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Boyer JA, Sharma M, Dorso MA, Mai N, Amor C, Reiter JM, Kannan R, Gadal S, Xu J, Miele M, Li Z, Chen X, Chang Q, Pareja F, Worland S, Warner D, Sperry S, Chiang GG, Thompson PA, Yang G, Ouerfelli O, de Stanchina E, Wendel HG, Rosen EY, Chandarlapaty S, Rosen N. eIF4A controls translation of estrogen receptor alpha and is a therapeutic target in advanced breast cancer. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.05.08.593195. [PMID: 38766126 PMCID: PMC11100762 DOI: 10.1101/2024.05.08.593195] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2024]
Abstract
The majority of human breast cancers are dependent on hormone-stimulated estrogen receptor alpha (ER) and are sensitive to its inhibition. Treatment resistance arises in most advanced cancers due to genetic alterations that promote ligand independent activation of ER itself or ER target genes. Whereas re-targeting of the ER ligand binding domain (LBD) with newer ER antagonists can work in some cases, these drugs are largely ineffective in many genetic backgrounds including ER fusions that lose the LBD or in cancers that hyperactivate ER targets. By identifying the mechanism of ER translation, we herein present an alternative strategy to target ER and difficult to treat ER variants. We find that ER translation is cap-independent and mTOR inhibitor insensitive, but dependent on 5' UTR elements and sensitive to pharmacologic inhibition of the translation initiation factor eIF4A, an mRNA helicase. EIF4A inhibition rapidly reduces expression of ER and short-lived targets of ER such as cyclin D1 and other components of the cyclin D-CDK complex in breast cancer cells. These effects translate into suppression of growth of a variety of ligand-independent breast cancer models including those driven by ER fusion proteins that lack the ligand binding site. The efficacy of eIF4A inhibition is enhanced when it is combined with fulvestrant-an ER degrader. Concomitant inhibition of ER synthesis and induction of its degradation causes synergistic and durable inhibition of ER expression and tumor growth. The clinical importance of these findings is confirmed by results of an early clinical trial (NCT04092673) of the selective eIF4A inhibitor zotatifin in patients with estrogen receptor positive metastatic breast cancer. Multiple clinical responses have been observed on combination therapy including durable regressions. These data suggest that eIF4A inhibition could be a useful new strategy for treating advanced ER+ breast cancer.
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Affiliation(s)
- Jacob A. Boyer
- Louis V. Gerstner Jr. Graduate School of Biomedical Sciences, Memorial Sloan-Kettering Cancer Center, New York, NY, USA
- Program in Molecular Pharmacology, Department of Medicine, Memorial Sloan-Kettering Cancer Center (MSKCC), New York, NY, USA
- Ludwig Institute for Cancer Research, Princeton University, Princeton, NJ, USA
| | - Malvika Sharma
- Program in Molecular Pharmacology, Department of Medicine, Memorial Sloan-Kettering Cancer Center (MSKCC), New York, NY, USA
| | - Madeline A. Dorso
- Human Oncology and Pathogenesis Program, Memorial Sloan Kettering Cancer Center, New York, New York
| | - Nicholas Mai
- Department of Medicine, Memorial Sloan Kettering Cancer Center, New York, NY, USA
| | - Corina Amor
- Louis V. Gerstner Jr. Graduate School of Biomedical Sciences, Memorial Sloan-Kettering Cancer Center, New York, NY, USA
- Department of Cancer Biology and Genetics, Sloan Kettering Institute, Memorial Sloan Kettering Cancer Center, New York, NY, USA
| | - Jason M. Reiter
- Program in Molecular Pharmacology, Department of Medicine, Memorial Sloan-Kettering Cancer Center (MSKCC), New York, NY, USA
| | - Ram Kannan
- Department of Cancer Biology and Genetics, Sloan Kettering Institute, Memorial Sloan Kettering Cancer Center, New York, NY, USA
| | - Sunyana Gadal
- Program in Molecular Pharmacology, Department of Medicine, Memorial Sloan-Kettering Cancer Center (MSKCC), New York, NY, USA
| | - Jianing Xu
- Program in Molecular Pharmacology, Department of Medicine, Memorial Sloan-Kettering Cancer Center (MSKCC), New York, NY, USA
| | - Matthew Miele
- Microchemistry and Proteomics Core Facility, Memorial Sloan Kettering Cancer Center, New York, NY, USA
| | - Zhuoning Li
- Microchemistry and Proteomics Core Facility, Memorial Sloan Kettering Cancer Center, New York, NY, USA
| | - Xiaoping Chen
- Antitumor Assessment Core Facility, Memorial Sloan Kettering Cancer Center, New York, NY 11065, USA
| | - Qing Chang
- Antitumor Assessment Core Facility, Memorial Sloan Kettering Cancer Center, New York, NY 11065, USA
| | - Fresia Pareja
- Department of Pathology and Laboratory Medicine, Memorial Sloan Kettering Cancer Center, New York, NY, USA
| | - Stephan Worland
- Department of Cancer Biology, eFFECTOR Therapeutics, Inc., San Diego, CA, United States
| | - Douglas Warner
- Department of Cancer Biology, eFFECTOR Therapeutics, Inc., San Diego, CA, United States
| | - Sam Sperry
- Department of Cancer Biology, eFFECTOR Therapeutics, Inc., San Diego, CA, United States
| | - Gary G. Chiang
- Department of Cancer Biology, eFFECTOR Therapeutics, Inc., San Diego, CA, United States
| | - Peggy A. Thompson
- Department of Cancer Biology, eFFECTOR Therapeutics, Inc., San Diego, CA, United States
| | - Guangli Yang
- The Organic Synthesis Core Facility, MSK, New York, NY, USA
| | | | - Elisa de Stanchina
- Antitumor Assessment Core Facility, Memorial Sloan Kettering Cancer Center, New York, NY 11065, USA
| | - Hans-Guido Wendel
- Department of Cancer Biology and Genetics, Sloan Kettering Institute, Memorial Sloan Kettering Cancer Center, New York, NY, USA
| | - Ezra Y. Rosen
- Department of Medicine, Memorial Sloan Kettering Cancer Center, New York, NY, USA
| | - Sarat Chandarlapaty
- Human Oncology and Pathogenesis Program, Memorial Sloan Kettering Cancer Center, New York, New York
- Department of Medicine, Memorial Sloan Kettering Cancer Center, New York, NY, USA
- Department of Medicine, Weill Cornell Medicine, New York, NY, USA
| | - Neal Rosen
- Program in Molecular Pharmacology, Department of Medicine, Memorial Sloan-Kettering Cancer Center (MSKCC), New York, NY, USA
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2
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Fuentes Y, Olguín V, López-Ulloa B, Mendonça D, Ramos H, Abdalla A, Guajardo-Contreras G, Niu M, Rojas-Araya B, Mouland A, López-Lastra M. Heterogeneous nuclear ribonucleoprotein K promotes cap-independent translation initiation of retroviral mRNAs. Nucleic Acids Res 2024; 52:2625-2647. [PMID: 38165048 PMCID: PMC10954487 DOI: 10.1093/nar/gkad1221] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2023] [Revised: 12/07/2023] [Accepted: 12/15/2023] [Indexed: 01/03/2024] Open
Abstract
Translation initiation of the human immunodeficiency virus-type 1 (HIV-1) genomic mRNA (vRNA) is cap-dependent or mediated by an internal ribosome entry site (IRES). The HIV-1 IRES requires IRES-transacting factors (ITAFs) for function. In this study, we evaluated the role of the heterogeneous nuclear ribonucleoprotein K (hnRNPK) as a potential ITAF for the HIV-1 IRES. In HIV-1-expressing cells, the depletion of hnRNPK reduced HIV-1 vRNA translation. Furthermore, both the depletion and overexpression of hnRNPK modulated HIV-1 IRES activity. Phosphorylations and protein arginine methyltransferase 1 (PRMT1)-induced asymmetrical dimethylation (aDMA) of hnRNPK strongly impacted the protein's ability to promote the activity of the HIV-1 IRES. We also show that hnRNPK acts as an ITAF for the human T cell lymphotropic virus-type 1 (HTLV-1) IRES, present in the 5'UTR of the viral sense mRNA, but not for the IRES present in the antisense spliced transcript encoding the HTLV-1 basic leucine zipper protein (sHBZ). This study provides evidence for a novel role of the host hnRNPK as an ITAF that stimulates IRES-mediated translation initiation for the retroviruses HIV-1 and HTLV-1.
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Affiliation(s)
- Yazmín Fuentes
- Laboratorio de Virología Molecular, Instituto Milenio de Inmunología e Inmunoterapia, Departamento de Enfermedades Infecciosas e Inmunología Pediátrica, Escuela de Medicina, Pontificia Universidad Católica de Chile, Marcoleta 391, Santiago, Chile
| | - Valeria Olguín
- Laboratorio de Virología Molecular, Instituto Milenio de Inmunología e Inmunoterapia, Departamento de Enfermedades Infecciosas e Inmunología Pediátrica, Escuela de Medicina, Pontificia Universidad Católica de Chile, Marcoleta 391, Santiago, Chile
| | - Brenda López-Ulloa
- Laboratorio de Virología Molecular, Instituto Milenio de Inmunología e Inmunoterapia, Departamento de Enfermedades Infecciosas e Inmunología Pediátrica, Escuela de Medicina, Pontificia Universidad Católica de Chile, Marcoleta 391, Santiago, Chile
| | - Dafne Mendonça
- Laboratorio de Virología Molecular, Instituto Milenio de Inmunología e Inmunoterapia, Departamento de Enfermedades Infecciosas e Inmunología Pediátrica, Escuela de Medicina, Pontificia Universidad Católica de Chile, Marcoleta 391, Santiago, Chile
| | - Hade Ramos
- Laboratorio de Virología Molecular, Instituto Milenio de Inmunología e Inmunoterapia, Departamento de Enfermedades Infecciosas e Inmunología Pediátrica, Escuela de Medicina, Pontificia Universidad Católica de Chile, Marcoleta 391, Santiago, Chile
| | - Ana Luiza Abdalla
- HIV-1 RNA Trafficking Laboratory, Lady Davis Institute at the Jewish General Hospital, Montréal, Quebec H3T 1E2, Canada
- Department of Microbiology and Immunology, McGill University, Montreal, Quebec H4A 3J1, Canada
| | - Gabriel Guajardo-Contreras
- HIV-1 RNA Trafficking Laboratory, Lady Davis Institute at the Jewish General Hospital, Montréal, Quebec H3T 1E2, Canada
- Department of Medicine, McGill University, Montreal, Quebec H4A 3J1, Canada
| | - Meijuan Niu
- HIV-1 RNA Trafficking Laboratory, Lady Davis Institute at the Jewish General Hospital, Montréal, Quebec H3T 1E2, Canada
| | - Barbara Rojas-Araya
- Laboratorio de Virología Molecular, Instituto Milenio de Inmunología e Inmunoterapia, Departamento de Enfermedades Infecciosas e Inmunología Pediátrica, Escuela de Medicina, Pontificia Universidad Católica de Chile, Marcoleta 391, Santiago, Chile
| | - Andrew J Mouland
- HIV-1 RNA Trafficking Laboratory, Lady Davis Institute at the Jewish General Hospital, Montréal, Quebec H3T 1E2, Canada
- Department of Microbiology and Immunology, McGill University, Montreal, Quebec H4A 3J1, Canada
- Department of Medicine, McGill University, Montreal, Quebec H4A 3J1, Canada
| | - Marcelo López-Lastra
- Laboratorio de Virología Molecular, Instituto Milenio de Inmunología e Inmunoterapia, Departamento de Enfermedades Infecciosas e Inmunología Pediátrica, Escuela de Medicina, Pontificia Universidad Católica de Chile, Marcoleta 391, Santiago, Chile
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3
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Dorn G, Gmeiner C, de Vries T, Dedic E, Novakovic M, Damberger FF, Maris C, Finol E, Sarnowski CP, Kohlbrecher J, Welsh TJ, Bolisetty S, Mezzenga R, Aebersold R, Leitner A, Yulikov M, Jeschke G, Allain FHT. Integrative solution structure of PTBP1-IRES complex reveals strong compaction and ordering with residual conformational flexibility. Nat Commun 2023; 14:6429. [PMID: 37833274 PMCID: PMC10576089 DOI: 10.1038/s41467-023-42012-z] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2022] [Accepted: 09/27/2023] [Indexed: 10/15/2023] Open
Abstract
RNA-binding proteins (RBPs) are crucial regulators of gene expression, often composed of defined domains interspersed with flexible, intrinsically disordered regions. Determining the structure of ribonucleoprotein (RNP) complexes involving such RBPs necessitates integrative structural modeling due to their lack of a single stable state. In this study, we integrate magnetic resonance, mass spectrometry, and small-angle scattering data to determine the solution structure of the polypyrimidine-tract binding protein 1 (PTBP1/hnRNP I) bound to an RNA fragment from the internal ribosome entry site (IRES) of the encephalomyocarditis virus (EMCV). This binding, essential for enhancing the translation of viral RNA, leads to a complex structure that demonstrates RNA and protein compaction, while maintaining pronounced conformational flexibility. Acting as an RNA chaperone, PTBP1 orchestrates the IRES RNA into a few distinct conformations, exposing the RNA stems outward. This conformational diversity is likely common among RNP structures and functionally important. Our approach enables atomic-level characterization of heterogeneous RNP structures.
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Affiliation(s)
- Georg Dorn
- Institute of Biochemistry, Department of Biology, ETH Zürich, Zürich, Switzerland
| | - Christoph Gmeiner
- Laboratory of Physical Chemistry, Department of Chemistry and Applied Biosciences, ETH Zürich, Zürich, Switzerland
| | - Tebbe de Vries
- Institute of Biochemistry, Department of Biology, ETH Zürich, Zürich, Switzerland
| | - Emil Dedic
- Institute of Biochemistry, Department of Biology, ETH Zürich, Zürich, Switzerland
| | - Mihajlo Novakovic
- Institute of Biochemistry, Department of Biology, ETH Zürich, Zürich, Switzerland
| | - Fred F Damberger
- Institute of Biochemistry, Department of Biology, ETH Zürich, Zürich, Switzerland
| | - Christophe Maris
- Institute of Biochemistry, Department of Biology, ETH Zürich, Zürich, Switzerland
| | - Esteban Finol
- Institute of Biochemistry, Department of Biology, ETH Zürich, Zürich, Switzerland
| | - Chris P Sarnowski
- Institute of Molecular Systems Biology, Department of Biology, ETH Zürich, Zürich, Switzerland
| | - Joachim Kohlbrecher
- Laboratory for Neutron Scattering and Imaging, Paul Scherrer Institut, Villigen, Switzerland
| | - Timothy J Welsh
- Laboratory of Physical Chemistry, Department of Chemistry and Applied Biosciences, ETH Zürich, Zürich, Switzerland
| | - Sreenath Bolisetty
- Laboratory of Food & Soft Materials, Institute of Food, Nutrition and Health, Department for Health Sciences and Technology, ETH Zürich, Zürich, Switzerland
| | - Raffaele Mezzenga
- Laboratory of Food & Soft Materials, Institute of Food, Nutrition and Health, Department for Health Sciences and Technology, ETH Zürich, Zürich, Switzerland
| | - Ruedi Aebersold
- Institute of Molecular Systems Biology, Department of Biology, ETH Zürich, Zürich, Switzerland
| | - Alexander Leitner
- Institute of Molecular Systems Biology, Department of Biology, ETH Zürich, Zürich, Switzerland
| | - Maxim Yulikov
- Laboratory of Physical Chemistry, Department of Chemistry and Applied Biosciences, ETH Zürich, Zürich, Switzerland.
| | - Gunnar Jeschke
- Laboratory of Physical Chemistry, Department of Chemistry and Applied Biosciences, ETH Zürich, Zürich, Switzerland.
| | - Frédéric H-T Allain
- Institute of Biochemistry, Department of Biology, ETH Zürich, Zürich, Switzerland.
