1
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Kerry J, Specker EJ, Mizzoni M, Brumwell A, Fell L, Goodbrand J, Rosen MN, Uniacke J. Autophagy-dependent alternative splicing of ribosomal protein S24 produces a more stable isoform that aids in hypoxic cell survival. FEBS Lett 2024; 598:503-520. [PMID: 38281767 DOI: 10.1002/1873-3468.14804] [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: 11/05/2023] [Revised: 12/08/2023] [Accepted: 12/24/2023] [Indexed: 01/30/2024]
Abstract
Cells remodel splicing and translation machineries to mount specialized gene expression responses to stress. Here, we show that hypoxic human cells in 2D and 3D culture models increase the relative abundance of a longer mRNA variant of ribosomal protein S24 (RPS24L) compared to a shorter mRNA variant (RPS24S) by favoring the inclusion of a 22 bp cassette exon. Mechanistically, RPS24L and RPS24S are induced and repressed, respectively, by distinct pathways in hypoxia: RPS24L is induced in an autophagy-dependent manner, while RPS24S is reduced by mTORC1 repression in a hypoxia-inducible factor-dependent manner. RPS24L produces a more stable protein isoform that aids in hypoxic cell survival and growth, which could be exploited by cancer cells in the tumor microenvironment.
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Affiliation(s)
- Jenna Kerry
- Department of Molecular and Cellular Biology, University of Guelph, Canada
| | - Erin J Specker
- Department of Molecular and Cellular Biology, University of Guelph, Canada
| | - Morgan Mizzoni
- Department of Molecular and Cellular Biology, University of Guelph, Canada
| | - Andrea Brumwell
- Department of Molecular and Cellular Biology, University of Guelph, Canada
| | - Leslie Fell
- Department of Molecular and Cellular Biology, University of Guelph, Canada
| | - Jenna Goodbrand
- Department of Molecular and Cellular Biology, University of Guelph, Canada
| | - Michael N Rosen
- Department of Molecular and Cellular Biology, University of Guelph, Canada
| | - James Uniacke
- Department of Molecular and Cellular Biology, University of Guelph, Canada
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2
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Meyer K, Ling KH, Yeo PL, Spathopoulou A, Drake D, Choi J, Aron L, Garcia-Corral M, Ko T, Lee EA, Tam JM, Perlis RH, Church GM, Tsai LH, Yankner BA. Impaired neural stress resistance and loss of REST in bipolar disorder. Mol Psychiatry 2024; 29:153-164. [PMID: 37938767 DOI: 10.1038/s41380-023-02313-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/04/2023] [Revised: 07/27/2023] [Accepted: 10/25/2023] [Indexed: 11/09/2023]
Abstract
Neurodevelopmental changes and impaired stress resistance have been implicated in the pathogenesis of bipolar disorder (BD), but the underlying regulatory mechanisms are unresolved. Here we describe a human cerebral organoid model of BD that exhibits altered neural development, elevated neural network activity, and a major shift in the transcriptome. These phenotypic changes were reproduced in cerebral organoids generated from iPS cell lines derived in different laboratories. The BD cerebral organoid transcriptome showed highly significant enrichment for gene targets of the transcriptional repressor REST. This was associated with reduced nuclear REST and REST binding to target gene recognition sites. Reducing the oxygen concentration in organoid cultures to a physiological range ameliorated the developmental phenotype and restored REST expression. These effects were mimicked by treatment with lithium. Reduced nuclear REST and derepression of REST targets genes were also observed in the prefrontal cortex of BD patients. Thus, an impaired cellular stress response in BD cerebral organoids leads to altered neural development and transcriptional dysregulation associated with downregulation of REST. These findings provide a new model and conceptual framework for exploring the molecular basis of BD.
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Affiliation(s)
- Katharina Meyer
- Department of Genetics, Harvard Medical School, Boston, MA, 02115, USA
| | - King-Hwa Ling
- Department of Genetics, Harvard Medical School, Boston, MA, 02115, USA
| | - Pei-Ling Yeo
- Department of Genetics, Harvard Medical School, Boston, MA, 02115, USA
| | | | - Derek Drake
- Department of Genetics, Harvard Medical School, Boston, MA, 02115, USA
| | - Jaejoon Choi
- Department of Genetics, Harvard Medical School, Boston, MA, 02115, USA
| | - Liviu Aron
- Department of Genetics, Harvard Medical School, Boston, MA, 02115, USA
| | - Mariana Garcia-Corral
- Wyss Institute for Biologically Inspired Engineering, Harvard University, Boston, MA, 02115, USA
| | - Tak Ko
- The Picower Institute for Learning and Memory, Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA
| | - Eunjung Alice Lee
- Division of Genetics and Genomics, Manton Center for Orphan Disease Research, Boston Children's Hospital, Boston, MA, 02115, USA
| | - Jenny M Tam
- Department of Genetics, Harvard Medical School, Boston, MA, 02115, USA
- Wyss Institute for Biologically Inspired Engineering, Harvard University, Boston, MA, 02115, USA
| | - Roy H Perlis
- Center for Quantitative Health, Center for Genomic Medicine and Department of Psychiatry, Massachusetts General Hospital, Boston, MA, USA
| | - George M Church
- Department of Genetics, Harvard Medical School, Boston, MA, 02115, USA
- Wyss Institute for Biologically Inspired Engineering, Harvard University, Boston, MA, 02115, USA
| | - Li-Huei Tsai
- The Picower Institute for Learning and Memory, Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA
| | - Bruce A Yankner
- Department of Genetics, Harvard Medical School, Boston, MA, 02115, USA.
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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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Chettouh-Hammas N, Fasani F, Boileau A, Gosset D, Busco G, Grillon C. Improvement of Antioxidant Defences in Keratinocytes Grown in Physioxia: Comparison of 2D and 3D Models. OXIDATIVE MEDICINE AND CELLULAR LONGEVITY 2023; 2023:6829931. [PMID: 37360501 PMCID: PMC10290565 DOI: 10.1155/2023/6829931] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/06/2023] [Revised: 04/25/2023] [Accepted: 05/27/2023] [Indexed: 06/28/2023]
Abstract
Keratinocytes prevent skin photoaging by ensuring the defence against oxidative stress, an excessive production of reactive oxygen species (ROS). They are localized within the epidermis where the oxygen level (1-3% O2), named physioxia, is low compared to other organs. Oxygen is essential for life but also generates ROS. Most of the in vitro studies on keratinocyte antioxidant capacities are performed under atmospheric oxygen, named normoxia, which is very far from the physiological microenvironment, thus submitting cells to an overoxygenation. The present study is aimed at investigating the antioxidant status of keratinocyte grown under physioxia in both 2D and 3D models. First, we show that the basal antioxidant profiles of keratinocytes display important differences when comparing the HaCaT cell line, primary keratinocytes (NHEK), reconstructed epidermis (RHE), and skin explants. Physioxia was shown to promote a strong proliferation of keratinocytes in monolayers and in RHE, resulting in a thinner epidermis likely due to a slowdown in cell differentiation. Interestingly, cells in physioxia exhibited a lower ROS production upon stress, suggesting a better protection against oxidative stress. To understand this effect, we studied the antioxidant enzymes and reported a lower or equivalent level of mRNA for all enzymes in physioxia conditions compared to normoxia, but a higher activity for catalase and superoxide dismutases, whatever the culture model. The unchanged catalase amount, in NHEK and RHE, suggests an overactivation of the enzyme in physioxia, whereas the higher amount of SOD2 can explain the strong activity. Taken together, our results demonstrate the role of oxygen in the regulation of the antioxidant defences in keratinocytes, topic of particular importance for studying skin aging. Additionally, the present work points out the interest of the choice of both the keratinocyte culture model and the oxygen level to be as close as possible to the in situ skin.
