; 13:1088941. [PMID: 36620028 PMCID: PMC9810816 DOI: 10.3389/fmicb.2022.1088941] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2022] [Accepted: 12/02/2022] [Indexed: 12/24/2022] Open
Abstract
A set of 41 synthetic 5'UTRs with different theoretical translation initiation rates were generated to explore the role of 5'UTRs in the regulation of protein levels in Escherichia coli. The roles of the synthetic 5'UTRs in regulating the expression of different reporter genes were analyzed in vivo. Protein levels varied substantially between the different constructs but for most of the 5'UTRs, protein levels were not correlated with theoretical translation initiation rates. Large variations in mRNA concentrations were measured with the different 5'UTRs even though the same concentration of transcription inducer was used in each case. 5'UTRs were also found to strongly affect mRNA stability, and these changes in mRNA stability often contributed to observed differences in mRNA concentration. Unexpectedly, the effect of the 5'UTRs on mRNA half-lives was found to vary depending on the downstream reporter gene. These results clearly demonstrate that 5'UTRs contribute to gene expression regulation at the level of translation initiation and of mRNA stability, to an extent that depends on the nature of the downstream gene.
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Andreev DE, Niepmann M, Shatsky IN. Elusive Trans-Acting Factors Which Operate with Type I (Poliovirus-like) IRES Elements. Int J Mol Sci 2022; 23:ijms232415497. [PMID: 36555135 PMCID: PMC9778869 DOI: 10.3390/ijms232415497] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2022] [Revised: 12/02/2022] [Accepted: 12/05/2022] [Indexed: 12/12/2022] Open
Abstract
The phenomenon of internal initiation of translation was discovered in 1988 on poliovirus mRNA. The prototypic cis-acting element in the 5' untranslated region (5'UTR) of poliovirus mRNA, which is able to direct initiation at an internal start codon without the involvement of a cap structure, has been called an IRES (Internal Ribosome Entry Site or Segment). Despite its early discovery, poliovirus and other related IRES elements of type I are poorly characterized, and it is not yet clear which host proteins (a.k.a. IRES trans-acting factors, ITAFs) are required for their full activity in vivo. Here we discuss recent and old results devoted to type I IRESes and provide evidence that Poly(rC) binding protein 2 (PCBP2), Glycyl-tRNA synthetase (GARS), and Cold Shock Domain Containing E1 (CSDE1, also known as UNR) are major regulators of type I IRES activity.
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Affiliation(s)
- Dmitry E. Andreev
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, 117997 Moscow, Russia
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, 119234 Moscow, Russia
| | - Michael Niepmann
- Institute of Biochemistry, Medical Faculty, Justus-Liebig-University, 35392 Giessen, Germany
| | - Ivan N. Shatsky
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, 119234 Moscow, Russia
- Correspondence:
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Wang J, Shin BS, Alvarado C, Kim JR, Bohlen J, Dever TE, Puglisi JD. Rapid 40S scanning and its regulation by mRNA structure during eukaryotic translation initiation. Cell 2022; 185:4474-4487.e17. [PMID: 36334590 PMCID: PMC9691599 DOI: 10.1016/j.cell.2022.10.005] [Citation(s) in RCA: 24] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2022] [Revised: 08/22/2022] [Accepted: 10/05/2022] [Indexed: 11/06/2022]
Abstract
How the eukaryotic 43S preinitiation complex scans along the 5' untranslated region (5' UTR) of a capped mRNA to locate the correct start codon remains elusive. Here, we directly track yeast 43S-mRNA binding, scanning, and 60S subunit joining by real-time single-molecule fluorescence spectroscopy. 43S engagement with mRNA occurs through a slow, ATP-dependent process driven by multiple initiation factors including the helicase eIF4A. Once engaged, 43S scanning occurs rapidly and directionally at ∼100 nucleotides per second, independent of multiple cycles of ATP hydrolysis by RNA helicases post ribosomal loading. Scanning ribosomes can proceed through RNA secondary structures, but 5' UTR hairpin sequences near start codons drive scanning ribosomes at start codons backward in the 5' direction, requiring rescanning to arrive once more at a start codon. Direct observation of scanning ribosomes provides a mechanistic framework for translational regulation by 5' UTR structures and upstream near-cognate start codons.
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Affiliation(s)
- Jinfan Wang
- Department of Structural Biology, Stanford University School of Medicine, Stanford, CA, USA
| | - Byung-Sik Shin
- Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, USA
| | - Carlos Alvarado
- Department of Structural Biology, Stanford University School of Medicine, Stanford, CA, USA
| | - Joo-Ran Kim
- Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, USA
| | - Jonathan Bohlen
- Laboratory of Human Genetics of Infectious Diseases, Necker Branch, Institut National de la Santé et de la Recherche Médicale U1163, Paris, France; University of Paris, Imagine Institute, Paris, France
| | - Thomas E Dever
- Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, USA.
| | - Joseph D Puglisi
- Department of Structural Biology, Stanford University School of Medicine, Stanford, CA, USA.