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4
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Volegova MP, Hermosillo C, Cate JHD. The Helix-Loop-Helix motif of human EIF3A regulates translation of proliferative cellular mRNAs. PLoS One 2023; 18:e0292080. [PMID: 37768948 PMCID: PMC10538695 DOI: 10.1371/journal.pone.0292080] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2023] [Accepted: 09/12/2023] [Indexed: 09/30/2023] Open
Abstract
Improper regulation of translation initiation, a vital checkpoint of protein synthesis in the cell, has been linked to a number of cancers. Overexpression of protein subunits of eukaryotic translation initiation factor 3 (eIF3) is associated with increased translation of mRNAs involved in cell proliferation. In addition to playing a major role in general translation initiation by serving as a scaffold for the assembly of translation initiation complexes, eIF3 regulates translation of specific cellular mRNAs and viral RNAs. Mutations in the N-terminal Helix-Loop-Helix (HLH) RNA-binding motif of the EIF3A subunit interfere with Hepatitis C Virus Internal Ribosome Entry Site (IRES) mediated translation initiation in vitro. Here we show that the EIF3A HLH motif controls translation of a small set of cellular transcripts enriched in oncogenic mRNAs, including MYC. We demonstrate that the HLH motif of EIF3A acts specifically on the 5' UTR of MYC mRNA and modulates the function of EIF4A1 on select transcripts during translation initiation. In Ramos lymphoma cell lines, which are dependent on MYC overexpression, mutations in the HLH motif greatly reduce MYC expression, impede proliferation and sensitize cells to anti-cancer compounds. These results reveal the potential of the EIF3A HLH motif in eIF3 as a promising chemotherapeutic target.
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Affiliation(s)
- Marina P. Volegova
- Department of Molecular and Cell Biology, University of California, Berkeley, CA, United States of America
| | - Cynthia Hermosillo
- Department of Molecular and Cell Biology, University of California, Berkeley, CA, United States of America
| | - Jamie H. D. Cate
- Department of Molecular and Cell Biology, University of California, Berkeley, CA, United States of America
- Department of Chemistry, University of California, Berkeley, CA, United States of America
- Molecular Biosciences and Integrated Bioimaging, Lawrence Berkeley National Laboratory, Berkeley, CA, United States of America
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5
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Inchingolo MA, Diman A, Adamczewski M, Humphreys T, Jaquier-Gubler P, Curran JA. TP53BP1, a dual-coding gene, uses promoter switching and translational reinitiation to express a smORF protein. iScience 2023; 26:106757. [PMID: 37216125 PMCID: PMC10193022 DOI: 10.1016/j.isci.2023.106757] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2022] [Revised: 03/07/2023] [Accepted: 04/24/2023] [Indexed: 05/24/2023] Open
Abstract
The complexity of the metazoan proteome is significantly increased by the expression of small proteins (<100 aa) derived from smORFs within lncRNAs, uORFs, 3' UTRs and, reading frames overlapping the CDS. These smORF encoded proteins (SEPs) have diverse roles, ranging from the regulation of cellular physiological to essential developmental functions. We report the characterization of a new member of this protein family, SEP53BP1, derived from a small internal ORF that overlaps the CDS encoding 53BP1. Its expression is coupled to the utilization of an alternative, cell-type specific promoter coupled to translational reinitiation events mediated by a uORF in the alternative 5' TL of the mRNA. This uORF-mediated reinitiation at an internal ORF is also observed in zebrafish. Interactome studies indicate that the human SEP53BP1 associates with components of the protein turnover pathway including the proteasome, and the TRiC/CCT chaperonin complex, suggesting that it may play a role in cellular proteostasis.
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Affiliation(s)
- Marta A. Inchingolo
- Department of Microbiology and Molecular Medicine, Faculty of Medicine, University of Geneva, Geneva, Switzerland
| | - Aurélie Diman
- Department of Microbiology and Molecular Medicine, Faculty of Medicine, University of Geneva, Geneva, Switzerland
| | - Maxime Adamczewski
- Department of Microbiology and Molecular Medicine, Faculty of Medicine, University of Geneva, Geneva, Switzerland
- Faculté de Médecine et Pharmacie, Université Grenoble Alpes, Grenoble, France
| | - Tom Humphreys
- Department of Microbiology and Molecular Medicine, Faculty of Medicine, University of Geneva, Geneva, Switzerland
- Faculty of Biology, Medicine and Health, University of Manchester, Manchester, UK
| | - Pascale Jaquier-Gubler
- Department of Microbiology and Molecular Medicine, Faculty of Medicine, University of Geneva, Geneva, Switzerland
| | - Joseph A. Curran
- Department of Microbiology and Molecular Medicine, Faculty of Medicine, University of Geneva, Geneva, Switzerland
- Institute of Genetics and Genomics of Geneva (iGE3), University of Geneva, Geneva, Switzerland
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6
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Yeh DW, Zhao X, Siddique HR, Zheng M, Choi HY, Machida T, Narayanan P, Kou Y, Punj V, Tahara SM, Feldman DE, Chen L, Machida K. MSI2 promotes translation of multiple IRES-containing oncogenes and virus to induce self-renewal of tumor initiating stem-like cells. Cell Death Discov 2023; 9:141. [PMID: 37117191 PMCID: PMC10147607 DOI: 10.1038/s41420-023-01427-9] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2023] [Revised: 03/22/2023] [Accepted: 04/03/2023] [Indexed: 04/30/2023] Open
Abstract
RNA-binding protein Musashi 2 (MSI2) is elevated in several cancers and is linked to poor prognosis. Here, we tested if MSI2 promotes MYC and viral mRNA translation to induce self-renewal via an internal ribosome entry sequence (IRES). We performed RIP-seq using anti-MSI2 antibody in tumor-initiating stem-like cells (TICs). MSI2 binds the internal ribosome entry site (IRES)-containing oncogene mRNAs including MYC, JUN and VEGFA as well as HCV IRES to increase their synthesis and promote self-renewal and tumor-initiation at the post-transcriptional level. MSI2 binds a lncRNA to interfere with processing of a miRNA that reduced MYC translation in basal conditions. Deregulation of this integrated MSI2-lncRNA-MYC regulatory loop drives self-renewal and tumorigenesis through increased IRES-dependent translation of MYC mRNA. Overexpression of MSI2 in TICs promoted their self-renewal and tumor-initiation properties. Inhibition of MSI2-RNA binding reduced HCV IRES activity, viral replication and liver hyperplasia in humanized mice predisposed by virus infection and alcohol high-cholesterol high-fat diet. Together MSI2, integrating the MYC oncogenic pathway, can be employed as a therapeutic target in the treatment of HCC patients. A hypothetical model shows that MSI2 binds and activates cap-independent translation of MYC, c-JUN mRNA and HCV through MSI2-binding to Internal Ribosome Entry Sites (IRES) resulting in upregulated MYC, c-JUN and viral protein synthesis and subsequent liver oncogenesis. Inhibitor of the interaction between MYC IRES and MSI2 reduces liver hyperplasia, viral mRNA translation and tumor formation.
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Affiliation(s)
- Da-Wei Yeh
- Department of Molecular Microbiology and Immunology, University of Southern California Keck School of Medicine, Los Angeles, 90033, USA
| | - Xuyao Zhao
- Department of Molecular Microbiology and Immunology, University of Southern California Keck School of Medicine, Los Angeles, 90033, USA
| | - Hifzur R Siddique
- Department of Molecular Microbiology and Immunology, University of Southern California Keck School of Medicine, Los Angeles, 90033, USA
- Molecular Cancer Genetics & Translational Research Lab, Section of Genetics, Department of Zoology, Aligarh Muslim University, Aligarh, 202002, India
| | - Mengmei Zheng
- Department of Molecular Microbiology and Immunology, University of Southern California Keck School of Medicine, Los Angeles, 90033, USA
| | - Hye Yeon Choi
- Department of Molecular Microbiology and Immunology, University of Southern California Keck School of Medicine, Los Angeles, 90033, USA
| | - Tatsuya Machida
- Department of Molecular Microbiology and Immunology, University of Southern California Keck School of Medicine, Los Angeles, 90033, USA
| | - Padmini Narayanan
- Department of Molecular Microbiology and Immunology, University of Southern California Keck School of Medicine, Los Angeles, 90033, USA
| | - Yi Kou
- Viterbi School of Engineering, University of Southern California, Los Angeles, 90089, USA
| | - Vasu Punj
- Department of Medicine, Keck School of Medicine, University of Southern California, Los Angeles, 90033, USA
| | - Stanley M Tahara
- Department of Molecular Microbiology and Immunology, University of Southern California Keck School of Medicine, Los Angeles, 90033, USA
| | - Douglas E Feldman
- Department of Molecular Microbiology and Immunology, University of Southern California Keck School of Medicine, Los Angeles, 90033, USA
| | - Lin Chen
- Viterbi School of Engineering, University of Southern California, Los Angeles, 90089, USA
| | - Keigo Machida
- Department of Molecular Microbiology and Immunology, University of Southern California Keck School of Medicine, Los Angeles, 90033, USA.
- Southern California Research Center for ALPD and Cirrhosis, Los Angeles, 90033, USA.
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7
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Fan X, Yang Y, Chen C, Wang Z. Pervasive translation of circular RNAs driven by short IRES-like elements. Nat Commun 2022; 13:3751. [PMID: 35768398 PMCID: PMC9242994 DOI: 10.1038/s41467-022-31327-y] [Citation(s) in RCA: 63] [Impact Index Per Article: 31.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2021] [Accepted: 06/09/2022] [Indexed: 12/30/2022] Open
Abstract
Some circular RNAs (circRNAs) were found to be translated through IRES-driven mechanism, however the scope and functions of circRNA translation are unclear because endogenous IRESs are rare. To determine the prevalence and mechanism of circRNA translation, we develop a cell-based system to screen random sequences and identify 97 overrepresented hexamers that drive cap-independent circRNA translation. These IRES-like short elements are significantly enriched in endogenous circRNAs and sufficient to drive circRNA translation. We further identify multiple trans-acting factors that bind these IRES-like elements to initiate translation. Using mass-spectrometry data, hundreds of circRNA-coded peptides are identified, most of which have low abundance due to rapid degradation. As judged by mass-spectrometry, 50% of translatable endogenous circRNAs undergo rolling circle translation, several of which are experimentally validated. Consistently, mutations of the IRES-like element in one circRNA reduce its translation. Collectively, our findings suggest a pervasive translation of circRNAs, providing profound implications in translation control. Unbiased screen of random sequences identified many short IRES-like elements to drive circular RNA translation and hundreds of rolling circle translation events, suggesting a pervasive cap-independent translation in human transcriptome.
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Affiliation(s)
- Xiaojuan Fan
- Bio-med Big Data Center, CAS Key Laboratory of Computational Biology, CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Nutrition and Health, Shanghai, China.,University of Chinese Academy of Sciences, Chinese Academy of Sciences, Beijing, China
| | - Yun Yang
- Bio-med Big Data Center, CAS Key Laboratory of Computational Biology, CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Nutrition and Health, Shanghai, China.,CirCode BioMedicine, Pudong, Shanghai, China
| | - Chuyun Chen
- Bio-med Big Data Center, CAS Key Laboratory of Computational Biology, CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Nutrition and Health, Shanghai, China
| | - Zefeng Wang
- Bio-med Big Data Center, CAS Key Laboratory of Computational Biology, CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Nutrition and Health, Shanghai, China. .,University of Chinese Academy of Sciences, Chinese Academy of Sciences, Beijing, China.
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8
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Fan X, Zhao Z, Ma L, Huang X, Zhan Q, Song Y. PTBP1 promotes IRES-mediated translation of cyclin B1 in cancer. Acta Biochim Biophys Sin (Shanghai) 2022; 54:696-707. [PMID: 35643957 PMCID: PMC9828304 DOI: 10.3724/abbs.2022046] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2021] [Accepted: 01/11/2022] [Indexed: 11/25/2022] Open
Abstract
Cyclin B1 is an essential cyclin-dependent protein that involves in the G2/M transition. Multiple studies report that cyclin B1 is upregulated in cancers and promotes cancer progression. However, the mechanism of cyclin B1 upregulation remains unclear. Here we report that the 5'UTR of cyclin B1 mRNA contains an internal ribosome entry site (IRES) by using a bicistronic fluorescent reporter. We show that IRES can initiate the translation of cyclin B1, and the IRES-mediated translation is further activated under cell stress. Interacting trans-acting factors (ITAFs) are required by most IRES to initiate the translation. We find that PTBP1 promotes the IRES-mediated translation of cyclin B1 by binding to the 5'UTR of cyclin B1. On top of that, PTBP1 promotes the malignancy of ESCC cells. Our data suggest that the IRES-mediated translation of cyclin B1 plays an essential role in the cyclin B1 upregulation in cancers.
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Affiliation(s)
- Xinyi Fan
- State Key Laboratory of Molecular OncologyNational Cancer Center/National Clinical Research Center for Cancer/Cancer HospitalChinese Academy of Medical Sciences and Peking Union Medical CollegeBeijing 100021 China
- Department of Radiation OncologyWeill Cornell Medical CollegeNew YorkNY10065USA
| | - Zitong Zhao
- State Key Laboratory of Molecular OncologyNational Cancer Center/National Clinical Research Center for Cancer/Cancer HospitalChinese Academy of Medical Sciences and Peking Union Medical CollegeBeijing 100021 China
| | - Liying Ma
- State Key Laboratory of Molecular OncologyNational Cancer Center/National Clinical Research Center for Cancer/Cancer HospitalChinese Academy of Medical Sciences and Peking Union Medical CollegeBeijing 100021 China
| | | | - Qimin Zhan
- State Key Laboratory of Molecular OncologyNational Cancer Center/National Clinical Research Center for Cancer/Cancer HospitalChinese Academy of Medical Sciences and Peking Union Medical CollegeBeijing 100021 China
- Key Laboratory of Carcinogenesis and Translational Research (Ministry of Education/Beijing)Laboratory of Molecular OncologyPeking University Cancer Hospital & InstituteBeijing100142China
| | - Yongmei Song
- State Key Laboratory of Molecular OncologyNational Cancer Center/National Clinical Research Center for Cancer/Cancer HospitalChinese Academy of Medical Sciences and Peking Union Medical CollegeBeijing 100021 China
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9
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Liedmann S, Liu X, Guy CS, Crawford JC, Rodriguez DA, Kuzuoğlu-Öztürk D, Guo A, Verbist KC, Temirov J, Chen MJ, Ruggero D, Zhang H, Thomas PG, Green DR. Localization of a TORC1-eIF4F translation complex during CD8 + T cell activation drives divergent cell fate. Mol Cell 2022; 82:2401-2414.e9. [PMID: 35597236 DOI: 10.1016/j.molcel.2022.04.016] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2021] [Revised: 02/22/2022] [Accepted: 04/12/2022] [Indexed: 11/30/2022]
Abstract
Activated CD8+ T lymphocytes differentiate into heterogeneous subsets. Using super-resolution imaging, we found that prior to the first division, dynein-dependent vesicular transport polarized active TORC1 toward the microtubule-organizing center (MTOC) at the proximal pole. This active TORC1 was physically associated with active eIF4F, required for the translation of c-myc mRNA. As a consequence, c-myc-translating polysomes polarized toward the cellular pole proximal to the immune synapse, resulting in localized c-myc translation. Upon division, the TORC1-eIF4A complex preferentially sorted to the proximal daughter cell, facilitating asymmetric c-Myc synthesis. Transient disruption of eIF4A activity at first division skewed long-term cell fate trajectories to memory-like function. Using a genetic barcoding approach, we found that first-division sister cells often displayed differences in transcriptional profiles that largely correlated with c-Myc and TORC1 target genes. Our findings provide mechanistic insights as to how distinct T cell fate trajectories can be established during the first division.