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Affiliation(s)
- Nadira Chettouh-Hammas
- Center for Molecular Biophysics UPR4301 CNRS, Rue Charles Sadron, 45071 Orléans Cedex 2, France
| | - Fabienne Fasani
- Center for Molecular Biophysics UPR4301 CNRS, Rue Charles Sadron, 45071 Orléans Cedex 2, France
| | - Amandine Boileau
- Center for Molecular Biophysics UPR4301 CNRS, Rue Charles Sadron, 45071 Orléans Cedex 2, France
| | - David Gosset
- Center for Molecular Biophysics UPR4301 CNRS, Rue Charles Sadron, 45071 Orléans Cedex 2, France
| | - Giovanni Busco
- Center for Molecular Biophysics UPR4301 CNRS, Rue Charles Sadron, 45071 Orléans Cedex 2, France
| | - Catherine Grillon
- Center for Molecular Biophysics UPR4301 CNRS, Rue Charles Sadron, 45071 Orléans Cedex 2, France
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5
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Montiel-Dávalos A, Ayala Y, Hernández G. The dark side of mRNA translation and the translation machinery in glioblastoma. Front Cell Dev Biol 2023; 11:1086964. [PMID: 36994107 PMCID: PMC10042294 DOI: 10.3389/fcell.2023.1086964] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2022] [Accepted: 03/03/2023] [Indexed: 03/14/2023] Open
Abstract
Among the different types of cancer affecting the central nervous system (CNS), glioblastoma (GB) is classified by the World Health Organization (WHO) as the most common and aggressive CNS cancer in adults. GB incidence is more frequent among persons aged 45–55 years old. GB treatments are based on tumor resection, radiation, and chemotherapies. The current development of novel molecular biomarkers (MB) has led to a more accurate prediction of GB progression. Moreover, clinical, epidemiological, and experimental studies have established genetic variants consistently associated with the risk of suffering GB. However, despite the advances in these fields, the survival expectancy of GB patients is still shorter than 2 years. Thus, fundamental processes inducing tumor onset and progression remain to be elucidated. In recent years, mRNA translation has been in the spotlight, as its dysregulation is emerging as a key cause of GB. In particular, the initiation phase of translation is most involved in this process. Among the crucial events, the machinery performing this phase undergoes a reconfiguration under the hypoxic conditions in the tumor microenvironment. In addition, ribosomal proteins (RPs) have been reported to play translation-independent roles in GB development. This review focuses on the research elucidating the tight relationship between translation initiation, the translation machinery, and GB. We also summarize the state-of-the-art drugs targeting the translation machinery to improve patients’ survival. Overall, the recent advances in this field are shedding new light on the dark side of translation in GB.
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6
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Christie M, Igreja C. eIF4E-homologous protein (4EHP): a multifarious cap-binding protein. FEBS J 2023; 290:266-285. [PMID: 34758096 DOI: 10.1111/febs.16275] [Citation(s) in RCA: 11] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2021] [Revised: 10/29/2021] [Accepted: 11/09/2021] [Indexed: 02/05/2023]
Abstract
The cap-binding protein 4EHP/eIF4E2 has been a recent object of interest in the field of post-transcriptional gene regulation and translational control. From ribosome-associated quality control, to RNA decay and microRNA-mediated gene silencing, this member of the eIF4E protein family regulates gene expression through numerous pathways. Low in abundance but ubiquitously expressed, 4EHP interacts with different binding partners to form multiple protein complexes that regulate translation in a variety of biological contexts. Documented functions of 4EHP primarily relate to its role as a translational repressor, but recent findings indicate that it might also participate in the activation of translation in specific settings. In this review, we discuss the known functions, properties and mechanisms that involve 4EHP in the control of gene expression. We also discuss our current understanding of how 4EHP processes are regulated in eukaryotic cells, and the diseases implicated with dysregulation of 4EHP-mediated translational control.
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Affiliation(s)
- Mary Christie
- School of Life and Environmental Sciences, The University of Sydney, NSW, Australia
| | - Cátia Igreja
- Department for Integrative Evolutionary Biology, Max Planck Institute for Developmental Biology, Tübingen, Germany
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7
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Melanson G, Du Bois AC, Webster C, Uniacke J. ISGylation
directly modifies hypoxia‐inducible factor‐2α and enhances its polysome association. FEBS Lett 2022; 596:2834-2850. [DOI: 10.1002/1873-3468.14476] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2022] [Revised: 07/28/2022] [Accepted: 08/15/2022] [Indexed: 11/11/2022]
Affiliation(s)
- Gaelan Melanson
- Department of Molecular and Cellular Biology University of Guelph Guelph Ontario Canada
| | - Antonia C. Du Bois
- Department of Molecular and Cellular Biology University of Guelph Guelph Ontario Canada
| | - Caroline Webster
- Department of Molecular and Cellular Biology University of Guelph Guelph Ontario Canada
| | - James Uniacke
- Department of Molecular and Cellular Biology University of Guelph Guelph Ontario Canada
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8
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Piossek F, Beneke S, Schlichenmaier N, Mucic G, Drewitz S, Dietrich DR. Physiological oxygen and co-culture with human fibroblasts facilitate in vivo-like properties in human renal proximal tubular epithelial cells. Chem Biol Interact 2022; 361:109959. [DOI: 10.1016/j.cbi.2022.109959] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2021] [Revised: 04/08/2022] [Accepted: 04/12/2022] [Indexed: 11/28/2022]
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9
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Méndez-Solís O, Bendjennat M, Naipauer J, Theodoridis PR, Ho JJD, Verdun RE, Hare JM, Cesarman E, Lee S, Mesri EA. Kaposi's sarcoma herpesvirus activates the hypoxia response to usurp HIF2α-dependent translation initiation for replication and oncogenesis. Cell Rep 2021; 37:110144. [PMID: 34965440 PMCID: PMC9121799 DOI: 10.1016/j.celrep.2021.110144] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2021] [Revised: 05/19/2021] [Accepted: 11/29/2021] [Indexed: 12/19/2022] Open
Abstract
Kaposi's sarcoma herpesvirus (KSHV) is an angiogenesis-inducing oncovirus whose ability to usurp the oxygen-sensing machinery is central to its oncogenicity. By upregulating the hypoxia-inducible factors (HIFs), KSHV reprograms infected cells to a hypoxia-like state, triggering angiogenesis. Here we identify a link between KSHV replicative biology and oncogenicity by showing that KSHV's ability to regulate HIF2α levels and localization to the endoplasmic reticulum (ER) in normoxia enables translation of viral lytic mRNAs through the HIF2α-regulated eIF4E2 translation-initiation complex. This mechanism of translation in infected cells is critical for lytic protein synthesis and contributes to KSHV-induced PDGFRA activation and VEGF secretion. Thus, KSHV regulation of the oxygen-sensing machinery allows virally infected cells to initiate translation via the mTOR-dependent eIF4E1 or the HIF2α-dependent, mTOR-independent, eIF4E2. This "translation initiation plasticity" (TRIP) is an oncoviral strategy used to optimize viral protein expression that links molecular strategies of viral replication to angiogenicity and oncogenesis.
