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Borden KLB. The eukaryotic translation initiation factor eIF4E unexpectedly acts in splicing thereby coupling mRNA processing with translation: eIF4E induces widescale splicing reprogramming providing system-wide connectivity between splicing, nuclear mRNA export and translation. Bioessays 2024; 46:e2300145. [PMID: 37926700 PMCID: PMC11021180 DOI: 10.1002/bies.202300145] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2023] [Revised: 10/17/2023] [Accepted: 10/24/2023] [Indexed: 11/07/2023]
Abstract
Recent findings position the eukaryotic translation initiation factor eIF4E as a novel modulator of mRNA splicing, a process that impacts the form and function of resultant proteins. eIF4E physically interacts with the spliceosome and with some intron-containing transcripts implying a direct role in some splicing events. Moreover, eIF4E drives the production of key components of the splicing machinery underpinning larger scale impacts on splicing. These drive eIF4E-dependent reprogramming of the splicing signature. This work completes a series of studies demonstrating eIF4E acts in all the major mRNA maturation steps whereby eIF4E drives production of the RNA processing machinery and escorts some transcripts through various maturation steps. In this way, eIF4E couples the mRNA processing-export-translation axis linking nuclear mRNA processing to cytoplasmic translation. eIF4E elevation is linked to worse outcomes in acute myeloid leukemia patients where these activities are dysregulated. Understanding these effects provides new insight into post-transcriptional control and eIF4E-driven cancers.
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Affiliation(s)
- Katherine L. B. Borden
- Institute for Research in Immunology and Cancer and Department of Pathology and Cell BiologyUniversity of MontrealMontrealQuebecCanada
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2
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Nemes K, Gil JF, Liebe S, Mansi M, Poimenopoulou E, Lennefors BL, Varrelmann M, Savenkov EI. Intermolecular base-pairing interactions, a unique topology and exoribonuclease-resistant noncoding RNAs drive formation of viral chimeric RNAs in plants. THE NEW PHYTOLOGIST 2024; 241:861-877. [PMID: 37897070 DOI: 10.1111/nph.19346] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/04/2023] [Accepted: 10/02/2023] [Indexed: 10/29/2023]
Abstract
In plants, exoribonuclease-resistant RNAs (xrRNAs) are produced by many viruses. Whereas xrRNAs contribute to the pathogenicity of these viruses, the role of xrRNAs in the virus infectious cycle remains elusive. Here, we show that xrRNAs produced by a benyvirus (a multipartite RNA virus with four genomic segments) in plants are involved in the formation of monocistronic coat protein (CP)-encoding chimeric RNAs. Naturally occurring chimeric RNAs, we discovered, are composed of 5'-end of RNA 2 and 3'-end of either RNA 3 or RNA 4 bearing conservative exoribonuclease-resistant 'coremin' region. Using computational tools and site-directed mutagenesis, we show that de novo formation of chimeric RNAs requires intermolecular base-pairing interaction between 'coremin' and 3'-proximal part of the CP gene of RNA 2 as well as a stem-loop structure immediately adjacent to the CP gene. Moreover, knockdown of the expression of the XRN4 gene, encoding 5'→3' exoribonuclease, inhibits biogenesis of both xrRNAs and chimeric RNAs. Our findings suggest a novel mechanism involving a unique tropology of the intermolecular base-pairing complex between xrRNAs and RNA2 to promote formation of chimeric RNAs in plants. XrRNAs, essential for chimeric RNA biogenesis, are generated through the action of cytoplasmic Xrn 4 5'→3' exoribonuclease conserved in all plant species.
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Affiliation(s)
- Katalin Nemes
- Department of Plant Biology, Linnean Center for Plant Biology, Swedish University of Agricultural Sciences (SLU), Uppsala, 75007, Sweden
| | - Jose F Gil
- Department of Plant Biology, Linnean Center for Plant Biology, Swedish University of Agricultural Sciences (SLU), Uppsala, 75007, Sweden
- VEDAS Corporación de Investigación e Innovación (VEDAS CII), Medellín, 050024, Colombia
| | - Sebastian Liebe
- Department of Phytopathology, Institute of Sugar Beet Research, Göttingen, 37079, Germany
| | - Mansi Mansi
- Department of Plant Biology, Linnean Center for Plant Biology, Swedish University of Agricultural Sciences (SLU), Uppsala, 75007, Sweden
| | - Efstratia Poimenopoulou
- Department of Plant Biology, Linnean Center for Plant Biology, Swedish University of Agricultural Sciences (SLU), Uppsala, 75007, Sweden
| | | | - Mark Varrelmann
- Department of Phytopathology, Institute of Sugar Beet Research, Göttingen, 37079, Germany
| | - Eugene I Savenkov
- Department of Plant Biology, Linnean Center for Plant Biology, Swedish University of Agricultural Sciences (SLU), Uppsala, 75007, Sweden
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3
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Hernández G, Vazquez-Pianzola P. eIF4E as a molecular wildcard in metazoans RNA metabolism. Biol Rev Camb Philos Soc 2023; 98:2284-2306. [PMID: 37553111 DOI: 10.1111/brv.13005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2023] [Revised: 07/01/2023] [Accepted: 07/25/2023] [Indexed: 08/10/2023]
Abstract
The evolutionary origin of eukaryotes spurred the transition from prokaryotic-like translation to a more sophisticated, eukaryotic translation. During this process, successive gene duplication of a single, primordial eIF4E gene encoding the mRNA cap-binding protein eukaryotic translation initiation factor 4E (eIF4E) gave rise to a plethora of paralog genes across eukaryotes that underwent further functional diversification in RNA metabolism. The ability to take different roles is due to eIF4E promiscuity in binding many partner proteins, rendering eIF4E a highly versatile and multifunctional player that functions as a molecular wildcard. Thus, in metazoans, eIF4E paralogs are involved in various processes, including messenger RNA (mRNA) processing, export, translation, storage, and decay. Moreover, some paralogs display differential expression in tissues and developmental stages and show variable biochemical properties. In this review, we discuss recent advances shedding light on the functional diversification of eIF4E in metazoans. We emphasise humans and two phylogenetically distant species which have become paradigms for studies on development, namely the fruit fly Drosophila melanogaster and the roundworm Caenorhabditis elegans.
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Affiliation(s)
- Greco Hernández
- mRNA and Cancer Laboratory, Unit of Biomedical Research on Cancer, National Institute of Cancer (Instituto Nacional de Cancerología, INCan), 22 San Fernando Ave., Tlalpan, Mexico City, 14080, Mexico
| | - Paula Vazquez-Pianzola
- Institute of Cell Biology, University of Bern, Baltzerstrasse 4, Berne, 3012, Switzerland
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4
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Assouline S, Gasiorek J, Bergeron J, Lambert C, Culjkovic-Kraljacic B, Cocolakis E, Zakaria C, Szlachtycz D, Yee K, Borden KLB. Molecular targeting of the UDP-glucuronosyltransferase enzymes in high-eukaryotic translation initiation factor 4E refractory/relapsed acute myeloid leukemia patients: a randomized phase II trial of vismodegib, ribavirin with or without decitabine. Haematologica 2023; 108:2946-2958. [PMID: 36951168 PMCID: PMC10620574 DOI: 10.3324/haematol.2023.282791] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2023] [Accepted: 03/16/2023] [Indexed: 03/24/2023] Open
Abstract
Drug resistance underpins poor outcomes in many malignancies including refractory and relapsed acute myeloid leukemia (R/R AML). Glucuronidation is a common mechanism of drug inactivation impacting many AML therapies, e.g., cytarabine, decitabine, azacytidine and venetoclax. In AML cells, the capacity for glucuronidation arises from increased production of the UDP-glucuronosyltransferase 1A (UGT1A) enzymes. UGT1A elevation was first observed in AML patients who relapsed after response to ribavirin, a drug used to target the eukaryotic translation initiation factor eIF4E, and subsequently in patients who relapsed on cytarabine. UGT1A elevation resulted from increased expression of the sonic-hedgehog transcription factor GLI1. Vismodegib inhibited GLI1, decreased UGT1A levels, reduced glucuronidation of ribavirin and cytarabine, and re-sensitized cells to these drugs. Here, we examined if UGT1A protein levels, and thus glucuronidation activity, were targetable in humans and if this corresponded to clinical response. We conducted a phase II trial using vismodegib with ribavirin, with or without decitabine, in largely heavily pre-treated patients with high-eIF4E AML. Pre-therapy molecular assessment of patients' blasts indicated highly elevated UGT1A levels relative to healthy volunteers. Among patients with partial response, blast response or prolonged stable disease, vismodegib reduced UGT1A levels, which corresponded to effective targeting of eIF4E by ribavirin. In all, our studies are the first to demonstrate that UGT1A protein, and thus glucuronidation, are targetable in humans. These studies pave the way for the development of therapies that impair glucuronidation, one of the most common drug deactivation modalities. Clinicaltrials.gov: NCT02073838.