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Weiss B, Jaquier-Gubler P, Curran JA. Preinitiation Complex Loading onto mRNAs with Long versus Short 5' TLs. Int J Mol Sci 2022; 23. [PMID: 36362157 DOI: 10.3390/ijms232113369] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2022] [Revised: 10/27/2022] [Accepted: 10/28/2022] [Indexed: 11/06/2022] Open
Abstract
The first step in translation initiation consists in the recruitment of the small ribosome onto the mRNA. This preinitiation complex (PIC) loads via interactions with eIF4F that has assembled on the 5' cap. It then scans the 5' TL (transcript leader) to locate a start site. The molecular architecture of the PIC-mRNA complex over the cap is beginning to be resolved. As part of this, we have been examining the role of the 5' TL length. We observed in vivo initiation events on AUG codons positioned within 3 nts of the 5' cap and robust initiation in vitro at start sites immediately downstream of the 5' end. Ribosomal toe-printing confirmed the positioning of these codons within the P site, indicating that the ribosome reads from the +1 position. To explore differences in the eIF4E-5' cap interaction in the context of long versus short TL, we followed the fate of the eIF4E-cap interaction using a novel solid phase in vitro expression assay. We observed that ribosome recruitment onto a short TL disrupts the eIF4E-cap contact releasing all the mRNA from the solid phase, whereas with a long the mRNA distributes between both phases. These results are discussed in the context of current recruitment models.
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Pechar GS, Donaire L, Gosalvez B, García‐Almodovar C, Sánchez‐Pina MA, Truniger V, Aranda MA. Editing melon eIF4E associates with virus resistance and male sterility. Plant Biotechnol J 2022; 20:2006-2022. [PMID: 35778883 PMCID: PMC9491454 DOI: 10.1111/pbi.13885] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/28/2022] [Revised: 06/19/2022] [Accepted: 06/23/2022] [Indexed: 05/20/2023]
Abstract
The cap-binding protein eIF4E, through its interaction with eIF4G, constitutes the core of the eIF4F complex, which plays a key role in the circularization of mRNAs and their subsequent cap-dependent translation. In addition to its fundamental role in mRNA translation initiation, other functions have been described or suggested for eIF4E, including acting as a proviral factor and participating in sexual development. We used CRISPR/Cas9 genome editing to generate melon eif4e knockout mutant lines. Editing worked efficiently in melon, as we obtained transformed plants with a single-nucleotide deletion in homozygosis in the first eIF4E exon already in a T0 generation. Edited and non-transgenic plants of a segregating F2 generation were inoculated with Moroccan watermelon mosaic virus (MWMV); homozygous mutant plants showed virus resistance, while heterozygous and non-mutant plants were infected, in agreement with our previous results with plants silenced in eIF4E. Interestingly, all homozygous edited plants of the T0 and F2 generations showed a male sterility phenotype, while crossing with wild-type plants restored fertility, displaying a perfect correlation between the segregation of the male sterility phenotype and the segregation of the eif4e mutation. Morphological comparative analysis of melon male flowers along consecutive developmental stages showed postmeiotic abnormal development for both microsporocytes and tapetum, with clear differences in the timing of tapetum degradation in the mutant versus wild-type. An RNA-Seq analysis identified critical genes in pollen development that were down-regulated in flowers of eif4e/eif4e plants, and suggested that eIF4E-specific mRNA translation initiation is a limiting factor for male gametes formation in melon.
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Affiliation(s)
- Giuliano S. Pechar
- Department of Stress Biology and Plant PathologyCentro de Edafología y Biología Aplicada del Segura (CEBAS)‐CSICMurciaSpain
| | - Livia Donaire
- Department of Stress Biology and Plant PathologyCentro de Edafología y Biología Aplicada del Segura (CEBAS)‐CSICMurciaSpain
| | - Blanca Gosalvez
- Department of Stress Biology and Plant PathologyCentro de Edafología y Biología Aplicada del Segura (CEBAS)‐CSICMurciaSpain
| | - Carlos García‐Almodovar
- Department of Stress Biology and Plant PathologyCentro de Edafología y Biología Aplicada del Segura (CEBAS)‐CSICMurciaSpain
| | - María Amelia Sánchez‐Pina
- Department of Stress Biology and Plant PathologyCentro de Edafología y Biología Aplicada del Segura (CEBAS)‐CSICMurciaSpain
| | - Verónica Truniger
- Department of Stress Biology and Plant PathologyCentro de Edafología y Biología Aplicada del Segura (CEBAS)‐CSICMurciaSpain
| | - Miguel A. Aranda
- Department of Stress Biology and Plant PathologyCentro de Edafología y Biología Aplicada del Segura (CEBAS)‐CSICMurciaSpain
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Lehman SL, Wechsler T, Schwartz K, Brown LE, Porco JA, Devine WG, Pelletier J, Shankavaram UT, Camphausen K, Tofilon PJ. Inhibition of the Translation Initiation Factor eIF4A Enhances Tumor Cell Radiosensitivity. Mol Cancer Ther 2022; 21:1406-1414. [PMID: 35732578 PMCID: PMC9452469 DOI: 10.1158/1535-7163.mct-22-0037] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2022] [Revised: 04/12/2022] [Accepted: 06/16/2022] [Indexed: 11/16/2022]
Abstract
A fundamental component of cellular radioresponse is the translational control of gene expression. Because a critical regulator of translational control is the eukaryotic translation initiation factor 4F (eIF4F) cap binding complex, we investigated whether eIF4A, the RNA helicase component of eIF4F, can serve as a target for radiosensitization. Knockdown of eIF4A using siRNA reduced translational efficiency, as determined from polysome profiles, and enhanced tumor cell radiosensitivity as determined by clonogenic survival. The increased radiosensitivity was accompanied by a delayed dispersion of radiation-induced γH2AX foci, suggestive of an inhibition of DNA double-strand break repair. Studies were then extended to (-)-SDS-1-021, a pharmacologic inhibitor of eIF4A. Treatment of cells with the rocaglate (-)-SDS-1-021 resulted in a decrease in translational efficiency as well as protein synthesis. (-)-SDS-1-021 treatment also enhanced the radiosensitivity of tumor cell lines. This (-)-SDS-1-021-induced radiosensitization was accompanied by a delay in radiation-induced γH2AX foci dispersal, consistent with a causative role for the inhibition of double-strand break repair. In contrast, although (-)-SDS-1-021 inhibited translation and protein synthesis in a normal fibroblast cell line, it had no effect on radiosensitivity of normal cells. Subcutaneous xenografts were then used to evaluate the in vivo response to (-)-SDS-1-021 and radiation. Treatment of mice bearing subcutaneous xenografts with (-)-SDS-1-021 decreased tumor translational efficiency as determined by polysome profiles. Although (-)-SDS-1-021 treatment alone had no effect on tumor growth, it significantly enhanced the radiation-induced growth delay. These results suggest that eIF4A is a tumor-selective target for radiosensitization.