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Affiliation(s)
- Omayra Méndez-Solís
- Tumor Biology Program, Sylvester Comprehensive Cancer Center, University of Miami Miller School of Medicine, Miami, FL 33136, USA; Miami Center for AIDS Research, Department of Microbiology and Immunology, University of Miami Miller School of Medicine, Miami, FL 33136, USA
| | - Mourad Bendjennat
- Tumor Biology Program, Sylvester Comprehensive Cancer Center, University of Miami Miller School of Medicine, Miami, FL 33136, USA; Miami Center for AIDS Research, Department of Microbiology and Immunology, University of Miami Miller School of Medicine, Miami, FL 33136, USA; Department of Radiation Oncology, University of Miami Miller School of Medicine, Miami, FL 33136, USA
| | - Julian Naipauer
- Tumor Biology Program, Sylvester Comprehensive Cancer Center, University of Miami Miller School of Medicine, Miami, FL 33136, USA; Miami Center for AIDS Research, Department of Microbiology and Immunology, University of Miami Miller School of Medicine, Miami, FL 33136, USA
| | - Phaedra R Theodoridis
- Tumor Biology Program, Sylvester Comprehensive Cancer Center, University of Miami Miller School of Medicine, Miami, FL 33136, USA; Department of Biochemistry and Molecular Biology, University of Miami Miller School of Medicine, Miami, FL 33136, USA
| | - J J David Ho
- Tumor Biology Program, Sylvester Comprehensive Cancer Center, University of Miami Miller School of Medicine, Miami, FL 33136, USA; Department of Biochemistry and Molecular Biology, University of Miami Miller School of Medicine, Miami, FL 33136, USA
| | - Ramiro E Verdun
- Cancer Epigenetics Program, Sylvester Comprehensive Cancer Center, University of Miami Miller School of Medicine, Miami, FL 33136, USA; Department of Medicine, University of Miami Miller School of Medicine, Miami, FL 33136, USA
| | - Joshua M Hare
- Department of Medicine, University of Miami Miller School of Medicine, Miami, FL 33136, USA; Interdisciplinary Stem Cell Institute, University of Miami Miller School of Medicine, Miami, FL 33136, USA
| | - Ethel Cesarman
- Department of Pathology and Laboratory Medicine, Weill Cornell Medicine, New York, NY 10021, USA
| | - Stephen Lee
- Tumor Biology Program, Sylvester Comprehensive Cancer Center, University of Miami Miller School of Medicine, Miami, FL 33136, USA; Department of Biochemistry and Molecular Biology, University of Miami Miller School of Medicine, Miami, FL 33136, USA.
| | - Enrique A Mesri
- Tumor Biology Program, Sylvester Comprehensive Cancer Center, University of Miami Miller School of Medicine, Miami, FL 33136, USA; Miami Center for AIDS Research, Department of Microbiology and Immunology, University of Miami Miller School of Medicine, Miami, FL 33136, USA.
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10
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Sinha NK, Ordureau A, Best K, Saba JA, Zinshteyn B, Sundaramoorthy E, Fulzele A, Garshott DM, Denk T, Thoms M, Paulo JA, Harper JW, Bennett EJ, Beckmann R, Green R. EDF1 coordinates cellular responses to ribosome collisions. eLife 2020; 9:e58828. [PMID: 32744497 PMCID: PMC7486125 DOI: 10.7554/elife.58828] [Citation(s) in RCA: 83] [Impact Index Per Article: 20.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2020] [Accepted: 08/02/2020] [Indexed: 12/11/2022] Open
Abstract
Translation of aberrant mRNAs induces ribosomal collisions, thereby triggering pathways for mRNA and nascent peptide degradation and ribosomal rescue. Here we use sucrose gradient fractionation combined with quantitative proteomics to systematically identify proteins associated with collided ribosomes. This approach identified Endothelial differentiation-related factor 1 (EDF1) as a novel protein recruited to collided ribosomes during translational distress. Cryo-electron microscopic analyses of EDF1 and its yeast homolog Mbf1 revealed a conserved 40S ribosomal subunit binding site at the mRNA entry channel near the collision interface. EDF1 recruits the translational repressors GIGYF2 and EIF4E2 to collided ribosomes to initiate a negative-feedback loop that prevents new ribosomes from translating defective mRNAs. Further, EDF1 regulates an immediate-early transcriptional response to ribosomal collisions. Our results uncover mechanisms through which EDF1 coordinates multiple responses of the ribosome-mediated quality control pathway and provide novel insights into the intersection of ribosome-mediated quality control with global transcriptional regulation.