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Affiliation(s)
- Swantje Liedmann
- Department of Immunology, St. Jude Children's Research Hospital, Memphis, TN 38105, USA.
| | - Xueyan Liu
- Department of Mathematics, University of New Orleans, New Orleans, LA 70148, USA
| | - Clifford S Guy
- Department of Immunology, St. Jude Children's Research Hospital, Memphis, TN 38105, USA
| | - Jeremy Chase Crawford
- Department of Immunology, St. Jude Children's Research Hospital, Memphis, TN 38105, USA
| | - Diego A Rodriguez
- Department of Immunology, St. Jude Children's Research Hospital, Memphis, TN 38105, USA
| | - Duygu Kuzuoğlu-Öztürk
- Department of Urology, Helen Diller Family Comprehensive Cancer Center, University of California, San Francisco, San Francisco, CA 94158, USA
| | - Ao Guo
- Department of Immunology, St. Jude Children's Research Hospital, Memphis, TN 38105, USA
| | - Katherine C Verbist
- Department of Immunology, St. Jude Children's Research Hospital, Memphis, TN 38105, USA
| | - Jamshid Temirov
- Department of Cell & Molecular Biology, St. Jude Children's Research Hospital, Memphis, TN 38105, USA
| | - Mark J Chen
- Department of Immunology, St. Jude Children's Research Hospital, Memphis, TN 38105, USA
| | - Davide Ruggero
- Department of Urology, Helen Diller Family Comprehensive Cancer Center, University of California, San Francisco, San Francisco, CA 94158, USA; Department of Cellular and Molecular Pharmacology, University of California, San Francisco, San Francisco, CA 94158, USA
| | - Hui Zhang
- Department of Preventive Medicine, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, USA
| | - Paul G Thomas
- Department of Immunology, St. Jude Children's Research Hospital, Memphis, TN 38105, USA
| | - Douglas R Green
- Department of Immunology, St. Jude Children's Research Hospital, Memphis, TN 38105, USA.
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10
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Kovalski JR, Kuzuoglu‐Ozturk D, Ruggero D. Protein synthesis control in cancer: selectivity and therapeutic targeting. EMBO J 2022; 41:e109823. [PMID: 35315941 PMCID: PMC9016353 DOI: 10.15252/embj.2021109823] [Citation(s) in RCA: 36] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2021] [Revised: 12/10/2021] [Accepted: 12/16/2021] [Indexed: 11/09/2022] Open
Abstract
Translational control of mRNAs is a point of convergence for many oncogenic signals through which cancer cells tune protein expression in tumorigenesis. Cancer cells rely on translational control to appropriately adapt to limited resources while maintaining cell growth and survival, which creates a selective therapeutic window compared to non-transformed cells. In this review, we first discuss how cancer cells modulate the translational machinery to rapidly and selectively synthesize proteins in response to internal oncogenic demands and external factors in the tumor microenvironment. We highlight the clinical potential of compounds that target different translation factors as anti-cancer therapies. Next, we detail how RNA sequence and structural elements interface with the translational machinery and RNA-binding proteins to coordinate the translation of specific pro-survival and pro-growth programs. Finally, we provide an overview of the current and emerging technologies that can be used to illuminate the mechanisms of selective translational control in cancer cells as well as within the microenvironment.
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Affiliation(s)
- Joanna R Kovalski
- Helen Diller Family Comprehensive Cancer CenterUniversity of California, San FranciscoSan FranciscoCAUSA
- Department of UrologyUniversity of California, San FranciscoSan FranciscoCAUSA
| | - Duygu Kuzuoglu‐Ozturk
- Helen Diller Family Comprehensive Cancer CenterUniversity of California, San FranciscoSan FranciscoCAUSA
- Department of UrologyUniversity of California, San FranciscoSan FranciscoCAUSA
| | - Davide Ruggero
- Helen Diller Family Comprehensive Cancer CenterUniversity of California, San FranciscoSan FranciscoCAUSA
- Department of UrologyUniversity of California, San FranciscoSan FranciscoCAUSA
- Department of Cellular and Molecular PharmacologyUniversity of California, San FranciscoSan FranciscoCAUSA
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11
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Rouse WB, Andrews RJ, Booher NJ, Wang J, Woodman M, Dow E, Jessop TC, Moss WN. Prediction and analysis of functional RNA structures within the integrative genomics viewer. NAR Genom Bioinform 2022; 4:lqab127. [PMID: 35047817 PMCID: PMC8759568 DOI: 10.1093/nargab/lqab127] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2021] [Revised: 12/03/2021] [Accepted: 12/22/2021] [Indexed: 12/14/2022] Open
Abstract
In recent years, interest in RNA secondary structure has exploded due to its implications in almost all biological functions and its newly appreciated capacity as a therapeutic agent/target. This surge of interest has driven the development and adaptation of many computational and biochemical methods to discover novel, functional structures across the genome/transcriptome. To further enhance efforts to study RNA secondary structure, we have integrated the functional secondary structure prediction tool ScanFold, into IGV. This allows users to directly perform structure predictions and visualize results—in conjunction with probing data and other annotations—in one program. We illustrate the utility of this new tool by mapping the secondary structural landscape of the human MYC precursor mRNA. We leverage the power of vast ‘omics’ resources by comparing individually predicted structures with published data including: biochemical structure probing, RNA binding proteins, microRNA binding sites, RNA modifications, single nucleotide polymorphisms, and others that allow functional inferences to be made and aid in the discovery of potential drug targets. This new tool offers the RNA community an easy to use tool to find, analyze, and characterize RNA secondary structures in the context of all available data, in order to find those worthy of further analyses.
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Affiliation(s)
| | | | | | | | | | | | | | - Walter N Moss
- To whom correspondence should be addressed. Tel: +1 515 294 6116;
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12
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RNA-Binding Proteins as Regulators of Internal Initiation of Viral mRNA Translation. Viruses 2022; 14:v14020188. [PMID: 35215780 PMCID: PMC8879377 DOI: 10.3390/v14020188] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2021] [Revised: 01/03/2022] [Accepted: 01/14/2022] [Indexed: 12/17/2022] Open
Abstract
Viruses are obligate intracellular parasites that depend on the host’s protein synthesis machinery for translating their mRNAs. The viral mRNA (vRNA) competes with the host mRNA to recruit the translational machinery, including ribosomes, tRNAs, and the limited eukaryotic translation initiation factor (eIFs) pool. Many viruses utilize non-canonical strategies such as targeting host eIFs and RNA elements known as internal ribosome entry sites (IRESs) to reprogram cellular gene expression, ensuring preferential translation of vRNAs. In this review, we discuss vRNA IRES-mediated translation initiation, highlighting the role of RNA-binding proteins (RBPs), other than the canonical translation initiation factors, in regulating their activity.
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13
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Godet AC, Roussel E, David F, Hantelys F, Morfoisse F, Alves J, Pujol F, Ader I, Bertrand E, Burlet-Schiltz O, Froment C, Henras AK, Vitali P, Lacazette E, Tatin F, Garmy-Susini B, Prats AC. Long non-coding RNA Neat1 and paraspeckle components are translational regulators in hypoxia. eLife 2022; 11:69162. [PMID: 36546462 PMCID: PMC9799981 DOI: 10.7554/elife.69162] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2021] [Accepted: 12/18/2022] [Indexed: 12/24/2022] Open
Abstract
Internal ribosome entry sites (IRESs) drive translation initiation during stress. In response to hypoxia, (lymph)angiogenic factors responsible for tissue revascularization in ischemic diseases are induced by the IRES-dependent mechanism. Here, we searched for IRES trans-acting factors (ITAFs) active in early hypoxia in mouse cardiomyocytes. Using knock-down and proteomics approaches, we show a link between a stressed-induced nuclear body, the paraspeckle, and IRES-dependent translation. Furthermore, smiFISH experiments demonstrate the recruitment of IRES-containing mRNA into paraspeckle during hypoxia. Our data reveal that the long non-coding RNA Neat1, an essential paraspeckle component, is a key translational regulator, active on IRESs of (lymph)angiogenic and cardioprotective factor mRNAs. In addition, paraspeckle proteins p54nrb and PSPC1 as well as nucleolin and RPS2, two p54nrb-interacting proteins identified by mass spectrometry, are ITAFs for IRES subgroups. Paraspeckle thus appears as a platform to recruit IRES-containing mRNAs and possibly host IRESome assembly. Polysome PCR array shows that Neat1 isoforms regulate IRES-dependent translation and, more widely, translation of mRNAs involved in stress response.
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Affiliation(s)
| | - Emilie Roussel
- UMR 1297-I2MC, Inserm, Université de ToulouseToulouseFrance
| | - Florian David
- UMR 1297-I2MC, Inserm, Université de ToulouseToulouseFrance
| | | | | | - Joffrey Alves
- UMR 1297-I2MC, Inserm, Université de ToulouseToulouseFrance
| | | | - Isabelle Ader
- UMR 1301-RESTORE, Inserm, CNRS 5070, Etablissement Français du Sang-Occitanie (EFS), National Veterinary School of Toulouse (ENVT), Université de ToulouseToulouseFrance
| | | | - Odile Burlet-Schiltz
- Institut de Pharmacologie et Biologie Structurale (IPBS), Université de Toulouse, CNRSToulouseFrance
| | - Carine Froment
- Institut de Pharmacologie et Biologie Structurale (IPBS), Université de Toulouse, CNRSToulouseFrance
| | - Anthony K Henras
- Molecular, Cellular and Developmental Biology Unit (MCD), Centre de Biologie Intégrative (CBI), Université de ToulouseToulouseFrance
| | - Patrice Vitali
- Molecular, Cellular and Developmental Biology Unit (MCD), Centre de Biologie Intégrative (CBI), Université de ToulouseToulouseFrance
| | - Eric Lacazette
- UMR 1297-I2MC, Inserm, Université de ToulouseToulouseFrance
| | - Florence Tatin
- UMR 1297-I2MC, Inserm, Université de ToulouseToulouseFrance
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14
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Hon KW, Zainal Abidin SA, Othman I, Naidu R. The Crosstalk Between Signaling Pathways and Cancer Metabolism in Colorectal Cancer. Front Pharmacol 2021; 12:768861. [PMID: 34887764 PMCID: PMC8650587 DOI: 10.3389/fphar.2021.768861] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2021] [Accepted: 11/05/2021] [Indexed: 12/12/2022] Open
Abstract
Colorectal cancer (CRC) is one of the most frequently diagnosed cancers worldwide. Metabolic reprogramming represents an important cancer hallmark in CRC. Reprogramming core metabolic pathways in cancer cells, such as glycolysis, glutaminolysis, oxidative phosphorylation, and lipid metabolism, is essential to increase energy production and biosynthesis of precursors required to support tumor initiation and progression. Accumulating evidence demonstrates that activation of oncogenes and loss of tumor suppressor genes regulate metabolic reprogramming through the downstream signaling pathways. Protein kinases, such as AKT and c-MYC, are the integral components that facilitate the crosstalk between signaling pathways and metabolic pathways in CRC. This review provides an insight into the crosstalk between signaling pathways and metabolic reprogramming in CRC. Targeting CRC metabolism could open a new avenue for developing CRC therapy by discovering metabolic inhibitors and repurposing protein kinase inhibitors/monoclonal antibodies.
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Affiliation(s)
| | | | | | - Rakesh Naidu
- Jeffrey Cheah School of Medicine and Health Sciences, Monash University Malaysia, Bandar Sunway, Malaysia
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15
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Przedborski M, Sharon D, Chan S, Kohandel M. A mean-field approach for modeling the propagation of perturbations in biochemical reaction networks. Eur J Pharm Sci 2021; 165:105919. [PMID: 34175448 DOI: 10.1016/j.ejps.2021.105919] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2021] [Revised: 05/17/2021] [Accepted: 06/20/2021] [Indexed: 12/12/2022]
Abstract
Often, the time evolution of a biochemical reaction network is crucial for determining the effects of combining multiple pharmaceuticals. Here we illustrate a mathematical framework for modeling the dominant temporal behaviour of a complicated molecular pathway or biochemical reaction network in response to an arbitrary perturbation, such as resulting from the administration of a therapeutic agent. The method enables the determination of the temporal evolution of a target protein as the perturbation propagates through its regulatory network. The mathematical approach is particularly useful when the experimental data that is available for characterizing or parameterizing the regulatory network is limited or incomplete. To illustrate the method, we consider the examples of the regulatory networks for the target proteins c-Myc and Chop, which play an important role in venetoclax resistance in acute myeloid leukemia. First we show how the networks that regulate each target protein can be reduced to a mean-field model by identifying the distinct effects that groups of proteins in the regulatory network have on the target protein. Then we show how limited protein-level data can be used to further simplify the mean-field model to pinpoint the dominant effects of the network perturbation on the target protein. This enables a further reduction in the number of parameters in the model. The result is an ordinary differential equation model that captures the temporal evolution of the expression of a target protein when one or more proteins in its regulatory network have been perturbed. Finally, we show how the dominant effects predicted by the mathematical model agree with RNA sequencing data for the regulatory proteins comprising the molecular network, despite the model not having a priori knowledge of this data. Thus, while the approach gives a simplified model for the expression of the target protein, it allows for the interpretation of the effects of the perturbation on the regulatory network itself. This method can be easily extended to sets of target proteins to model components of a larger systems biology model, and provides an approach for partially integrating RNA sequencing data and protein expression data. Moreover, it is a general approach that can be used to study drug effects on specific protein(s) in any disease or condition.
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Affiliation(s)
- Michelle Przedborski
- Department of Applied Mathematics, University of Waterloo, Waterloo, ON, Canada.
| | - David Sharon
- Princess Margaret Cancer Centre, Toronto, ON, Canada
| | - Steven Chan
- Princess Margaret Cancer Centre, Toronto, ON, Canada
| | - Mohammad Kohandel
- Department of Applied Mathematics, University of Waterloo, Waterloo, ON, Canada
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16
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van den Akker GGH, Zacchini F, Housmans BAC, van der Vloet L, Caron MMJ, Montanaro L, Welting TJM. Current Practice in Bicistronic IRES Reporter Use: A Systematic Review. Int J Mol Sci 2021; 22:5193. [PMID: 34068921 PMCID: PMC8156625 DOI: 10.3390/ijms22105193] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2021] [Revised: 05/05/2021] [Accepted: 05/12/2021] [Indexed: 12/26/2022] Open
Abstract
Bicistronic reporter assays have been instrumental for transgene expression, understanding of internal ribosomal entry site (IRES) translation, and identification of novel cap-independent translational elements (CITE). We observed a large methodological variability in the use of bicistronic reporter assays and data presentation or normalization procedures. Therefore, we systematically searched the literature for bicistronic IRES reporter studies and analyzed methodological details, data visualization, and normalization procedures. Two hundred fifty-seven publications were identified using our search strategy (published 1994-2020). Experimental studies on eukaryotic adherent cell systems and the cell-free translation assay were included for further analysis. We evaluated the following methodological details for 176 full text articles: the bicistronic reporter design, the cell line or type, transfection methods, and time point of analyses post-transfection. For the cell-free translation assay, we focused on methods of in vitro transcription, type of translation lysate, and incubation times and assay temperature. Data can be presented in multiple ways: raw data from individual cistrons, a ratio of the two, or fold changes thereof. In addition, many different control experiments have been suggested when studying IRES-mediated translation. In addition, many different normalization and control experiments have been suggested when studying IRES-mediated translation. Therefore, we also categorized and summarized their use. Our unbiased analyses provide a representative overview of bicistronic IRES reporter use. We identified parameters that were reported inconsistently or incompletely, which could hamper data reproduction and interpretation. On the basis of our analyses, we encourage adhering to a number of practices that should improve transparency of bicistronic reporter data presentation and improve methodological descriptions to facilitate data replication.
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Affiliation(s)
- Guus Gijsbertus Hubert van den Akker
- Department of Orthopedic Surgery, Maastricht University, Medical Center+, 6229 ER Maastricht, The Netherlands; (G.G.H.v.d.A.); (B.A.C.H.); (L.v.d.V.); (M.M.J.C.)
| | - Federico Zacchini
- Department of Experimental, Diagnostic and Specialty Medicine, Bologna University, I-40138 Bologna, Italy; (F.Z.); (L.M.)
- Centro di Ricerca Biomedica Applicata—CRBA, Bologna University, Policlinico di Sant’Orsola, I-40138 Bologna, Italy
| | - Bas Adrianus Catharina Housmans
- Department of Orthopedic Surgery, Maastricht University, Medical Center+, 6229 ER Maastricht, The Netherlands; (G.G.H.v.d.A.); (B.A.C.H.); (L.v.d.V.); (M.M.J.C.)
| | - Laura van der Vloet
- Department of Orthopedic Surgery, Maastricht University, Medical Center+, 6229 ER Maastricht, The Netherlands; (G.G.H.v.d.A.); (B.A.C.H.); (L.v.d.V.); (M.M.J.C.)
| | - Marjolein Maria Johanna Caron
- Department of Orthopedic Surgery, Maastricht University, Medical Center+, 6229 ER Maastricht, The Netherlands; (G.G.H.v.d.A.); (B.A.C.H.); (L.v.d.V.); (M.M.J.C.)
| | - Lorenzo Montanaro
- Department of Experimental, Diagnostic and Specialty Medicine, Bologna University, I-40138 Bologna, Italy; (F.Z.); (L.M.)