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Affiliation(s)
| | | | | | - Lauren E Brown
- Department of Chemistry and Center for Molecular Discovery (BU-CMD), Boston University, Boston, Massachusetts
| | - John A Porco
- Department of Chemistry and Center for Molecular Discovery (BU-CMD), Boston University, Boston, Massachusetts
| | - William G Devine
- Department of Chemistry and Center for Molecular Discovery (BU-CMD), Boston University, Boston, Massachusetts
| | - Jerry Pelletier
- Department of Biochemistry, Oncology and Goodman Cancer Centre, McGill University, Montreal, Quebec, Canada
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Izidoro MS, Sokabe M, Villa N, Merrick WC, Fraser CS. Human eukaryotic initiation factor 4E (eIF4E) and the nucleotide-bound state of eIF4A regulate eIF4F binding to RNA. J Biol Chem 2022; 298:102368. [PMID: 35963437 PMCID: PMC9483636 DOI: 10.1016/j.jbc.2022.102368] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2022] [Revised: 08/05/2022] [Accepted: 08/09/2022] [Indexed: 11/30/2022] Open
Abstract
During translation initiation, the underlying mechanism by which the eukaryotic initiation factor (eIF) 4E, eIF4A, and eIF4G components of eIF4F coordinate their binding activities to regulate eIF4F binding to mRNA is poorly defined. Here, we used fluorescence anisotropy to generate thermodynamic and kinetic frameworks for the interaction of uncapped RNA with human eIF4F. We demonstrate that eIF4E binding to an autoinhibitory domain in eIF4G generates a high-affinity binding conformation of the eIF4F complex for RNA. In addition, we show that the nucleotide-bound state of the eIF4A component further regulates uncapped RNA binding by eIF4F, with a four-fold decrease in the equilibrium dissociation constant observed in the presence versus the absence of ATP. Monitoring uncapped RNA dissociation in real time reveals that ATP reduces the dissociation rate constant of RNA for eIF4F by ∼4-orders of magnitude. Thus, release of ATP from eIF4A places eIF4F in a dynamic state that has very fast association and dissociation rates from RNA. Monitoring the kinetic framework for eIF4A binding to eIF4G revealed two different rate constants that likely reflect two conformational states of the eIF4F complex. Furthermore, we determined that the eIF4G autoinhibitory domain promotes a more stable, less dynamic, eIF4A-binding state, which is overcome by eIF4E binding. Overall, our data support a model whereby eIF4E binding to eIF4G/4A stabilizes a high-affinity RNA-binding state of eIF4F and enables eIF4A to adopt a more dynamic interaction with eIF4G. This dynamic conformation may contribute to the ability of eIF4F to rapidly bind and release mRNA during scanning.
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Affiliation(s)
- Mario Servulo Izidoro
- Department of Molecular and Cellular Biology, College of Biological Sciences, University of California, Davis, CA 95616
| | - Masaaki Sokabe
- Department of Molecular and Cellular Biology, College of Biological Sciences, University of California, Davis, CA 95616
| | - Nancy Villa
- Department of Molecular and Cellular Biology, College of Biological Sciences, University of California, Davis, CA 95616
| | - William C Merrick
- Department of Molecular and Cellular Biology, College of Biological Sciences, University of California, Davis, CA 95616
| | - Christopher S Fraser
- Department of Molecular and Cellular Biology, College of Biological Sciences, University of California, Davis, CA 95616.
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39
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Brown ZP, Abaeva IS, De S, Hellen CUT, Pestova TV, Frank J. Molecular architecture of 40S translation initiation complexes on the hepatitis C virus IRES. EMBO J 2022; 41:e110581. [PMID: 35822879 DOI: 10.15252/embj.2022110581] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2022] [Revised: 06/01/2022] [Accepted: 06/14/2022] [Indexed: 02/05/2023] Open
Abstract
Hepatitis C virus mRNA contains an internal ribosome entry site (IRES) that mediates end-independent translation initiation, requiring a subset of eukaryotic initiation factors (eIFs). Biochemical studies revealed that direct binding of the IRES to the 40S ribosomal subunit places the initiation codon into the P site, where it base pairs with eIF2-bound Met-tRNAiMet forming a 48S initiation complex. Subsequently, eIF5 and eIF5B mediate subunit joining, yielding an elongation-competent 80S ribosome. Initiation can also proceed without eIF2, in which case Met-tRNAiMet is recruited directly by eIF5B. However, the structures of initiation complexes assembled on the HCV IRES, the transitions between different states, and the accompanying conformational changes have remained unknown. To fill these gaps, we now obtained cryo-EM structures of IRES initiation complexes, at resolutions up to 3.5 Å, that cover all major stages from the initial ribosomal association, through eIF2-containing 48S initiation complexes, to eIF5B-containing complexes immediately prior to subunit joining. These structures provide insights into the dynamic network of 40S/IRES contacts, highlight the role of IRES domain II, and reveal conformational changes that occur during the transition from eIF2- to eIF5B-containing 48S complexes and prepare them for subunit joining.
