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Wu S, Wagner G. Computational inference of eIF4F complex function and structure in human cancers. Proc Natl Acad Sci U S A 2024; 121:e2313589121. [PMID: 38266053 PMCID: PMC10835048 DOI: 10.1073/pnas.2313589121] [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: 08/10/2023] [Accepted: 12/18/2023] [Indexed: 01/26/2024] Open
Abstract
The canonical eukaryotic initiation factor 4F (eIF4F) complex, composed of eIF4G1, eIF4A1, and the cap-binding protein eIF4E, plays a crucial role in cap-dependent translation initiation in eukaryotic cells. An alternative cap-independent initiation can occur, involving only eIF4G1 and eIF4A1 through internal ribosome entry sites (IRESs). This mechanism is considered complementary to cap-dependent initiation, particularly in tumors under stress conditions. However, the selection and molecular mechanism of specific translation initiation remains poorly understood in human cancers. Thus, we analyzed gene copy number variations (CNVs) in TCGA tumor samples and found frequent amplification of genes involved in translation initiation. Copy number gains in EIF4G1 and EIF3E frequently co-occur across human cancers. Additionally, EIF4G1 expression strongly correlates with genes from cancer cell survival pathways including cell cycle and lipogenesis, in tumors with EIF4G1 amplification or duplication. Furthermore, we revealed that eIF4G1 and eIF4A1 protein levels strongly co-regulate with ribosomal subunits, eIF2, and eIF3 complexes, while eIF4E co-regulates with 4E-BP1, ubiquitination, and ESCRT proteins. Utilizing Alphafold predictions, we modeled the eIF4F structure with and without eIF4E binding. For cap-dependent initiation, our modeling reveals extensive interactions between the N-terminal eIF4E-binding domain of eIF4G1 and eIF4E. Furthermore, the eIF4G1 HEAT-2 domain positions eIF4E near the eIF4A1 N-terminal domain (NTD), resulting in the collaborative enclosure of the RNA binding cavity within eIF4A1. In contrast, during cap-independent initiation, the HEAT-2 domain directly binds the eIF4A1-NTD, leading to a stronger interaction between eIF4G1 and eIF4A1, thus closing the mRNA binding cavity without the involvement of eIF4E.
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Affiliation(s)
- Su Wu
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA02115
| | - Gerhard Wagner
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA02115
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2
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Hu B, Liu T, Wu Z, Phan SH. P53 regulates CCAAT/Enhancer binding protein β gene expression. Gene 2023; 884:147675. [PMID: 37541559 DOI: 10.1016/j.gene.2023.147675] [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: 05/17/2023] [Revised: 07/13/2023] [Accepted: 07/28/2023] [Indexed: 08/06/2023]
Abstract
BACKGROUND The transcription factor CCAAT/enhancer-binding protein β (C/EBPβ) is implicated in diverse processes and diseases. Its two isoforms, namely liver-enriched activator protein (LAP) and liver-enriched inhibitor protein (LIP) are translated from the same mRNA. They share the same C-terminal DNA binding domain except LAP has an extra N-terminal activation domain. Probably due to its higher affinity for its DNA cognate sequences, LIP can inhibit LAP transcriptional activity even at substoichiometric levels. However, the regulatory mechanism of C/EBPβ gene expression and the LAP: LIP ratio is unclear. METHODS In this study, the C/EBPβ promoter sequence was scanned for conserved P53 response element (P53RE), and binding of P53 to the C/EBPβ promoter was tested by Electrophoretic Mobility Shift Assay (EMSA) and chromatin immunoprecipitation assay. P53 over-expression and dominant negative P53 expression plasmids were transfected into rat lung fibroblasts and tested for C/EBPβ gene transcription and expression. Western blot analysis was used to test the regulation of C/EBPβ LAP and LIP isoforms. Constructs containing the LAP 5'untranslated region (5'UTR) or the LIP 5'UTR region were used to test the importance of 5'UTR in the control of C/EBPβ LAP and LIP translation. RESULTS The C/EBPβ promoter sequence was found to contain a conserved P53 response element (P53RE), which binds P53 as demonstrated by Electrophoresis Mobility Shift Assay and chromatin immunoprecipitation assays. P53 over-expression suppressed while dominant negative P53 stimulated C/EBPβ gene transcription and expression. Western blot analysis showed that P53 differentially regulated the translation of the C/EBPβ LAP and LIP isoforms through the regulation of eIF4E and eIF4E-BP1. Further studies with constructs containing the LAP 5'untranslated region (5'UTR) or the LIP 5'UTR region showed that the 5'UTR is important in differential control of C/EBPβ LAP and LIP translation. CONCLUSION Analysis of the effects of P53 on C/EBPβ expression revealed a novel mechanism by which P53 could antagonize the effects of C/EBPβ on its target gene expression. For the first time, P53 is shown to be a repressor of C/EBPβ gene expression at both transcriptional and translational levels, with a differential effect in the magnitude of the effect on LAP vs. LIP isoforms.
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Affiliation(s)
- Biao Hu
- Department of Internal Medicine, University of Michigan Medical School, 1600 Huron Parkway, Ann Arbor, MI 48109 USA
| | - Tianju Liu
- Department of Pathology, University of Michigan Medical School, 109 Zina Pitcher Place, Ann Arbor, MI 48109 USA
| | - Zhe Wu
- Department of Pathology, University of Michigan Medical School, 109 Zina Pitcher Place, Ann Arbor, MI 48109 USA
| | - Sem H Phan
- Department of Pathology, University of Michigan Medical School, 109 Zina Pitcher Place, Ann Arbor, MI 48109 USA.
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Liu L, Bai J, Hu L, Jiang D. Hypoxia-mediated activation of hypoxia-inducible factor-1α in triple-negative breast cancer: A review. Medicine (Baltimore) 2023; 102:e35493. [PMID: 37904441 PMCID: PMC10615493 DOI: 10.1097/md.0000000000035493] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/17/2023] [Accepted: 09/13/2023] [Indexed: 11/01/2023] Open
Abstract
Triple-negative breast cancer (TNBC) is a subtype of breast cancer (BC) that is highly aggressive and hypoxic compared with other subtypes. The role of hypoxia-inducible factor 1α (HIF-1α) as a key hypoxic transcription factor in oncogenic processes has been extensively studied. Recently, it has been shown that HIF-1α regulates the complex biological processes of TNBC, such as glycolysis, angiogenesis, invasion and metastasis, BC stem cells enrichment, and immune escape, to promote TNBC survival and development through the activation of downstream target genes. This article discusses the expression of the HIF-1α transcription factor in TNBC and the Hypoxia-mediated activation of hypoxia-inducible factor-1α in triple-negative BC. It offers a fresh approach to clinical research and treatment for TNBC.
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Affiliation(s)
- Lihui Liu
- Liaoning University of Traditional Chinese Medicine, Shenyang, China
- Department of Breast Surgery, Cancer Hospital of Dalian University of Technology, Cancer Hospital of China Medical University, Liaoning Cancer Hospital and Institute, Shenyang, China
| | - Jie Bai
- Department of Breast Surgery, Cancer Hospital of Dalian University of Technology, Cancer Hospital of China Medical University, Liaoning Cancer Hospital and Institute, Shenyang, China
| | - Lanxin Hu
- The Affiliated Traditional Chinese Medicine Hospital of Southwest Medical University, Luzhou, China
| | - Daqing Jiang
- Department of Breast Surgery, Cancer Hospital of Dalian University of Technology, Cancer Hospital of China Medical University, Liaoning Cancer Hospital and Institute, Shenyang, China
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4
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Clark NK, Harris MT, Dahl WB, Knotts Z, Marr MT. The Insulin Receptor and Insulin like Growth Factor Receptor 5' UTRs Support Translation Initiation Independently of EIF4G1. Mol Cell Biol 2023; 43:485-499. [PMID: 37724583 PMCID: PMC10569357 DOI: 10.1080/10985549.2023.2255120] [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: 07/22/2022] [Accepted: 08/25/2023] [Indexed: 09/21/2023] Open
Abstract
IRES mediated translation initiation requires a different repertoire of factors than canonical cap-dependent translation. Treatments that inhibit the canonical translation factor EIF4G1 have little or no effect on the ability of the Insr and Igf1r cellular IRESes to promote translation. Transcripts for two cellular receptors contain RNA elements that facilitate translation initiation without intact EIF4G1. Cellular IRES mechanisms may resemble viral type III IRESes allowing them to promote translate with a limited number of initiation factors allowing them to work under stress conditions when canonical translation is repressed.