- Centro di Ricerca Biomedica Applicata—CRBA, Bologna University, Policlinico di Sant’Orsola, I-40138 Bologna, Italy
- Programma Dipartimentale in Medicina di Laboratorio, IRCCS Azienda Ospedaliero-Universitaria di Bologna, Via Albertoni 15, I-40138 Bologna, Italy
| | - Tim Johannes Maria Welting
- Department of Orthopedic Surgery, Maastricht University, Medical Center+, 6229 ER Maastricht, The Netherlands; (G.G.H.v.d.A.); (B.A.C.H.); (L.v.d.V.); (M.M.J.C.)
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17
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Alboushi L, Hackett AP, Naeli P, Bakhti M, Jafarnejad SM. Multifaceted control of mRNA translation machinery in cancer. Cell Signal 2021; 84:110037. [PMID: 33975011 DOI: 10.1016/j.cellsig.2021.110037] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2020] [Accepted: 05/06/2021] [Indexed: 12/15/2022]
Abstract
The mRNA translation machinery is tightly regulated through several, at times overlapping, mechanisms that modulate its efficiency and accuracy. Due to their fast rate of growth and metabolism, cancer cells require an excessive amount of mRNA translation and protein synthesis. However, unfavorable conditions, such as hypoxia, amino acid starvation, and oxidative stress, which are abundant in cancer, as well as many anti-cancer treatments inhibit mRNA translation. Cancer cells adapt to the various internal and environmental stresses by employing specialised transcript-specific translation to survive and gain a proliferative advantage. We will highlight the major signaling pathways and mechanisms of translation that regulate the global or mRNA-specific translation in response to the intra- or extra-cellular signals and stresses that are key components in the process of tumourigenesis.
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Affiliation(s)
- Lilas Alboushi
- Patrick G. Johnston Centre for Cancer Research, Queen's University Belfast, Belfast, UK
| | - Angela P Hackett
- Patrick G. Johnston Centre for Cancer Research, Queen's University Belfast, Belfast, UK
| | - Parisa Naeli
- Patrick G. Johnston Centre for Cancer Research, Queen's University Belfast, Belfast, UK
| | - Mostafa Bakhti
- Institute of Diabetes and Regeneration Research, Helmholtz Zentrum München, 85764 Neuherberg, Germany
| | - Seyed Mehdi Jafarnejad
- Patrick G. Johnston Centre for Cancer Research, Queen's University Belfast, Belfast, UK.
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18
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The internal ribosome entry site of the Dengue virus mRNA is active when cap-dependent translation initiation is inhibited. J Virol 2021; 95:JVI.01998-20. [PMID: 33298544 PMCID: PMC8092825 DOI: 10.1128/jvi.01998-20] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Dengue virus (DENV) is an enveloped, positive-sense, single-stranded RNA virus belonging to the Flaviviridae family. Translation initiation of the DENV mRNA can occur following a cap-dependent or a cap-independent mechanism. Two non-mutually exclusive cap-independent mechanisms of translation initiation have been described for the DENV mRNA. The first corresponds to a 5'end-dependent internal ribosome entry site (IRES)-independent mechanism, while the second relies on IRES-dependent initiation. In this report, we study the recently discovered DENV IRES. Results show that the DENV IRES is functional in the rabbit reticulocyte (RRL) in vitro translation system. In accordance, the activity of DENV IRES was resistant to the cleavage of eIF4G by the Foot-and-mouth disease virus leader protease in RRL. In cells, the DENV IRES exhibited only a marginal activity under standard culture conditions. The DENV IRES showed weak activity in HEK 293T cells; however, the DENV IRES activity was significantly enhanced in HEK 293T cells expressing the Human rhinovirus 2A protease. These findings suggest that the DENV IRES enables viral protein synthesis under conditions that suppress canonical translation initiation.IMPORTANCE Dengue virus (DENV), the etiological agent of Dengue, a febrile and hemorrhagic disease, infects millions of people per year in tropical and subtropical countries. When infecting cells, DENV induces stress conditions known to inhibit canonical protein synthesis. Under these conditions, DENV mRNA thrives using non-canonical modes of translation initiation. In this study, we characterize the mechanism dependent upon an internal ribosome entry site (IRES). Herein, we describe the activity of the DENV IRES in vitro and cells. We show that in cells, DENV IRES enables the viral mRNA to translate under conditions that suppress canonical translation initiation.
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19
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Phung B, Cieśla M, Sanna A, Guzzi N, Beneventi G, Cao Thi Ngoc P, Lauss M, Cabrita R, Cordero E, Bosch A, Rosengren F, Häkkinen J, Griewank K, Paschen A, Harbst K, Olsson H, Ingvar C, Carneiro A, Tsao H, Schadendorf D, Pietras K, Bellodi C, Jönsson G. The X-Linked DDX3X RNA Helicase Dictates Translation Reprogramming and Metastasis in Melanoma. Cell Rep 2020; 27:3573-3586.e7. [PMID: 31216476 DOI: 10.1016/j.celrep.2019.05.069] [Citation(s) in RCA: 54] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2019] [Revised: 03/22/2019] [Accepted: 05/17/2019] [Indexed: 12/15/2022] Open
Abstract
The X-linked DDX3X gene encodes an ATP-dependent DEAD-box RNA helicase frequently altered in various human cancers, including melanomas. Despite its important roles in translation and splicing, how DDX3X dysfunction specifically rewires gene expression in melanoma remains completely unknown. Here, we uncover a DDX3X-driven post-transcriptional program that dictates melanoma phenotype and poor disease prognosis. Through an unbiased analysis of translating ribosomes, we identified the microphthalmia-associated transcription factor, MITF, as a key DDX3X translational target that directs a proliferative-to-metastatic phenotypic switch in melanoma cells. Mechanistically, DDX3X controls MITF mRNA translation via an internal ribosome entry site (IRES) embedded within the 5' UTR. Through this exquisite translation-based regulatory mechanism, DDX3X steers MITF protein levels dictating melanoma metastatic potential in vivo and response to targeted therapy. Together, these findings unravel a post-transcriptional layer of gene regulation that may provide a unique therapeutic vulnerability in aggressive male melanomas.
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Affiliation(s)
- Bengt Phung
- Division of Oncology, Department of Clinical Sciences, Lund University, Lund, Sweden
| | - Maciej Cieśla
- Division of Molecular Hematology, Lund Stem Cell Center, Lund University, Lund, Sweden
| | - Adriana Sanna
- Division of Oncology, Department of Clinical Sciences, Lund University, Lund, Sweden
| | - Nicola Guzzi
- Division of Molecular Hematology, Lund Stem Cell Center, Lund University, Lund, Sweden
| | - Giulia Beneventi
- Division of Molecular Hematology, Lund Stem Cell Center, Lund University, Lund, Sweden
| | - Phuong Cao Thi Ngoc
- Division of Molecular Hematology, Lund Stem Cell Center, Lund University, Lund, Sweden
| | - Martin Lauss
- Division of Oncology, Department of Clinical Sciences, Lund University, Lund, Sweden
| | - Rita Cabrita
- Division of Oncology, Department of Clinical Sciences, Lund University, Lund, Sweden
| | - Eugenia Cordero
- Department of Laboratory Medicine, Lund University, Lund, Sweden
| | - Ana Bosch
- Division of Oncology, Department of Clinical Sciences, Lund University, Lund, Sweden
| | - Frida Rosengren
- Division of Oncology, Department of Clinical Sciences, Lund University, Lund, Sweden
| | - Jari Häkkinen
- Division of Oncology, Department of Clinical Sciences, Lund University, Lund, Sweden
| | - Klaus Griewank
- Department of Dermatology, University Hospital of Essen, Essen, Germany
| | - Annette Paschen
- Department of Dermatology, University Hospital of Essen, Essen, Germany
| | - Katja Harbst
- Division of Oncology, Department of Clinical Sciences, Lund University, Lund, Sweden
| | - Håkan Olsson
- Division of Oncology, Department of Clinical Sciences, Lund University, Lund, Sweden
| | | | - Ana Carneiro
- Division of Oncology, Department of Clinical Sciences, Lund University, Lund, Sweden; Department of Oncology and Hematology, Skåne University Hospital, Lund, Sweden
| | - Hensin Tsao
- Department of Dermatology, Harvard Medical School, Boston, MA, USA
| | - Dirk Schadendorf
- Department of Dermatology, University Hospital of Essen, Essen, Germany
| | - Kristian Pietras
- Department of Laboratory Medicine, Lund University, Lund, Sweden
| | - Cristian Bellodi
- Division of Molecular Hematology, Lund Stem Cell Center, Lund University, Lund, Sweden.
| | - Göran Jönsson
- Division of Oncology, Department of Clinical Sciences, Lund University, Lund, Sweden.
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20
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Maris C, Jayne S, Damberger FF, Beusch I, Dorn G, Ravindranathan S, Allain FHT. A transient α-helix in the N-terminal RNA recognition motif of polypyrimidine tract binding protein senses RNA secondary structure. Nucleic Acids Res 2020; 48:4521-4537. [PMID: 32170319 PMCID: PMC7192611 DOI: 10.1093/nar/gkaa155] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2019] [Revised: 02/22/2020] [Accepted: 03/04/2020] [Indexed: 12/14/2022] Open
Abstract
The polypyrimidine tract binding protein (PTB) is a multi-domain protein involved in alternative splicing, mRNA localization, stabilization, polyadenylation and translation initiation from internal ribosome entry sites (IRES). In this latter process, PTB promotes viral translation by interacting extensively with complex structured regions in the 5′-untranslated regions of viral RNAs at pyrimidine-rich targets located in single strand and hairpin regions. To better understand how PTB recognizes structured elements in RNA targets, we solved the solution structure of the N-terminal RNA recognition motif (RRM) in complex with an RNA hairpin embedding the loop sequence UCUUU, which is frequently found in IRESs of the picornovirus family. Surprisingly, a new three-turn α3 helix C-terminal to the RRM, folds upon binding the RNA hairpin. Although α3 does not mediate any contacts to the RNA, it acts as a sensor of RNA secondary structure, suggesting a role for RRM1 in detecting pyrimidine tracts in the context of structured RNA. Moreover, the degree of helix formation depends on the RNA loop sequence. Finally, we show that the α3 helix region, which is highly conserved in vertebrates, is crucial for PTB function in enhancing Encephalomyocarditis virus IRES activity.
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Affiliation(s)
| | - Sandrine Jayne
- Department of Biology, ETH Zurich, 8093 Zürich, Switzerland
| | | | - Irene Beusch
- Department of Biology, ETH Zurich, 8093 Zürich, Switzerland
| | - Georg Dorn
- Department of Biology, ETH Zurich, 8093 Zürich, Switzerland
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21
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Barrera A, Olguín V, Vera-Otarola J, López-Lastra M. Cap-independent translation initiation of the unspliced RNA of retroviruses. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2020; 1863:194583. [PMID: 32450258 DOI: 10.1016/j.bbagrm.2020.194583] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 04/08/2020] [Revised: 05/12/2020] [Accepted: 05/18/2020] [Indexed: 12/12/2022]
Abstract
Retroviruses are a unique family of RNA viruses that utilize a virally encoded reverse transcriptase (RT) to replicate their genomic RNA (gRNA) through a proviral DNA intermediate. The provirus is permanently integrated into the host cell chromosome and is expressed by the host cell transcription, RNA processing, and translation machinery. Retroviral messenger RNAs (mRNAs) entirely resemble a cellular mRNA as they have a 5'cap structure, 5'untranslated region (UTR), an open reading frame (ORF), 3'UTR, and a 3'poly(A) tail. The primary transcription product interacts with the cellular RNA processing machinery and is spliced, exported to the cytoplasm, and translated. However, a proportion of the pre-mRNA subverts typical RNA processing giving rise to the full-length RNA. In the cytoplasm, the full-length retroviral RNA fulfills a dual role acting as mRNA and as the gRNA. Simple retroviruses generate two pools of full-length RNA, one for each purpose. However, complex retroviruses have a single pool of full-length RNA, which is destined for translation or encapsidation. As for eukaryotic mRNAs, translational control of retroviral protein synthesis is mostly exerted at the step of initiation. Interestingly, some retroviral mRNAs, both simple and complex, use a dual mechanism to initiate protein synthesis, a cap-dependent initiation mechanism, or via internal initiation using an internal ribosome entry site (IRES). In this review, we describe and discuss data regarding the molecular mechanism driving the canonical cap-dependent and IRES-mediated translation initiation for retroviral mRNA, focusing the discussion mainly on the most studied retroviral mRNA, the HIV-1 mRNA.
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Affiliation(s)
- Aldo Barrera
- Laboratorio de Virología Molecular, Instituto Milenio de Inmunología e Inmunoterapia, Centro de Investigaciones Médicas, Departamento de Enfermedades Infecciosas e Inmunología Pediátrica, Escuela de Medicina, Pontificia Universidad Católica de Chile, Marcoleta 391, Santiago, Chile
| | - Valeria Olguín
- Laboratorio de Virología Molecular, Instituto Milenio de Inmunología e Inmunoterapia, Centro de Investigaciones Médicas, Departamento de Enfermedades Infecciosas e Inmunología Pediátrica, Escuela de Medicina, Pontificia Universidad Católica de Chile, Marcoleta 391, Santiago, Chile
| | - Jorge Vera-Otarola
- Laboratorio de Virología Molecular, Instituto Milenio de Inmunología e Inmunoterapia, Centro de Investigaciones Médicas, Departamento de Enfermedades Infecciosas e Inmunología Pediátrica, Escuela de Medicina, Pontificia Universidad Católica de Chile, Marcoleta 391, Santiago, Chile
| | - Marcelo López-Lastra
- Laboratorio de Virología Molecular, Instituto Milenio de Inmunología e Inmunoterapia, Centro de Investigaciones Médicas, Departamento de Enfermedades Infecciosas e Inmunología Pediátrica, Escuela de Medicina, Pontificia Universidad Católica de Chile, Marcoleta 391, Santiago, Chile.
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22
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Ultrasound Assisted Exosomal Delivery of Tissue Responsive mRNA for Enhanced Efficacy and Minimized Off-Target Effects. MOLECULAR THERAPY-NUCLEIC ACIDS 2020; 20:558-567. [PMID: 32334416 PMCID: PMC7182664 DOI: 10.1016/j.omtn.2020.03.016] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/06/2020] [Revised: 03/17/2020] [Accepted: 03/30/2020] [Indexed: 12/15/2022]
Abstract
Exosome-mediated nucleic acids delivery has been emerging as a promising strategy for gene therapy. However, the intrinsic off-target effects due to non-specific uptake of exosomes by other tissues remain the big hurdle for clinical application. In this study, we aimed to enhance the efficacy and minimize the off-target effects by simultaneously encapsulating engineered mRNA translationally activated by tissue-specific microRNA (miRNA) and increasing targeted delivery efficiency via ultrasound-targeted microbubble destruction (UTMD). Briefly, the upstream of interest transcript was engineered to harbor an internal ribosome entry site (IRES) modified with two miRNA recognition sites. In vitro reporter experiments revealed that the engineered mRNA could be encapsulated into exosomes and can be translationally activated by corresponding miRNAs in the recipient cells. By a proof-of-principle in vivo experiment, we encapsulated miR-148a (an adipose relatively specific miRNA)-responsive PGC1α mRNA into exosomes and delivered the exosomes into the adipose tissue with the aid of UTMD. Efficient PGC1α translation was activated in the adipose tissue, together with obvious browning induction. Moreover, there was much lower off-target translation of PGC1 α in lungs and other tissues. Taken together, our study establishes a novel adipose-specific exosome delivery strategy to enhance efficacy and minimize off-target effects simultaneously.