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Affiliation(s)
- Zuben P Brown
- Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY, USA
| | - Irina S Abaeva
- Department of Cell Biology, SUNY Downstate Health Sciences University, Brooklyn, NY, USA
| | - Swastik De
- Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY, USA
| | - Christopher U T Hellen
- Department of Cell Biology, SUNY Downstate Health Sciences University, Brooklyn, NY, USA
| | - Tatyana V Pestova
- Department of Cell Biology, SUNY Downstate Health Sciences University, Brooklyn, NY, USA
| | - Joachim Frank
- Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY, USA.,Department of Biological Sciences, Columbia University, New York, NY, USA
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40
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Condé L, Allatif O, Ohlmann T, de Breyne S. Translation of SARS-CoV-2 gRNA Is Extremely Efficient and Competitive despite a High Degree of Secondary Structures and the Presence of an uORF. Viruses 2022; 14:1505. [PMID: 35891485 PMCID: PMC9322171 DOI: 10.3390/v14071505] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2022] [Revised: 07/06/2022] [Accepted: 07/07/2022] [Indexed: 12/15/2022] Open
Abstract
The SARS-CoV-2 infection generates up to nine different sub-genomic mRNAs (sgRNAs), in addition to the genomic RNA (gRNA). The 5'UTR of each viral mRNA shares the first 75 nucleotides (nt.) at their 5'end, called the leader, but differentiates by a variable sequence (0 to 190 nt. long) that follows the leader. As a result, each viral mRNA has its own specific 5'UTR in term of length, RNA structure, uORF and Kozak context; each one of these characteristics could affect mRNA expression. In this study, we have measured and compared translational efficiency of each of the ten viral transcripts. Our data show that most of them are very efficiently translated in all translational systems tested. Surprisingly, the gRNA 5'UTR, which is the longest and the most structured, was also the most efficient to initiate translation. This property is conserved in the 5'UTR of SARS-CoV-1 but not in MERS-CoV strain, mainly due to the regulation imposed by the uORF. Interestingly, the translation initiation mechanism on the SARS-CoV-2 gRNA 5'UTR requires the cap structure and the components of the eIF4F complex but showed no dependence in the presence of the poly(A) tail in vitro. Our data strongly suggest that translation initiation on SARS-CoV-2 mRNAs occurs via an unusual cap-dependent mechanism.
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Affiliation(s)
| | | | - Théophile Ohlmann
- CIRI, Centre International de Recherche en Infectiologie, (Team Ohlmann), Univ Lyon, Inserm U1111, Université Claude Bernard Lyon 1, CNRS UMR5308, ENS de Lyon, F-69007 Lyon, France; (L.C.); (O.A.)
| | - Sylvain de Breyne
- CIRI, Centre International de Recherche en Infectiologie, (Team Ohlmann), Univ Lyon, Inserm U1111, Université Claude Bernard Lyon 1, CNRS UMR5308, ENS de Lyon, F-69007 Lyon, France; (L.C.); (O.A.)
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41
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de Jesus V, Schmid J, Fürtig B. Binding of 30S Ribosome Induces Single-stranded Conformation Within and Downstream of the Expression Platform in a Translational Riboswitch. J Mol Biol 2022;:167668. [PMID: 35667471 DOI: 10.1016/j.jmb.2022.167668] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2022] [Revised: 04/29/2022] [Accepted: 05/31/2022] [Indexed: 11/23/2022]
Abstract
Translational riboswitches are bacterial gene regulatory elements found in the 5'-untranslated region of mRNAs. They operate through a conformational refolding reaction that is triggered by a concentration change of a modulating small molecular ligand. The translation initiation region (TIR) is either released from or incorporated into base pairing interactions through the conformational switch. Hence, initiation of translation is regulated by the accessibility of the Shine-Dalgarno sequence and start codon. Interaction with the 30S ribosome is indispensable for the structural switch between functional OFF and ON states. However, on a molecular level it is still not fully resolved how the ribosome is accommodated near or at the translation initiation region in the context of translational riboswitches. The standby model of translation initiation postulates a binding site where the mRNA enters the ribosome and where it resides until the initiation site becomes unstructured and accessible. We here investigated the adenine-sensing riboswitch from Vibrio vulnificus. By application of a 19F labelling strategy for NMR spectroscopy that utilizes ligation techniques to synthesize differentially 19F labelled riboswitch molecules we show that nucleotides directly downstream of the riboswitch domain are first involved in productive interaction with the 30S ribosomal subunit. Upon the concerted action of ligand and the ribosomal protein rS1 the TIR becomes available and subsequently the 30S ribosome can slide towards the TIR. It will be interesting to see whether this is a general feature in translational riboswitches or if riboswitches exist where this region is structured and represent yet another layer of regulation.