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Affiliation(s)
- Nicholas K. Clark
- Department of Biology and Rosenstiel Basic Medical Sciences Research Center, Brandeis University, Waltham, Massachusetts, USA
- mRNA Center of Excellence, Sanofi, Waltham, Massachusetts, USA
| | - Meghan T. Harris
- Department of Biology and Rosenstiel Basic Medical Sciences Research Center, Brandeis University, Waltham, Massachusetts, USA
- Myeloid Therapeutics, Cambridge, Massachusetts, USA
| | - William B. Dahl
- Department of Biology and Rosenstiel Basic Medical Sciences Research Center, Brandeis University, Waltham, Massachusetts, USA
| | - Zachary Knotts
- Department of Biology and Rosenstiel Basic Medical Sciences Research Center, Brandeis University, Waltham, Massachusetts, USA
| | - Michael T. Marr
- Department of Biology and Rosenstiel Basic Medical Sciences Research Center, Brandeis University, Waltham, Massachusetts, USA
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5
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Wu S, Wagner G. Computational inference of eIF4F complex function and structure in human cancers. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.08.10.552450. [PMID: 37609226 PMCID: PMC10441403 DOI: 10.1101/2023.08.10.552450] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/24/2023]
Abstract
The canonical eukaryotic initiation factor 4F (eIF4F) complex, composed of eIF4G1, eIF4A1, and the cap-binding protein eIF4E, plays a crucial role in cap-dependent translation initiation in eukaryotic cells (1). However, cap-independent initiation can occur through internal ribosomal entry sites (IRESs), involving only eIF4G1 and eIF4A1 present, which is considered to be a complementary process to cap-dependent initiation in tumors under stress conditions (2). The selection and molecular mechanism of specific translation initiation in human cancers remains poorly understood. Thus, we analyzed gene copy number variations (CNVs) in TCGA tumor samples and found frequent amplification of genes involved in translation initiation. Copy number gains in EIF4G1 and EIF3E frequently co-occur across human cancers. Additionally, EIF4G1 expression strongly correlates with genes from cancer cell survival pathways including cell cycle and lipogenesis, in tumors with EIF4G1 amplification or duplication. Furthermore, we revealed that eIF4G1 and eIF4A1 protein levels strongly co-regulate with ribosomal subunits, eIF2, and eIF3 complexes, while eIF4E co-regulates with 4E-BP1, ubiquitination, and ESCRT proteins. Using Alphafold predictions, we modeled the eIF4F structure with and without eIF4G1-eIF4E binding. The modeling for cap-dependent initiation suggests that eIF4G1 interacts with eIF4E through its N-terminal eIF4E-binding domain, bringing eIF4E near the eIF4A1 mRNA binding cavity and closing the cavity with both eIF4G1 HEAT-2 domain and eIF4E. In the cap-independent mechanism, α-helix 5 of eIF4G1 HEAT-2 domain instead directly interacts with the eIF4A1 N-terminal domain to close the mRNA binding cavity without eIF4E involvement, resulting in a stronger interaction between eIF4G1 and eIF4A1. Significance Statement Translation initiation is primarily governed by eIF4F, employing a "cap-dependent" mechanism, but eIF4F dysregulation may lead to a "cap-independent" mechanism in stressed cancer cells. We found frequent amplification of translation initiation genes, and co-occurring copy number gains of EIF4G1 and EIF3E genes in human cancers. EIF4G1 amplification or duplication may be positively selected for its beneficial impact on the overexpression of cancer survival genes. The co-regulation of eIF4G1 and eIF4A1, distinctly from eIF4E, reveals eIF4F dysregulation favoring cap-independent initiation. Alphafold predicts changes in the eIF4F complex assembly to accommodate both initiation mechanisms. These findings have significant implications for evaluating cancer cell vulnerability to eIF4F inhibition and developing treatments that target cancer cells with dependency on the translation initiation mechanism.
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Martínez-Alonso E, Escobar-Peso A, Guerra-Pérez N, Roca M, Masjuan J, Alcázar A. Dihydropyrimidinase-Related Protein 2 Is a New Partner in the Binding between 4E-BP2 and eIF4E Related to Neuronal Death after Cerebral Ischemia. Int J Mol Sci 2023; 24:ijms24098246. [PMID: 37175950 PMCID: PMC10179276 DOI: 10.3390/ijms24098246] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2023] [Revised: 04/23/2023] [Accepted: 04/29/2023] [Indexed: 05/15/2023] Open
Abstract
Transient cerebral ischemia induces neuronal degeneration, followed in time by secondary delayed neuronal death that is strongly correlated with a permanent inhibition of protein synthesis in vulnerable brain regions, while protein translational rates are recovered in resistant areas. In the translation-regulation initiation step, the eukaryotic initiation factor (eIF) 4E is a key player regulated by its association with eIF4E-binding proteins (4E-BPs), mostly 4E-BP2 in brain tissue. In a previous work, we identified dihydropyrimidinase-related protein 2 (DRP2) as a 4E-BP2-interacting protein. Here, using a proteomic approach in a model of transient cerebral ischemia, a detailed study of DRP2 was performed in order to address the challenge of translation restoration in vulnerable regions. In this report, several DRP2 isoforms that have a specific interaction with both 4E-BP2 and eIF4E were identified, showing significant and opposite differences in this association, and being differentially detected in resistant and vulnerable regions in response to ischemia reperfusion. Our results provide the first evidence of DRP2 isoforms as potential regulators of the 4E-BP2-eIF4E association that would have consequences in the delayed neuronal death under ischemic-reperfusion stress. The new knowledge reported here identifies DRP2 as a new target to promote neuronal survival after cerebral ischemia.
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Affiliation(s)
- Emma Martínez-Alonso
- Department of Research, Hospital Universitario Ramón y Cajal, IRYCIS, 28034 Madrid, Spain
- Proteomics Unit, Hospital Universitario Ramón y Cajal, IRYCIS, 28034 Madrid, Spain
| | - Alejandro Escobar-Peso
- Department of Research, Hospital Universitario Ramón y Cajal, IRYCIS, 28034 Madrid, Spain
| | - Natalia Guerra-Pérez
- Department of Genetics, Physiology and Microbiology, Faculty of Biological Sciences, Universidad Complutense de Madrid, 28040 Madrid, Spain
| | - Marcel Roca
- Department of Research, Hospital Universitario Ramón y Cajal, IRYCIS, 28034 Madrid, Spain
| | - Jaime Masjuan
- Department of Neurology, Hospital Universitario Ramón y Cajal, IRYCIS, 28034 Madrid, Spain
- Department of Neurology, Facultad de Medicina, Universidad de Alcalá, 28871 Alcalá de Henares, Spain
| | - Alberto Alcázar
- Department of Research, Hospital Universitario Ramón y Cajal, IRYCIS, 28034 Madrid, Spain
- Proteomics Unit, Hospital Universitario Ramón y Cajal, IRYCIS, 28034 Madrid, Spain
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7
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Jaramillo-Mesa H, Rakotondrafara AM. All eggs in one basket: How potyvirus infection is controlled at a single cap-independent translation event. Semin Cell Dev Biol 2023; 148-149:51-61. [PMID: 36608998 DOI: 10.1016/j.semcdb.2022.12.011] [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: 10/27/2022] [Revised: 12/28/2022] [Accepted: 12/30/2022] [Indexed: 01/06/2023]
Abstract
Regulation of protein synthesis is a strong determinant of potyviral pathogenicity. The Potyviridae family is the largest family of plant-infecting positive sense RNA viruses. Similar to the animal-infecting Picornaviridae family, the potyviral RNA genome lacks a 5' cap, and instead has a viral protein (VPg) linked to its 5' end. Potyviral genomes are mainly translated into one large polyprotein relying on a single translation event to express all their protein repertoire. In the absence of the 5' cap, the Potyviridae family depends on cis-acting elements in their 5' untranslated regions (UTR) to recruit the translation machinery. In this review, we summarize the diverse 5'UTR-driven, cap-independent translation mechanisms employed by the Potyviridae family including scanning-dependent mechanism, internal initiation, and the stimulatory role of the VPg. These mechanisms have direct implications on potyviral pathogenicity, including host range specificity and resistance. Finally, we discuss how these viral strategies could not only inform new avenues for engineering and/or breeding for crop resistance but would also provide opportunities for the development of biotechnological tools for large-scale protein production in plant systems.