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23
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Roobol A, Roobol J, Smith ME, Carden MJ, Hershey JWB, Willis AE, Smales CM. Engineered transient and stable overexpression of translation factors eIF3i and eIF3c in CHOK1 and HEK293 cells gives enhanced cell growth associated with increased c-Myc expression and increased recombinant protein synthesis. Metab Eng 2020; 59:98-105. [PMID: 32061967 PMCID: PMC7118365 DOI: 10.1016/j.ymben.2020.02.001] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2019] [Revised: 01/31/2020] [Accepted: 02/09/2020] [Indexed: 01/23/2023]
Abstract
There is a desire to engineer mammalian host cell lines to improve cell growth/biomass accumulation and recombinant biopharmaceutical protein production in industrially relevant cell lines such as the CHOK1 and HEK293 cell lines. The over-expression of individual subunits of the eukaryotic translation factor eIF3 in mammalian cells has previously been shown to result in oncogenic properties being imparted on cells, including increased cell proliferation and growth and enhanced global protein synthesis rates. Here we report on the engineering of CHOK1 and HEK cells to over-express the eIF3i and eIF3c subunits of the eIF3 complex and the resultant impact on cell growth and a reporter of exogenous recombinant protein production. Transient over-expression of eIF3i in HEK293 and CHOK1 cells resulted in a modest increase in total eIF3i amounts (maximum 40% increase above control) and an approximate 10% increase in global protein synthesis rates in CHOK1 cells. Stable over-expression of eIF3i in CHOK1 cells was not achievable, most likely due to the already high levels of eIF3i in CHO cells compared to HEK293 cells, but was achieved in HEK293 cells. HEK293 cells engineered to over-express eIF3i had faster growth that was associated with increased c-Myc expression, achieved higher cell biomass and gave enhanced yields of a reporter of recombinant protein production. Whilst CHOK1 cells could not be engineered to over-express eIF3i directly, they could be engineered to over-express eIF3c, which resulted in a subsequent increase in eIF3i amounts and c-Myc expression. The CHOK1 eIF3c engineered cells grew to higher cell numbers and had enhanced cap- and IRES-dependent recombinant protein synthesis. Collectively these data show that engineering of subunits of the eIF3 complex can enhance cell growth and recombinant protein synthesis in mammalian cells in a cell specific manner that has implications for the engineering or selection of fast growing or high producing cells for production of recombinant proteins. We have engineered the overexpression of eIF3i and eIF3c in CHOK1 and HEK293 cells. HEK293 cells overexpressing eIF3i had faster growth and increased c-Myc expression. Direct stable overexpression of eIF3i in CHOK1 cells was not achievable. Overexpression of eIF3c in CHOK1 cells resulted in an increase in eIF3i. eIF3c overexpressing CHOK1 cells had enhanced recombinant protein synthesis.
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Affiliation(s)
- Anne Roobol
- Industrial Biotechnology Centre and School of Biosciences, University of Kent, Canterbury, Kent, CT2 7NJ, UK
| | - Joanne Roobol
- Industrial Biotechnology Centre and School of Biosciences, University of Kent, Canterbury, Kent, CT2 7NJ, UK
| | - Matthew E Smith
- Industrial Biotechnology Centre and School of Biosciences, University of Kent, Canterbury, Kent, CT2 7NJ, UK
| | - Martin J Carden
- Industrial Biotechnology Centre and School of Biosciences, University of Kent, Canterbury, Kent, CT2 7NJ, UK
| | - John W B Hershey
- Department of Biochemistry and Molecular Medicine, School of Medicine, University of California, Davis, CA, 95616, USA
| | - Anne E Willis
- MRC Toxicology Unit, University of Cambridge, Lancaster Rd, Leicester, LE1 9HN, UK.
| | - C Mark Smales
- Industrial Biotechnology Centre and School of Biosciences, University of Kent, Canterbury, Kent, CT2 7NJ, UK.
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24
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Yang Y, Wang Z. IRES-mediated cap-independent translation, a path leading to hidden proteome. J Mol Cell Biol 2019; 11:911-919. [PMID: 31504667 PMCID: PMC6884710 DOI: 10.1093/jmcb/mjz091] [Citation(s) in RCA: 128] [Impact Index Per Article: 25.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2019] [Revised: 07/05/2019] [Accepted: 07/18/2019] [Indexed: 01/06/2023] Open
Abstract
Most eukaryotic mRNAs are translated in a cap-dependent fashion; however, under stress conditions, the cap-independent translation driven by internal ribosomal entry sites (IRESs) can serve as an alternative mechanism for protein production. Many IRESs have been discovered from viral or cellular mRNAs to promote ribosome assembly and initiate translation by recruiting different trans-acting factors. Although the mechanisms of translation initiation driven by viral IRESs are relatively well understood, the existence of cellular IRESs is still under debate due to the limitations of translation reporter systems used to assay IRES activities. A recent screen identified > 1000 putative IRESs from viral and human mRNAs, expanding the scope and mechanism for cap-independent translation. Additionally, a large number of circular RNAs lacking free ends were identified in eukaryotic cells, many of which are found to be translated through IRESs. These findings suggest that IRESs may play a previously unappreciated role in driving translation of the new type of mRNA, implying a hidden proteome produced from cap-independent translation.
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Affiliation(s)
- Yun Yang
- CAS Key Laboratory of Computational Biology, Biomedical Big Data Center, CAS-MPG Partner Institute for Computational Biology, Shanghai Institute of Nutrition and Health, Chinese Academy of Sciences, Shanghai 200031, China
| | - Zefeng Wang
- CAS Key Laboratory of Computational Biology, Biomedical Big Data Center, CAS-MPG Partner Institute for Computational Biology, Shanghai Institute of Nutrition and Health, Chinese Academy of Sciences, Shanghai 200031, China
- University of Chinese Academy of Sciences, Chinese Academy of Sciences, Shanghai 200031, China
- CAS Center for Excellence in Molecular Cell Science, Chinese Academy of Sciences, Shanghai 200031, China
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25
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Spiniello M, Steinbrink MI, Cesnik AJ, Miller RM, Scalf M, Shortreed MR, Smith LM. Comprehensive in vivo identification of the c-Myc mRNA protein interactome using HyPR-MS. RNA (NEW YORK, N.Y.) 2019; 25:1337-1352. [PMID: 31296583 PMCID: PMC6800478 DOI: 10.1261/rna.072157.119] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/26/2019] [Accepted: 06/27/2019] [Indexed: 05/10/2023]
Abstract
Proteins bind mRNA through their entire life cycle from transcription to degradation. We analyzed c-Myc mRNA protein interactors in vivo using the HyPR-MS method to capture the crosslinked mRNA by hybridization and then analyzed the bound proteins using mass spectrometry proteomics. Using HyPR-MS, 229 c-Myc mRNA-binding proteins were identified, confirming previously proposed interactors, suggesting new interactors, and providing information related to the roles and pathways known to involve c-Myc. We performed structural and functional analysis of these proteins and validated our findings with a combination of RIP-qPCR experiments, in vitro results released in past studies, publicly available RIP- and eCLIP-seq data, and results from software tools for predicting RNA-protein interactions.
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Affiliation(s)
- Michele Spiniello
- Department of Chemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
- Department of Medicine of Precision, University of Studi della Campania Luigi Vanvitelli, Naples 80138, Italy
- Division of Immuno-Hematology and Transfusion Medicine, Cardarelli Hospital, Naples 80131, Italy
| | - Maisie I Steinbrink
- Department of Chemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
| | - Anthony J Cesnik
- Department of Chemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
| | - Rachel M Miller
- Department of Chemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
| | - Mark Scalf
- Department of Chemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
| | - Michael R Shortreed
- Department of Chemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
| | - Lloyd M Smith
- Department of Chemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
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26
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Inhibition of Caspase-2 Translation by the mRNA Binding Protein HuR: A Novel Path of Therapy Resistance in Colon Carcinoma Cells? Cells 2019; 8:cells8080797. [PMID: 31366165 PMCID: PMC6721497 DOI: 10.3390/cells8080797] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2019] [Revised: 07/26/2019] [Accepted: 07/29/2019] [Indexed: 12/28/2022] Open
Abstract
An increased expression and cytoplasmic abundance of the ubiquitous RNA binding protein human antigen R (HuR) is critically implicated in the dysregulated control of post- transcriptional gene expression during colorectal cancer development and is frequently associated with a high grade of malignancy and therapy resistance. Regardless of the fact that HuR elicits a broad cell survival program by increasing the stability of mRNAs coding for prominent anti-apoptotic factors, recent data suggest that HuR is critically involved in the regulation of translation, particularly, in the internal ribosome entry site (IRES) controlled translation of cell death regulatory proteins. Accordingly, data from human colon carcinoma cells revealed that HuR maintains constitutively reduced protein and activity levels of caspase-2 through negative interference with IRES-mediated translation. This review covers recent advances in the understanding of mechanisms underlying HuR's modulatory activity on IRES-triggered translation. With respect to the unique regulatory features of caspase-2 and its multiple roles (e.g., in DNA-damage-induced apoptosis, cell cycle regulation and maintenance of genomic stability), the pathophysiological consequences of negative caspase-2 regulation by HuR and its impact on therapy resistance of colorectal cancers will be discussed in detail. The negative HuR-caspase-2 axis may offer a novel target for tumor sensitizing therapies.
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27
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O’Leary CA, Andrews RJ, Tompkins VS, Chen JL, Childs-Disney JL, Disney MD, Moss WN. RNA structural analysis of the MYC mRNA reveals conserved motifs that affect gene expression. PLoS One 2019; 14:e0213758. [PMID: 31206539 PMCID: PMC6576772 DOI: 10.1371/journal.pone.0213758] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2019] [Accepted: 05/30/2019] [Indexed: 12/15/2022] Open
Abstract
The MYC gene encodes a human transcription factor and proto-oncogene that is dysregulated in over half of all known cancers. To better understand potential post-transcriptional regulatory features affecting MYC expression, we analyzed secondary structures in the MYC mRNA using a program that is optimized for finding small locally-folded motifs with a high propensity for function. This was accomplished by calculating folding metrics across the MYC sequence using a sliding analysis window and generating unique consensus base pairing models weighted by their lower-than-random predicted folding energy. A series of 30 motifs were identified, primarily in the 5' and 3' untranslated regions, which show evidence of structural conservation and compensating mutations across vertebrate MYC homologs. This analysis was able to recapitulate known elements found within an internal ribosomal entry site, as well as discover a novel element in the 3' UTR that is unusually stable and conserved. This novel motif was shown to affect MYC expression, potentially via the modulation of miRNA target accessibility or other trans-regulatory factors. In addition to providing basic insights into mechanisms that regulate MYC expression, this study provides numerous, potentially druggable RNA targets for the MYC gene, which is considered “undruggable” at the protein level.
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Affiliation(s)
- Collin A. O’Leary
- Roy J. Carver Department of Biophysics, Biochemistry and Molecular Biology, Iowa State University, Ames, IA, United States of America
| | - Ryan J. Andrews
- Roy J. Carver Department of Biophysics, Biochemistry and Molecular Biology, Iowa State University, Ames, IA, United States of America
| | - Van S. Tompkins
- Roy J. Carver Department of Biophysics, Biochemistry and Molecular Biology, Iowa State University, Ames, IA, United States of America
| | - Jonathan L. Chen
- Department of Chemistry, The Scripps Research Institute, Jupiter, FL, United States of America
| | | | - Matthew D. Disney
- Department of Chemistry, The Scripps Research Institute, Jupiter, FL, United States of America
| | - Walter N. Moss
- Roy J. Carver Department of Biophysics, Biochemistry and Molecular Biology, Iowa State University, Ames, IA, United States of America
- * E-mail:
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28
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Ji Q, Cai G, Liu X, Zhang Y, Wang Y, Zhou L, Sui H, Li Q. MALAT1 regulates the transcriptional and translational levels of proto-oncogene RUNX2 in colorectal cancer metastasis. Cell Death Dis 2019; 10:378. [PMID: 31097689 PMCID: PMC6522477 DOI: 10.1038/s41419-019-1598-x] [Citation(s) in RCA: 74] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2018] [Revised: 04/12/2019] [Accepted: 04/12/2019] [Indexed: 12/18/2022]
Abstract
Ectopic expression of lncRNA-MALAT1 has been discovered in recurrent colorectal cancer (CRC) and metastatic sites in postsurgical patients, however, its biological mechanism remained unelucidated. Our study first revealed the novel roles of MALAT1 in promoting CRC metastasis through two mechanisms: first, MALAT1 binds miR-15 family members, to “de-inhibit” their effect on LRP6 expression, enhances β-catenin signaling, leading to elevated transcriptional levels of downstream target genes RUNX2. Second, MALAT1 binds SFPQ, and dissociates SFPQ/PTBP2 dimer to release free PTBP2, which elevates translational levels of RUNX2, through interacting with IRES domain in the 5′UTR of the corresponding RUNX2 mRNAs. Moreover, increased RUNX2 expression levels were detected in recurrent CRC tumors, which were closely associated with TMN stages, metastasis, as well as CRC patients’ survival. Our study demonstrated that MALAT1 and RUNX2 may serve as two biomarkers for predicting the recurrence and metastasis of CRC patients.
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Affiliation(s)
- Qing Ji
- Department of Medical Oncology, Shuguang Hospital, Shanghai University of Traditional Chinese Medicine, 201203, Shanghai, China
| | - Guoxiang Cai
- Department of Colorectal Surgery, Fudan University Shanghai Cancer Center, 200032, Shanghai, China
| | - Xuan Liu
- Department of Medical Oncology, Shuguang Hospital, Shanghai University of Traditional Chinese Medicine, 201203, Shanghai, China
| | - Yi Zhang
- Department of Medical Oncology, Shuguang Hospital, Shanghai University of Traditional Chinese Medicine, 201203, Shanghai, China
| | - Yan Wang
- Department of Medical Oncology, Shuguang Hospital, Shanghai University of Traditional Chinese Medicine, 201203, Shanghai, China
| | - Lihong Zhou
- Department of Medical Oncology, Shuguang Hospital, Shanghai University of Traditional Chinese Medicine, 201203, Shanghai, China
| | - Hua Sui
- Department of Medical Oncology, Shuguang Hospital, Shanghai University of Traditional Chinese Medicine, 201203, Shanghai, China
| | - Qi Li
- Department of Medical Oncology, Shuguang Hospital, Shanghai University of Traditional Chinese Medicine, 201203, Shanghai, China.
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29
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Kwan T, Thompson SR. Noncanonical Translation Initiation in Eukaryotes. Cold Spring Harb Perspect Biol 2019; 11:cshperspect.a032672. [PMID: 29959190 DOI: 10.1101/cshperspect.a032672] [Citation(s) in RCA: 68] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
The vast majority of eukaryotic messenger RNAs (mRNAs) initiate translation through a canonical, cap-dependent mechanism requiring a free 5' end and 5' cap and several initiation factors to form a translationally active ribosome. Stresses such as hypoxia, apoptosis, starvation, and viral infection down-regulate cap-dependent translation during which alternative mechanisms of translation initiation prevail to express proteins required to cope with the stress, or to produce viral proteins. The diversity of noncanonical initiation mechanisms encompasses a broad range of strategies and cellular cofactors. Herein, we provide an overview and, whenever possible, a mechanistic understanding of the various noncanonical mechanisms of initiation used by cells and viruses. Despite many unanswered questions, recent advances have propelled our understanding of the scope, diversity, and mechanisms of alternative initiation.