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Affiliation(s)
- Sarit Assouline
- Jewish General Hospital and McGill University 3755 Cote Ste Catherine, Montreal, Quebec H3T1E2.
| | - Jadwiga Gasiorek
- Institute for Research in Immunology and Cancer and Department of Pathology and Cell Biology, University of Montreal, Montreal, Quebec
| | - Julie Bergeron
- CEMTL installation Maisonneuve Rosemont, 5415 boul. de l'Assomption, Montreal H1T 2M4
| | - Caroline Lambert
- Institute for Research in Immunology and Cancer and Department of Pathology and Cell Biology, University of Montreal, Montreal, Quebec
| | - Biljana Culjkovic-Kraljacic
- Institute for Research in Immunology and Cancer and Department of Pathology and Cell Biology, University of Montreal, Montreal, Quebec
| | - Eftihia Cocolakis
- Jewish General Hospital and McGill University 3755 Cote Ste Catherine, Montreal, Quebec H3T1E2
| | - Chadi Zakaria
- Jewish General Hospital and McGill University 3755 Cote Ste Catherine, Montreal, Quebec H3T1E2
| | - David Szlachtycz
- Jewish General Hospital and McGill University 3755 Cote Ste Catherine, Montreal, Quebec H3T1E2
| | - Karen Yee
- Princess Margaret Cancer Centre, Division of Medical Oncology and Hematology, Toronto, Ontario
| | - Katherine L B Borden
- Institute for Research in Immunology and Cancer and Department of Pathology and Cell Biology, University of Montreal, Montreal, Quebec.
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5
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Youssef M, Hitti C, Puppin Chaves Fulber J, Kamen AA. Enabling mRNA Therapeutics: Current Landscape and Challenges in Manufacturing. Biomolecules 2023; 13:1497. [PMID: 37892179 PMCID: PMC10604719 DOI: 10.3390/biom13101497] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2023] [Revised: 10/05/2023] [Accepted: 10/06/2023] [Indexed: 10/29/2023] Open
Abstract
Recent advances and discoveries in the structure and role of mRNA as well as novel lipid-based delivery modalities have enabled the advancement of mRNA therapeutics into the clinical trial space. The manufacturing of these products is relatively simple and eliminates many of the challenges associated with cell culture production of viral delivery systems for gene and cell therapy applications, allowing rapid production of mRNA for personalized treatments, cancer therapies, protein replacement and gene editing. The success of mRNA vaccines during the COVID-19 pandemic highlighted the immense potential of this technology as a vaccination platform, but there are still particular challenges to establish mRNA as a widespread therapeutic tool. Immunostimulatory byproducts can pose a barrier for chronic treatments and different production scales may need to be considered for these applications. Moreover, long-term storage of mRNA products is notoriously difficult. This review provides a detailed overview of the manufacturing steps for mRNA therapeutics, including sequence design, DNA template preparation, mRNA production and formulation, while identifying the challenges remaining in the dose requirements, long-term storage and immunotolerance of the product.
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Affiliation(s)
| | | | | | - Amine A. Kamen
- Department of Bioengineering, McGill University, Montreal, QC H3A 0G4, Canada; (M.Y.); (C.H.); (J.P.C.F.)
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6
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Zuberek J, Warzecha M, Dobrowolski M, Modrak-Wojcik A. An intramolecular disulphide bond in human 4E-T affects its binding to eIF4E1a protein. EUROPEAN BIOPHYSICS JOURNAL : EBJ 2023; 52:497-510. [PMID: 37798395 PMCID: PMC10618305 DOI: 10.1007/s00249-023-01684-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/04/2023] [Revised: 09/14/2023] [Accepted: 09/16/2023] [Indexed: 10/07/2023]
Abstract
The cap at the 5'terminus of mRNA is a key determinant of gene expression in eukaryotic cells, which among others is required for cap dependent translation and protects mRNA from degradation. These properties of cap are mediated by several proteins. One of them is 4E-Transporter (4E-T), which plays an important role in translational repression, mRNA decay and P-bodies formation. 4E-T is also one of several proteins that interact with eukaryotic initiation factor 4E (eIF4E), a cap binding protein which is a key component of the translation initiation machinery. The molecular mechanisms underlying the interactions of these two proteins are crucial for mRNA processing. Studying the interactions between human eIF4E1a and the N-terminal fragment of 4E-T that possesses unstructured 4E-binding motifs under non-reducing conditions, we observed that 4E-T preferentially forms an intramolecular disulphide bond. This "disulphide loop" reduces affinity of 4E-T for eIF4E1a by about 300-fold. Considering that only human 4E-T possesses two cysteines located between the 4E binding motifs, we proposed that the disulphide bond may act as a switch to regulate interactions between the two proteins.
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Affiliation(s)
- Joanna Zuberek
- Division of Biophysics, Institute of Experimental Physics, Faculty of Physics, University of Warsaw, Warsaw, Poland.
| | - Marek Warzecha
- Division of Biophysics, Institute of Experimental Physics, Faculty of Physics, University of Warsaw, Warsaw, Poland
| | - Mateusz Dobrowolski
- Division of Biophysics, Institute of Experimental Physics, Faculty of Physics, University of Warsaw, Warsaw, Poland
| | - Anna Modrak-Wojcik
- Division of Biophysics, Institute of Experimental Physics, Faculty of Physics, University of Warsaw, Warsaw, Poland
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7
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Gao X, Jin Y, Zhu W, Wu X, Wang J, Guo C. Regulation of Eukaryotic Translation Initiation Factor 4E as a Potential Anticancer Strategy. J Med Chem 2023; 66:12678-12696. [PMID: 37725577 DOI: 10.1021/acs.jmedchem.3c00636] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/21/2023]
Abstract
Eukaryotic translation initiation factors (eIFs) are highly expressed in cancer cells, especially eIF4E, the central regulatory node driving cancer cell growth and a potential target for anticancer drugs. eIF4E-targeting strategies primarily focus on inhibiting eIF4E synthesis, interfering with eIF4E/eIF4G interactions, and targeting eIF4E phosphorylation and peptide inhibitors. Although some small-molecule inhibitors are in clinical trials, no eIF4E inhibitors are available for clinical use. We provide an overview of the regulatory mechanisms of eIF4E and summarize the progress in developing and discovering eIF4E inhibitor strategies. We propose that interference with eIF4E/eIF4G interactions will provide a new perspective for the design of eIF4E inhibitors and may be a preferred strategy.
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Affiliation(s)
- Xintao Gao
- College of Chemical Engineering, Qingdao University of Science and Technology, Qingdao 266042, China
| | - Yonglong Jin
- The Affiliated Hospital of Qingdao University, Qingdao 266000, China
| | - Wenyong Zhu
- Department of Thoracic Surgery, Qilu Hospital (Qingdao), Cheeloo College of Medicine, Shandong University, Qingdao, 266035, China
| | - Xiaochen Wu
- College of Chemical Engineering, Qingdao University of Science and Technology, Qingdao 266042, China
| | - Jing Wang
- Department of Biology Science and Technology, Baotou Teacher's College, Baotou 014030, China
| | - Chuanlong Guo
- College of Chemical Engineering, Qingdao University of Science and Technology, Qingdao 266042, China
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8
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Ma J, Yan S, Zhao Y, Yan H, Zhang Q, Li X. Blockade of PD-1 and LAG-3 expression on CD8+ T cells promotes the tumoricidal effects of CD8+ T cells. Front Immunol 2023; 14:1265255. [PMID: 37841254 PMCID: PMC10568325 DOI: 10.3389/fimmu.2023.1265255] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2023] [Accepted: 09/13/2023] [Indexed: 10/17/2023] Open
Abstract
Background The diffuse large B-cell lymphoma (DLBCL) has the highest incidence of all lymphomas worldwide. To investigate the functions of lymphocyte activation gene 3 (LAG-3) and programmed cell death 1 (PD-1) in tissues and peripheral blood of patients with DLBCL, the expression of LAG-3 and PD-1 genes in DLBCL-TCGA were analyzed. Methods LAG-3 and PD-1 mRNA levels in DLBCL were analyzed using data from The Cancer Genome Atlas (TCGA) database. Utilize the Genotype-Tissue Expression (GTEx) database for assessing the variance in the expression of LAG-3, PD-1, and other associated factors between the tissues of DLBCL patients and healthy individuals. Immunohistochemistry was applied to detect the expression of LAG-3 and PD-1 levels in 137 cases of DLBCL tissues and 20 cases of reactive lymphoid hyperplasia. The prognostic value of LAG-3 and PD-1 were assessed using the Kaplan-Meier curve. The Estimation of Stromal and Immune cells in Malignant Tumor tissues using Expression data (ESTIMATE) and ssGSEA algorithm were used to explore the immune microenvironment of DLBCL. Additionally, the expression and co-expression of LAG-3 and PD-1 were detected on CD4 and CD8 T cells in peripheral blood samples from 100 cases of DLBCL tissues and 30 cases of healthy individuals using flow cytometry. Results According to TCGA database, LAG-3 and PD-1 gene expression levels were significantly up-regulated in DLBCL tissues. LAG-3 and PD-1 levels were also strongly positively correlated with those of most infiltrating immune cells. Overall survival of patients with high LAG-3 and PD-1 co-expression was significantly shorter than that of patients with low co-expression. In DLBCL patients, LAG-3 and PD-1 were highly expressed in peripheral blood CD8+ T cells. In addition, LAG-3 was highly expressed in CD4+ T cells, while the expression of PD-1 in CD4+ T cells of DLBCL patients showed no significant difference compared to healthy individuals. Additionally, CD8+ T cells and SU-DHL6/OCI-LY3 from patients with DLBCL were co-cultured in vitro; after addition of LAG-3 and/or PD-1 inhibitors alone, an increased perforin and granzyme B secretion levels by CD8+ T cells were detected, as well as an increase in the overall proportion of tumor cells undergoing apoptosis. Conclusion High LAG-3 and PD-1 levels significantly inhibit CD8+ T cell function, resulting in weakened ability to kill tumor cells. Combined LAG-3 and PD-1 blockade can restore CD8+ T cell function and provides a potential avenue for development of personalized cellular immunotherapy for DLBCL.