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Affiliation(s)
- Niladri K Sinha
- Department of Molecular Biology and Genetics, Howard Hughes Medical Institute, Johns Hopkins University School of MedicineBaltimoreUnited States
| | - Alban Ordureau
- Department of Cell Biology, Blavatnik Institute of Harvard Medical SchoolBostonUnited States
| | - Katharina Best
- Gene Center, Department of Biochemistry, Ludwig-Maximilians-Universität MünchenMunichGermany
| | - James A Saba
- Department of Molecular Biology and Genetics, Howard Hughes Medical Institute, Johns Hopkins University School of MedicineBaltimoreUnited States
| | - Boris Zinshteyn
- Department of Molecular Biology and Genetics, Howard Hughes Medical Institute, Johns Hopkins University School of MedicineBaltimoreUnited States
| | - Elayanambi Sundaramoorthy
- Section of Cell and Developmental Biology, Division of Biological Sciences, University of California, San DiegoSan DiegoUnited States
| | - Amit Fulzele
- Section of Cell and Developmental Biology, Division of Biological Sciences, University of California, San DiegoSan DiegoUnited States
| | - Danielle M Garshott
- Section of Cell and Developmental Biology, Division of Biological Sciences, University of California, San DiegoSan DiegoUnited States
| | - Timo Denk
- Gene Center, Department of Biochemistry, Ludwig-Maximilians-Universität MünchenMunichGermany
| | - Matthias Thoms
- Gene Center, Department of Biochemistry, Ludwig-Maximilians-Universität MünchenMunichGermany
| | - Joao A Paulo
- Department of Cell Biology, Blavatnik Institute of Harvard Medical SchoolBostonUnited States
| | - J Wade Harper
- Department of Cell Biology, Blavatnik Institute of Harvard Medical SchoolBostonUnited States
| | - Eric J Bennett
- Section of Cell and Developmental Biology, Division of Biological Sciences, University of California, San DiegoSan DiegoUnited States
| | - Roland Beckmann
- Gene Center, Department of Biochemistry, Ludwig-Maximilians-Universität MünchenMunichGermany
| | - Rachel Green
- Department of Molecular Biology and Genetics, Howard Hughes Medical Institute, Johns Hopkins University School of MedicineBaltimoreUnited States
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11
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Zhu S, Estévez JM, Liao H, Zhu Y, Yang T, Li C, Wang Y, Li L, Liu X, Pacheco JM, Guo H, Yu F. The RALF1-FERONIA Complex Phosphorylates eIF4E1 to Promote Protein Synthesis and Polar Root Hair Growth. MOLECULAR PLANT 2020; 13:698-716. [PMID: 31904511 DOI: 10.1016/j.molp.2019.12.014] [Citation(s) in RCA: 69] [Impact Index Per Article: 17.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/08/2019] [Revised: 12/07/2019] [Accepted: 12/31/2019] [Indexed: 05/04/2023]
Abstract
The molecular links between extracellular signals and the regulation of localized protein synthesis in plant cells are poorly understood. Here, we show that in Arabidopsis thaliana, the extracellular peptide RALF1 and its receptor, the FERONIA receptor kinase, promote root hair (RH) tip growth by modulating protein synthesis. We found that RALF1 promotes FERONIA-mediated phosphorylation of eIF4E1, a eukaryotic translation initiation factor that plays a crucial role in the control of mRNA translation rate. Phosphorylated eIF4E1 increases mRNA affinity and modulates mRNA translation and, thus, protein synthesis. The mRNAs targeted by the RALF1-FERONIA-eIF4E1 module include ROP2 and RSL4, which are important regulators of RH cell polarity and growth. RALF1 and FERONIA are expressed in a polar manner in RHs, which facilitate eIF4E1 polar localization and thus may control local ROP2 translation. Moreover, we demonstrated that high-level accumulation of RSL4 exerts negative-feedback regulation of RALF1 expression by directly binding the RALF1 gene promoter, determining the final RH size. Our study reveals that the link between RALF1-FERONIA signaling and protein synthesis constitutes a novel component regulating cell expansion in these polar growing cells.
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Affiliation(s)
- Sirui Zhu
- State Key Laboratory of Chemo/Biosensing and Chemometrics, College of Biology, and Hunan Key Laboratory of Plant Functional Genomics and Developmental Regulation, Hunan University, Changsha 410082, P.R. China
| | - José Manuel Estévez
- Fundación Instituto Leloir, Buenos Aires C1405BWE, Argentina and IIBBA-CONICET, Buenos Aires C1405BWE, Argentina; Centro de Biotecnología Vegetal, Facultad de Ciencias de la Vida, Universidad Andres Bello, Santiago RM 8370146, Chile
| | - Hongdong Liao
- State Key Laboratory of Chemo/Biosensing and Chemometrics, College of Biology, and Hunan Key Laboratory of Plant Functional Genomics and Developmental Regulation, Hunan University, Changsha 410082, P.R. China
| | - Yonghua Zhu
- State Key Laboratory of Chemo/Biosensing and Chemometrics, College of Biology, and Hunan Key Laboratory of Plant Functional Genomics and Developmental Regulation, Hunan University, Changsha 410082, P.R. China
| | - Tao Yang
- National Engineering Laboratory for Rice and Byproduct Deep Processing, Central South University of Forestry and Technology, Changsha 410004, P.R. China
| | - Chiyu Li
- State Key Laboratory of Chemo/Biosensing and Chemometrics, College of Biology, and Hunan Key Laboratory of Plant Functional Genomics and Developmental Regulation, Hunan University, Changsha 410082, P.R. China
| | - Yichuan Wang
- Institute of Plant and Food Science, Department of Biology, Southern University of Science and Technology, Shenzhen, Guangdong 518055, P.R. China
| | - Lan Li
- State Key Laboratory of Chemo/Biosensing and Chemometrics, College of Biology, and Hunan Key Laboratory of Plant Functional Genomics and Developmental Regulation, Hunan University, Changsha 410082, P.R. China
| | - Xuanming Liu
- State Key Laboratory of Chemo/Biosensing and Chemometrics, College of Biology, and Hunan Key Laboratory of Plant Functional Genomics and Developmental Regulation, Hunan University, Changsha 410082, P.R. China
| | - Javier Martinez Pacheco
- Fundación Instituto Leloir, Buenos Aires C1405BWE, Argentina and IIBBA-CONICET, Buenos Aires C1405BWE, Argentina
| | - Hongwei Guo
- Institute of Plant and Food Science, Department of Biology, Southern University of Science and Technology, Shenzhen, Guangdong 518055, P.R. China
| | - Feng Yu
- State Key Laboratory of Chemo/Biosensing and Chemometrics, College of Biology, and Hunan Key Laboratory of Plant Functional Genomics and Developmental Regulation, Hunan University, Changsha 410082, P.R. China; State Key Laboratory of Hybrid Rice, Hunan Hybrid Rice Research Center, Changsha 410125, P.R. China.