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Affiliation(s)
- Helena Jaramillo-Mesa
- Department of Plant Pathology, University of Wisconsin-Madison, 1630 Linden Drive, Madison, WI 53704, USA
| | - Aurélie M Rakotondrafara
- Department of Plant Pathology, University of Wisconsin-Madison, 1630 Linden Drive, Madison, WI 53704, USA.
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8
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Liu Q, Guan C, Liu C, Li H, Wu J, Sun C. Targeting hypoxia-inducible factor-1alpha: A new strategy for triple-negative breast cancer therapy. Biomed Pharmacother 2022; 156:113861. [DOI: 10.1016/j.biopha.2022.113861] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2022] [Revised: 09/30/2022] [Accepted: 10/08/2022] [Indexed: 11/02/2022] Open
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Seneff S, Nigh G, Kyriakopoulos AM, McCullough PA. Innate immune suppression by SARS-CoV-2 mRNA vaccinations: The role of G-quadruplexes, exosomes, and MicroRNAs. Food Chem Toxicol 2022; 164:113008. [PMID: 35436552 PMCID: PMC9012513 DOI: 10.1016/j.fct.2022.113008] [Citation(s) in RCA: 60] [Impact Index Per Article: 30.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2022] [Revised: 04/03/2022] [Accepted: 04/08/2022] [Indexed: 12/12/2022]
Abstract
The mRNA SARS-CoV-2 vaccines were brought to market in response to the public health crises of Covid-19. The utilization of mRNA vaccines in the context of infectious disease has no precedent. The many alterations in the vaccine mRNA hide the mRNA from cellular defenses and promote a longer biological half-life and high production of spike protein. However, the immune response to the vaccine is very different from that to a SARS-CoV-2 infection. In this paper, we present evidence that vaccination induces a profound impairment in type I interferon signaling, which has diverse adverse consequences to human health. Immune cells that have taken up the vaccine nanoparticles release into circulation large numbers of exosomes containing spike protein along with critical microRNAs that induce a signaling response in recipient cells at distant sites. We also identify potential profound disturbances in regulatory control of protein synthesis and cancer surveillance. These disturbances potentially have a causal link to neurodegenerative disease, myocarditis, immune thrombocytopenia, Bell's palsy, liver disease, impaired adaptive immunity, impaired DNA damage response and tumorigenesis. We show evidence from the VAERS database supporting our hypothesis. We believe a comprehensive risk/benefit assessment of the mRNA vaccines questions them as positive contributors to public health.
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Affiliation(s)
- Stephanie Seneff
- Computer Science and Artificial Intelligence Laboratory, MIT, Cambridge, MA, USA, 02139.
| | - Greg Nigh
- Immersion Health, Portland, OR, 97214, USA.
| | - Anthony M Kyriakopoulos
- Research and Development, Nasco AD Biotechnology Laboratory, Department of Research and Development, Sachtouri 11, 18536, Piraeus, Greece.
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Phosphorylation of Eukaryotic Initiation Factor 4G1 (eIF4G1) at Ser1147 Is Specific for eIF4G1 Bound to eIF4E in Delayed Neuronal Death after Ischemia. Int J Mol Sci 2022; 23:ijms23031830. [PMID: 35163752 PMCID: PMC8836865 DOI: 10.3390/ijms23031830] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2021] [Revised: 01/24/2022] [Accepted: 01/30/2022] [Indexed: 11/26/2022] Open
Abstract
Ischemic strokes are caused by a reduction in cerebral blood flow and both the ischemic period and subsequent reperfusion induce brain injury, with different tissue damage depending on the severity of the ischemic insult, its duration, and the particular areas of the brain affected. In those areas vulnerable to cerebral ischemia, the inhibition of protein translation is an essential process of the cellular response leading to delayed neuronal death. In particular, translation initiation is rate-limiting for protein synthesis and the eukaryotic initiation factor (eIF) 4F complex is indispensable for cap-dependent protein translation. In the eIF4F complex, eIF4G is a scaffolding protein that provides docking sites for the assembly of eIF4A and eIF4E, binding to the cap structure of the mRNA and stabilizing all proteins of the complex. The eIF4F complex constituents, eIF4A, eIF4E, and eIF4G, participate in translation regulation by their phosphorylation at specific sites under cellular stress conditions, modulating the activity of the cap-binding complex and protein translation. This work investigates the phosphorylation of eIF4G1 involved in the eIF4E/eIF4G1 association complex, and their regulation in ischemia-reperfusion (IR) as a stress-inducing condition. IR was induced in an animal model of transient cerebral ischemia and the results were studied in the resistant cortical region and in the vulnerable hippocampal CA1 region. The presented data demonstrate the phosphorylation of eIF4G1 at Ser1147, Ser1185, and Ser1231 in both brain regions and in control and ischemic conditions, being the phosphorylation of eIF4G1 at Ser1147 the only one found in the eIF4E/eIF4G association complex from the cap-containing matrix (m7GTP-Sepharose). In addition, our work reveals the specific modulation of the phosphorylation of eIF4G1 at Ser1147 in the vulnerable region, with increased levels and colocalization with eIF4E in response to IR. These findings contribute to elucidate the molecular mechanism of protein translation regulation that underlies in the balance of cell survival/death during pathophysiological stress, such as cerebral ischemia.
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11
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Dierschke SK, Dennis MD. Retinal Protein O-GlcNAcylation and the Ocular Renin-angiotensin System: Signaling Cross-roads in Diabetic Retinopathy. Curr Diabetes Rev 2022; 18:e011121190177. [PMID: 33430751 PMCID: PMC8272735 DOI: 10.2174/1573399817999210111205933] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/26/2020] [Revised: 11/14/2020] [Accepted: 11/16/2020] [Indexed: 01/23/2023]
Abstract
It is well established that diabetes and its associated hyperglycemia negatively impact retinal function, yet we know little about the role played by augmented flux through the Hexosamine Biosynthetic Pathway (HBP). This offshoot of the glycolytic pathway produces UDP-Nacetyl- glucosamine, which serves as the substrate for post-translational O-linked modification of proteins in a process referred to as O-GlcNAcylation. HBP flux and subsequent protein O-GlcNAcylation serve as nutrient sensors, enabling cells to integrate metabolic information to appropriately modulate fundamental cellular processes including gene expression. Here we summarize the impact of diabetes on retinal physiology, highlighting recent studies that explore the role of O-GlcNAcylation- induced variation in mRNA translation in retinal dysfunction and the pathogenesis of Diabetic Retinopathy (DR). Augmented O-GlcNAcylation results in wide variation in the selection of mRNAs for translation, in part, due to O-GlcNAcylation of the translational repressor 4E-BP1. Recent studies demonstrate that 4E-BP1 plays a critical role in regulating O-GlcNAcylation-induced changes in the translation of the mRNAs encoding Vascular Endothelial Growth Factor (VEGF), a number of important mitochondrial proteins, and CD40, a key costimulatory molecule involved in diabetes-induced retinal inflammation. Remarkably, 4E-BP1/2 ablation delays the onset of diabetes- induced visual dysfunction in mice. Thus, pharmacological interventions to prevent the impact of O-GlcNAcylation on 4E-BP1 may represent promising therapeutics to address the development and progression of DR. In this regard, we discuss the potential interplay between retinal O-GlcNAcylation and the ocular renin-angiotensin system as a potential therapeutic target of future interventions.