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Affiliation(s)
- Jiajia Ma
- Department of Pathology, Xinjiang Medical University Affiliated Tumor Hospital, Urumqi, Xinjiang, China
| | - Shufang Yan
- Department of Critical Care, Medicine of Karamay Central Hospital, Karamay, Xinjiang, China
| | - Ying Zhao
- Department of General Practice, Third People’s Hospital of Xinjiang Uygur Autonomous Region, Urumuqi, Xinjiang, China
| | - Huifang Yan
- Department of Pathology, Xinjiang Medical University Affiliated Tumor Hospital, Urumqi, Xinjiang, China
| | - Qian Zhang
- Department of Pathology, Xinjiang Medical University Affiliated Tumor Hospital, Urumqi, Xinjiang, China
| | - Xinxia Li
- Department of Pathology, Xinjiang Medical University Affiliated Tumor Hospital, Urumqi, Xinjiang, China
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9
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Nuclear-targeted 4E-BP1 is dephosphorylated, induces nuclear translocation of eIF4E, and alters mRNA translation. Exp Cell Res 2022; 418:113246. [PMID: 35697076 DOI: 10.1016/j.yexcr.2022.113246] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2022] [Revised: 06/02/2022] [Accepted: 06/04/2022] [Indexed: 11/23/2022]
Abstract
Mechanistic target of rapamycin complex 1 (mTORC1) phosphorylates and inhibits eukaryotic translation initiation factor 4E (eIF4E)-binding protein 1 (4E-BP1). This leads to the release of eIF4E from 4E-BP1 and the initiation of eIF4E-dependent mRNA translation. In this study, we examined the expression of a 4E-BP1-based reporter (mTORC1 activity reporter; TORCAR) with various localization signal tags to clarify the relationship between the localization of 4E-BP1 and its phosphorylation. Phosphorylation of 4E-BP1 at threonine 37/46 and serine 65 was efficient at lysosomes and the plasma membrane, whereas it was significantly decreased in the nucleus. In addition, the localization of endogenous eIF4E shifted from the cytoplasm to the nucleus only when nuclear-localized TORCAR was expressed. Nuclear-localized TORCAR decreased cyclin D1 protein levels and altered cell cycle distribution. These data provide an experimental tool to manipulate the localization of endogenous eIF4E without affecting mTORC1 and highlight the important role of nuclear-cytoplasmic shuttling of eIF4E.
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10
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Mars JC, Ghram M, Culjkovic-Kraljacic B, Borden KLB. The Cap-Binding Complex CBC and the Eukaryotic Translation Factor eIF4E: Co-Conspirators in Cap-Dependent RNA Maturation and Translation. Cancers (Basel) 2021; 13:6185. [PMID: 34944805 PMCID: PMC8699206 DOI: 10.3390/cancers13246185] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2021] [Revised: 11/30/2021] [Accepted: 12/02/2021] [Indexed: 12/26/2022] Open
Abstract
The translation of RNA into protein is a dynamic process which is heavily regulated during normal cell physiology and can be dysregulated in human malignancies. Its dysregulation can impact selected groups of RNAs, modifying protein levels independently of transcription. Integral to their suitability for translation, RNAs undergo a series of maturation steps including the addition of the m7G cap on the 5' end of RNAs, splicing, as well as cleavage and polyadenylation (CPA). Importantly, each of these steps can be coopted to modify the transcript signal. Factors that bind the m7G cap escort these RNAs through different steps of maturation and thus govern the physical nature of the final transcript product presented to the translation machinery. Here, we describe these steps and how the major m7G cap-binding factors in mammalian cells, the cap binding complex (CBC) and the eukaryotic translation initiation factor eIF4E, are positioned to chaperone transcripts through RNA maturation, nuclear export, and translation in a transcript-specific manner. To conceptualize a framework for the flow and integration of this genetic information, we discuss RNA maturation models and how these integrate with translation. Finally, we discuss how these processes can be coopted by cancer cells and means to target these in malignancy.
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Affiliation(s)
- Jean-Clement Mars
- Institute for Research in Immunology and Cancer (IRIC), Université de Montréal, Pavillion Marcelle-Coutu, Chemin Polytechnique, Montreal, QC H3T 1J4, Canada
| | - Mehdi Ghram
- Institute for Research in Immunology and Cancer (IRIC), Université de Montréal, Pavillion Marcelle-Coutu, Chemin Polytechnique, Montreal, QC H3T 1J4, Canada
| | - Biljana Culjkovic-Kraljacic
- Institute for Research in Immunology and Cancer (IRIC), Université de Montréal, Pavillion Marcelle-Coutu, Chemin Polytechnique, Montreal, QC H3T 1J4, Canada
| | - Katherine L B Borden
- Institute for Research in Immunology and Cancer (IRIC), Université de Montréal, Pavillion Marcelle-Coutu, Chemin Polytechnique, Montreal, QC H3T 1J4, Canada
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11
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Control of the eIF4E activity: structural insights and pharmacological implications. Cell Mol Life Sci 2021; 78:6869-6885. [PMID: 34541613 PMCID: PMC8558276 DOI: 10.1007/s00018-021-03938-z] [Citation(s) in RCA: 27] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2021] [Revised: 08/28/2021] [Accepted: 09/08/2021] [Indexed: 12/17/2022]
Abstract
The central role of eukaryotic translation initiation factor 4E (eIF4E) in controlling mRNA translation has been clearly assessed in the last decades. eIF4E function is essential for numerous physiological processes, such as protein synthesis, cellular growth and differentiation; dysregulation of its activity has been linked to ageing, cancer onset and progression and neurodevelopmental disorders, such as autism spectrum disorder (ASD) and Fragile X Syndrome (FXS). The interaction between eIF4E and the eukaryotic initiation factor 4G (eIF4G) is crucial for the assembly of the translational machinery, the initial step of mRNA translation. A well-characterized group of proteins, named 4E-binding proteins (4E-BPs), inhibits the eIF4E–eIF4G interaction by competing for the same binding site on the eIF4E surface. 4E-BPs and eIF4G share a single canonical motif for the interaction with a conserved hydrophobic patch of eIF4E. However, a second non-canonical and not conserved binding motif was recently detected for eIF4G and several 4E-BPs. Here, we review the structural features of the interaction between eIF4E and its molecular partners eIF4G and 4E-BPs, focusing on the implications of the recent structural and biochemical evidence for the development of new therapeutic strategies. The design of novel eIF4E-targeting molecules that inhibit translation might provide new avenues for the treatment of several conditions.
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12
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Xu W, Kannan S, Verma CS, Nacro K. Update on the Development of MNK Inhibitors as Therapeutic Agents. J Med Chem 2021; 65:983-1007. [PMID: 34533957 DOI: 10.1021/acs.jmedchem.1c00368] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Mitogen-activated protein kinase-interacting kinases 1 and 2 (MNK1/2) represent a central class of enzymes that are activated by extracellular signal-regulated kinase (ERK) or p38 mitogen-activated protein (MAP) kinases. MNK1 and MNK2 coordinate cellular signaling, control production of inflammatory chemokines, and regulate cell proliferation and survival. MNK1/2 are referred to as serine/threonine kinases as they phosphorylate serine or threonine residues on their substrates. Upon activation, MNK1/2 phosphorylate eukaryotic translation initiation factor 4E (eIF4E) at Ser209, which in turn initiates ribosome assembly and protein translation. Deleterious overexpression of MNK1/2 and/or eIF4E have been reported in several diseases including cancers, neurological disorders, autism, and inflammation. Recently, there have been intense efforts toward the development of potent and selective inhibitors of MNK1/2 in both academia and industry. Herein, we review the current understanding of the structural and biological aspects of MNK1/2 and provide an update of pharmacological inhibitors of MNK1/2 including candidates in clinical trials.
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Affiliation(s)
- Weijun Xu
- Experimental Drug Development Centre (EDDC), A*STAR, 10 Biopolis Road, Chromos #05-01, 138670, Singapore
| | | | - Chandra S Verma
- Bioinformatics Institute (BII), A*STAR, 30 Biopolis Street, #07-01 Matrix, 138671, Singapore.,Department of Biological Sciences, National University of Singapore, 16 Science Drive 4, 117558, Singapore.,School of Biological Sciences, Nanyang Technological University, 60 Nanyang Drive, 637551, Singapore
| | - Kassoum Nacro
- Experimental Drug Development Centre (EDDC), A*STAR, 10 Biopolis Road, Chromos #05-01, 138670, Singapore
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13
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Keane L, Antignano I, Riechers SP, Zollinger R, Dumas AA, Offermann N, Bernis ME, Russ J, Graelmann F, McCormick PN, Esser J, Tejera D, Nagano A, Wang J, Chelala C, Biederbick Y, Halle A, Salomoni P, Heneka MT, Capasso M. mTOR-dependent translation amplifies microglia priming in aging mice. J Clin Invest 2021; 131:132727. [PMID: 33108356 DOI: 10.1172/jci132727] [Citation(s) in RCA: 32] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2019] [Accepted: 10/14/2020] [Indexed: 12/20/2022] Open
Abstract
Microglia maintain homeostasis in the brain. However, with age, they become primed and respond more strongly to inflammatory stimuli. We show here that microglia from aged mice had upregulated mTOR complex 1 signaling controlling translation, as well as protein levels of inflammatory mediators. Genetic ablation of mTOR signaling showed a dual yet contrasting effect on microglia priming: it caused an NF-κB-dependent upregulation of priming genes at the mRNA level; however, mice displayed reduced cytokine protein levels, diminished microglia activation, and milder sickness behavior. The effect on translation was dependent on reduced phosphorylation of 4EBP1, resulting in decreased binding of eIF4E to eIF4G. Similar changes were present in aged human microglia and in damage-associated microglia, indicating that upregulation of mTOR-dependent translation is an essential aspect of microglia priming in aging and neurodegeneration.