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12
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Brumwell A, Fell L, Obress L, Uniacke J. Hypoxia influences polysome distribution of human ribosomal protein S12 and alternative splicing of ribosomal protein mRNAs. RNA (NEW YORK, N.Y.) 2020; 26:361-371. [PMID: 31911497 PMCID: PMC7025504 DOI: 10.1261/rna.070318.119] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/08/2019] [Accepted: 01/02/2020] [Indexed: 06/10/2023]
Abstract
Ribosomes were once considered static in their composition because of their essential role in protein synthesis and kingdom-wide conservation. The existence of tolerated mutations in select ribosomal proteins (RPs), such as in Diamond-Blackfan anemia, is evidence that not all ribosome components are essential. Heterogeneity in the protein composition of eukaryotic ribosomes is an emerging concept with evidence that different pools of ribosomes exist with transcript-specificity. Here, we show that the polysome association of ribosomal proteins is altered by low oxygen (hypoxia), a feature of the tumor microenvironment, in human cells. We quantified ribosomal protein abundance in actively translating polysomes of normoxic and hypoxic HEK293 cells by tandem mass tags mass spectrometry. Our data suggest that RPS12 (eS12) is enriched in hypoxic monosomes, which increases the heavy polysome association of structured transcripts APAF-1 and XIAP. Furthermore, hypoxia induced five alternative splicing events within a subset of RP mRNAs in cell lines. One of these events in RPS24 (eS24 protein) alters the coding sequence to produce two protein isoforms that can incorporate into ribosomes. This splicing event is greatly induced in spheroids and correlates with tumor hypoxia in human prostate cancer. Our data suggest that hypoxia may influence the composition of the human ribosome through changes in RP incorporation and the production of hypoxia-specific RP isoforms.
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Affiliation(s)
- Andrea Brumwell
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario N1G 2W1, Canada
| | - Leslie Fell
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario N1G 2W1, Canada
| | - Lindsay Obress
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario N1G 2W1, Canada
| | - James Uniacke
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario N1G 2W1, Canada
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13
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DEAD Box Protein Family Member DDX28 Is a Negative Regulator of Hypoxia-Inducible Factor 2α- and Eukaryotic Initiation Factor 4E2-Directed Hypoxic Translation. Mol Cell Biol 2020; 40:MCB.00610-19. [PMID: 31907278 DOI: 10.1128/mcb.00610-19] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2019] [Accepted: 12/20/2019] [Indexed: 12/27/2022] Open
Abstract
Hypoxia is a deficiency in oxygen delivery to tissues and is connected to physiological and pathophysiological processes such as embryonic development and cancer. The master regulators of oxygen homeostasis in mammalian cells are the heterodimeric hypoxia-inducible transcription factors 1 and 2 (HIF-1 and HIF-2, respectively). The oxygen-labile HIF-2α subunit has been implicated not only in transcription but also as a regulator of eukaryotic initiation factor 4E2 (eIF4E2)-directed hypoxic translation. Here, we have identified the DEAD box protein family member DDX28 as an interactor and negative regulator of HIF-2α that suppresses HIF-2α's ability to activate eIF4E2-directed translation. Stable silencing of DDX28 via short hairpin RNA (shRNA) in hypoxic human U87MG glioblastoma cells caused an increase of eIF4E2 binding to the m7GTP cap structure and the translation of eIF4E2 target mRNAs (including the HIF-2α mRNA itself). DDX28 depletion elevated nuclear and cytoplasmic HIF-2α protein, but HIF-2α transcriptional activity did not increase, possibly due to its already high nuclear abundance in hypoxic control cells. Depletion of DDX28 conferred a proliferative advantage to hypoxic, but not normoxic, cells. DDX28 protein levels are reduced in several cancers, including gliomas, relative to levels in normal tissue. Therefore, we uncover a regulatory mechanism for this potential tumor suppressor in the repression of HIF-2α- and eIF4E2-mediated translation activation of oncogenic mRNAs.
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14
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Genuth NR, Barna M. Heterogeneity and specialized functions of translation machinery: from genes to organisms. Nat Rev Genet 2019; 19:431-452. [PMID: 29725087 DOI: 10.1038/s41576-018-0008-z] [Citation(s) in RCA: 141] [Impact Index Per Article: 28.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Regulation of mRNA translation offers the opportunity to diversify the expression and abundance of proteins made from individual gene products in cells, tissues and organisms. Emerging evidence has highlighted variation in the composition and activity of several large, highly conserved translation complexes as a means to differentially control gene expression. Heterogeneity and specialized functions of individual components of the ribosome and of the translation initiation factor complexes eIF3 and eIF4F, which are required for recruitment of the ribosome to the mRNA 5' untranslated region, have been identified. In this Review, we summarize the evidence for selective mRNA translation by components of these macromolecular complexes as a means to dynamically control the translation of the proteome in time and space. We further discuss the implications of this form of gene expression regulation for a growing number of human genetic disorders associated with mutations in the translation machinery.
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Affiliation(s)
- Naomi R Genuth
- Departments of Genetics and Developmental Biology, Stanford University, Stanford, CA, USA.,Department of Biology, Stanford University, Stanford, CA, USA
| | - Maria Barna
- Departments of Genetics and Developmental Biology, Stanford University, Stanford, CA, USA.
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15
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Timpano S, Guild BD, Specker EJ, Melanson G, Medeiros PJ, Sproul SLJ, Uniacke J. Physioxic human cell culture improves viability, metabolism, and mitochondrial morphology while reducing DNA damage. FASEB J 2019; 33:5716-5728. [PMID: 30649960 DOI: 10.1096/fj.201802279r] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Multicellular organisms balance oxygen delivery and toxicity by having oxygen pass through several barriers before cellular delivery. In human cell culture, these physiologic barriers are removed, exposing cells to higher oxygen levels. Human cells cultured in ambient air may appear normal, but this is difficult to assess without a comparison at physiologic oxygen. Here, we examined the effects of culturing human cells throughout the spectrum of oxygen availability on oxidative damage to macromolecules, viability, proliferation, the antioxidant and DNA damage responses, metabolism, and mitochondrial fusion and morphology. We surveyed 4 human cell lines cultured for 3 d at 7 oxygen conditions between 1 and 21% O2. We show that oxygen levels and cellular benefit are not inversely proportional, but the benefit peaks within the physioxic range. Normoxic cells are in a perpetual state of responding to damaged macromolecules and mitochondrial networks relative to physioxic cells, which could compromise an investigation. These data contribute to the concept of an optimal oxygen availability for cell culture in the physioxic range where the oxygen is not too high to reduce oxidative damage, and not too low for efficient oxidative metabolism, but just right: the Goldiloxygen zone.-Timpano, S., Guild, B. D., Specker, E. J., Melanson, G., Medeiros, P. J., Sproul, S. L. J., Uniacke, J. Physioxic human cell culture improves viability, metabolism, and mitochondrial morphology while reducing DNA damage.