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Affiliation(s)
- Thaddaeus Kwan
- Department of Microbiology, University of Alabama at Birmingham, Birmingham, Alabama 35294
| | - Sunnie R Thompson
- Department of Microbiology, University of Alabama at Birmingham, Birmingham, Alabama 35294
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30
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Sriram A, Bohlen J, Teleman AA. Translation acrobatics: how cancer cells exploit alternate modes of translational initiation. EMBO Rep 2018; 19:embr.201845947. [PMID: 30224410 DOI: 10.15252/embr.201845947] [Citation(s) in RCA: 61] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2018] [Revised: 07/09/2018] [Accepted: 08/16/2018] [Indexed: 12/11/2022] Open
Abstract
Recent work has brought to light many different mechanisms of translation initiation that function in cells in parallel to canonical cap-dependent initiation. This has important implications for cancer. Canonical cap-dependent translation initiation is inhibited by many stresses such as hypoxia, nutrient limitation, proteotoxic stress, or genotoxic stress. Since cancer cells are often exposed to these stresses, they rely on alternate modes of translation initiation for protein synthesis and cell growth. Cancer mutations are now being identified in components of the translation machinery and in cis-regulatory elements of mRNAs, which both control translation of cancer-relevant genes. In this review, we provide an overview on the various modes of non-canonical translation initiation, such as leaky scanning, translation re-initiation, ribosome shunting, IRES-dependent translation, and m6A-dependent translation, and then discuss the influence of stress on these different modes of translation. Finally, we present examples of how these modes of translation are dysregulated in cancer cells, allowing them to grow, to proliferate, and to survive, thereby highlighting the importance of translational control in cancer.
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Affiliation(s)
- Ashwin Sriram
- German Cancer Research Center (DKFZ), Heidelberg, Germany.,Heidelberg University, Heidelberg, Germany
| | - Jonathan Bohlen
- German Cancer Research Center (DKFZ), Heidelberg, Germany.,Heidelberg University, Heidelberg, Germany
| | - Aurelio A Teleman
- German Cancer Research Center (DKFZ), Heidelberg, Germany .,Heidelberg University, Heidelberg, Germany
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31
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Xiao JF, Sun QY, Ding LW, Chien W, Liu XY, Mayakonda A, Jiang YY, Loh XY, Ran XB, Doan NB, Castor B, Chia D, Said JW, Tan KT, Yang H, Fu XY, Lin DC, Koeffler HP. The c-MYC-BMI1 axis is essential for SETDB1-mediated breast tumourigenesis. J Pathol 2018; 246:89-102. [PMID: 29926931 DOI: 10.1002/path.5126] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2017] [Revised: 05/26/2018] [Accepted: 06/11/2018] [Indexed: 12/21/2022]
Abstract
Characterising the activated oncogenic signalling that leads to advanced breast cancer is of clinical importance. Here, we showed that SET domain, bifurcated 1 (SETDB1), a histone H3 lysine 9 methyltransferase, is aberrantly expressed and behaves as an oncogenic driver in breast cancer. SETDB1 enhances c-MYC and cyclin D1 expression by promoting the internal ribosome entry site (IRES)-mediated translation of MYC/CCND1 mRNA, resulting in prominent signalling of c-MYC to promote cell cycle progression, and provides a growth/self-renewal advantage to breast cancer cells. The activated c-MYC-BMI1 axis is essential for SETDB1-mediated breast tumourigenesis, because silencing of either c-MYC or BMI1 profoundly impairs the enhanced growth/colony formation conferred by SETDB1. Furthermore, c-MYC directly binds to the SETDB1 promoter region and enhances its transcription, suggesting a positive regulatory interplay between SETDB1 and c-MYC. In this study, we identified SETDB1 as a prominent oncogene and characterised the underlying mechanism whereby SETDB1 drives breast cancer, providing a therapeutic rationale for targeting SETDB1-BMI1 signalling in breast cancer. Copyright © 2018 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.
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Affiliation(s)
- Jin-Fen Xiao
- Cancer Science Institute of Singapore, National University of Singapore, Singapore
| | - Qiao-Yang Sun
- Cancer Science Institute of Singapore, National University of Singapore, Singapore
| | - Ling-Wen Ding
- Cancer Science Institute of Singapore, National University of Singapore, Singapore
| | - Wenwen Chien
- Division of Hematology/Oncology, Cedar-Sinai Medical Center, UCLA School of Medicine, Los Angeles, CA, USA
| | - Xin-Yu Liu
- Cancer Science Institute of Singapore, National University of Singapore, Singapore
| | - Anand Mayakonda
- Cancer Science Institute of Singapore, National University of Singapore, Singapore
| | - Yan-Yi Jiang
- Cancer Science Institute of Singapore, National University of Singapore, Singapore
| | - Xin-Yi Loh
- Cancer Science Institute of Singapore, National University of Singapore, Singapore
| | - Xue-Bin Ran
- Cancer Science Institute of Singapore, National University of Singapore, Singapore
| | - Ngan B Doan
- Department of Pathology, University of California, Los Angeles, CA, USA
| | - Brandon Castor
- Department of Pathology, University of California, Los Angeles, CA, USA
| | - David Chia
- Departments of Pathology and Laboratory Medicine, University of California, Los Angeles, CA, USA
| | - Jonathan W Said
- Department of Pathology, University of California, Los Angeles, CA, USA
| | - Kar Tong Tan
- Cancer Science Institute of Singapore, National University of Singapore, Singapore
| | - Henry Yang
- Cancer Science Institute of Singapore, National University of Singapore, Singapore
| | - Xin-Yuan Fu
- Cancer Science Institute of Singapore, National University of Singapore, Singapore.,Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore, Singapore
| | - De-Chen Lin
- Division of Hematology/Oncology, Cedar-Sinai Medical Center, UCLA School of Medicine, Los Angeles, CA, USA
| | - H Phillip Koeffler
- Cancer Science Institute of Singapore, National University of Singapore, Singapore.,Division of Hematology/Oncology, Cedar-Sinai Medical Center, UCLA School of Medicine, Los Angeles, CA, USA
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Harvey RF, Smith TS, Mulroney T, Queiroz RML, Pizzinga M, Dezi V, Villenueva E, Ramakrishna M, Lilley KS, Willis AE. Trans-acting translational regulatory RNA binding proteins. WILEY INTERDISCIPLINARY REVIEWS. RNA 2018; 9:e1465. [PMID: 29341429 PMCID: PMC5947564 DOI: 10.1002/wrna.1465] [Citation(s) in RCA: 61] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/31/2017] [Revised: 10/31/2017] [Accepted: 12/04/2017] [Indexed: 12/13/2022]
Abstract
The canonical molecular machinery required for global mRNA translation and its control has been well defined, with distinct sets of proteins involved in the processes of translation initiation, elongation and termination. Additionally, noncanonical, trans-acting regulatory RNA-binding proteins (RBPs) are necessary to provide mRNA-specific translation, and these interact with 5' and 3' untranslated regions and coding regions of mRNA to regulate ribosome recruitment and transit. Recently it has also been demonstrated that trans-acting ribosomal proteins direct the translation of specific mRNAs. Importantly, it has been shown that subsets of RBPs often work in concert, forming distinct regulatory complexes upon different cellular perturbation, creating an RBP combinatorial code, which through the translation of specific subsets of mRNAs, dictate cell fate. With the development of new methodologies, a plethora of novel RNA binding proteins have recently been identified, although the function of many of these proteins within mRNA translation is unknown. In this review we will discuss these methodologies and their shortcomings when applied to the study of translation, which need to be addressed to enable a better understanding of trans-acting translational regulatory proteins. Moreover, we discuss the protein domains that are responsible for RNA binding as well as the RNA motifs to which they bind, and the role of trans-acting ribosomal proteins in directing the translation of specific mRNAs. This article is categorized under: RNA Interactions with Proteins and Other Molecules > RNA-Protein Complexes Translation > Translation Regulation Translation > Translation Mechanisms.
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Affiliation(s)
| | - Tom S. Smith
- Cambridge Centre for Proteomics, Department of BiochemistryUniversity of CambridgeCambridgeUK
| | | | - Rayner M. L. Queiroz
- Cambridge Centre for Proteomics, Department of BiochemistryUniversity of CambridgeCambridgeUK
| | | | | | - Eneko Villenueva
- Cambridge Centre for Proteomics, Department of BiochemistryUniversity of CambridgeCambridgeUK
| | | | - Kathryn S. Lilley
- Cambridge Centre for Proteomics, Department of BiochemistryUniversity of CambridgeCambridgeUK
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Miyazaki Y, Du X, Muramatsu SI, Gomez CM. An miRNA-mediated therapy for SCA6 blocks IRES-driven translation of the CACNA1A second cistron. Sci Transl Med 2017; 8:347ra94. [PMID: 27412786 DOI: 10.1126/scitranslmed.aaf5660] [Citation(s) in RCA: 51] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2016] [Accepted: 06/21/2016] [Indexed: 12/17/2022]
Abstract
Spinocerebellar ataxia type 6 (SCA6) is a dominantly inherited neurodegenerative disease characterized by slowly progressive ataxia and Purkinje cell degeneration. SCA6 is caused by a polyglutamine repeat expansion within a second CACNA1A gene product, α1ACT. α1ACT expression is under the control of an internal ribosomal entry site (IRES) present within the CACNA1A coding region. Whereas SCA6 allele knock-in mice show indistinguishable phenotypes from wild-type littermates, expression of SCA6-associated α1ACT (α1ACTSCA6) driven by a Purkinje cell-specific promoter in mice produces slowly progressive ataxia and cerebellar atrophy. We developed an early-onset SCA6 mouse model using an adeno-associated virus (AAV)-based gene delivery system to ectopically express CACNA1A IRES-driven α1ACTSCA6 to test the potential of CACNA1A IRES-targeting therapies. Mice expressing AAV9-mediated CACNA1A IRES-driven α1ACTSCA6 exhibited early-onset ataxia, motor deficits, and Purkinje cell degeneration. We identified miR-3191-5p as a microRNA (miRNA) that targeted CACNA1A IRES and preferentially inhibited the CACNA1A IRES-driven translation of α1ACT in an Argonaute 4 (Ago4)-dependent manner. We found that eukaryotic initiation factors (eIFs), eIF4AII and eIF4GII, interacted with the CACNA1A IRES to enhance α1ACT translation. Ago4-bound miR-3191-5p blocked the interaction of eIF4AII and eIF4GII with the CACNA1A IRES, attenuating IRES-driven α1ACT translation. Furthermore, AAV9-mediated delivery of miR-3191-5p protected mice from the ataxia, motor deficits, and Purkinje cell degeneration caused by CACNA1A IRES-driven α1ACTSCA6 We have established proof of principle that viral delivery of an miRNA can rescue a disease phenotype through modulation of cellular IRES activity in a mouse model.
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Affiliation(s)
- Yu Miyazaki
- Department of Neurology, University of Chicago, Chicago, IL 60637, USA
| | - Xiaofei Du
- Department of Neurology, University of Chicago, Chicago, IL 60637, USA
| | - Shin-Ichi Muramatsu
- Division of Neurology, Department of Medicine, Jichi Medical University, Tochigi 3290498, Japan. Center for Gene and Cell Therapy, Institute of Medical Science, University of Tokyo, Tokyo 1088639, Japan
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Gritsenko AA, Weingarten-Gabbay S, Elias-Kirma S, Nir R, de Ridder D, Segal E. Sequence features of viral and human Internal Ribosome Entry Sites predictive of their activity. PLoS Comput Biol 2017; 13:e1005734. [PMID: 28922394 PMCID: PMC5630158 DOI: 10.1371/journal.pcbi.1005734] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2016] [Revised: 10/06/2017] [Accepted: 08/22/2017] [Indexed: 01/25/2023] Open
Abstract
Translation of mRNAs through Internal Ribosome Entry Sites (IRESs) has emerged as a prominent mechanism of cellular and viral initiation. It supports cap-independent translation of select cellular genes under normal conditions, and in conditions when cap-dependent translation is inhibited. IRES structure and sequence are believed to be involved in this process. However due to the small number of IRESs known, there have been no systematic investigations of the determinants of IRES activity. With the recent discovery of thousands of novel IRESs in human and viruses, the next challenge is to decipher the sequence determinants of IRES activity. We present the first in-depth computational analysis of a large body of IRESs, exploring RNA sequence features predictive of IRES activity. We identified predictive k-mer features resembling IRES trans-acting factor (ITAF) binding motifs across human and viral IRESs, and found that their effect on expression depends on their sequence, number and position. Our results also suggest that the architecture of retroviral IRESs differs from that of other viruses, presumably due to their exposure to the nuclear environment. Finally, we measured IRES activity of synthetically designed sequences to confirm our prediction of increasing activity as a function of the number of short IRES elements.
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Affiliation(s)
- Alexey A. Gritsenko
- The Delft Bioinformatics Laboratory, Department of Intelligent Systems, Delft University of Technology, Delft, The Netherlands
- Platform Green Synthetic Biology, Delft, The Netherlands
- Kluyver Centre for Genomics of Industrial Fermentation, Delft, The Netherlands
| | - Shira Weingarten-Gabbay
- Department of Computer Science and Applied Mathematics, Weizmann Institute of Science, Rehovot, Israel
- Department of Molecular Cell Biology, Weizmann Institute of Science, Rehovot, Israel
| | - Shani Elias-Kirma
- Department of Computer Science and Applied Mathematics, Weizmann Institute of Science, Rehovot, Israel
- Department of Molecular Cell Biology, Weizmann Institute of Science, Rehovot, Israel
| | - Ronit Nir
- Department of Computer Science and Applied Mathematics, Weizmann Institute of Science, Rehovot, Israel
- Department of Molecular Cell Biology, Weizmann Institute of Science, Rehovot, Israel
| | - Dick de Ridder
- The Delft Bioinformatics Laboratory, Department of Intelligent Systems, Delft University of Technology, Delft, The Netherlands
- Platform Green Synthetic Biology, Delft, The Netherlands
- Kluyver Centre for Genomics of Industrial Fermentation, Delft, The Netherlands
- Bioinformatics Group, Wageningen University, Wageningen, The Netherlands
| | - Eran Segal
- Department of Computer Science and Applied Mathematics, Weizmann Institute of Science, Rehovot, Israel
- Department of Molecular Cell Biology, Weizmann Institute of Science, Rehovot, Israel
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Shen W, Liang XH, Sun H, De Hoyos CL, Crooke ST. Depletion of NEAT1 lncRNA attenuates nucleolar stress by releasing sequestered P54nrb and PSF to facilitate c-Myc translation. PLoS One 2017; 12:e0173494. [PMID: 28288210 PMCID: PMC5348036 DOI: 10.1371/journal.pone.0173494] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2016] [Accepted: 02/21/2017] [Indexed: 12/03/2022] Open
Abstract
Altered expression of NEAT1, the architectural long non-coding RNA (lncRNA) of nuclear paraspeckles, has been reported during tumorigenesis, as well as under various cellular stress conditions. Here we report that the depletion of NEAT1 lncRNA alleviates nucleolar stress during RNAP I inhibition through releasing sequestered P54nrb and PSF to facilitate the IRES-dependent translation of c-Myc. RNAP I inhibitor CX5461 disrupts the SL1-rDNA interaction and induces nucleolar disruption, demonstrated by the accumulation of fibrillarin-containing nucleoplasmic foci and nucleolar clearance of ribosomal proteins in HeLa cells. Antisense oligonucleotide-mediated depletion of NEAT1 lncRNA significantly attenuated the RNAP I inhibition and its related nucleolar disruption. Interestingly, induction in the levels of c-Myc protein was observed in NEAT1-depeleted cells under RNAP I inhibition. NEAT1-associated paraspeckle proteins P54nrb and PSF have been reported as positive regulators of c-Myc translation through interaction with c-Myc IRES. Indeed, an increased association of P54nrb and PSF with c-Myc mRNA was observed in NEAT1-depleted cells. Moreover, apoptosis was observed in HeLa cells depleted of P54nrb and PSF, further confirming the positive involvement of P54nrb and PSF in cell proliferation. Together, our results suggest that NEAT1 depletion rescues CX5461-induced nucleolar stress through facilitating c-Myc translation by relocating P54nrb/PSF from nuclear paraspeckles to c-Myc mRNAs.