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Affiliation(s)
- Lily Keane
- German Center for Neurodegenerative Diseases (DZNE), Bonn, Germany.,Centre for Tumour Microenvironment and
| | | | | | | | | | - Nina Offermann
- German Center for Neurodegenerative Diseases (DZNE), Bonn, Germany
| | - Maria E Bernis
- German Center for Neurodegenerative Diseases (DZNE), Bonn, Germany
| | - Jenny Russ
- German Center for Neurodegenerative Diseases (DZNE), Bonn, Germany
| | | | | | - Julia Esser
- German Center for Neurodegenerative Diseases (DZNE), Bonn, Germany
| | - Dario Tejera
- German Center for Neurodegenerative Diseases (DZNE), Bonn, Germany
| | - Ai Nagano
- Centre for Cancer Genomics and Computational Biology, Barts Cancer Institute, Queen Mary University of London, London, United Kingdom
| | - Jun Wang
- Centre for Cancer Genomics and Computational Biology, Barts Cancer Institute, Queen Mary University of London, London, United Kingdom
| | - Claude Chelala
- Centre for Cancer Genomics and Computational Biology, Barts Cancer Institute, Queen Mary University of London, London, United Kingdom
| | | | - Annett Halle
- German Center for Neurodegenerative Diseases (DZNE), Bonn, Germany
| | - Paolo Salomoni
- German Center for Neurodegenerative Diseases (DZNE), Bonn, Germany
| | - Michael T Heneka
- German Center for Neurodegenerative Diseases (DZNE), Bonn, Germany
| | - Melania Capasso
- German Center for Neurodegenerative Diseases (DZNE), Bonn, Germany.,Centre for Tumour Microenvironment and
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14
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Han Y, Zhang W, Zhou B, Zeng P, Tian Z, Cai J. Chromosome-level genome assembly of Welwitschia mirabilis, a unique Namib Desert species. Mol Ecol Resour 2021; 22:391-403. [PMID: 34288504 DOI: 10.1111/1755-0998.13475] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2021] [Revised: 07/12/2021] [Accepted: 07/13/2021] [Indexed: 11/30/2022]
Abstract
Welwitschia mirabilis, which is endemic to the Namib Desert, is the only living species within the family Welwitschiaceae. This species has an extremely long lifespan of up to 2,000 years and bears a single pair of opposite leaves that persist whilst alive. However, the underlying genetic mechanisms and evolution of the species remain poorly elucidated. Here, we report on a chromosome-level genome assembly for W. mirabilis, with a 6.30-Gb genome sequence and contig N50 of 27.50 Mb. In total, 39,019 protein-coding genes were predicted from the genome. Two brassinosteroid-related genes (BRI1 and CYCD3), key regulators of cell division and elongation, were strongly selected in W. mirabilis and may contribute to their long ever-growing leaves. Furthermore, 29 gene families in the mitogen-activated protein kinase signalling pathway showed significant expansion, which may contribute to the desert adaptations of the plant. Three positively selected genes (EHMT1, EIF4E, SOD2) may be involved in the mechanisms leading to long lifespan. Based on molecular clock dating and fossil calibrations, the divergence time of W. mirabilis and Gnetum montanum was estimated at ~123.5 million years ago. Reconstruction of population dynamics from genome data coincided well with the aridification of the Namib Desert. The genome sequence detailed in the current study provides insight into the evolution of W. mirabilis and should be an important resource for further study on gnetophyte and gymnosperm evolution.
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Affiliation(s)
- Yuwei Han
- School of Ecology and Environment, Northwestern Polytechnical University, Xi'an, China
| | - Weixiong Zhang
- State Key Laboratory of Quality Research in Chinese Medicine, Institute of Chinese Medical Sciences, University of Macau, Macau, China
| | - Botong Zhou
- School of Ecology and Environment, Northwestern Polytechnical University, Xi'an, China
| | - Peng Zeng
- State Key Laboratory of Quality Research in Chinese Medicine, Institute of Chinese Medical Sciences, University of Macau, Macau, China
| | - Zunzhe Tian
- School of Ecology and Environment, Northwestern Polytechnical University, Xi'an, China
| | - Jing Cai
- School of Ecology and Environment, Northwestern Polytechnical University, Xi'an, China
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15
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Borden K, Culjkovic-Kraljacic B, Cowling VH. To cap it all off, again: dynamic capping and recapping of coding and non-coding RNAs to control transcript fate and biological activity. Cell Cycle 2021; 20:1347-1360. [PMID: 34241559 PMCID: PMC8344758 DOI: 10.1080/15384101.2021.1930929] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
The addition of the methyl-7-guanosine (m7G) “cap” on the 5' ends of coding and some non-coding RNAs is essential for their protein coding capacity and biochemical activity, respectively. It was previously considered that capping was a constitutive process that generates a complete cap on all transcripts at steady-state. However, development of new methodologies demonstrated that steady-state capping is a dynamic and regulatable feature of many coding and non-coding RNAs. Indeed, capping status of specific RNAs can flux during differentiation and development, thereby impacting on their protein-coding capacity and activity. Moreover, in some primary cancer specimens, capping can be elevated for transcripts encoding proteins involved in proliferation and survival corresponding to their increased protein levels. Overexpression of one of the capping enzymes (RNMT), the transcription factor MYC or the eukaryotic translation initiation factor eIF4E all led to increased levels of steady-state capping of selected transcripts. Additionally, transcripts can be decapped and recapped, allowing these to be sequestered until needed. This review provides a summary of the major advances in enzymatic and affinity-based approaches to quantify m7G capping. Further, we summarize the evidence for regulation of capping. Capping has emerged as a significant regulatory step in RNA metabolism which is poised to impact a myriad of biological processes.
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Affiliation(s)
- Klb Borden
- Department of Pathology and Cell Biology, Institute of Research in Immunology and Cancer, University of Montreal, Montreal, Canada
| | - B Culjkovic-Kraljacic
- Department of Pathology and Cell Biology, Institute of Research in Immunology and Cancer, University of Montreal, Montreal, Canada
| | - V H Cowling
- Centre for Gene Regulation and Expression, School of Life Sciences, University of Dundee, Dundee, UK, UK
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16
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Wood S, Willbanks A, Cheng JX. The Role of RNA Modifications and RNA-modifying Proteins in Cancer Therapy and Drug Resistance. Curr Cancer Drug Targets 2021; 21:326-352. [PMID: 33504307 DOI: 10.2174/1568009621666210127092828] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2020] [Revised: 12/03/2020] [Accepted: 12/03/2020] [Indexed: 11/22/2022]
Abstract
The advent of new genome-wide sequencing technologies has uncovered abnormal RNA modifications and RNA editing in a variety of human cancers. The discovery of reversible RNA N6-methyladenosine (RNA: m6A) by fat mass and obesity-associated protein (FTO) demethylase has led to exponential publications on the pathophysiological functions of m6A and its corresponding RNA modifying proteins (RMPs) in the past decade. Some excellent reviews have summarized the recent progress in this field. Compared to the extent of research into RNA: m6A and DNA 5-methylcytosine (DNA: m5C), much less is known about other RNA modifications and their associated RMPs, such as the role of RNA: m5C and its RNA cytosine methyltransferases (RCMTs) in cancer therapy and drug resistance. In this review, we will summarize the recent progress surrounding the function, intramolecular distribution and subcellular localization of several major RNA modifications, including 5' cap N7-methylguanosine (m7G) and 2'-O-methylation (Nm), m6A, m5C, A-to-I editing, and the associated RMPs. We will then discuss dysregulation of those RNA modifications and RMPs in cancer and their role in cancer therapy and drug resistance.
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Affiliation(s)
- Shaun Wood
- Department of Pathology, Hematopathology Section, University of Chicago, Chicago, IL60637, United States
| | - Amber Willbanks
- Department of Pathology, Hematopathology Section, University of Chicago, Chicago, IL60637, United States
| | - Jason X Cheng
- Department of Pathology, Hematopathology Section, University of Chicago, Chicago, IL60637, United States
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17
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de Lima GB, de Lima Cavalcanti TYV, de Brito ANALM, de Assis LA, Andrade-Vieira RP, Freire ER, da Silva Assunção TR, de Souza Reis CR, Zanchin NIT, Guimarães BG, de-Melo-Neto OP. The translation initiation factor EIF4E5 from Leishmania: crystal structure and interacting partners. RNA Biol 2021; 18:2433-2449. [PMID: 33945405 DOI: 10.1080/15476286.2021.1918919] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022] Open
Abstract
The mRNA cap-binding protein, eIF4E, mediates the recognition of the mRNA 5' end and, as part of the heterotrimeric eIF4F complex, facilitates the recruitment of the ribosomal subunits to initiate eukaryotic translation. Various regulatory events involving eIF4E and a second eIF4F subunit, eIF4G, are required for proper control of translation initiation. In pathogenic trypanosomatids, six eIF4Es and five eIF4Gs have been described, several forming different eIF4F-like complexes with yet unresolved roles. EIF4E5 is one of the least known of the trypanosomatid eIF4Es and has not been characterized in Leishmania species. Here, we used immunoprecipitation assays, combined with mass-spectrometry, to identify major EIF4E5 interacting proteins in L. infantum. A constitutively expressed, HA-tagged, EIF4E5 co-precipitated mainly with EIF4G1 and binding partners previously described in Trypanosoma brucei, EIF4G1-IP, RBP43 and the 14-3-3 proteins. In contrast, no clear co-precipitation with EIF4G2, also previously reported, was observed. EIF4E5 also co-precipitated with protein kinases, possibly associated with cell-cycle regulation, selected RNA binding proteins and histones. Phosphorylated residues were identified and mapped to the Leishmania-specific C-terminal end. Mutagenesis of the tryptophan residue (W53) postulated to mediate interactions with protein partners or of a neighbouring tryptophan conserved in Leishmania (W45) did not substantially impair the identified interactions. Finally, the crystal structure of Leishmania EIF4E5 evidences remarkable differences in the eIF4G interfacing region, when compared with human eIF4E-1 and with its Trypanosoma orthologue. Mapping of its C-terminal end near the cap-binding site also imply relevant differences in cap-binding function and/or regulation.