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Affiliation(s)
- Sara Timpano
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario, Canada
| | - Brianna D Guild
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario, Canada
| | - Erin J Specker
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario, Canada
| | - Gaelan Melanson
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario, Canada
| | - Philip J Medeiros
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario, Canada
| | - Shannon L J Sproul
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario, Canada
| | - James Uniacke
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario, Canada
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16
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Physiological Hypoxia (Physioxia) Impairs the Early Adhesion of Single Lymphoma Cell to Marrow Stromal Cell and Extracellular Matrix. Optical Tweezers Study. Int J Mol Sci 2018; 19:ijms19071880. [PMID: 29949925 PMCID: PMC6073489 DOI: 10.3390/ijms19071880] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2018] [Revised: 06/20/2018] [Accepted: 06/21/2018] [Indexed: 12/29/2022] Open
Abstract
Adhesion is critical for the maintenance of cellular structures as well as intercellular communication, and its dysfunction occurs prevalently during cancer progression. Recently, a growing number of studies indicated the ability of oxygen to regulate adhesion molecules expression, however, the influence of physiological hypoxia (physioxia) on cell adhesion remains elusive. Thus, here we aimed: (i) to develop an optical tweezers based assay to precisely evaluate single diffuse large B-cell lymphoma (DLBCL) cell adhesion to neighbor cells (mesenchymal stromal cells) and extracellular matrix (Matrigel) under normoxia and physioxia; and, (ii) to explore the role of integrins in adhesion of single lymphoma cell. We identified the pronouncedly reduced adhesive properties of lymphoma cell lines and primary lymphocytes B under physioxia to both stromal cells and Matrigel. Corresponding effects were shown in bulk adhesion assays. Then we emphasized that impaired β1, β2 integrins, and cadherin-2 expression, studied by confocal microscopy, account for reduction in lymphocyte adhesion in physioxia. Additionally, the blockade studies conducted with anti-integrin antibodies have revealed the critical role of integrins in lymphoma adhesion. To summarize, the presented approach allows for precise confirmation of the changes in single cell adhesion properties provoked by physiological hypoxia. Thus, our findings reveal an unprecedented role of using physiologically relevant oxygen conditioning and single cell adhesion approaches when investigating tumor adhesion in vitro.
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17
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Yang H, Chennamaneni LR, Ho MWT, Ang SH, Tan ESW, Jeyaraj DA, Yeap YS, Liu B, Ong EH, Joy JK, Wee JLK, Kwek P, Retna P, Dinie N, Nguyen TTH, Tai SJ, Manoharan V, Pendharkar V, Low CB, Chew YS, Vuddagiri S, Sangthongpitag K, Choong ML, Lee MA, Kannan S, Verma CS, Poulsen A, Lim S, Chuah C, Ong TS, Hill J, Matter A, Nacro K. Optimization of Selective Mitogen-Activated Protein Kinase Interacting Kinases 1 and 2 Inhibitors for the Treatment of Blast Crisis Leukemia. J Med Chem 2018; 61:4348-4369. [PMID: 29683667 DOI: 10.1021/acs.jmedchem.7b01714] [Citation(s) in RCA: 36] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Chronic myeloid leukemia (CML) is a myeloproliferative disease caused by bcr-abl1, a constitutively active tyrosine kinase fusion gene responsible for an abnormal proliferation of leukemic stem cells (LSCs). Inhibition of BCR-ABL1 kinase activity offers long-term relief to CML patients. However, for a proportion of them, BCR-ABL1 inhibition will become ineffective at treating the disease, and CML will progress to blast crisis (BC) CML with poor prognosis. BC-CML is often associated with excessive phosphorylated eukaryotic translation initiation factor 4E (eIF4E), which renders LSCs capable of proliferating via self-renewal, oblivious to BCR-ABL1 inhibition. In vivo, eIF4E is exclusively phosphorylated on Ser209 by MNK1/2. Consequently, a selective inhibitor of MNK1/2 should reduce the level of phosphorylated eIF4E and re-sensitize LSCs to BCR-ABL1 inhibition, thus hindering the proliferation of BC LSCs. We report herein the structure-activity relationships and pharmacokinetic properties of a selective MNK1/2 inhibitor clinical candidate, ETC-206, which in combination with dasatinib prevents BC-CML LSC self-renewal in vitro and enhances dasatinib antitumor activity in vivo.
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Affiliation(s)
- Haiyan Yang
- Experimental Therapeutics Centre (ETC) , A*STAR , 31 Biopolis Way, Nanos #03-01 , 138669 Singapore
| | - Lohitha Rao Chennamaneni
- Organic Chemistry, Institute of Chemical and Engineering Sciences (ICES), A*STAR , 8 Biomedical Grove, Neuros, #07-01 , 138665 Singapore
| | - Melvyn Wai Tuck Ho
- Experimental Therapeutics Centre (ETC) , A*STAR , 31 Biopolis Way, Nanos #03-01 , 138669 Singapore
| | - Shi Hua Ang
- Experimental Therapeutics Centre (ETC) , A*STAR , 31 Biopolis Way, Nanos #03-01 , 138669 Singapore
| | - Eldwin Sum Wai Tan
- Experimental Therapeutics Centre (ETC) , A*STAR , 31 Biopolis Way, Nanos #03-01 , 138669 Singapore
| | | | - Yoon Sheng Yeap
- Experimental Therapeutics Centre (ETC) , A*STAR , 31 Biopolis Way, Nanos #03-01 , 138669 Singapore
| | - Boping Liu
- Experimental Therapeutics Centre (ETC) , A*STAR , 31 Biopolis Way, Nanos #03-01 , 138669 Singapore
| | - Esther Hq Ong
- Experimental Therapeutics Centre (ETC) , A*STAR , 31 Biopolis Way, Nanos #03-01 , 138669 Singapore
| | - Joma Kanikadu Joy
- Experimental Therapeutics Centre (ETC) , A*STAR , 31 Biopolis Way, Nanos #03-01 , 138669 Singapore
| | - John Liang Kuan Wee
- Experimental Therapeutics Centre (ETC) , A*STAR , 31 Biopolis Way, Nanos #03-01 , 138669 Singapore
| | - Perlyn Kwek
- Experimental Therapeutics Centre (ETC) , A*STAR , 31 Biopolis Way, Nanos #03-01 , 138669 Singapore
| | - Priya Retna