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Affiliation(s)
- Sadie K. Dierschke
- Department of Cellular and Molecular Physiology, Penn State College of Medicine
| | - Michael D. Dennis
- Department of Cellular and Molecular Physiology, Penn State College of Medicine
- Department of Ophthalmology, Penn State College of Medicine
- Address correspondence to this author at the Department of Cellular and Molecular Physiology, H166, Penn State College of Medicine, 500 University Drive Hershey, PA 17033; Tel: (717)531-0003 Ext-282596; Fax: (717)531-7667;
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Synergetic contributions of viral VP1, VP3, and 3C to activation of the AKT-AMPK-MAPK-MTOR signaling pathway for Seneca Valley virus-induced autophagy. J Virol 2021; 96:e0155021. [PMID: 34757844 DOI: 10.1128/jvi.01550-21] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Seneca Valley virus (SVV), a member of the Picornaviridae family, can activate autophagy via the PERK and ATF6 unfolded protein response pathways and facilitate viral replication; however, the precise molecular mechanism that regulates SVV-induced autophagy remains unclear. Here, we revealed that SVV infection inhibited the phosphorylation of mechanistic target of rapamycin kinase (MTOR) and activated phosphorylation of the serine/threonine kinase AKT. We observed that activating adenosine monophosphate-activated protein kinase (AMPK), extracellular signal-regulated kinase (ERK) mitogen-activated protein kinase (MAPK), and p38 MAPK signaling by SVV infection promoted autophagy induction and viral replication; additionally, the SVV-induced autophagy was independent of the ULK1 complex. We further evaluated the role of viral protein(s) in the AKT-AMPK-MAPK-MTOR pathway during SVV-induced autophagy and found that VP1 induced autophagy, as evidenced by puncta colocalization with microtubule-associated protein 1 light chain 3 (LC3) in the cytoplasm and enhanced LC3-II levels. This might be associated with the interaction of VP1 with sequestosome 1 and promoting its degradation. In addition, the expression of VP1 enhanced AKT phosphorylation and AMPK phosphorylation, while MTOR phosphorylation was inhibited. These results indicate that VP1 induces autophagy by the AKT-AMPK-MTOR pathway. Additionally, expression of VP3 and 3C was found to activate autophagy induction via the ERK1/2 MAPK-MTOR and p38 MAPK-MTOR pathway. Taken together, our data suggest that SVV-induced autophagy has finely-tuned molecular mechanisms in which VP1, VP3, and 3C contribute synergistically to the AKT-AMPK-MAPK-MTOR pathway. IMPORTANCE Autophagy is an essential cellular catabolic process to sustain normal physiological processes that modulated by a variety of signaling pathways. Invading virus is a stimulus to induce autophagy that regulates viral replication. It has been demonstrated that Seneca Valley virus (SVV) induced autophagy via the PERK and ATF6 unfolded protein response pathways. However, the precise signaling pathway involved in autophagy is still poorly understood. In this study, our results demonstrated that viral proteins VP1, VP3, and 3C contribute synergistically to activation of the AKT-AMPK-MAPK-MTOR signaling pathway for SVV-induced autophagy. These findings reveal systemically the finely-tuned mocleular mechanism of SVV-induced autophagy, thereby facilitating to deeper insight into the development of potential control strategies against SVV infection.
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Martínez-Alonso E, Guerra-Pérez N, Escobar-Peso A, Regidor I, Masjuan J, Alcázar A. Differential Association of 4E-BP2-Interacting Proteins Is Related to Selective Delayed Neuronal Death after Ischemia. Int J Mol Sci 2021; 22:ijms221910327. [PMID: 34638676 PMCID: PMC8509075 DOI: 10.3390/ijms221910327] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2021] [Revised: 09/21/2021] [Accepted: 09/22/2021] [Indexed: 12/30/2022] Open
Abstract
Cerebral ischemia induces an inhibition of protein synthesis and causes cell death and neuronal deficits. These deleterious effects do not occur in resilient areas of the brain, where protein synthesis is restored. In cellular stress conditions, as brain ischemia, translational repressors named eukaryotic initiation factor (eIF) 4E-binding proteins (4E-BPs) specifically bind to eIF4E and are critical in the translational control. We previously described that 4E-BP2 protein, highly expressed in brain, can be a molecular target for the control of cell death or survival in the reperfusion after ischemia in an animal model of transient cerebral ischemia. Since these previous studies showed that phosphorylation would not be the regulation that controls the binding of 4E-BP2 to eIF4E under ischemic stress, we decided to investigate the differential detection of 4E-BP2-interacting proteins in two brain regions with different vulnerability to ischemia-reperfusion (IR) in this animal model, to discover new potential 4E-BP2 modulators and biomarkers of cerebral ischemia. For this purpose, 4E-BP2 immunoprecipitates from the resistant cortical region and the vulnerable hippocampal cornu ammonis 1 (CA1) region were analyzed by two-dimensional (2-D) fluorescence difference in gel electrophoresis (DIGE), and after a biological variation analysis, 4E-BP2-interacting proteins were identified by matrix-assisted laser desorption/ionization-time of flight (MALDI-TOF) mass spectrometry. Interestingly, among the 4E-BP2-interacting proteins identified, heat shock 70 kDa protein-8 (HSC70), dihydropyrimidinase-related protein-2 (DRP2), enolase-1, ubiquitin carboxyl-terminal hydrolase isozyme-L1 (UCHL1), adenylate kinase isoenzyme-1 (ADK1), nucleoside diphosphate kinase-A (NDKA), and Rho GDP-dissociation inhibitor-1 (Rho-GDI), were of notable interest, showing significant differences in their association with 4E-BP2 between resistant and vulnerable regions to ischemic stress. Our data contributes to the first characterization of the 4E-BP2 interactome, increasing the knowledge in the molecular basis of the protection and vulnerability of the ischemic regions and opens the way to detect new biomarkers and therapeutic targets for diagnosis and treatment of cerebral ischemia.
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Affiliation(s)
- Emma Martínez-Alonso
- Department of Research, Hospital Universitario Ramón y Cajal, IRYCIS, Ctra. Colmenar km 9.1, 28034 Madrid, Spain; (E.M.-A.); (N.G.-P.); (A.E.-P.)
- Proteomics Unit, Hospital Universitario Ramón y Cajal, IRYCIS, Ctra. Colmenar km 9.1, 28034 Madrid, Spain
| | - Natalia Guerra-Pérez
- Department of Research, Hospital Universitario Ramón y Cajal, IRYCIS, Ctra. Colmenar km 9.1, 28034 Madrid, Spain; (E.M.-A.); (N.G.-P.); (A.E.-P.)