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Affiliation(s)
- Gustavo Barbosa de Lima
- Departamento de Microbiologia, Instituto Aggeu Magalhães, FIOCRUZ-PE, Av. Moraes Rego s/n, Recife-PE, Brazil
| | - Thaíse Yasmine Vasconcelos de Lima Cavalcanti
- Departamento de Microbiologia, Instituto Aggeu Magalhães, FIOCRUZ-PE, Av. Moraes Rego s/n, Recife-PE, Brazil.,Programa de Pós-Graduação em Genética, Universidade Federal de Pernambuco, Recife-PE, Brazil
| | - Adriana Neuman Albuquerque Lins Moura de Brito
- Departamento de Microbiologia, Instituto Aggeu Magalhães, FIOCRUZ-PE, Av. Moraes Rego s/n, Recife-PE, Brazil.,Programa de Pós-Graduação em Genética, Universidade Federal de Pernambuco, Recife-PE, Brazil
| | - Ludmilla Arruda de Assis
- Departamento de Microbiologia, Instituto Aggeu Magalhães, FIOCRUZ-PE, Av. Moraes Rego s/n, Recife-PE, Brazil
| | | | - Eden Ribeiro Freire
- Departamento de Microbiologia, Instituto Aggeu Magalhães, FIOCRUZ-PE, Av. Moraes Rego s/n, Recife-PE, Brazil.,Laboratório de Biologia Estrutural e Engenharia de Proteínas, Instituto Carlos Chagas, FIOCRUZ-PR, Curitiba-PR, Brazil
| | | | | | - Nilson Ivo Tonin Zanchin
- Laboratório de Biologia Estrutural e Engenharia de Proteínas, Instituto Carlos Chagas, FIOCRUZ-PR, Curitiba-PR, Brazil
| | - Beatriz Gomes Guimarães
- Laboratório de Biologia Estrutural e Engenharia de Proteínas, Instituto Carlos Chagas, FIOCRUZ-PR, Curitiba-PR, Brazil
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18
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Majeed ST, Batool A, Majeed R, Bhat NN, Zargar MA, Andrabi KI. mTORC1 induces eukaryotic translation initiation factor 4E interaction with TOS-S6 kinase 1 and its activation. Cell Cycle 2021; 20:839-854. [PMID: 33938392 DOI: 10.1080/15384101.2021.1901038] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022] Open
Abstract
Eukaryotic translation initiation factor 4E was recently shown to be a substrate of mTORC1, suggesting it may be a mediator of mTORC1 signaling. Here, we present evidence that eIF4E phosphorylated at S209 interacts with TOS motif of S6 Kinase1 (S6K1). We also show that this interaction is sufficient to overcome rapamycin sensitivity and mTORC1 dependence of S6K1. Furthermore, we show that eIF4E-TOS interaction relieves S6K1 from auto-inhibition due to carboxy terminal domain (CTD) and primes it for hydrophobic motif (HM) phosphorylation and activation in mTORC1 independent manner. We conclude that the role of mTORC1 is restricted to engaging eIF4E with S6K1-TOS motif to influence its state of HM phosphorylation and inducing its activation.
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Affiliation(s)
- Sheikh Tahir Majeed
- Growth Factor Signaling Laboratory, Department of Biotechnology, University of Kashmir, Srinagar, India.,Department of Biotechnology, Central University of Kashmir, Ganderbal, India
| | - Asiya Batool
- Growth Factor Signaling Laboratory, Department of Biotechnology, University of Kashmir, Srinagar, India.,Division of Cancer Pharmacology, Indian Institute of Integrative Medicine, Srinagar, India
| | - Rabiya Majeed
- Growth Factor Signaling Laboratory, Department of Biotechnology, University of Kashmir, Srinagar, India.,Department of Biochemistry, University of Kashmir, Srinagar, India
| | - Nadiem Nazir Bhat
- Growth Factor Signaling Laboratory, Department of Biotechnology, University of Kashmir, Srinagar, India
| | | | - Khurshid Iqbal Andrabi
- Growth Factor Signaling Laboratory, Department of Biotechnology, University of Kashmir, Srinagar, India
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19
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The Nuclear Pore Complex and mRNA Export in Cancer. Cancers (Basel) 2020; 13:cancers13010042. [PMID: 33375634 PMCID: PMC7796397 DOI: 10.3390/cancers13010042] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2020] [Revised: 12/11/2020] [Accepted: 12/22/2020] [Indexed: 02/07/2023] Open
Abstract
Export of mRNAs from the nucleus to the cytoplasm is a key regulatory step in the expression of proteins. mRNAs are transported through the nuclear pore complex (NPC). Export of mRNAs responds to a variety of cellular stimuli and stresses. Revelations of the specific effects elicited by NPC components and associated co-factors provides a molecular basis for the export of selected RNAs, independent of bulk mRNA export. Aberrant RNA export has been observed in primary human cancer specimens. These cargo RNAs encode factors involved in nearly all facets of malignancy. Indeed, the NPC components involved in RNA export as well as the RNA export machinery can be found to be dysregulated, mutated, or impacted by chromosomal translocations in cancer. The basic mechanisms associated with RNA export with relation to export machinery and relevant NPC components are described. Therapeutic strategies targeting this machinery in clinical trials is also discussed. These findings firmly position RNA export as a targetable feature of cancer along with transcription and translation.
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20
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Davis MR, Delaleau M, Borden KLB. Nuclear eIF4E Stimulates 3'-End Cleavage of Target RNAs. Cell Rep 2020; 27:1397-1408.e4. [PMID: 31042468 PMCID: PMC6661904 DOI: 10.1016/j.celrep.2019.04.008] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2017] [Revised: 02/16/2019] [Accepted: 03/29/2019] [Indexed: 11/27/2022] Open
Abstract
The eukaryotic translation initiation factor eIF4E is nuclear and cytoplasmic where it plays roles in export and translation of specific transcripts, respectively. When we were studying its mRNA export activity, we unexpectedly discovered that eIF4E drives the protein expression of elements of the 3′-end core cleavage complex involved in cleavage and polyadenylation (CPA), including CPSF3, the enzyme responsible for cleavage, as well as its co-factors CPSF1, CPSF2, CPSF4, Symplekin, WDR33, and FIP1L1. Using multiple strategies, we demonstrate that eIF4E stimulates 3′-end cleavage of selected RNAs. eIF4E physically interacts with CPSF3, CPSF1, and uncleaved target RNA, suggesting it acts directly and indirectly on the pathway. Through these effects, eIF4E can generate better substrates for its mRNA export and translation activities. Thus, we identified an unanticipated function for eIF4E in 3′-end processing of specific target RNAs, and this function could potentially affect the expression of a broad range of oncoproteins. Davis et al. demonstrate that the eukaryotic translation initiation factor eIF4E, which is usually associated with nuclear export and translation of specific transcripts, also acts in 3′-end processing of selected RNAs. Through these effects, eIF4E can generate better substrates for its export and translation activities and, thus, modulate the proteome.
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Affiliation(s)
- Margaret Rose Davis
- Institute of Research in Immunology and Cancer (IRIC), Department of Pathology and Cell Biology, Université de Montréal, Pavillon Marcelle-Coutu, 2950 Chemin de Polytechnique, Montreal, QC H3T 1J4, Canada
| | - Mildred Delaleau
- Institute of Research in Immunology and Cancer (IRIC), Department of Pathology and Cell Biology, Université de Montréal, Pavillon Marcelle-Coutu, 2950 Chemin de Polytechnique, Montreal, QC H3T 1J4, Canada
| | - Katherine L B Borden
- Institute of Research in Immunology and Cancer (IRIC), Department of Pathology and Cell Biology, Université de Montréal, Pavillon Marcelle-Coutu, 2950 Chemin de Polytechnique, Montreal, QC H3T 1J4, Canada.
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21
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Borden KLB, Volpon L. The diversity, plasticity, and adaptability of cap-dependent translation initiation and the associated machinery. RNA Biol 2020; 17:1239-1251. [PMID: 32496897 PMCID: PMC7549709 DOI: 10.1080/15476286.2020.1766179] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Translation initiation is a critical facet of gene expression with important impacts that underlie cellular responses to stresses and environmental cues. Its dysregulation in many diseases position this process as an important area for the development of new therapeutics. The gateway translation factor eIF4E is typically considered responsible for ‘global’ or ‘canonical’ m7G cap-dependent translation. However, eIF4E impacts translation of specific transcripts rather than the entire translatome. There are many alternative cap-dependent translation mechanisms that also contribute to the translation capacity of the cell. We review the diversity of these, juxtaposing more recently identified mechanisms with eIF4E-dependent modalities. We also explore the multiplicity of functions played by translation factors, both within and outside protein synthesis, and discuss how these differentially contribute to their ultimate physiological impacts. For comparison, we discuss some modalities for cap-independent translation. In all, this review highlights the diverse mechanisms that engage and control translation in eukaryotes.