- Experimental Therapeutics Centre (ETC) , A*STAR , 31 Biopolis Way, Nanos #03-01 , 138669 Singapore
| | - Nurul Dinie
- Experimental Therapeutics Centre (ETC) , A*STAR , 31 Biopolis Way, Nanos #03-01 , 138669 Singapore
| | - Thuy Thi Hanh Nguyen
- Experimental Therapeutics Centre (ETC) , A*STAR , 31 Biopolis Way, Nanos #03-01 , 138669 Singapore
| | - Shi Jing Tai
- Experimental Therapeutics Centre (ETC) , A*STAR , 31 Biopolis Way, Nanos #03-01 , 138669 Singapore
| | - Vithya Manoharan
- Experimental Therapeutics Centre (ETC) , A*STAR , 31 Biopolis Way, Nanos #03-01 , 138669 Singapore
| | - Vishal Pendharkar
- Experimental Therapeutics Centre (ETC) , A*STAR , 31 Biopolis Way, Nanos #03-01 , 138669 Singapore
| | - Choon Bing Low
- Experimental Therapeutics Centre (ETC) , A*STAR , 31 Biopolis Way, Nanos #03-01 , 138669 Singapore
| | - Yun Shan Chew
- Experimental Therapeutics Centre (ETC) , A*STAR , 31 Biopolis Way, Nanos #03-01 , 138669 Singapore
| | - Susmitha Vuddagiri
- Experimental Therapeutics Centre (ETC) , A*STAR , 31 Biopolis Way, Nanos #03-01 , 138669 Singapore
| | - Kanda Sangthongpitag
- Experimental Therapeutics Centre (ETC) , A*STAR , 31 Biopolis Way, Nanos #03-01 , 138669 Singapore
| | - Meng Ling Choong
- Experimental Therapeutics Centre (ETC) , A*STAR , 31 Biopolis Way, Nanos #03-01 , 138669 Singapore
| | - May Ann Lee
- Experimental Therapeutics Centre (ETC) , A*STAR , 31 Biopolis Way, Nanos #03-01 , 138669 Singapore
| | | | - Chandra S Verma
- Bioinformatics Institute (BII) , A*STAR , 30 Biopolis Street, #07-01 Matrix , 138671 Singapore.,School of Biological Sciences , Nanyang Technological University , 60 Nanyang Drive , 637551 Singapore.,Department of Biological Sciences , National University of Singapore , 14 Science Drive 4 , 117543 Singapore
| | - Anders Poulsen
- Experimental Therapeutics Centre (ETC) , A*STAR , 31 Biopolis Way, Nanos #03-01 , 138669 Singapore
| | - Sharon Lim
- Duke-NUS Medical School , 8 College Road , 169857 Singapore
| | - Charles Chuah
- Duke-NUS Medical School , 8 College Road , 169857 Singapore
| | - Tiong Sin Ong
- Duke-NUS Medical School , 8 College Road , 169857 Singapore.,Department of Medicine , Duke University Medical Center , Durham , North Carolina 27710 , United States
| | - Jeffrey Hill
- Experimental Therapeutics Centre (ETC) , A*STAR , 31 Biopolis Way, Nanos #03-01 , 138669 Singapore
| | - Alex Matter
- Experimental Therapeutics Centre (ETC) , A*STAR , 31 Biopolis Way, Nanos #03-01 , 138669 Singapore
| | - Kassoum Nacro
- Experimental Therapeutics Centre (ETC) , A*STAR , 31 Biopolis Way, Nanos #03-01 , 138669 Singapore
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18
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The eIF4E2-Directed Hypoxic Cap-Dependent Translation Machinery Reveals Novel Therapeutic Potential for Cancer Treatment. OXIDATIVE MEDICINE AND CELLULAR LONGEVITY 2017; 2017:6098107. [PMID: 29317983 PMCID: PMC5727761 DOI: 10.1155/2017/6098107] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/15/2017] [Accepted: 11/02/2017] [Indexed: 12/29/2022]
Abstract
Hypoxia is an aspect of the tumor microenvironment that is linked to radiation and chemotherapy resistance, metastasis, and poor prognosis. The ability of hypoxic tumor cells to achieve these cancer hallmarks is, in part, due to changes in their gene expression profiles. Cancer cells have a high demand for protein synthesis, and translational control is subsequently deregulated. Various mechanisms of translation initiation are active to improve the translation efficiency of select transcripts to drive cancer progression. This review will focus on a noncanonical cap-dependent translation initiation mechanism that utilizes the eIF4E homolog eIF4E2, a hypoxia-activated cap-binding protein that is implicated in hypoxic cancer cell migration, invasion, and tumor growth in mouse xenografts. A historical perspective about eIF4E2 and its various aliases will be provided followed by an evaluation of potential therapeutic strategies. The recent successes of disabling canonical translation and eIF4E with drugs should highlight the novel therapeutic potential of targeting the homologous eIF4E2 in the treatment of hypoxic solid tumors.
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19
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Hypoxia activates cadherin-22 synthesis via eIF4E2 to drive cancer cell migration, invasion and adhesion. Oncogene 2017; 37:651-662. [PMID: 28991229 DOI: 10.1038/onc.2017.372] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2017] [Revised: 08/28/2017] [Accepted: 08/31/2017] [Indexed: 12/12/2022]
Abstract
Hypoxia is a driver of cell movement in processes such as development and tumor progression. The cellular response to hypoxia involves a transcriptional program mediated by hypoxia-inducible factors, but translational control has emerged as a significant contributor. In this study, we demonstrate that a cell-cell adhesion molecule, cadherin-22, is upregulated in hypoxia via mTORC1-independent translational control by the initiation factor eIF4E2. We identify new functions of cadherin-22 as a hypoxia-specific cell-surface molecule involved in cancer cell migration, invasion and adhesion. Silencing eIF4E2 or cadherin-22 significantly impaired MDA-MB-231 breast carcinoma and U87MG glioblastoma cell migration and invasion only in hypoxia, while reintroduction of the respective exogenous gene restored the normal phenotype. Cadherin-22 was evenly distributed throughout spheroids and required for their formation and support of a hypoxic core. Conversely, E-cadherin translation was repressed by hypoxia and only expressed in the oxygenated cells of U87MG spheroids. Furthermore, immunofluorescence on paraffin-embedded human tissue from 40 glioma and 40 invasive ductal breast carcinoma patient specimens revealed that cadherin-22 expression colocalized with areas of hypoxia and significantly correlated with tumor grade and progression-free survival or stage and tumor size, respectively. This study broadens our understanding of tumor progression and metastasis by highlighting cadherin-22 as a potential new target of cancer therapy to disable hypoxic cancer cell motility and adhesion.