- Department of Genetics, Physiology and Microbiology, Faculty of Biological Sciences, Complutense University of Madrid, Av. Complutense, 28040 Madrid, Spain
| | - Alejandro Escobar-Peso
- Department of Research, Hospital Universitario Ramón y Cajal, IRYCIS, Ctra. Colmenar km 9.1, 28034 Madrid, Spain; (E.M.-A.); (N.G.-P.); (A.E.-P.)
| | - Ignacio Regidor
- Department of Neurophysiology, Hospital Universitario Ramón y Cajal, IRYCIS, Ctra. Colmenar km 9.1, 28034 Madrid, Spain;
| | - Jaime Masjuan
- Department of Neurology, Hospital Universitario Ramón y Cajal, IRYCIS, Ctra. Colmenar km 9.1, 28034 Madrid, Spain;
- Department of Neurology, Facultad de Medicina, Universidad de Alcalá, Ctra. Madrid-Barcelona km 33.6, 28871 Alcalá de Henares, Spain
| | - Alberto Alcázar
- Department of Research, Hospital Universitario Ramón y Cajal, IRYCIS, Ctra. Colmenar km 9.1, 28034 Madrid, Spain; (E.M.-A.); (N.G.-P.); (A.E.-P.)
- Proteomics Unit, Hospital Universitario Ramón y Cajal, IRYCIS, Ctra. Colmenar km 9.1, 28034 Madrid, Spain
- Correspondence:
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14
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Wu S, Wagner G. Deep computational analysis details dysregulation of eukaryotic translation initiation complex eIF4F in human cancers. Cell Syst 2021; 12:907-923.e6. [PMID: 34358439 DOI: 10.1016/j.cels.2021.07.002] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2020] [Revised: 04/22/2021] [Accepted: 07/09/2021] [Indexed: 12/28/2022]
Abstract
eIF4F plays diverse roles in human cancers, which complicate the development of an overarching understanding of its functional and regulatory impacts across tumor types. Typically, eIF4F drives initiation from the mRNA 5' end (cap) and is composed of eIF4G1, eIF4A1, and cap-binding eIF4E. Cap-independent initiation is possible without eIF4E, from internal ribosomal entry sites (IRESs). By analyzing large public datasets, we found that cancers selectively overexpress EIF4G1 more than EIF4E. That expression imbalance supports EIF4G1 as a prognostic indicator in patients with cancer. It also attenuates "housekeeping" pathways that are usually regulated in a tissue-specific manner via cap-dependent initiation in healthy tissues and reinforce regulation of cancer-preferred pathways in cap-independent contexts. Cap-independent initiation is mechanistically attributable to eIF4G1 hyperphosphorylation that promotes binding to eIF4A1 and reduced eIF4E availability. Collectively, these findings reveal a novel model of dysregulated eIF4F function and highlight the clinical relevance of cap-(in)dependent initiation in cancer.
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Affiliation(s)
- Su Wu
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02115, USA.
| | - Gerhard Wagner
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02115, USA.
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15
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Caron MMJ, Eveque M, Cillero-Pastor B, Heeren RMA, Housmans B, Derks K, Cremers A, Peffers MJ, van Rhijn LW, van den Akker G, Welting TJM. Sox9 Determines Translational Capacity During Early Chondrogenic Differentiation of ATDC5 Cells by Regulating Expression of Ribosome Biogenesis Factors and Ribosomal Proteins. Front Cell Dev Biol 2021; 9:686096. [PMID: 34235151 PMCID: PMC8256280 DOI: 10.3389/fcell.2021.686096] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2021] [Accepted: 05/17/2021] [Indexed: 12/13/2022] Open
Abstract
Introduction In addition to the well-known cartilage extracellular matrix-related expression of Sox9, we demonstrated that chondrogenic differentiation of progenitor cells is driven by a sharply defined bi-phasic expression of Sox9: an immediate early and a late (extracellular matrix associated) phase expression. In this study, we aimed to determine what biological processes are driven by Sox9 during this early phase of chondrogenic differentiation. Materials Sox9 expression in ATDC5 cells was knocked down by siRNA transfection at the day before chondrogenic differentiation or at day 6 of differentiation. Samples were harvested at 2 h and 7 days of differentiation. The transcriptomes (RNA-seq approach) and proteomes (Label-free proteomics approach) were compared using pathway and network analyses. Total protein translational capacity was evaluated with the SuNSET assay, active ribosomes were evaluated with polysome profiling, and ribosome modus was evaluated with bicistronic reporter assays. Results Early Sox9 knockdown severely inhibited chondrogenic differentiation weeks later. Sox9 expression during the immediate early phase of ATDC5 chondrogenic differentiation regulated the expression of ribosome biogenesis factors and ribosomal protein subunits. This was accompanied by decreased translational capacity following Sox9 knockdown, and this correlated to lower amounts of active mono- and polysomes. Moreover, cap- versus IRES-mediated translation was altered by Sox9 knockdown. Sox9 overexpression was able to induce reciprocal effects to the Sox9 knockdown. Conclusion Here, we identified an essential new function for Sox9 during early chondrogenic differentiation. A role for Sox9 in regulation of ribosome amount, activity, and/or composition may be crucial in preparation for the demanding proliferative phase and subsequent cartilage extracellular matrix production of chondroprogenitors in the growth plate in vivo.
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Affiliation(s)
- Marjolein M J Caron
- Laboratory for Experimental Orthopedics, Department of Orthopedic Surgery, CAPHRI Care and Public Health Research Institute, Maastricht University Medical Center, Maastricht, Netherlands
| | - Maxime Eveque
- Maastricht MultiModal Molecular Imaging Institute (M4I), Division of Imaging Mass Spectrometry, Maastricht University Medical Center, Maastricht, Netherlands
| | - Berta Cillero-Pastor
- Maastricht MultiModal Molecular Imaging Institute (M4I), Division of Imaging Mass Spectrometry, Maastricht University Medical Center, Maastricht, Netherlands
| | - Ron M A Heeren
- Maastricht MultiModal Molecular Imaging Institute (M4I), Division of Imaging Mass Spectrometry, Maastricht University Medical Center, Maastricht, Netherlands
| | - Bas Housmans
- Laboratory for Experimental Orthopedics, Department of Orthopedic Surgery, CAPHRI Care and Public Health Research Institute, Maastricht University Medical Center, Maastricht, Netherlands
| | - Kasper Derks
- Department of Clinical Genetics, Maastricht University Medical Center, Maastricht, Netherlands
| | - Andy Cremers
- Laboratory for Experimental Orthopedics, Department of Orthopedic Surgery, CAPHRI Care and Public Health Research Institute, Maastricht University Medical Center, Maastricht, Netherlands
| | - Mandy J Peffers
- Department of Musculoskeletal Biology, Institute of Life Course and Medical Sciences, University of Liverpool, Liverpool, United Kingdom
| | - Lodewijk W van Rhijn
- Laboratory for Experimental Orthopedics, Department of Orthopedic Surgery, CAPHRI Care and Public Health Research Institute, Maastricht University Medical Center, Maastricht, Netherlands
| | - Guus van den Akker
- Laboratory for Experimental Orthopedics, Department of Orthopedic Surgery, CAPHRI Care and Public Health Research Institute, Maastricht University Medical Center, Maastricht, Netherlands
| | - Tim J M Welting
- Laboratory for Experimental Orthopedics, Department of Orthopedic Surgery, CAPHRI Care and Public Health Research Institute, Maastricht University Medical Center, Maastricht, Netherlands
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Wang H, Liu J, Zhang Y, Sun L, Zhao M, Luo B. Eukaryotic initiating factor eIF4E is targeted by EBV-encoded miR-BART11-3p and regulates cell cycle and apoptosis in EBV-associated gastric carcinoma. Virus Genes 2021; 57:358-368. [PMID: 34146250 DOI: 10.1007/s11262-021-01854-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2020] [Accepted: 06/08/2021] [Indexed: 12/26/2022]
Abstract
The eukaryotic translation initiation factor 4E (eIF4E) is a component of the eukaryotic translation initiation factor 4F, a significant complex in the protein translation process. It has been found to be closely related to many human tumors, such as gastric carcinoma. It is known that the Epstein-Barr virus (EBV) upregulates eIF4E in various ways in nasopharyngeal carcinoma. However, there are very few studies on eIF4E in EBV-associated gastric carcinoma. We found that the expression level of eIF4E in EBV-associated gastric carcinoma was lower than other types of gastric carcinoma, and the downregulation of eIF4E could lead to increased apoptosis of gastric carcinoma cells, retardation at S phase, and decreased cell migration. The dual luciferase reporter experiment showed that EBV-miR-BART11-3p could directly target the 3'-UTR region of eIF4E, and BART11-3p is the key factor leading to the downregulation of eIF4E. It could provide a new evidence for EBV-regulating host gene to affect the development of gastric carcinoma.