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Affiliation(s)
- Katherine L B Borden
- Institute of Research in Immunology and Cancer (IRIC), Department of Pathology and Cell Biology, Université de Montréal , Montreal, Québec, Canada
| | - Laurent Volpon
- Institute of Research in Immunology and Cancer (IRIC), Department of Pathology and Cell Biology, Université de Montréal , Montreal, Québec, Canada
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22
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Choi SH, Kim S, Jones KA. Gene expression regulation by CDK12: a versatile kinase in cancer with functions beyond CTD phosphorylation. Exp Mol Med 2020; 52:762-771. [PMID: 32451425 PMCID: PMC7272620 DOI: 10.1038/s12276-020-0442-9] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2019] [Revised: 04/08/2020] [Accepted: 04/13/2020] [Indexed: 12/21/2022] Open
Abstract
Cyclin-dependent kinases (CDKs) play critical roles in cell cycle progression and gene expression regulation. In human cancer, transcription-associated CDKs can activate oncogenic gene expression programs, whereas cell cycle-regulatory CDKs mainly induce uncontrolled proliferation. Cyclin-dependent kinase 12 (CDK12) belongs to the CDK family of serine/threonine kinases and has been recently found to have multiple roles in gene expression regulation and tumorigenesis. Originally, CDK12 was thought to be one of the transcription-associated CDKs, acting with its cyclin partner Cyclin K to promote the phosphorylation of the C-terminal domain (CTD) of RNA polymerase II and induce transcription elongation. However, recent studies have demonstrated that CDK12 also controls multiple gene expression processes, including transcription termination, mRNA splicing, and translation. Most importantly, CDK12 mutations are frequently found in human tumors. Loss of CDK12 function causes defective expression of DNA damage response (DDR) genes, which eventually results in genome instability, a hallmark of human cancer. Here, we discuss the diverse roles of CDK12 in gene expression regulation and human cancer, focusing on newly identified CDK12 kinase functions in cellular processes and highlighting CDK12 as a promising therapeutic target for human cancer treatment. Better understanding of the roles played by a protein kinase, an enzyme that adds phosphate groups to other molecules, in healthy and diseased states may help scientists identify novel cancer treatments. Cyclin-dependent kinases (CDKs) are a family of protein kinases crucial to cell cycling and gene expression. CDK12 can activate and modulate cancer-related gene expression, but, according to a review by Seung Hyuk Choi and colleagues at the Salk Institute for Biological Studies in La Jolla, USA, further investigations into its exact functioning and control mechanisms are required. CDK12 mutations are frequently found in aggressive breast and ovarian cancers, while loss of CDK12 function results in abnormal expression of DNA damage response genes and genome instability. CDK12 may also regulate drug resistance in cancer cells. The team suggests that therapies targeting CDK12 are worth exploring.
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Affiliation(s)
- Seung Hyuk Choi
- Regulatory Biology Laboratory, The Salk Institute for Biological Studies, La Jolla, CA, 92037, USA.
| | - Seongjae Kim
- Molecular Neurobiology Laboratory, The Salk Institute for Biological Studies, La Jolla, CA, 92037, USA
| | - Katherine A Jones
- Regulatory Biology Laboratory, The Salk Institute for Biological Studies, La Jolla, CA, 92037, USA
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23
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Batool A, Majeed ST, Aashaq S, Majeed R, Andrabi KI. Eukaryotic Initiation Factor 4E phosphorylation acts a switch for its binding to 4E-BP1 and mRNA cap assembly. Biochem Biophys Res Commun 2020; 527:489-495. [PMID: 32336547 DOI: 10.1016/j.bbrc.2020.04.086] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2020] [Accepted: 04/16/2020] [Indexed: 11/28/2022]
Abstract
Translational regulation has invited considerable interest consequent of its circumstantial dysregulation during cancer genesis. eIF4E (Eukaryotic Initiation Factor 4E) has been identified as an important factor involved in tumor progression by way of instrumenting the convergence of oncogenic signals for up-regulation of Cap-dependent translation. In the backdrop of dramatic eIF4E over-expression in a large population of human cancers, we suggest that the tumorigenic property of eIF4E is strictly attributed to its phosphorylation state. We provide evidence that while phosphorylated eIF4E fails to be sequestered by 4E-BP1, its dephosphorylated form shows overwhelming binding with 4E-BP1 without any consideration to the state of 4E-BP1 phosphorylation to suggest that eIF4E-4EBP1 binding is governed by eIF4E phosphorylation instead of 4E-BP1. We also show that eIF4E engages in Cap-assembly formation preferably in a phosphorylation-dependent manner to suggest that eIF4E phosphorylation rather than 4E-BP1 regulates its availability for Cap-assembly.
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Affiliation(s)
- Asiya Batool
- Department of Biotechnology, Science Block, University of Kashmir, Srinagar, 190006, J&K, India
| | - Sheikh Tahir Majeed
- Department of Biotechnology, Science Block, University of Kashmir, Srinagar, 190006, J&K, India
| | - Sabreena Aashaq
- Department of Biotechnology, Science Block, University of Kashmir, Srinagar, 190006, J&K, India
| | - Rabiya Majeed
- Department of Biotechnology, Science Block, University of Kashmir, Srinagar, 190006, J&K, India
| | - Khurshid Iqbal Andrabi
- Department of Biotechnology, Science Block, University of Kashmir, Srinagar, 190006, J&K, India.
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24
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Lama D, Verma CS. Deciphering the mechanistic effects of eIF4E phosphorylation on mRNA-cap recognition. Protein Sci 2019; 29:1373-1386. [PMID: 31811670 DOI: 10.1002/pro.3798] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2019] [Revised: 12/05/2019] [Accepted: 12/05/2019] [Indexed: 12/23/2022]
Abstract
The mRNA cap-binding oncoprotein "eIF4E" is phosphorylated at residue S209 by Mnk kinases, and is closely associated with tumor development and progression. Despite being well-established, mechanistic details at the molecular level of mRNA recognition by eIF4E due to phosphorylation have not been clearly elucidated. We investigated this through molecular modeling and simulations of the S209 phosphorylated derivative of eIF4E and explored the associated implication on the binding of the different variants of mRNA-cap analogs. A key feature that emerges as a result of eIF4E phosphorylation is a salt-bridge network between the phosphorylated S209 (pS209) and a specific pair of lysine residues (K159 and K162) within the cap-binding interface on eIF4E. This interaction linkage stabilizes the otherwise dynamic C-terminal region of the protein, resulting in the attenuation of the overall plasticity and accessibility of the binding pocket. The pS209-K159 salt-bridge also results in an energetically less favorable environment for the bound mRNA-cap primarily due to electrostatic repulsion between the negative potentials from the phosphates in the cap and those appearing as a result of phosphorylation of S209. These observations collectively imply that the binding of the mRNA-cap will be adversely affected in the phosphorylated derivative of eIF4E. We propose a mechanistic model highlighting the role of eIF4E phosphorylation as a regulatory tool in modulating eIF4E: mRNA-cap recognition and its potential impact on translation initiation.
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Affiliation(s)
- Dilraj Lama
- Biomolecular Modelling and Design Division, Bioinformatics Institute, A*STAR (Agency for Science, Technology and Research), Singapore, Singapore.,Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, Stockholm, Sweden
| | - Chandra S Verma
- Biomolecular Modelling and Design Division, Bioinformatics Institute, A*STAR (Agency for Science, Technology and Research), Singapore, Singapore.,Department of Biological Sciences, National University of Singapore, Singapore, Singapore.,School of Biological Sciences, Nanyang Technological University, Singapore, Singapore
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25
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Santos Pereira-Dutra F, Cancela M, Valandro Meneghetti B, Bunselmeyer Ferreira H, Mariante Monteiro K, Zaha A. Functional characterization of the translation initiation factor eIF4E of Echinococcus granulosus. Parasitol Res 2019; 118:2843-2855. [PMID: 31401657 DOI: 10.1007/s00436-019-06421-8] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2019] [Accepted: 08/02/2019] [Indexed: 01/24/2023]
Abstract
The eukaryotic initiation factor 4E (eIF4E) specifically recognizes the 5' mRNA cap, a rate-limiting step in the translation initiation process. Although the 7-methylguanosine cap (MMGcap) is the most common 5' cap structure in eukaryotes, the trans-splicing process that occurs in several organism groups, including nematodes and flatworms, leads to the addition of a trimethylguanosine cap (TMGcap) to some RNA transcripts. In some helminths, eIF4E can have a dual capacity to bind both MMGcap and TMGcap. In the present work, we evaluated the distribution of eIF4E protein sequences in platyhelminths and we showed that only one gene coding for eIF4E is present in most parasitic flatworms. Based on this result, we cloned the Echinococcus granulosus cDNA sequence encoding eIF4E in Escherichia coli, expressed the recombinant eIF4E as a fusion protein to GST, and tested its ability to capture mRNAs through the 5' cap using pull-down assay and qPCR. Our results indicate that the recombinant eIF4E was able to bind preferentially 5'-capped mRNAs compared with rRNAs from total RNA preparations of E. granulosus. By qPCR, we observed an enrichment in MMG-capped mRNA compared with TMG-capped mRNAs among Eg-eIF4E-GST pull-down RNAs. Eg-eIF4E structural model using the Schistosoma mansoni eIF4E as template showed to be well preserved with only a few differences between chemically similar amino acid residues at the binding sites. These data showed that E. granulosus eIF4E can be used as a potential tool to study full-length 5'-capped mRNA, besides being a potential drug target against parasitic flatworms.