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Affiliation(s)
- Wen Shen
- Department of Core Antisense Research, IONIS Pharmaceuticals, Inc. 2855 Gazelle Court, Carlsbad, CA, United States of America
| | - Xue-hai Liang
- Department of Core Antisense Research, IONIS Pharmaceuticals, Inc. 2855 Gazelle Court, Carlsbad, CA, United States of America
| | - Hong Sun
- Department of Core Antisense Research, IONIS Pharmaceuticals, Inc. 2855 Gazelle Court, Carlsbad, CA, United States of America
| | - Cheryl L. De Hoyos
- Department of Core Antisense Research, IONIS Pharmaceuticals, Inc. 2855 Gazelle Court, Carlsbad, CA, United States of America
| | - Stanley T. Crooke
- Department of Core Antisense Research, IONIS Pharmaceuticals, Inc. 2855 Gazelle Court, Carlsbad, CA, United States of America
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Bisio A, Latorre E, Andreotti V, Bressac-de Paillerets B, Harland M, Scarra GB, Ghiorzo P, Spitale RC, Provenzani A, Inga A. The 5'-untranslated region of p16INK4a melanoma tumor suppressor acts as a cellular IRES, controlling mRNA translation under hypoxia through YBX1 binding. Oncotarget 2016; 6:39980-94. [PMID: 26498684 PMCID: PMC4741874 DOI: 10.18632/oncotarget.5387] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2015] [Accepted: 10/05/2015] [Indexed: 12/20/2022] Open
Abstract
CDKN2A/p16INK4a is an essential tumor suppressor gene that controls cell cycle progression and replicative senescence. It is also the main melanoma susceptibility gene. Here we report that p16INK4a 5'UTR mRNA acts as a cellular Internal Ribosome Entry Site (IRES). The potential for p16INK4a 5'UTR to drive cap-independent translation was evaluated by dual-luciferase assays using bicistronic and monocistronic vectors. Results of reporters' relative activities coupled to control analyses for actual bicistronic mRNA transcription, indicated that the wild type p16INK4a 5'UTR could stimulate cap-independent translation. Notably, hypoxic stress and the treatment with mTOR inhibitors enhanced the translation-stimulating property of p16INK4a 5'UTR. RNA immunoprecipitation performed in melanoma-derived SK-Mel-28 and in a patient-derived lymphoblastoid cell line indicated that YBX1 can bind the wild type p16INK4a mRNA increasing its translation efficiency, particularly during hypoxic stress. Modulation of YBX1 expression further supported its involvement in cap-independent translation of the wild type p16INK4a but not a c.-42T>A variant. RNA SHAPE assays revealed local flexibility changes for the c.-42T>A variant at the predicted YBX1 binding site region. Our results indicate that p16INK4a 5'UTR contains a cellular IRES that can enhance mRNA translation efficiency, in part through YBX1.
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Affiliation(s)
- Alessandra Bisio
- Laboratory of Transcriptional Networks, Centre for Integrative Biology, CIBIO, University of Trento, Trento, Italy
| | - Elisa Latorre
- Laboratory of Genomic Screening, Centre for Integrative Biology, CIBIO, University of Trento, Trento, Italy
| | - Virginia Andreotti
- Laboratory of Genetics of Rare Hereditary Cancers, DiMI, University of Genoa, Italy and IRCCS AOU San Martino-IST, Genoa, Italy
| | | | - Mark Harland
- Section of Epidemiology and Biostatistics, Leeds Institute of Cancer and Pathology, University of Leeds, Leeds, UK
| | - Giovanna Bianchi Scarra
- Laboratory of Genetics of Rare Hereditary Cancers, DiMI, University of Genoa, Italy and IRCCS AOU San Martino-IST, Genoa, Italy
| | - Paola Ghiorzo
- Laboratory of Genetics of Rare Hereditary Cancers, DiMI, University of Genoa, Italy and IRCCS AOU San Martino-IST, Genoa, Italy
| | - Robert C Spitale
- Department of Pharmaceutical Sciences, University of California, Irvine, CA, USA
| | - Alessandro Provenzani
- Laboratory of Genomic Screening, Centre for Integrative Biology, CIBIO, University of Trento, Trento, Italy
| | - Alberto Inga
- Laboratory of Transcriptional Networks, Centre for Integrative Biology, CIBIO, University of Trento, Trento, Italy
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KSR1 and EPHB4 Regulate Myc and PGC1β To Promote Survival of Human Colon Tumors. Mol Cell Biol 2016; 36:2246-61. [PMID: 27273865 DOI: 10.1128/mcb.00087-16] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2016] [Accepted: 05/26/2016] [Indexed: 01/05/2023] Open
Abstract
Identification and characterization of survival pathways active in tumor cells but absent in normal tissues provide opportunities to develop effective anticancer therapies with reduced toxicity to the patient. We show here that, like kinase suppressor of Ras 1 (KSR1), EPH (erythropoietin-producing hepatocellular carcinoma) receptor B4 (EPHB4) is aberrantly overexpressed in human colon tumor cell lines and selectively required for their survival. KSR1 and EPHB4 support tumor cell survival by promoting the expression of downstream targets, Myc and the transcriptional coactivator peroxisome proliferator-activated receptor gamma coactivator 1β (PGC1β). While KSR1 promotes the aberrant expression of Myc and the PGC1β protein via a posttranscriptional mechanism, EPHB4 has a greater effect on Myc and PGC1β expression via its ability to elevate mRNA levels. Subsequent analysis of the posttranscriptional regulation demonstrated that KSR1 promotes the translation of Myc protein. These findings reveal novel KSR1- and EPHB4-dependent signaling pathways supporting the survival of colorectal cancer cells through regulation of Myc and PGC1β, suggesting that inhibition of KSR1 or EPHB4 effectors may lead to selective toxicity in colorectal tumors.
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38
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Weingarten-Gabbay S, Segal E. Toward a systematic understanding of translational regulatory elements in human and viruses. RNA Biol 2016; 13:927-933. [PMID: 27442807 DOI: 10.1080/15476286.2016.1212802] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
Translational regulation is a critical step in the production of proteins from genomic material in both human and viruses. However, unlike other steps of the central dogma, such as transcriptional regulation, little is known about the cis-regulatory elements involved. In a recent study we devised a high-throughput bicistronic reporter assay for the discovery and the characterization of thousands of novel Internal Ribosome Entry Sites (IRESs) in human and hundreds of viral genomes. Our results provide insights into the landscape of IRES elements in human and viral transcripts and the cis-regulatory sequences underlying their activity. Here, we discuss these results as well as emerging insights from other studies, providing new views about translational regulation in human and viruses. In addition, we highlight recent high-throughput technologies in the field and discuss how combining insights from high- and low-throughput approaches can illuminate yet uncovered mechanisms of translational regulation.
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Affiliation(s)
- Shira Weingarten-Gabbay
- a Department of Computer Science and Applied Mathematics , Weizmann Institute of Science , Rehovot , Israel.,b Department of Molecular Cell Biology , Weizmann Institute of Science , Rehovot , Israel
| | - Eran Segal
- a Department of Computer Science and Applied Mathematics , Weizmann Institute of Science , Rehovot , Israel.,b Department of Molecular Cell Biology , Weizmann Institute of Science , Rehovot , Israel
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39
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Walters B, Thompson SR. Cap-Independent Translational Control of Carcinogenesis. Front Oncol 2016; 6:128. [PMID: 27252909 PMCID: PMC4879784 DOI: 10.3389/fonc.2016.00128] [Citation(s) in RCA: 43] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2016] [Accepted: 05/10/2016] [Indexed: 01/04/2023] Open
Abstract
Translational regulation has been shown to play an important role in cancer and tumor progression. Despite this fact, the role of translational control in cancer is an understudied and under appreciated field, most likely due to the technological hurdles and paucity of methods available to establish that changes in protein levels are due to translational regulation. Tumors are subjected to many adverse stress conditions such as hypoxia or starvation. Under stress conditions, translation is globally downregulated through several different pathways in order to conserve energy and nutrients. Many of the proteins that are synthesized during stress in order to cope with the stress use a non-canonical or cap-independent mechanism of initiation. Tumor cells have utilized these alternative mechanisms of translation initiation to promote survival during tumor progression. This review will specifically discuss the role of cap-independent translation initiation, which relies on an internal ribosome entry site (IRES) to recruit the ribosomal subunits internally to the messenger RNA. We will provide an overview of the role of IRES-mediated translation in cancer by discussing the types of genes that use IRESs and the conditions under which these mechanisms of initiation are used. We will specifically focus on three well-studied examples: Apaf-1, p53, and c-Jun, where IRES-mediated translation has been demonstrated to play an important role in tumorigenesis or tumor progression.
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Affiliation(s)
- Beth Walters
- Department of Microbiology, University of Alabama at Birmingham , Birmingham, AL , USA
| | - Sunnie R Thompson
- Department of Microbiology, University of Alabama at Birmingham , Birmingham, AL , USA
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40
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Promoter-Dependent Translation Controlled by p54nrb and hnRNPM during Myoblast Differentiation. PLoS One 2015; 10:e0136466. [PMID: 26332123 PMCID: PMC4558007 DOI: 10.1371/journal.pone.0136466] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2015] [Accepted: 08/04/2015] [Indexed: 01/08/2023] Open
Abstract
Fibroblast growth factor 1 (FGF1) is induced during myoblast differentiation at both transcriptional and translational levels. Here, we identify hnRNPM and p54nrb/NONO present in protein complexes bound to the FGF1 promoter and to the mRNA internal ribosome entry site (IRES). Knockdown or overexpression of these proteins indicate that they cooperate in activating IRES-dependent translation during myoblast differentiation, in a promoter-dependent manner. Importantly, mRNA transfection and promoter deletion experiments clearly demonstrate the impact of the FGF1 promoter on the activation of IRES-dependent translation via p54nrb and hnRNPM. Accordingly, knockdown of either p54 or hnRNPM also blocks endogenous FGF1 induction and myotube formation, demonstrating the physiological relevance of this mechanism and the role of these two proteins in myogenesis. Our study demonstrates the cooperative function of hnRNPM and p54nrb as regulators of IRES-dependent translation and indicates the involvement of a promoter-dependent mechanism.
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41
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In vitro translation in a hybrid cell free lysate with exogenous cellular ribosomes. Biochem J 2015; 467:387-98. [PMID: 25628018 DOI: 10.1042/bj20141498] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Cell free protein synthesis systems (CFPS) have been widely used to express proteins and to explore the pathways of gene expression. In the present manuscript, we describe the design of a novel adaptable hybrid in vitro translation system which is assembled with ribosomes isolated from many different origins. We first show that this hybrid system exhibits all important features such as efficiency, sensitivity, reproducibility and the ability to translate specialized mRNAs in less than 1 h. In addition, the unique design of this cell free assay makes it highly adaptable to utilize ribosomes isolated from many different organs, tissues or cell types.
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42
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Yu H, He K, Wang L, Hu J, Gu J, Zhou C, Lu R, Jin Y. Stk40 represses adipogenesis through translational control of CCAAT/enhancer-binding proteins. J Cell Sci 2015; 128:2881-90. [PMID: 26065429 DOI: 10.1242/jcs.170282] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2015] [Accepted: 06/04/2015] [Indexed: 01/08/2023] Open
Abstract
A better understanding of molecular regulation in adipogenesis might help the development of efficient strategies to cope with obesity-related diseases. Here, we report that CCAAT/enhancer-binding protein (C/EBP) β and C/EBPδ, two crucial pro-adipogenic transcription factors, are controlled at a translational level by serine/threonine kinase 40 (Stk40). Genetic knockout (KO) or knockdown (KD) of Stk40 leads to increased protein levels of C/EBP proteins and adipocyte differentiation in mouse embryonic fibroblasts (MEFs), fetal liver stromal cells, and mesenchymal stem cells (MSCs). In contrast, overexpression of Stk40 abolishes the enhanced C/EBP protein translation and adipogenesis observed in Stk40-KO and -KD cells. Functionally, knockdown of C/EBPβ eliminates the enhanced adipogenic differentiation in Stk40-KO and -KD cells substantially. Mechanistically, deletion of Stk40 enhances phosphorylation of eIF4E-binding protein 1, leading to increased eIF4E-dependent translation of C/EBPβ and C/EBPδ. Knockdown of eIF4E in MSCs decreases translation of C/EBP proteins. Moreover, Stk40-KO fetal livers display an increased adipogenic program and aberrant lipid and steroid metabolism. Collectively, our study uncovers a new repressor of C/EBP protein translation as well as adipogenesis and provides new insights into the molecular mechanism underpinning the adipogenic program.
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Affiliation(s)
- Hongyao Yu
- Laboratory of Molecular Developmental Biology, Shanghai Jiao Tong University School of Medicine, 280 South Chongqing Road, Shanghai 200025, China
| | - Ke He
- Laboratory of Molecular Developmental Biology, Shanghai Jiao Tong University School of Medicine, 280 South Chongqing Road, Shanghai 200025, China
| | - Lina Wang
- Laboratory of Molecular Developmental Biology, Shanghai Jiao Tong University School of Medicine, 280 South Chongqing Road, Shanghai 200025, China
| | - Jing Hu
- Laboratory of Molecular Developmental Biology, Shanghai Jiao Tong University School of Medicine, 280 South Chongqing Road, Shanghai 200025, China
| | - Junjie Gu
- Laboratory of Molecular Developmental Biology, Shanghai Jiao Tong University School of Medicine, 280 South Chongqing Road, Shanghai 200025, China
| | - Chenlin Zhou
- Key Laboratory of Stem Cell Biology, Institute of Health Sciences, Shanghai Institute for Biological Sciences, Chinese Academy of Sciences, 320 Yueyang Road, Shanghai 200031, China
| | - Rui Lu
- Key Laboratory of Stem Cell Biology, Institute of Health Sciences, Shanghai Institute for Biological Sciences, Chinese Academy of Sciences, 320 Yueyang Road, Shanghai 200031, China
| | - Ying Jin
- Laboratory of Molecular Developmental Biology, Shanghai Jiao Tong University School of Medicine, 280 South Chongqing Road, Shanghai 200025, China Key Laboratory of Stem Cell Biology, Institute of Health Sciences, Shanghai Institute for Biological Sciences, Chinese Academy of Sciences, 320 Yueyang Road, Shanghai 200031, China
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43
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Csibi A, Lee G, Yoon SO, Tong H, Ilter D, Elia I, Fendt SM, Roberts TM, Blenis J. The mTORC1/S6K1 pathway regulates glutamine metabolism through the eIF4B-dependent control of c-Myc translation. Curr Biol 2014; 24:2274-80. [PMID: 25220053 DOI: 10.1016/j.cub.2014.08.007] [Citation(s) in RCA: 204] [Impact Index Per Article: 20.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2013] [Revised: 07/12/2014] [Accepted: 08/05/2014] [Indexed: 12/13/2022]
Abstract
Growth-promoting signaling molecules, including the mammalian target of rapamycin complex 1 (mTORC1), drive the metabolic reprogramming of cancer cells required to support their biosynthetic needs for rapid growth and proliferation. Glutamine is catabolyzed to α-ketoglutarate (αKG), a tricarboxylic acid (TCA) cycle intermediate, through two deamination reactions, the first requiring glutaminase (GLS) to generate glutamate and the second occurring via glutamate dehydrogenase (GDH) or transaminases. Activation of the mTORC1 pathway has been shown previously to promote the anaplerotic entry of glutamine to the TCA cycle via GDH. Moreover, mTORC1 activation also stimulates the uptake of glutamine, but the mechanism is unknown. It is generally thought that rates of glutamine utilization are limited by mitochondrial uptake via GLS, suggesting that, in addition to GDH, mTORC1 could regulate GLS. Here we demonstrate that mTORC1 positively regulates GLS and glutamine flux through this enzyme. We show that mTORC1 controls GLS levels through the S6K1-dependent regulation of c-Myc (Myc). Molecularly, S6K1 enhances Myc translation efficiency by modulating the phosphorylation of eukaryotic initiation factor eIF4B, which is critical to unwind its structured 5' untranslated region (5'UTR). Finally, our data show that the pharmacological inhibition of GLS is a promising target in pancreatic cancers expressing low levels of PTEN.