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Affiliation(s)
- Hanqing Wang
- Department of Pathogenic Biology, School of Basic Medicine, Qingdao University, Qingdao, Sandong, PR China
| | - Juanjuan Liu
- School of Basic Medicine, Qingdao University, Qingdao, Sandong, PR China
| | - Yan Zhang
- Department of Clinical Laboratory, Zibo Central Hospital, Zibo, Sandong, PR China
| | - Lingling Sun
- Department of Pathology, Affiliated Hospital of Qingdao University Medical College, 308 NingXia Road, Qingdao, 266021, PR China
| | - Menghe Zhao
- Department of Pathogenic Biology, School of Basic Medicine, Qingdao University, Qingdao, Sandong, PR China
| | - Bing Luo
- Department of Pathogenic Biology, School of Basic Medicine, Qingdao University, Qingdao, Sandong, PR China.
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17
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Shrivastava R, Tupperwar N, Schwartz B, Baron N, Shapira M. LeishIF4E-5 Is a Promastigote-Specific Cap-Binding Protein in Leishmania. Int J Mol Sci 2021; 22:3979. [PMID: 33921489 PMCID: PMC8069130 DOI: 10.3390/ijms22083979] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2021] [Revised: 04/01/2021] [Accepted: 04/08/2021] [Indexed: 12/17/2022] Open
Abstract
Leishmania parasites cycle between sand fly vectors and mammalian hosts, transforming from extracellular promastigotes that reside in the vectors' alimentary canal to obligatory intracellular non-motile amastigotes that are harbored by macrophages of the mammalian hosts. The transition between vector and host exposes them to a broad range of environmental conditions that induces a developmental program of gene expression, with translation regulation playing a key role. The Leishmania genome encodes six paralogs of the cap-binding protein eIF4E. All six isoforms show a relatively low degree of conservation with eIF4Es of other eukaryotes, as well as among themselves. This variability could suggest that they have been assigned discrete roles that could contribute to their survival under the changing environmental conditions. Here, we describe LeishIF4E-5, a LeishIF4E paralog. Despite the low sequence conservation observed between LeishIF4E-5 and other LeishIF4Es, the three aromatic residues in its cap-binding pocket are conserved, in accordance with its cap-binding activity. However, the cap-binding activity of LeishIF4E-5 is restricted to the promastigote life form and not observed in amastigotes. The overexpression of LeishIF4E-5 shows a decline in cell proliferation and an overall reduction in global translation. Immuno-cytochemical analysis shows that LeishIF4E-5 is localized in the cytoplasm, with a non-uniform distribution. Mass spectrometry analysis of proteins that co-purify with LeishIF4E-5 highlighted proteins involved in RNA metabolism, along with two LeishIF4G paralogs, LeishIF4G-1 and LeishIF4G-2. These vary in their conserved eIF4E binding motif, possibly suggesting that they can form different complexes.
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Affiliation(s)
- Rohit Shrivastava
- Department of Life Sciences, Ben-Gurion University of the Negev, Beer-Sheva 84105, Israel; (R.S.); (N.T.); (B.S.); (N.B.)
| | - Nitin Tupperwar
- Department of Life Sciences, Ben-Gurion University of the Negev, Beer-Sheva 84105, Israel; (R.S.); (N.T.); (B.S.); (N.B.)
- CSIR-Centre for Cellular and Molecular Biology, Hyderabad 50007, India
| | - Bar Schwartz
- Department of Life Sciences, Ben-Gurion University of the Negev, Beer-Sheva 84105, Israel; (R.S.); (N.T.); (B.S.); (N.B.)
| | - Nofar Baron
- Department of Life Sciences, Ben-Gurion University of the Negev, Beer-Sheva 84105, Israel; (R.S.); (N.T.); (B.S.); (N.B.)
| | - Michal Shapira
- Department of Life Sciences, Ben-Gurion University of the Negev, Beer-Sheva 84105, Israel; (R.S.); (N.T.); (B.S.); (N.B.)
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18
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Reprogramming translation for gene therapy. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2021; 182:439-476. [PMID: 34175050 DOI: 10.1016/bs.pmbts.2021.01.028] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Translational control plays a fundamental role in the regulation of gene expression in eukaryotes. Modulating translational efficiency allows the cell to fine-tune the expression of genes, spatially control protein localization, and trigger fast responses to environmental stresses. Translational regulation involves mechanisms acting on multiple steps of the protein synthesis pathway: initiation, elongation, and termination. Many cis-acting elements present in the 5' UTR of transcripts can influence translation at the initiation step. Among them, the Kozak sequence impacts translational efficiency by regulating the recognition of the start codon; upstream open reading frames (uORFs) are associated with inhibition of translation of the downstream protein; internal ribosomal entry sites (IRESs) can promote cap-independent translation. CRISPR-Cas technology is a revolutionary gene-editing tool that has also been applied to the regulation of gene expression. In this chapter, we focus on the genome editing approaches developed to modulate the translational efficiency with the aim to find novel therapeutic approaches, in particular acting on the cis-elements, that regulate the initiation of protein synthesis.
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19
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Nobuta R, Machida K, Sato M, Hashimoto S, Toriumi Y, Nakajima S, Suto D, Imataka H, Inada T. eIF4G-driven translation initiation of downstream ORFs in mammalian cells. Nucleic Acids Res 2020; 48:10441-10455. [PMID: 32941651 PMCID: PMC7544200 DOI: 10.1093/nar/gkaa728] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2020] [Revised: 08/18/2020] [Accepted: 08/21/2020] [Indexed: 12/24/2022] Open
Abstract
Comprehensive genome-wide analysis has revealed the presence of translational elements in the 3′ untranslated regions (UTRs) of human transcripts. However, the mechanisms by which translation is initiated in 3′ UTRs and the physiological function of their products remain unclear. This study showed that eIF4G drives the translation of various downstream open reading frames (dORFs) in 3′ UTRs. The 3′ UTR of GCH1, which encodes GTP cyclohydrolase 1, contains an internal ribosome entry site (IRES) that initiates the translation of dORFs. An in vitro reconstituted translation system showed that the IRES in the 3′ UTR of GCH1 required eIF4G and conventional translation initiation factors, except eIF4E, for AUG-initiated translation of dORFs. The 3′ UTR of GCH1-mediated translation was resistant to the mTOR inhibitor Torin 1, which inhibits cap-dependent initiation by increasing eIF4E-unbound eIF4G. eIF4G was also required for the activity of various elements, including polyU and poliovirus type 2, a short element thought to recruit ribosomes by base-pairing with 18S rRNA. These findings indicate that eIF4G mediates translation initiation of various ORFs in mammalian cells, suggesting that the 3′ UTRs of mRNAs may encode various products.