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Affiliation(s)
- Filipe Santos Pereira-Dutra
- Laboratório de Biologia Molecular de Cestodeos, Centro de Biotecnologia, Universidade Federal do Rio Grande do Sul, UFRGS, Avenida Bento Gonçalves, 9500, Caixa Postal 15053, Porto Alegre, RS, CEP 91501-970, Brazil.,Programa de Pós-Graduação em Biologia Celular e Molecular, Centro de Biotecnologia, UFRGS, Porto Alegre, Brazil
| | - Martin Cancela
- Laboratório de Biologia Molecular de Cestodeos, Centro de Biotecnologia, Universidade Federal do Rio Grande do Sul, UFRGS, Avenida Bento Gonçalves, 9500, Caixa Postal 15053, Porto Alegre, RS, CEP 91501-970, Brazil.,Programa de Pós-Graduação em Biologia Celular e Molecular, Centro de Biotecnologia, UFRGS, Porto Alegre, Brazil
| | - Bruna Valandro Meneghetti
- Laboratório de Biologia Molecular de Cestodeos, Centro de Biotecnologia, Universidade Federal do Rio Grande do Sul, UFRGS, Avenida Bento Gonçalves, 9500, Caixa Postal 15053, Porto Alegre, RS, CEP 91501-970, Brazil.,Programa de Pós-Graduação em Biologia Celular e Molecular, Centro de Biotecnologia, UFRGS, Porto Alegre, Brazil
| | - Henrique Bunselmeyer Ferreira
- Laboratório de Biologia Molecular de Cestodeos, Centro de Biotecnologia, Universidade Federal do Rio Grande do Sul, UFRGS, Avenida Bento Gonçalves, 9500, Caixa Postal 15053, Porto Alegre, RS, CEP 91501-970, Brazil.,Programa de Pós-Graduação em Biologia Celular e Molecular, Centro de Biotecnologia, UFRGS, Porto Alegre, Brazil.,Departamento de Biologia Molecular e Biotecnologia, Instituto de Biociências, UFRGS, Porto Alegre, Brazil
| | - Karina Mariante Monteiro
- Laboratório de Biologia Molecular de Cestodeos, Centro de Biotecnologia, Universidade Federal do Rio Grande do Sul, UFRGS, Avenida Bento Gonçalves, 9500, Caixa Postal 15053, Porto Alegre, RS, CEP 91501-970, Brazil.,Programa de Pós-Graduação em Biologia Celular e Molecular, Centro de Biotecnologia, UFRGS, Porto Alegre, Brazil.,Departamento de Biologia Molecular e Biotecnologia, Instituto de Biociências, UFRGS, Porto Alegre, Brazil
| | - Arnaldo Zaha
- Laboratório de Biologia Molecular de Cestodeos, Centro de Biotecnologia, Universidade Federal do Rio Grande do Sul, UFRGS, Avenida Bento Gonçalves, 9500, Caixa Postal 15053, Porto Alegre, RS, CEP 91501-970, Brazil. .,Programa de Pós-Graduação em Biologia Celular e Molecular, Centro de Biotecnologia, UFRGS, Porto Alegre, Brazil. .,Departamento de Biologia Molecular e Biotecnologia, Instituto de Biociências, UFRGS, Porto Alegre, Brazil.
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Casaos J, Gorelick NL, Huq S, Choi J, Xia Y, Serra R, Felder R, Lott T, Kast RE, Suk I, Brem H, Tyler B, Skuli N. The Use of Ribavirin as an Anticancer Therapeutic: Will It Go Viral? Mol Cancer Ther 2019; 18:1185-1194. [DOI: 10.1158/1535-7163.mct-18-0666] [Citation(s) in RCA: 37] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2018] [Revised: 01/25/2019] [Accepted: 05/08/2019] [Indexed: 11/16/2022]
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G3BP1 and G3BP2 regulate translation of interferon-stimulated genes: IFITM1, IFITM2 and IFITM3 in the cancer cell line MCF7. Mol Cell Biochem 2019; 459:189-204. [PMID: 31172368 DOI: 10.1007/s11010-019-03562-3] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2018] [Accepted: 05/27/2019] [Indexed: 12/13/2022]
Abstract
G3BPs are members of an RNA-binding protein family and their aberrant expression is common in various cancers and there is growing evidence that G3BPs possess antiviral activities and are targeted by various viruses. G3BPs have also been implicated in both stabilization and degradation of specific mRNAs as well as translational control of mRNA targets. G3BPs have been shown to control translation of interferon-stimulated genes (ISGs), implying that G3BPs are involved in the regulation of the interferon system in response to viral infections and/or cellular stress. The interferon induced transmembrane (IFITM1, IFITM2 and IFITM3) proteins are antiviral proteins, and are also involved in cancer progression and metastasis. Therefore, these genes were selected in the studies reported here as potential transcript targets of G3BPs. Furthermore, G3BPs are involved in the regulation of the MEK pathway which also impacts on the translation of ISGs. Therefore, the role of this pathway was also analysed in regulation of IFITM1-3 proteins. Overall, this research study suggests that G3BPs are essential for the accumulation of IFITM1-3 proteins and intersect twice in the regulation of IFITM1-3 expression, first through MEK pathway and then through an interaction with the 3'-UTRs of its target transcripts. However, it is still to be determined whether the two apparent functions are part of a single control mechanism or the two functions are mutually exclusive.
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Batool A, Aashaq S, Andrabi KI. Eukaryotic initiation factor 4E (eIF4E): A recap of the cap-binding protein. J Cell Biochem 2019; 120:14201-14212. [PMID: 31074051 DOI: 10.1002/jcb.28851] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2019] [Revised: 04/09/2019] [Accepted: 04/11/2019] [Indexed: 12/29/2022]
Abstract
Eukaryotic initiation factor 4E (eIF4E), a fundamental effector and rate limiting element of protein synthesis, binds the 7-methylguanosine cap at the 5' end of eukaryotic messenger RNA (mRNA) specifically as a constituent of eIF4F translation initiation complex thus facilitating the recruitment of mRNA to the ribosomes. This review focusses on the engagement of signals contributing to growth factor originated maxim and their role in the activation of eIF4E to achieve a collective influence on cellular growth, with a key focus on conjuring vital processes like protein synthesis. The review invites considerable interest in elevating the appeal of eIF4E beyond its role in regulating translation viz a viz cancer genesis, attributed to its phosphorylation state that improves the prospect for the growth of the cancerous cell. This review highlights the latest studies that have envisioned to target these pathways and ultimately the translational machinery for therapeutic intervention. The review also brings forward the prospect of eIF4E to act as a converging juncture for signaling pathways like mTOR/PI3K and Mnk/MAPK to promote tumorigenesis.
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Affiliation(s)
- Asiya Batool
- Department of Biotechnology and Bioinformatics, University of Kashmir, Srinagar, Jammu and Kashmir, India
| | - Sabreena Aashaq
- Department of Biotechnology and Bioinformatics, University of Kashmir, Srinagar, Jammu and Kashmir, India
| | - Khurshid I Andrabi
- Department of Biotechnology and Bioinformatics, University of Kashmir, Srinagar, Jammu and Kashmir, India
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Choi SH, Martinez TF, Kim S, Donaldson C, Shokhirev MN, Saghatelian A, Jones KA. CDK12 phosphorylates 4E-BP1 to enable mTORC1-dependent translation and mitotic genome stability. Genes Dev 2019; 33:418-435. [PMID: 30819820 PMCID: PMC6446539 DOI: 10.1101/gad.322339.118] [Citation(s) in RCA: 47] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2018] [Accepted: 01/22/2019] [Indexed: 01/23/2023]
Abstract
Here, Choi et al. show that CDK12, the RNA polymerase II C-terminal domain kinase, which regulates genome stability, expression of DNA repair genes, and cancer cell drug resistance, also phosphorylates the mRNA 5′ cap-binding repressor 4E-BP1 to promote translation of mTORC1-dependent mRNAs. Using RIP-seq and Ribo-seq, the authors found that CDK12 regulates binding of eIF4G to many mTORC1 target mRNAs, and identified specific CDK12 “translation-only” target mRNAs. The RNA polymerase II (RNAPII) C-terminal domain kinase, CDK12, regulates genome stability, expression of DNA repair genes, and cancer cell resistance to chemotherapy and immunotherapy. In addition to its role in mRNA biosynthesis of DNA repair genes, we show here that CDK12 phosphorylates the mRNA 5′ cap-binding repressor, 4E-BP1, to promote translation of mTORC1-dependent mRNAs. In particular, we found that phosphorylation of 4E-BP1 by mTORC1 (T37 and T46) facilitates subsequent CDK12 phosphorylation at two Ser–Pro sites (S65 and T70) that control the exchange of 4E-BP1 with eIF4G at the 5′ cap of CHK1 and other target mRNAs. RNA immunoprecipitation coupled with deep sequencing (RIP-seq) revealed that CDK12 regulates release of 4E-BP1, and binding of eIF4G, to many mTORC1 target mRNAs, including those needed for MYC transformation. Genome-wide ribosome profiling (Ribo-seq) further identified specific CDK12 “translation-only” target mRNAs, including many mTORC1 target mRNAs as well as many subunits of mitotic and centromere/centrosome complexes. Accordingly, confocal imaging analyses revealed severe chromosome misalignment, bridging, and segregation defects in cells deprived of CDK12 or CCNK. We conclude that the nuclear RNAPII-CTD kinase CDK12 cooperates with mTORC1, and controls a specialized translation network that is essential for mitotic chromosome stability.