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20
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Vaklavas C, Blume SW, Grizzle WE. Translational Dysregulation in Cancer: Molecular Insights and Potential Clinical Applications in Biomarker Development. Front Oncol 2017; 7:158. [PMID: 28798901 PMCID: PMC5526920 DOI: 10.3389/fonc.2017.00158] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2017] [Accepted: 07/06/2017] [Indexed: 01/04/2023] Open
Abstract
Although transcript levels have been traditionally used as a surrogate measure of gene expression, it is increasingly recognized that the latter is extensively and dynamically modulated at the level of translation (messenger RNA to protein). Over the recent years, significant progress has been made in dissecting the complex posttranscriptional mechanisms that regulate gene expression. This advancement in knowledge came hand in hand with the progress made in the methodologies to study translation both at gene-specific as well as global genomic level. The majority of translational control is exerted at the level of initiation; nonetheless, protein synthesis can be modulated at the level of translation elongation, termination, and recycling. Sequence and structural elements and epitranscriptomic modifications of individual transcripts allow for dynamic gene-specific modulation of translation. Cancer cells usurp the regulatory mechanisms that govern translation to carry out translational programs that lead to the phenotypic hallmarks of cancer. Translation is a critical nexus in neoplastic transformation. Multiple oncogenes and signaling pathways that are activated, upregulated, or mutated in cancer converge on translation and their transformative impact "bottlenecks" at the level of translation. Moreover, this translational dysregulation allows cancer cells to adapt to a diverse array of stresses associated with a hostile microenviroment and antitumor therapies. All elements involved in the process of translation, from the transcriptional template, the components of the translational machinery, to the proteins that interact with the transcriptome, have been found to be qualitatively and/or quantitatively perturbed in cancer. This review discusses the regulatory mechanisms that govern translation in normal cells and how translation becomes dysregulated in cancer leading to the phenotypic hallmarks of malignancy. We also discuss how dysregulated mediators or components of translation can be utilized as biomarkers with potential diagnostic, prognostic, or predictive significance. Such biomarkers have the potential advantage of uniform applicability in the face of inherent tumor heterogeneity and deoxyribonucleic acid instability. As translation becomes increasingly recognized as a process gone awry in cancer and agents are developed to target it, the utility and significance of these potential biomarkers is expected to increase.
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Affiliation(s)
- Christos Vaklavas
- Department of Medicine, Division of Hematology/Oncology, University of Alabama at Birmingham, Birmingham, AL, United States
| | - Scott W Blume
- Department of Medicine, Division of Hematology/Oncology, University of Alabama at Birmingham, Birmingham, AL, United States
| | - William E Grizzle
- Department of Anatomic Pathology, University of Alabama at Birmingham, Birmingham, AL, United States
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21
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Timpano S, Melanson G, Evagelou SL, Guild BD, Specker EJ, Uniacke J. Analysis of Cap-binding Proteins in Human Cells Exposed to Physiological Oxygen Conditions. J Vis Exp 2016. [PMID: 28060265 DOI: 10.3791/55112] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022] Open
Abstract
Translational control is a focal point of gene regulation, especially during periods of cellular stress. Cap-dependent translation via the eIF4F complex is by far the most common pathway to initiate protein synthesis in eukaryotic cells, but stress-specific variations of this complex are now emerging. Purifying cap-binding proteins with an affinity resin composed of Agarose-linked m7GTP (a 5' mRNA cap analog) is a useful tool to identify factors involved in the regulation of translation initiation. Hypoxia (low oxygen) is a cellular stress encountered during fetal development and tumor progression, and is highly dependent on translation regulation. Furthermore, it was recently reported that human adult organs have a lower oxygen content (physioxia 1-9% oxygen) that is closer to hypoxia than the ambient air where cells are routinely cultured. With the ongoing characterization of a hypoxic eIF4F complex (eIF4FH), there is increasing interest in understanding oxygen-dependent translation initiation through the 5' mRNA cap. We have recently developed a human cell culture method to analyze cap-binding proteins that are regulated by oxygen availability. This protocol emphasizes that cell culture and lysis be performed in a hypoxia workstation to eliminate exposure to oxygen. Cells must be incubated for at least 24 hr for the liquid media to equilibrate with the atmosphere within the workstation. To avoid this limitation, pre-conditioned media (de-oxygenated) can be added to cells if shorter time points are required. Certain cap-binding proteins require interactions with a second base or can hydrolyze the m7GTP, therefore some cap interactors may be missed in the purification process. Agarose-linked to enzymatically resistant cap analogs may be substituted in this protocol. This method allows the user to identify novel oxygen-regulated translation factors involved in cap-dependent translation.
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Affiliation(s)
- Sara Timpano
- Department of Molecular and Cellular Biology, University of Guelph
| | - Gaelan Melanson
- Department of Molecular and Cellular Biology, University of Guelph
| | - Sonia L Evagelou
- Department of Molecular and Cellular Biology, University of Guelph
| | - Brianna D Guild
- Department of Molecular and Cellular Biology, University of Guelph
| | - Erin J Specker
- Department of Molecular and Cellular Biology, University of Guelph
| | - James Uniacke
- Department of Molecular and Cellular Biology, University of Guelph;
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22
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Zuberek J, Kuchta K, Hernández G, Sonenberg N, Ginalski K. Diverse cap-binding properties of Drosophila eIF4E isoforms. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2016; 1864:1292-303. [PMID: 27374989 DOI: 10.1016/j.bbapap.2016.06.015] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 06/07/2016] [Accepted: 06/28/2016] [Indexed: 10/21/2022]
Abstract
The majority of eukaryotic mRNAs are translated in a cap-dependent manner, which requires recognition of the mRNA 5' cap by eIF4E protein. Multiple eIF4E family members have been identified in most eukaryotic organisms. Drosophila melanogaster (Dm) has eight eIF4E related proteins; seven of them belong to Class I and one to Class II. Their biological roles with the exception of Dm eIF4E-1, Dm eIF4E-3 and Dm 4EHP, remain unknown. Here, we compare the molecular basis of Dm eIF4E's interactions with cap and eIF4G peptide by using homology modelling and fluorescence binding assays with various cap analogues. We found that despite the presence of conserved key residues responsible for cap recognition, the differences in binding different cap analogues among Class I Dm eIF4E isoforms are up to 14-fold. The highest affinity for cap analogues was observed for Dm eIF4E-3. We suggest that Dm eIF4E-3 and Dm eIF4E-5 bind the second nucleoside of the cap in an unusual manner via stacking interactions with a histidine or a phenylalanine residue, respectively. Moreover, the analysis of ternary complexes of eIF4G peptide-eIF4E-cap analogue showed cooperativity between eIF4G and cap binding only for Dm eIF4E-4, which exhibits the lowest affinity for cap analogues among all Dm eIF4Es.
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Affiliation(s)
- Joanna Zuberek
- Division of Biophysics, Institute of Experimental Physics, Faculty of Physics, University of Warsaw, Warsaw 02-089, Poland.
| | - Krzysztof Kuchta
- Laboratory of Bioinformatics and Systems Biology, Centre of New Technologies, University of Warsaw, Warsaw 02-097, Poland; College of Inter-Faculty Individual Studies in Mathematics and Natural Sciences, University of Warsaw, Warsaw 02-089, Poland.
| | - Greco Hernández
- Division of Basic Research, National Institute of Cancer (INCan), Tlalpan, Mexico City 14080, Mexico.
| | - Nahum Sonenberg
- Department of Biochemistry and Goodman Cancer Research Centre, McGill University, Montreal, QC H3A 1A3, Canada.
| | - Krzysztof Ginalski
- Laboratory of Bioinformatics and Systems Biology, Centre of New Technologies, University of Warsaw, Warsaw 02-097, Poland.
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