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Affiliation(s)
- Risa Nobuta
- Graduate School of Pharmaceutical Sciences, Tohoku University, Sendai 980-8578, Japan
| | - Kodai Machida
- Department of Applied Chemistry, Graduate School of Engineering, University of Hyogo, Himeji 671-2280, Japan
| | - Misaki Sato
- Graduate School of Pharmaceutical Sciences, Tohoku University, Sendai 980-8578, Japan
| | - Satoshi Hashimoto
- Graduate School of Pharmaceutical Sciences, Tohoku University, Sendai 980-8578, Japan
| | - Yasuhito Toriumi
- Graduate School of Pharmaceutical Sciences, Tohoku University, Sendai 980-8578, Japan
| | - Shizuka Nakajima
- Graduate School of Pharmaceutical Sciences, Tohoku University, Sendai 980-8578, Japan
| | - Daiki Suto
- Graduate School of Pharmaceutical Sciences, Tohoku University, Sendai 980-8578, Japan
| | - Hiroaki Imataka
- Department of Applied Chemistry, Graduate School of Engineering, University of Hyogo, Himeji 671-2280, Japan
| | - Toshifumi Inada
- Graduate School of Pharmaceutical Sciences, Tohoku University, Sendai 980-8578, Japan
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20
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An S, Kwon OS, Yu J, Jang SK. A cyclin-dependent kinase, CDK11/p58, represses cap-dependent translation during mitosis. Cell Mol Life Sci 2020; 77:4693-4708. [PMID: 32030451 PMCID: PMC7599166 DOI: 10.1007/s00018-019-03436-3] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2019] [Revised: 12/11/2019] [Accepted: 12/23/2019] [Indexed: 01/08/2023]
Abstract
During mitosis, translation of most mRNAs is strongly repressed; none of the several explanatory hypotheses suggested can fully explain the molecular basis of this phenomenon. Here we report that cyclin-dependent CDK11/p58-a serine/threonine kinase abundantly expressed during M phase-represses overall translation by phosphorylating a subunit (eIF3F) of the translation factor eIF3 complex that is essential for translation initiation of most mRNAs. Ectopic expression of CDK11/p58 strongly repressed cap-dependent translation, and knockdown of CDK11/p58 nullified the translational repression during M phase. We identified the phosphorylation sites in eIF3F responsible for M phase-specific translational repression by CDK11/p58. Alanine substitutions of CDK11/p58 target sites in eIF3F nullified its effects on cell cycle-dependent translational regulation. The mechanism of translational regulation by the M phase-specific kinase, CDK11/p58, has deep evolutionary roots considering the conservation of CDK11 and its target sites on eIF3F from C. elegans to humans.
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Affiliation(s)
- Sihyeon An
- PBC, Department of Life Sciences, Pohang University of Science and Technology (POSTECH), Cheongam-ro 77, Nam-gu, Pohang-si, Gyeongsangbuk-do, 37673, Republic of Korea
| | - Oh Sung Kwon
- PBC, Department of Life Sciences, Pohang University of Science and Technology (POSTECH), Cheongam-ro 77, Nam-gu, Pohang-si, Gyeongsangbuk-do, 37673, Republic of Korea
| | - Jinbae Yu
- PBC, Department of Life Sciences, Pohang University of Science and Technology (POSTECH), Cheongam-ro 77, Nam-gu, Pohang-si, Gyeongsangbuk-do, 37673, Republic of Korea
| | - Sung Key Jang
- PBC, Department of Life Sciences, Pohang University of Science and Technology (POSTECH), Cheongam-ro 77, Nam-gu, Pohang-si, Gyeongsangbuk-do, 37673, Republic of Korea.
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21
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Buoso E, Masi M, Long A, Chiappini C, Travelli C, Govoni S, Racchi M. Ribosomes as a nexus between translation and cancer progression: Focus on ribosomal Receptor for Activated C Kinase 1 (RACK1) in breast cancer. Br J Pharmacol 2020; 179:2813-2828. [PMID: 32726469 DOI: 10.1111/bph.15218] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2020] [Revised: 06/30/2020] [Accepted: 07/16/2020] [Indexed: 12/19/2022] Open
Abstract
Ribosomes coordinate spatiotemporal control of gene expression, contributing to the acquisition and maintenance of cancer phenotype. The link between ribosomes and cancer is found in the roles of individual ribosomal proteins in tumorigenesis and cancer progression, including the ribosomal protein, receptor for activated C kinase 1 (RACK1). RACK1 regulates cancer cell invasion and is localized in spreading initiation centres, structural adhesion complexes containing RNA binding proteins and poly-adenylated mRNAs that suggest a local translation process. As RACK1 is a ribosomal protein directly involved in translation and in breast cancer progression, we propose a new molecular mechanism for breast cancer cell migration and invasion, which considers the molecular differences between epithelial and mesenchymal cell profiles in order to characterize and provide novel targets for therapeutic strategies. Hence, we provide an analysis on how ribosomes translate cancer progression with a final focus on the ribosomal protein RACK1 in breast cancer.
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Affiliation(s)
- Erica Buoso
- Department of Drug Sciences, University of Pavia, Pavia, Italy
| | - Mirco Masi
- Department of Drug Sciences, University of Pavia, Pavia, Italy.,Scuola Universitaria Superiore IUSS Pavia, Pavia, Italy
| | - Aideen Long
- Department of Clinical Medicine, Institute of Molecular Medicine, Trinity College, Dublin, Ireland
| | | | | | - Stefano Govoni
- Department of Drug Sciences, University of Pavia, Pavia, Italy
| | - Marco Racchi
- Department of Drug Sciences, University of Pavia, Pavia, Italy
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22
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Haizel SA, Bhardwaj U, Gonzalez RL, Mitra S, Goss DJ. 5'-UTR recruitment of the translation initiation factor eIF4GI or DAP5 drives cap-independent translation of a subset of human mRNAs. J Biol Chem 2020; 295:11693-11706. [PMID: 32571876 DOI: 10.1074/jbc.ra120.013678] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2020] [Revised: 06/16/2020] [Indexed: 01/04/2023] Open
Abstract
During unfavorable conditions (e.g. tumor hypoxia or viral infection), canonical, cap-dependent mRNA translation is suppressed in human cells. Nonetheless, a subset of physiologically important mRNAs (e.g. hypoxia-inducible factor 1α [HIF-1α], fibroblast growth factor 9 [FGF-9], and p53) is still translated by an unknown, cap-independent mechanism. Additionally, expression levels of eukaryotic translation initiation factor 4GI (eIF4GI) and of its homolog, death-associated protein 5 (DAP5), are elevated. By examining the 5' UTRs of HIF-1α, FGF-9, and p53 mRNAs and using fluorescence anisotropy binding studies, luciferase reporter-based in vitro translation assays, and mutational analyses, we demonstrate here that eIF4GI and DAP5 specifically bind to the 5' UTRs of these cap-independently translated mRNAs. Surprisingly, we found that the eIF4E-binding domain of eIF4GI increases not only the binding affinity but also the selectivity among these mRNAs. We further demonstrate that the affinities of eIF4GI and DAP5 binding to these 5' UTRs correlate with the efficiency with which these factors drive cap-independent translation of these mRNAs. Integrating the results of our binding and translation assays, we conclude that eIF4GI or DAP5 is critical for recruitment of a specific subset of mRNAs to the ribosome, providing mechanistic insight into their cap-independent translation.