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Affiliation(s)
- Seung H Choi
- Regulatory Biology Laboratory, The Salk Institute for Biological Studies, La Jolla, California 92037, USA
| | - Thomas F Martinez
- Clayton Foundation Laboratory for Peptide Biology, The Salk Institute for Biological Studies, La Jolla, California 92037, USA
| | - Seongjae Kim
- Molecular Neurobiology Laboratory, The Salk Institute for Biological Studies, La Jolla, California 92037, USA
| | - Cynthia Donaldson
- Clayton Foundation Laboratory for Peptide Biology, The Salk Institute for Biological Studies, La Jolla, California 92037, USA
| | - Maxim N Shokhirev
- Razavi Newman Integrative Genomics and Bioinformatics Core, The Salk Institute for Biological Studies, La Jolla, California 92037, USA
| | - Alan Saghatelian
- Clayton Foundation Laboratory for Peptide Biology, The Salk Institute for Biological Studies, La Jolla, California 92037, USA
| | - Katherine A Jones
- Regulatory Biology Laboratory, The Salk Institute for Biological Studies, La Jolla, California 92037, USA
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Targeting EIF4E signaling with ribavirin in infant acute lymphoblastic leukemia. Oncogene 2018; 38:2241-2262. [PMID: 30478448 PMCID: PMC6440839 DOI: 10.1038/s41388-018-0567-7] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2017] [Revised: 08/17/2018] [Accepted: 10/11/2018] [Indexed: 01/02/2023]
Abstract
The poor outcomes in infant acute lymphoblastic leukemia (ALL) necessitate new treatments. Here we discover that EIF4E protein is elevated in most cases of infant ALL and test EIF4E targeting by the repurposed antiviral agent ribavirin, which has anticancer properties through EIF4E inhibition, as a potential treatment. We find that ribavirin treatment of actively dividing infant ALL cells on bone marrow stromal cells (BMSCs) at clinically achievable concentrations causes robust proliferation inhibition in proportion with EIF4E expression. Further, we find that ribavirin treatment of KMT2A-rearranged (KMT2A-R) infant ALL cells and the KMT2A-AFF1 cell line RS4:11 inhibits EIF4E, leading to decreases in oncogenic EIF4E-regulated cell growth and survival proteins. In ribavirin-sensitive KMT2A-R infant ALL cells and RS4:11 cells, EIF4E-regulated proteins with reduced levels of expression following ribavirin treatment include MYC, MCL1, NBN, BCL2 and BIRC5. Ribavirin-treated RS4:11 cells exhibit impaired EIF4E-dependent nuclear to cytoplasmic export and/or translation of the corresponding mRNAs, as well as reduced phosphorylation of the p-AKT1, p-EIF4EBP1, p-RPS6 and p-EIF4E signaling proteins. This leads to an S-phase cell cycle arrest in RS4:11 cells corresponding to the decreased proliferation. Ribavirin causes nuclear EIF4E to re-localize to the cytoplasm in KMT2A-AFF1 infant ALL and RS4:11 cells, providing further evidence for EIF4E inhibition. Ribavirin slows increases in peripheral blasts in KMT2A-R infant ALL xenograft-bearing mice. Ribavirin cooperates with chemotherapy, particularly L-asparaginase, in reducing live KMT2A-AFF1 infant ALL cells in BMSC co-cultures. This work establishes that EIF4E is broadly elevated across infant ALL and that clinically relevant ribavirin exposures have preclinical activity and effectively inhibit EIF4E in KMT2A-R cases, suggesting promise in EIF4E targeting using ribavirin as a means of treatment.
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Culjkovic-Kraljacic B, Borden KLB. The Impact of Post-transcriptional Control: Better Living Through RNA Regulons. Front Genet 2018; 9:512. [PMID: 30455716 PMCID: PMC6230556 DOI: 10.3389/fgene.2018.00512] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2018] [Accepted: 10/12/2018] [Indexed: 12/26/2022] Open
Abstract
Traditionally, cancer is viewed as a disease driven by genetic mutations and/or epigenetic and transcriptional dysregulation. While these are undoubtedly important drivers, many recent studies highlight the disconnect between the proteome and the genome or transcriptome. At least in part, this disconnect arises as a result of dysregulated RNA metabolism which underpins the altered proteomic landscape observed. Thus, it is important to understand the basic mechanisms governing post-transcriptional control and how these processes can be co-opted to drive cancer cell phenotypes. In some cases, groups of mRNAs that encode protein involved in specific oncogenic processes can be co-regulated at multiple processing levels in order to turn on entire biochemical pathways. Indeed, the RNA regulon model was postulated as a means to understand how cells coordinately regulate transcripts encoding proteins in the same biochemical pathways. In this review, we describe some of the basic mRNA processes that are dysregulated in cancer and the biological impact this has on the cell. This dysregulation can affect networks of RNAs simultaneously thereby underpinning the oncogenic phenotypes observed.
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Affiliation(s)
- Biljana Culjkovic-Kraljacic
- Institute for Research in Immunology and Cancer, Department of Pathology and Cell Biology, University of Montreal, Montreal, QC, Canada
| | - Katherine L B Borden
- Institute for Research in Immunology and Cancer, Department of Pathology and Cell Biology, University of Montreal, Montreal, QC, Canada
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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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Kocmik I, Piecyk K, Rudzinska M, Niedzwiecka A, Darzynkiewicz E, Grzela R, Jankowska-Anyszka M. Modified ARCA analogs providing enhanced translational properties of capped mRNAs. Cell Cycle 2018; 17:1624-1636. [PMID: 29954234 DOI: 10.1080/15384101.2018.1486164] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022] Open
Abstract
Nowadays gene manipulation techniques ("DNA therapy") undergo progressive development and become widely used in industry and medicine. Since new advances in mRNA technologies are capable for obtaining particles with increased stability and translational efficiency, RNA become an attractive alternative for advancement of DNA therapy. For the past years studies have been conducted to explore different modification in mRNA cap structure and its effect on RNA properties. Recently we have shown that modification of the cap structure at the N2 position of 7-methylguanosine leads to an enhancement in translation inhibition. Currently, we have decided to exploit translational properties of mRNA capped with the ARCA (anti-reversed cap) analogs modified within N2 position of purine moiety s. We designed and synthesized three new dinucleotide cap analogs and investigated them in the rabbit reticulocyte lysate (RRL) and the human embryonic kidney derived HEK293 cell line, in vitro translational model systems. The obtained data indicate that, in both translational assays, the cap analogs synthesized by us when incorporated into mRNA improved its translational properties compared to the ARCA capped transcripts. Furthermore, the introduced modifications enhanced stability of the capped transcripts in HEK293 cells, which become higher compared to that of the transcripts capped with regular cap or with ARCA. Additionally one of the synthesized cap analogs revealed strong translation inhibition potency in RRL system, with IC50 value 1.7 µM.
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Affiliation(s)
- Ilona Kocmik
- a Faculty of Chemistry , University of Warsaw , Warsaw , Poland
| | - Karolina Piecyk
- a Faculty of Chemistry , University of Warsaw , Warsaw , Poland
| | | | - Anna Niedzwiecka
- c Laboratory of Biological Physics , Institute of Physics, Polish Academy of Sciences , Warsaw , Poland
| | - Edward Darzynkiewicz
- b Centre of New Technologies , University of Warsaw , Warsaw , Poland.,d Division of Biophysics, Institute of Experimental Physics, Faculty of Physics , University of Warsaw , Warsaw , Poland
| | - Renata Grzela
- b Centre of New Technologies , University of Warsaw , Warsaw , Poland
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Piserà A, Campo A, Campo S. Structure and functions of the translation initiation factor eIF4E and its role in cancer development and treatment. J Genet Genomics 2018; 45:13-24. [DOI: 10.1016/j.jgg.2018.01.003] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2017] [Revised: 01/12/2018] [Accepted: 01/15/2018] [Indexed: 12/22/2022]
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The Role of Cytoplasmic mRNA Cap-Binding Protein Complexes in Trypanosoma brucei and Other Trypanosomatids. Pathogens 2017; 6:pathogens6040055. [PMID: 29077018 PMCID: PMC5750579 DOI: 10.3390/pathogens6040055] [Citation(s) in RCA: 44] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2017] [Revised: 10/21/2017] [Accepted: 10/22/2017] [Indexed: 11/16/2022] Open
Abstract
Trypanosomatid protozoa are unusual eukaryotes that are well known for having unusual ways of controlling their gene expression. The lack of a refined mode of transcriptional control in these organisms is compensated by several post-transcriptional control mechanisms, such as control of mRNA turnover and selection of mRNA for translation, that may modulate protein synthesis in response to several environmental conditions found in different hosts. In other eukaryotes, selection of mRNA for translation is mediated by the complex eIF4F, a heterotrimeric protein complex composed by the subunits eIF4E, eIF4G, and eIF4A, where the eIF4E binds to the 5'-cap structure of mature mRNAs. In this review, we present and discuss the characteristics of six trypanosomatid eIF4E homologs and their associated proteins that form multiple eIF4F complexes. The existence of multiple eIF4F complexes in trypanosomatids evokes exquisite mechanisms for differential mRNA recognition for translation.
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