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42
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Chen YL, Wen JD. Translation initiation site of mRNA is selected through dynamic interaction with the ribosome. Proc Natl Acad Sci U S A 2022; 119:e2118099119. [PMID: 35605125 DOI: 10.1073/pnas.2118099119] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
SignificanceRibosomes translate the genetic codes of messenger RNA (mRNA) to make proteins. Translation must begin at the correct initiation site; otherwise, abnormal proteins will be produced. Here, we show that a short ribosome-specific sequence in the upstream followed by an unstructured downstream sequence is a favorable initiation site. Those mRNAs lacking either of these two characteristics do not associate tightly with the ribosome. Initiator transfer RNA (tRNA) and initiation factors facilitate the binding. However, when the downstream site forms structures, initiation factor 3 triggers the dissociation of the accommodated initiator tRNA and the subsequent disassembly of the ribosome-mRNA complex. Thus, initiation factors help the ribosome distinguish unfavorable structured sequences that may not act as the mRNA translation initiation site.
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43
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Hernández G. The versatile relationships between eIF4E and eIF4E-interacting proteins. Trends Genet 2022; 38:801-804. [PMID: 35568601 DOI: 10.1016/j.tig.2022.04.003] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2022] [Revised: 04/10/2022] [Accepted: 04/11/2022] [Indexed: 11/18/2022]
Abstract
RNA metabolism and gene expression lie at the core of cellular life. eIF4E has emerged as a central interface in both processes as it plays critical roles in mRNA processing, transport, translation, and storage. Crucially, eIF4E depends on its association with a universe of proteins to form biologically meaningful complexes.
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Affiliation(s)
- Greco Hernández
- Translation and Cancer Laboratory, Unit of Biomedical Research on Cancer, National Institute of Cancer (Instituto Nacional de Cancerología, INCan). 22 San Fernando Avenue, Tlalpan, 14080-Mexico City, Mexico.
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44
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Stanciu A, Luo J, Funes L, Galbokke Hewage S, Kulkarni SD, Aitken CE. Corrigendum: eIF3 and Its mRNA-Entry-Channel Arm Contribute to the Recruitment of mRNAs With Long 5'-Untranslated Regions. Front Mol Biosci 2022; 9:896119. [PMID: 35517854 PMCID: PMC9065676 DOI: 10.3389/fmolb.2022.896119] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2022] [Accepted: 03/15/2022] [Indexed: 11/13/2022] Open
Abstract
[This corrects the article DOI: 10.3389/fmolb.2021.787664.].
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Affiliation(s)
- Andrei Stanciu
- Computer Science Department, Vassar College, Poughkeepsie, NY, United States
| | - Juncheng Luo
- Biochemistry Program, Vassar College, Poughkeepsie, NY, United States
| | - Lucy Funes
- Biology Department, Vassar College, Poughkeepsie, NY, United States
| | | | - Shardul D Kulkarni
- Department of Biochemistry & Molecular Biology, Penn State Eberly College of Medicine, University Park, PA, United States
| | - Colin Echeverría Aitken
- Biochemistry Program, Vassar College, Poughkeepsie, NY, United States.,Biology Department, Vassar College, Poughkeepsie, NY, United States
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45
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Jaramillo-Mesa H, Fischer E, Rakotondrafara AM. Multiple Cis-acting Polypyrimidine Tract Elements Regulate a Cooperative Mechanism for Triticum Mosaic Virus Internal Ribosomal Entry Site Activity. Front Plant Sci 2022; 13:864832. [PMID: 35498652 PMCID: PMC9042117 DOI: 10.3389/fpls.2022.864832] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/28/2022] [Accepted: 03/16/2022] [Indexed: 06/14/2023]
Abstract
Diverse elements within the 5' untranslated region of an mRNA can influence the translation efficiency at the main AUG codon. We previously identified a core picornaviral like Y16X11-AUG motif with 16-nt polypyrimidine CU tract separated by an 11-nt spacer sequence from the 13th AUG codon, which is recognized as the preferred initiation site within the Triticum mosaic virus (TriMV) internal ribosome entry site (IRES) element. The motif is proposed to function as an internal ribosomal landing site at the designated start codon. Here, we exposed the cooperative role of multiple CU-rich segments flanking the TriMV YX-AUG motif to reach and drive internal initiation of translation at the preferred start site. We propose that these auxiliary domains may enhance the ribosome capacity and their delivery at proximity of the correct initiation site. These polypyrimidine tracts can be modulated with a cryptic AUG in a position-dependent manner to replace the native YX-AUG motif, and thus uncovering a new layer of control of start codon selection. In line with these observations, mass spectrometry analysis of proteins directly interacting with translationally impaired TriMV IRES mutants that bear these motifs indicated an enrichment in 40S and 60S ribosomal related proteins, revealing a new function of polypyrimidine tracts to regulate IRES-driven translation. Accessibility of these RNA regions for in trans interaction was validated by SHAPE analysis of the entire TriMV leader sequence and supported by the ability of anti-sense oligonucleotides designed to block the CU tracts accessibility to impair IRES activity. This is the first evidence that defines the core modular domains required for ribosomal recruitment and start codon selection in a complex, multi-AUG viral 5' UTR for translation in plants.
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Niederer RO, Rojas-Duran MF, Zinshteyn B, Gilbert WV. Direct analysis of ribosome targeting illuminates thousand-fold regulation of translation initiation. Cell Syst 2022; 13:256-264.e3. [PMID: 35041803 PMCID: PMC8930539 DOI: 10.1016/j.cels.2021.12.002] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2021] [Revised: 07/15/2021] [Accepted: 12/09/2021] [Indexed: 12/15/2022]
Abstract
Translational control shapes the proteome in normal and pathophysiological conditions. Current high-throughput approaches reveal large differences in mRNA-specific translation activity but cannot identify the causative mRNA features. We developed direct analysis of ribosome targeting (DART) and used it to dissect regulatory elements within 5' untranslated regions that confer 1,000-fold differences in ribosome recruitment in biochemically accessible cell lysates. Using DART, we determined a functional role for most alternative 5' UTR isoforms expressed in yeast, revealed a general mode of increased translation via direct binding to a core translation factor, and identified numerous translational control elements including C-rich silencers that are sufficient to repress translation both in vitro and in vivo. DART enables systematic assessment of the translational regulatory potential of 5' UTR variants, whether native or disease-associated, and will facilitate engineering of mRNAs for optimized protein production in various systems.