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Affiliation(s)
- Alfredo Csibi
- Department of Cell Biology, Harvard Medical School, 240 Longwood Avenue, Boston, MA 02115, USA
| | - Gina Lee
- Department of Cell Biology, Harvard Medical School, 240 Longwood Avenue, Boston, MA 02115, USA
| | - Sang-Oh Yoon
- Department of Cell Biology, Harvard Medical School, 240 Longwood Avenue, Boston, MA 02115, USA
| | - Haoxuan Tong
- Department of Cancer Biology, Dana Farber Cancer Institute and Harvard Medical School, Boston, MA 02115, USA
| | - Didem Ilter
- Department of Cell Biology, Harvard Medical School, 240 Longwood Avenue, Boston, MA 02115, USA; Department of Pharmacology, Meyer Cancer Center, Weill Cornell Medical College, New York, NY 10065, USA
| | - Ilaria Elia
- Flemish Institute of Biotechnology (VIB), Vesalius Research Center, Herestraat 49, 3000 Leuven, Belgium; Department of Oncology, KU Leuven-University of Leuven, Herestraat 49, 3000 Leuven, Belgium
| | - Sarah-Maria Fendt
- Flemish Institute of Biotechnology (VIB), Vesalius Research Center, Herestraat 49, 3000 Leuven, Belgium; Department of Oncology, KU Leuven-University of Leuven, Herestraat 49, 3000 Leuven, Belgium
| | - Thomas M Roberts
- Department of Cancer Biology, Dana Farber Cancer Institute and Harvard Medical School, Boston, MA 02115, USA
| | - John Blenis
- Department of Cell Biology, Harvard Medical School, 240 Longwood Avenue, Boston, MA 02115, USA; Department of Pharmacology, Meyer Cancer Center, Weill Cornell Medical College, New York, NY 10065, USA.
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Wein N, Vulin A, Sofia Falzarano M, Al-Khalili Szigyarto C, Maiti B, Findlay A, Heller KN, Uhlén M, Bakthavachalu B, Messina S, Vita G, Passarelli C, Gualandi F, Wilton SD, Rodino-Klapac L, Yang L, Dunn DM, Schoenberg D, Weiss RB, Howard MT, Ferlini A, Flanigan KM. Translation from a DMD exon 5 IRES results in a functional dystrophin isoform that attenuates dystrophinopathy in humans and mice. Nat Med 2014; 20:992-1000. [PMID: 25108525 PMCID: PMC4165597 DOI: 10.1038/nm.3628] [Citation(s) in RCA: 89] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2014] [Accepted: 06/05/2014] [Indexed: 12/26/2022]
Abstract
Most mutations that truncate the reading frame of the DMD gene cause loss of dystrophin expression and lead to Duchenne muscular dystrophy. However, amelioration of disease severity has been shown to result from alternative translation initiation beginning in DMD exon 6 that leads to expression of a highly functional N-truncated dystrophin. Here we demonstrate that this isoform results from usage of an internal ribosome entry site (IRES) within exon 5 that is glucocorticoid inducible. We confirmed IRES activity by both peptide sequencing and ribosome profiling in muscle from individuals with minimal symptoms despite the presence of truncating mutations. We generated a truncated reading frame upstream of the IRES by exon skipping, which led to synthesis of a functional N-truncated isoform in both human subject-derived cell lines and in a new DMD mouse model, where expression of the truncated isoform protected muscle from contraction-induced injury and corrected muscle force to the same level as that observed in control mice. These results support a potential therapeutic approach for patients with mutations within the 5' exons of DMD.
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Affiliation(s)
- Nicolas Wein
- The Center for Gene Therapy, Nationwide Children’s Hospital; The Ohio State University, Columbus, Ohio, USA
| | - Adeline Vulin
- The Center for Gene Therapy, Nationwide Children’s Hospital; The Ohio State University, Columbus, Ohio, USA
| | - Maria Sofia Falzarano
- Section of Microbiology and Medical Genetics, Department of Medical Sciences, University of Ferrara, Ferrara, Italy
| | - Christina Al-Khalili Szigyarto
- Department of Proteomics and Nanobiotechnology, School of Biotechnology, KTH-Royal Institute of Technology, Stockholm, Sweden
| | - Baijayanta Maiti
- Department of Neurology, Washington University School of Medicine, St. Louis, Missouri
| | - Andrew Findlay
- The Center for Gene Therapy, Nationwide Children’s Hospital; The Ohio State University, Columbus, Ohio, USA
| | - Kristin N Heller
- The Center for Gene Therapy, Nationwide Children’s Hospital; The Ohio State University, Columbus, Ohio, USA
| | - Mathias Uhlén
- Department of Proteomics and Nanobiotechnology, School of Biotechnology, KTH-Royal Institute of Technology, Stockholm, Sweden
| | - Baskar Bakthavachalu
- Center for RNA Biology and Department of Molecular and Cellular Biochemistry, The Ohio State University, Columbus, Ohio, USA
| | - Sonia Messina
- Department of Neuroscience, University of Messina and Centro Clinico Nemo Sud, Messina, Italy
| | - Giuseppe Vita
- Department of Neuroscience, University of Messina and Centro Clinico Nemo Sud, Messina, Italy
| | | | - Francesca Gualandi
- Section of Microbiology and Medical Genetics, Department of Medical Sciences, University of Ferrara, Ferrara, Italy
| | - Steve D Wilton
- Centre for Comparative Genomics, Murdoch University, Perth, Australia
| | - Louise Rodino-Klapac
- The Center for Gene Therapy, Nationwide Children’s Hospital; The Ohio State University, Columbus, Ohio, USA
- Department of Pediatrics, The Ohio State University, Columbus, Ohio, USA
| | - Lin Yang
- Division of Biomedical Informatics, Department of Computer Science, University of Kentucky Lexington, Kentucky, USA
| | - Diane M. Dunn
- Department of Human Genetics, The University of Utah School of Medicine, Salt Lake City, Utah, USA
| | - Daniel Schoenberg
- Center for RNA Biology and Department of Molecular and Cellular Biochemistry, The Ohio State University, Columbus, Ohio, USA
| | - Robert B. Weiss
- Department of Human Genetics, The University of Utah School of Medicine, Salt Lake City, Utah, USA
| | - Michael T. Howard
- Department of Human Genetics, The University of Utah School of Medicine, Salt Lake City, Utah, USA
| | - Alessandra Ferlini
- Section of Microbiology and Medical Genetics, Department of Medical Sciences, University of Ferrara, Ferrara, Italy
| | - Kevin M. Flanigan
- The Center for Gene Therapy, Nationwide Children’s Hospital; The Ohio State University, Columbus, Ohio, USA
- Department of Pediatrics, The Ohio State University, Columbus, Ohio, USA
- Department of Neurology, The Ohio State University, Columbus, Ohio, USA
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Yong J, Grankvist N, Han J, Kaufman RJ. Eukaryotic translation initiation factor 2 α phosphorylation as a therapeutic target in diabetes. Expert Rev Endocrinol Metab 2014; 9:345-356. [PMID: 30763994 DOI: 10.1586/17446651.2014.927309] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Regulation of mRNA translation is of vital importance for a cell to adapt to environmental changes. To serve this purpose, intricate mechanisms controlling mRNA translation have evolved, of which the eukaryotic initiation factors eIF2 and eIF4 represent essential regulatory nodes for both stress sensing and signal transduction. Stress sensing by eIF2 α subunit (eIF2α) kinases, translation regulation by eIF2α subunit phosphorylation and subsequent dephosphorylation constitute a core molecular switch for stress adaptation and rapid metabolic regulation. It is not surprising; therefore, that dysfunction of such a pathway is implicated in human disease, especially metabolic syndrome and diabetes. In theory, therapeutic intervention to target the eIF2α phosphorylation pathway provides a promising therapeutic solution to tackle this debilitating syndrome. Careful evaluation of such therapies is crucially needed considering the central role of eIF2α pathway in cellular function for every organ.
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Affiliation(s)
| | | | - Jaeseok Han
- a Degenerative Diseases Program, Sanford|Burnham Medical Research Institute, 10901 North Torrey Pines Road, La Jolla, CA 92037, USA
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Souii A, Ben M'hadheb-Gharbi M, Gharbi J. Role of RNA structure motifs in IRES-dependent translation initiation of the coxsackievirus B3: new insights for developing live-attenuated strains for vaccines and gene therapy. Mol Biotechnol 2014; 55:179-202. [PMID: 23881360 DOI: 10.1007/s12033-013-9674-4] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Internal ribosome entry site (IRES) elements are highly structured RNA sequences that function to recruit ribosomes for the initiation of translation. In contrast to the canonical cap-binding, the mechanism of IRES-mediated translation initiation is still poorly understood. Translation initiation of the coxsackievirus B3 (CVB3), a causative agent of viral myocarditis, has been shown to be mediated by a highly ordered structure of the 5' untranslated region (5'UTR), which harbors an IRES. Taking into account that efficient initiation of mRNA translation depends on temporally and spatially orchestrated sequence of RNA-protein and RNA-RNA interactions, and that, at present, little is known about these interactions, we aimed to describe recent advances in our understanding of molecular structures and biochemical functions of the translation initiation process. Thus, this review will explore the IRES elements as important RNA structures and the significance of these structures in providing an alternative mechanism of translation initiation of the CVB3 RNA. Since translation initiation is the first intracellular step during the CVB3 infection cycle, the IRES region provides an ideal target for antiviral therapies. Interestingly, the 5' and 3'UTRs represent promising candidates for the study of CVB3 cardiovirulence and provide new insights for developing live-attenuated vaccines.
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Affiliation(s)
- Amira Souii
- Institut Supérieur de Biotechnologie de Monastir-Université de Monastir, Avenue Tahar Hadded, BP 74, 5000, Monastir, Tunisia
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Remodelling of a polypyrimidine tract-binding protein complex during apoptosis activates cellular IRESs. Cell Death Differ 2013; 21:161-71. [PMID: 24141718 PMCID: PMC3857619 DOI: 10.1038/cdd.2013.135] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2013] [Revised: 08/29/2013] [Accepted: 08/30/2013] [Indexed: 01/08/2023] Open
Abstract
Post-transcriptional control of gene expression is mediated by the interaction of RNA-binding proteins with their cognate mRNAs that specifically regulate their stability, localization and translation. mRNA-binding proteins are multifunctional and it has been proposed therefore that a combinatorial RNA-binding protein code exists that allows specific protein sub-complexes to control cytoplasmic gene expression under a range of pathophysiological conditions. We show that polypyrimidine tract-binding protein (PTB) is central to one such complex that forms in apoptotic cells. Thus, during apoptosis initiated by TNF-related apoptosis inducing ligand there is a change in the repertoire of RNA-binding proteins with which PTB interacts. We show that altering the cellular levels of PTB and its binding partners, either singly or in combination, is sufficient to directly change the rates of apoptosis with increased expression of PTB, YBX1, PSF and NONO/p54nrb accelerating this process. Mechanistically, we show that these proteins post-transcriptionally regulate gene expression, and therefore apoptotic rates, by interacting with and stimulating the activity of RNA elements (internal ribosome entry segments) found in mRNAs that are translated during apoptosis. Taken together, our data show that PTB function is controlled by a set of co-recruited proteins and importantly provide further evidence that it is possible to dictate cell fate by modulating cytoplasmic gene expression pathways alone.
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Plank TDM, Whitehurst JT, Kieft JS. Cell type specificity and structural determinants of IRES activity from the 5' leaders of different HIV-1 transcripts. Nucleic Acids Res 2013; 41:6698-714. [PMID: 23661682 PMCID: PMC3711417 DOI: 10.1093/nar/gkt358] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Internal ribosome entry site (IRES) RNAs are important regulators of gene expression, but their diverse molecular mechanisms remain partially understood. The HIV-1 gag transcript leader contains an IRES that may be a good model for understanding the function of many other IRESs. We investigated the possibility that this IRES’ function is linked to both the structure of the RNA and its cellular environment. We find that in the context of a bicistronic reporter construct, HIV-1 gag IRES’ activity is cell type-specific, with higher activity in T-cell culture systems that model the natural target cells for HIV-1 infection. This finding underscores how an IRES may be fine tuned to function in certain cells, perhaps owing to cell type-specific protein factors. Using RNA probing and mutagenesis, we demonstrate that the HIV-1 gag IRES does not use pre-folded RNA structure to drive function, a finding that gives insight into how conformationally dynamic IRESs operate. Furthermore, we find that a common exon drives IRES activity in a diverse set of alternatively spliced transcripts. We propose a mechanism in which a structurally plastic RNA element confers the ability to initiate translation internally, and activity from this common element is modulated by 3′ nucleotides added by alternative splicing.
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Affiliation(s)
- Terra-Dawn M Plank
- Department of Biochemistry and Molecular Genetics, University of Colorado Denver, School of Medicine, Aurora, Colorado, 80045, USA
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Abstract
Internal ribosome entry sites/segments (IRESs) were first discovered over 20 years ago in picornaviruses, followed by the discovery of two other types of IRES in hepatitis C virus (HCV), and the dicistroviruses, which infect invertebrates. In the meantime, reports of IRESs in eukaryotic cellular mRNAs started to appear, and the list of such putative IRESs continues to grow to the point in which it now stands at ~100, 80% of them in vertebrate mRNAs. Despite initial skepticism from some quarters, there now seems universal agreement that there is genuine internal ribosome entry on the viral IRESs. However, the same cannot be said for cellular mRNA IRESs, which continue to be shrouded in controversy. The aim of this article is to explain why vertebrate mRNA IRESs remain controversial, and to discuss ways in which these controversies might be resolved.
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Affiliation(s)
- Richard J Jackson
- Department of Biochemistry, University of Cambridge, Cambridge CB2 1QW, United Kingdom.
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50
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An upstream open reading frame modulates ebola virus polymerase translation and virus replication. PLoS Pathog 2013; 9:e1003147. [PMID: 23382680 PMCID: PMC3561295 DOI: 10.1371/journal.ppat.1003147] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2012] [Accepted: 12/06/2012] [Indexed: 12/18/2022] Open
Abstract
Ebolaviruses, highly lethal zoonotic pathogens, possess longer genomes than most other non-segmented negative-strand RNA viruses due in part to long 5′ and 3′ untranslated regions (UTRs) present in the seven viral transcriptional units. To date, specific functions have not been assigned to these UTRs. With reporter assays, we demonstrated that the Zaire ebolavirus (EBOV) 5′-UTRs lack internal ribosomal entry site function. However, the 5′-UTRs do differentially regulate cap-dependent translation when placed upstream of a GFP reporter gene. Most dramatically, the 5′-UTR derived from the viral polymerase (L) mRNA strongly suppressed translation of GFP compared to a β-actin 5′-UTR. The L 5′-UTR is one of four viral genes to possess upstream AUGs (uAUGs), and ablation of each uAUG enhanced translation of the primary ORF (pORF), most dramatically in the case of the L 5′-UTR. The L uAUG was sufficient to initiate translation, is surrounded by a “weak” Kozak sequence and suppressed pORF translation in a position-dependent manner. Under conditions where eIF2α was phosphorylated, the presence of the uORF maintained translation of the L pORF, indicating that the uORF modulates L translation in response to cellular stress. To directly address the role of the L uAUG in virus replication, a recombinant EBOV was generated in which the L uAUG was mutated to UCG. Strikingly, mutating two nucleotides outside of previously-defined protein coding and cis-acting regulatory sequences attenuated virus growth to titers 10–100-fold lower than a wild-type virus in Vero and A549 cells. The mutant virus also exhibited decreased viral RNA synthesis as early as 6 hours post-infection and enhanced sensitivity to the stress inducer thapsigargin. Cumulatively, these data identify novel mechanisms by which EBOV regulates its polymerase expression, demonstrate their relevance to virus replication and identify a potential therapeutic target. Filoviruses (Ebola and Marburg viruses) are emerging zoonotic pathogens that cause lethal hemorrhagic fever in humans and have the potential to be employed as bioterrorism agents. Currently, approved therapeutics to treat filovirus infections are not available and new treatment strategies could be facilitated by improved mechanistic insight into the virus replication cycle. Compared to other related viruses, filovirus messenger RNAs have unusually long 5′ untranslated regions (UTRs) with undefined functions. In the Zaire ebolavirus (EBOV) genome, four of its seven messenger RNAs have 5′-UTRs with a small upstream open reading frame (uORF). We found that a uORF present in the EBOV polymerase (L) 5′-UTR suppresses L protein production and established a reporter assay to demonstrate that this uORF maintains L translation following the induction of an innate immune response; a phenomenon observed with several uORF-containing cellular messenger RNAs. The presence of the uORF is important for optimal virus replication, because a mutant virus lacking the upstream reading frame replicates less efficiently than a wildtype virus, an attenuation which is more pronounced following the induction of cellular stress. These studies define a novel mechanism by which filovirus upstream open reading frames modulate virus protein translation in the face of an innate immune response and highlight their importance in filovirus replication.
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