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Affiliation(s)
- Rachel O Niederer
- Department of Molecular Biophysics & Biochemistry, Yale School of Medicine, New Haven, CT 06520, USA
| | - Maria F Rojas-Duran
- Department of Molecular Biophysics & Biochemistry, Yale School of Medicine, New Haven, CT 06520, USA
| | - Boris Zinshteyn
- Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Wendy V Gilbert
- Department of Molecular Biophysics & Biochemistry, Yale School of Medicine, New Haven, CT 06520, USA.
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Fujimoto Y, Keima T, Hashimoto M, Hagiwara-Komoda Y, Hosoe N, Nishida S, Nijo T, Oshima K, Verchot J, Namba S, Yamaji Y. Short 5' Untranslated Region Enables Optimal Translation of Plant Virus Tricistronic RNA via Leaky Scanning. J Virol 2022;:e0214421. [PMID: 35262378 DOI: 10.1128/jvi.02144-21] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Regardless of the general model of translation in eukaryotic cells, a number of studies suggested that many mRNAs encode multiple proteins. Leaky scanning, which supplies ribosomes to downstream open reading frames (ORFs) by readthrough of upstream ORFs, has great potential to translate polycistronic mRNAs. However, the mRNA elements controlling leaky scanning and their biological relevance have rarely been elucidated, with exceptions such as the Kozak sequence. Here, we have analyzed the strategy of a plant RNA virus to translate three movement proteins from a single RNA molecule through leaky scanning. The in planta and in vitro results indicate thatthe significantly shorter 5' untranslated region (UTR) of the most upstream ORF promotes leaky scanning, potentially fine-tuning the translation efficiency of the three proteins in a single RNA molecule to optimize viral propagation. Our results suggest that the remarkably short length of the leader sequence, like the Kozak sequence, is a translational regulatory element with a biologically important role, as previous studies have shown biochemically. IMPORTANCE Potexvirus, a group of plant viruses, infect a variety of crops, including cultivated crops. It has been thought that the three transition proteins that are essential for the cell-to-cell transfer of potexviruses are translated from two subgenomic RNAs, sgRNA1 and sgRNA2. However, sgRNA2 has not been clearly detected. In this study, we have shown that sgRNA1, but not sgRNA2, is the major translation template for the three movement proteins. In addition, we determined the transcription start site of sgRNA1 in flexiviruses and found that the efficiency of leaky scanning caused by the short 5' UTR of sgRNA1, a widely conserved feature, regulates the translation of the three movement proteins. When we tested the infection of viruses with mutations introduced into the length of the 5' UTR, we found that the movement efficiency of the virus was affected. Our results provide important additional information on the protein translation strategy of flexiviruses, including Potexvirus, and provide a basis for research on their control as well as the need to reevaluate the short 5' UTR as a translational regulatory element with an important role in vivo.
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Huth M, Santini L, Galimberti E, Ramesmayer J, Titz-Teixeira F, Sehlke R, Oberhuemer M, Stummer S, Herzog V, Garmhausen M, Romeike M, Chugunova A, Leesch F, Holcik L, Weipoltshammer K, Lackner A, Schoefer C, von Haeseler A, Buecker C, Pauli A, Ameres SL, Smith A, Beyer A, Leeb M. NMD is required for timely cell fate transitions by fine-tuning gene expression and regulating translation. Genes Dev 2022; 36:348-67. [PMID: 35241478 DOI: 10.1101/gad.347690.120] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2020] [Accepted: 02/11/2022] [Indexed: 11/25/2022]
Abstract
Here, Huth et al. investigated the role of components of the nonsense-mediated mRNA decay (NMD) pathway in regulating embryonic stem cell (ESC) differentiation, and show that NMD controls expression levels of the translation initiation factor Eif4a2 and its premature termination codon-encoding isoform (Eif4a2PTC). Their findings expose an intricate link between mRNA homeostasis and mTORC1 activity that must be maintained for normal dynamics of cell state transitions. Cell fate transitions depend on balanced rewiring of transcription and translation programs to mediate ordered developmental progression. Components of the nonsense-mediated mRNA decay (NMD) pathway have been implicated in regulating embryonic stem cell (ESC) differentiation, but the exact mechanism is unclear. Here we show that NMD controls expression levels of the translation initiation factor Eif4a2 and its premature termination codon-encoding isoform (Eif4a2PTC). NMD deficiency leads to translation of the truncated eIF4A2PTC protein. eIF4A2PTC elicits increased mTORC1 activity and translation rates and causes differentiation delays. This establishes a previously unknown feedback loop between NMD and translation initiation. Furthermore, our results show a clear hierarchy in the severity of target deregulation and differentiation phenotypes between NMD effector KOs (Smg5 KO > Smg6 KO > Smg7 KO), which highlights heterodimer-independent functions for SMG5 and SMG7. Together, our findings expose an intricate link between mRNA homeostasis and mTORC1 activity that must be maintained for normal dynamics of cell state transitions.
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Su R, Dong L, Li Y, Gao M, He PC, Liu W, Wei J, Zhao Z, Gao L, Han L, Deng X, Li C, Prince E, Tan B, Qing Y, Qin X, Shen C, Xue M, Zhou K, Chen Z, Xue J, Li W, Qin H, Wu X, Sun M, Nam Y, Chen CW, Huang W, Horne D, Rosen ST, He C, Chen J. METTL16 exerts an m 6A-independent function to facilitate translation and tumorigenesis. Nat Cell Biol 2022; 24:205-216. [PMID: 35145225 PMCID: PMC9070413 DOI: 10.1038/s41556-021-00835-2] [Citation(s) in RCA: 131] [Impact Index Per Article: 65.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2021] [Accepted: 12/21/2021] [Indexed: 12/23/2022]
Abstract
METTL16 has recently been identified as an RNA methyltransferase responsible for the deposition of N6-methyladenosine (m6A) in a few transcripts. Whether METTL16 methylates a large set of transcripts, similar to METTL3 and METTL14, remains unclear. Here we show that METTL16 exerts both methyltransferase activity-dependent and -independent functions in gene regulation. In the cell nucleus, METTL16 functions as an m6A writer to deposit m6A into hundreds of its specific messenger RNA targets. In the cytosol, METTL16 promotes translation in an m6A-independent manner. More specifically, METTL16 directly interacts with the eukaryotic initiation factors 3a and -b as well as ribosomal RNA through its Mtase domain, thereby facilitating the assembly of the translation-initiation complex and promoting the translation of over 4,000 mRNA transcripts. Moreover, we demonstrate that METTL16 is critical for the tumorigenesis of hepatocellular carcinoma. Collectively, our studies reveal previously unappreciated dual functions of METTL16 as an m6A writer and a translation-initiation facilitator, which together contribute to its essential function in tumorigenesis.
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MESH Headings
- Adenosine/analogs & derivatives
- Adenosine/metabolism
- Animals
- Carcinogenesis/genetics
- Carcinogenesis/metabolism
- Carcinogenesis/pathology
- Carcinoma, Hepatocellular/enzymology
- Carcinoma, Hepatocellular/genetics
- Carcinoma, Hepatocellular/pathology
- Cytosol/enzymology
- Eukaryotic Initiation Factor-3/genetics
- Eukaryotic Initiation Factor-3/metabolism
- Gene Expression Regulation, Neoplastic
- HEK293 Cells
- Hep G2 Cells
- Humans
- Liver Neoplasms/enzymology
- Liver Neoplasms/genetics
- Liver Neoplasms/pathology
- Methyltransferases/genetics
- Methyltransferases/metabolism
- Mice, Inbred NOD
- Mice, SCID
- Protein Biosynthesis
- RNA Processing, Post-Transcriptional
- RNA, Messenger/genetics
- RNA, Messenger/metabolism
- RNA, Ribosomal/genetics
- RNA, Ribosomal/metabolism
- Signal Transduction
- Tumor Burden
- Mice
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Affiliation(s)
- Rui Su
- Department of Systems Biology, Beckman Research Institute of City of Hope, Monrovia, CA, USA.
| | - Lei Dong
- Department of Systems Biology, Beckman Research Institute of City of Hope, Monrovia, CA, USA
| | - Yangchan Li
- Department of Systems Biology, Beckman Research Institute of City of Hope, Monrovia, CA, USA
- Department of Radiation Oncology, The First Affiliated Hospital of Sun Yat-sen University, Guangzhou, China
| | - Min Gao
- Department of Systems Biology, Beckman Research Institute of City of Hope, Monrovia, CA, USA
- Department of Pharmaceutics, School of Pharmaceutical Science, Jiangnan University, Wuxi, China
| | - P Cody He
- Department of Chemistry, Department of Biochemistry and Molecular Biology, and Institute for Biophysical Dynamics, The University of Chicago, Chicago, IL, USA
- Howard Hughes Medical Institute, The University of Chicago, Chicago, IL, USA
| | - Wei Liu
- Department of Systems Biology, Beckman Research Institute of City of Hope, Monrovia, CA, USA
- Department of Immunology, Hebei Medical University, Shijiazhuang, China
| | - Jiangbo Wei
- Department of Chemistry, Department of Biochemistry and Molecular Biology, and Institute for Biophysical Dynamics, The University of Chicago, Chicago, IL, USA
- Howard Hughes Medical Institute, The University of Chicago, Chicago, IL, USA
| | - Zhicong Zhao
- Department of Systems Biology, Beckman Research Institute of City of Hope, Monrovia, CA, USA
- Department of Liver Surgery, Renji Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Lei Gao
- Department of Systems Biology, Beckman Research Institute of City of Hope, Monrovia, CA, USA
| | - Li Han
- Department of Systems Biology, Beckman Research Institute of City of Hope, Monrovia, CA, USA
- School of Pharmacy, China Medical University, Shenyang, China
| | - Xiaolan Deng
- Department of Systems Biology, Beckman Research Institute of City of Hope, Monrovia, CA, USA
| | - Chenying Li
- Department of Systems Biology, Beckman Research Institute of City of Hope, Monrovia, CA, USA
- Key Laboratory of Hematopoietic Malignancies, The First Affiliated Hospital of Zhejiang University, Hangzhou, China
| | - Emily Prince
- Department of Systems Biology, Beckman Research Institute of City of Hope, Monrovia, CA, USA
| | - Brandon Tan
- Department of Systems Biology, Beckman Research Institute of City of Hope, Monrovia, CA, USA
| | - Ying Qing
- Department of Systems Biology, Beckman Research Institute of City of Hope, Monrovia, CA, USA
| | - Xi Qin
- Department of Systems Biology, Beckman Research Institute of City of Hope, Monrovia, CA, USA
| | - Chao Shen
- Department of Systems Biology, Beckman Research Institute of City of Hope, Monrovia, CA, USA
| | - Meilin Xue
- Department of Systems Biology, Beckman Research Institute of City of Hope, Monrovia, CA, USA
| | - Keren Zhou
- Department of Systems Biology, Beckman Research Institute of City of Hope, Monrovia, CA, USA
| | - Zhenhua Chen
- Department of Systems Biology, Beckman Research Institute of City of Hope, Monrovia, CA, USA
| | - Jianhuang Xue
- Department of Systems Biology, Beckman Research Institute of City of Hope, Monrovia, CA, USA
| | - Wei Li
- Department of Systems Biology, Beckman Research Institute of City of Hope, Monrovia, CA, USA
| | - Hanjun Qin
- The Integrative Genomics Core, Beckman Research Institute of City of Hope, Duarte, CA, USA
| | - Xiwei Wu
- The Integrative Genomics Core, Beckman Research Institute of City of Hope, Duarte, CA, USA
| | - Miao Sun
- Keck School of Medicine, University of Southern California, and Department of Pathology and Laboratory Medicine, Children's Hospital Los Angeles, Los Angeles, CA, USA
| | - Yunsun Nam
- Laboratory of RNA Biology, Cecil H. and Ida Green Center for Reproductive Biology Sciences, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Chun-Wei Chen
- Department of Systems Biology, Beckman Research Institute of City of Hope, Monrovia, CA, USA
- City of Hope Comprehensive Cancer Center, City of Hope, Duarte, CA, USA
| | - Wendong Huang
- Department of Diabetes Complications and Metabolism, Diabetes and Metabolism Research Institute, Beckman Research Institute of City of Hope, Duarte, CA, USA
- Graduate School of Biological Science, City of Hope, Duarte, CA, USA
| | - David Horne
- City of Hope Comprehensive Cancer Center, City of Hope, Duarte, CA, USA
- Department of Molecular Medicine, Beckman Research Institute of City of Hope, Duarte, CA, USA
| | - Steven T Rosen
- City of Hope Comprehensive Cancer Center, City of Hope, Duarte, CA, USA
- Department of Hematology and Hematopoietic Cell Transplantation, City of Hope, Duarte, CA, USA
- Gehr Family Center for Leukemia Research, City of Hope, Duarte, CA, USA
| | - Chuan He
- Department of Chemistry, Department of Biochemistry and Molecular Biology, and Institute for Biophysical Dynamics, The University of Chicago, Chicago, IL, USA.
- Howard Hughes Medical Institute, The University of Chicago, Chicago, IL, USA.
| | - Jianjun Chen
- Department of Systems Biology, Beckman Research Institute of City of Hope, Monrovia, CA, USA.
- City of Hope Comprehensive Cancer Center, City of Hope, Duarte, CA, USA.
- Gehr Family Center for Leukemia Research, City of Hope, Duarte, CA, USA.
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Zhang Y, Aleksashin NA, Klepacki D, Anderson C, Vázquez-Laslop N, Gross CA, Mankin AS. The context of the ribosome binding site in mRNAs defines specificity of action of kasugamycin, an inhibitor of translation initiation. Proc Natl Acad Sci U S A 2022; 119:e2118553119. [PMID: 35064089 DOI: 10.1073/pnas.2118553119] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/21/2021] [Indexed: 11/18/2022] Open
Abstract
Several antibiotics targeting the large ribosomal subunit interfere with translation in a context-specific manner, preventing ribosomes from polymerizing specific amino acid sequences. Here, we reveal kasugamycin as a small ribosomal subunit-targeting antibiotic whose action depends on the sequence context of the untranslated messenger RNA (mRNA) segments. We show that kasugamycin-induced ribosomal arrest at the start codons of the genes and the resulting inhibition of gene expression depend on the nature of the mRNA nucleotide immediately preceding the start codon and on the proximity of the stop codon of the upstream cistron. Our findings underlie the importance of mRNA context for the action of protein synthesis inhibitors and might help to guide the development of better antibiotics. Kasugamycin (KSG) is an aminoglycoside antibiotic widely used in agriculture and exhibits considerable medical potential. Previous studies suggested that KSG interferes with translation by blocking binding of canonical messenger RNA (mRNA) and initiator transfer tRNA (tRNA) to the small ribosomal subunit, thereby preventing initiation of protein synthesis. Here, by using genome-wide approaches, we show that KSG can interfere with translation even after the formation of the 70S initiation complex on mRNA, as the extent of KSG-mediated translation inhibition correlates with increased occupancy of start codons by 70S ribosomes. Even at saturating concentrations, KSG does not completely abolish translation, allowing for continuing expression of some Escherichia coli proteins. Differential action of KSG significantly depends on the nature of the mRNA residue immediately preceding the start codon, with guanine in this position being the most conducive to inhibition by the drug. In addition, the activity of KSG is attenuated by translational coupling as genes whose start codons overlap with the coding regions or the stop codons of the upstream cistrons tend to be less susceptible to drug-mediated inhibition. Altogether, our findings reveal KSG as an example of a small ribosomal subunit-targeting antibiotic with a well-pronounced context specificity of action.
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