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Affiliation(s)
- Solomon A Haizel
- Ph.D. Program in Biochemistry, The Graduate Center of the City University of New York, New York, New York, USA.,Department of Chemistry, Hunter College, New York, New York, USA
| | - Usha Bhardwaj
- Department of Chemistry, Hunter College, New York, New York, USA
| | - Ruben L Gonzalez
- Department of Chemistry, Columbia University, New York, New York, USA
| | - Somdeb Mitra
- Department of Chemistry, New York University, New York, New York, USA
| | - Dixie J Goss
- Ph.D. Program in Biochemistry, The Graduate Center of the City University of New York, New York, New York, USA .,Department of Chemistry, Hunter College, New York, New York, USA.,Ph.D. Program in Chemistry, The Graduate Center of the City University of New York, New York, New York, USA
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23
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Barrera A, Olguín V, Vera-Otarola J, López-Lastra M. Cap-independent translation initiation of the unspliced RNA of retroviruses. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2020; 1863:194583. [PMID: 32450258 DOI: 10.1016/j.bbagrm.2020.194583] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 04/08/2020] [Revised: 05/12/2020] [Accepted: 05/18/2020] [Indexed: 12/12/2022]
Abstract
Retroviruses are a unique family of RNA viruses that utilize a virally encoded reverse transcriptase (RT) to replicate their genomic RNA (gRNA) through a proviral DNA intermediate. The provirus is permanently integrated into the host cell chromosome and is expressed by the host cell transcription, RNA processing, and translation machinery. Retroviral messenger RNAs (mRNAs) entirely resemble a cellular mRNA as they have a 5'cap structure, 5'untranslated region (UTR), an open reading frame (ORF), 3'UTR, and a 3'poly(A) tail. The primary transcription product interacts with the cellular RNA processing machinery and is spliced, exported to the cytoplasm, and translated. However, a proportion of the pre-mRNA subverts typical RNA processing giving rise to the full-length RNA. In the cytoplasm, the full-length retroviral RNA fulfills a dual role acting as mRNA and as the gRNA. Simple retroviruses generate two pools of full-length RNA, one for each purpose. However, complex retroviruses have a single pool of full-length RNA, which is destined for translation or encapsidation. As for eukaryotic mRNAs, translational control of retroviral protein synthesis is mostly exerted at the step of initiation. Interestingly, some retroviral mRNAs, both simple and complex, use a dual mechanism to initiate protein synthesis, a cap-dependent initiation mechanism, or via internal initiation using an internal ribosome entry site (IRES). In this review, we describe and discuss data regarding the molecular mechanism driving the canonical cap-dependent and IRES-mediated translation initiation for retroviral mRNA, focusing the discussion mainly on the most studied retroviral mRNA, the HIV-1 mRNA.
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Affiliation(s)
- Aldo Barrera
- Laboratorio de Virología Molecular, Instituto Milenio de Inmunología e Inmunoterapia, Centro de Investigaciones Médicas, Departamento de Enfermedades Infecciosas e Inmunología Pediátrica, Escuela de Medicina, Pontificia Universidad Católica de Chile, Marcoleta 391, Santiago, Chile
| | - Valeria Olguín
- Laboratorio de Virología Molecular, Instituto Milenio de Inmunología e Inmunoterapia, Centro de Investigaciones Médicas, Departamento de Enfermedades Infecciosas e Inmunología Pediátrica, Escuela de Medicina, Pontificia Universidad Católica de Chile, Marcoleta 391, Santiago, Chile
| | - Jorge Vera-Otarola
- Laboratorio de Virología Molecular, Instituto Milenio de Inmunología e Inmunoterapia, Centro de Investigaciones Médicas, Departamento de Enfermedades Infecciosas e Inmunología Pediátrica, Escuela de Medicina, Pontificia Universidad Católica de Chile, Marcoleta 391, Santiago, Chile
| | - Marcelo López-Lastra
- Laboratorio de Virología Molecular, Instituto Milenio de Inmunología e Inmunoterapia, Centro de Investigaciones Médicas, Departamento de Enfermedades Infecciosas e Inmunología Pediátrica, Escuela de Medicina, Pontificia Universidad Católica de Chile, Marcoleta 391, Santiago, Chile.
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24
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Cho SY, Lee S, Yeom J, Kim HJ, Lee JH, Shin JW, Kwon MA, Lee KB, Jeong EM, Ahn HS, Shin DM, Kim K, Kim IG. Transglutaminase 2 mediates hypoxia-induced selective mRNA translation via polyamination of 4EBPs. Life Sci Alliance 2020; 3:3/3/e201900565. [PMID: 32075852 PMCID: PMC7032569 DOI: 10.26508/lsa.201900565] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2020] [Revised: 02/05/2020] [Accepted: 02/06/2020] [Indexed: 12/12/2022] Open
Abstract
This study highlights the role of transglutaminase 2 in selective mRNA translation of hypoxic cancer cells by polyamination-dependent modulation of 4EBPs, providing a target for cancer treatment. Hypoxia selectively enhances mRNA translation despite suppressed mammalian target of rapamycin complex 1 activity, contributing to gene expression reprogramming that promotes metastasis and survival of cancer cells. Little is known about how this paradoxical control of translation occurs. Here, we report a new pathway that links hypoxia to selective mRNA translation. Transglutaminase 2 (TG2) is a hypoxia-inducible factor 1–inducible enzyme that alters the activity of substrate proteins by polyamination or crosslinking. Under hypoxic conditions, TG2 polyaminated eukaryotic translation initiation factor 4E (eIF4E)-bound eukaryotic translation initiation factor 4E-binding proteins (4EBPs) at conserved glutamine residues. 4EBP1 polyamination enhances binding affinity for Raptor, thereby increasing phosphorylation of 4EBP1 and cap-dependent translation. Proteomic analyses of newly synthesized proteins in hypoxic cells revealed that TG2 activity preferentially enhanced the translation of a subset of mRNA containing G/C-rich 5′UTRs but not upstream ORF or terminal oligopyrimidine motifs. These results indicate that TG2 is a critical regulator in hypoxia-induced selective mRNA translation and provide a promising molecular target for the treatment of cancers.
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Affiliation(s)
- Sung-Yup Cho
- Department of Biochemistry and Molecular Biology, Seoul National University College of Medicine, Seoul, Korea .,Department of Biomedical Sciences, Seoul National University College of Medicine, Seoul, Korea.,Cancer Research Institute, Seoul National University College of Medicine, Seoul, Korea
| | - Seungun Lee
- Department of Biomedical Sciences, University of Ulsan College of Medicine, Seoul, Korea
| | - Jeonghun Yeom
- Department of Convergence Medicine, Asan Medical Center, Seoul, Korea
| | - Hyo-Jun Kim
- Department of Biochemistry and Molecular Biology, Seoul National University College of Medicine, Seoul, Korea
| | - Jin-Haeng Lee
- Department of Biochemistry and Molecular Biology, Seoul National University College of Medicine, Seoul, Korea
| | - Ji-Woong Shin
- Department of Biochemistry and Molecular Biology, Seoul National University College of Medicine, Seoul, Korea
| | - Mee-Ae Kwon
- Department of Biochemistry and Molecular Biology, Seoul National University College of Medicine, Seoul, Korea
| | - Ki Baek Lee
- Department of Biochemistry and Molecular Biology, Seoul National University College of Medicine, Seoul, Korea
| | - Eui Man Jeong
- Department of Biochemistry and Molecular Biology, Seoul National University College of Medicine, Seoul, Korea.,Institute of Human-Environment Interface Biology, Seoul National University College of Medicine, Seoul, Korea
| | - Hee Sung Ahn
- Department of Convergence Medicine, Asan Medical Center, Seoul, Korea
| | - Dong-Myung Shin
- Department of Biomedical Sciences, University of Ulsan College of Medicine, Seoul, Korea
| | - Kyunggon Kim
- Department of Biomedical Sciences, University of Ulsan College of Medicine, Seoul, Korea .,Department of Convergence Medicine, Asan Medical Center, Seoul, Korea
| | - In-Gyu Kim
- Department of Biochemistry and Molecular Biology, Seoul National University College of Medicine, Seoul, Korea .,Institute of Human-Environment Interface Biology, Seoul National University College of Medicine, Seoul, Korea
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25
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Smart D, Filippi I, Blume C, Smalley B, Davies D, McCormick CJ. Rhinovirus 2A is the key protease responsible for instigating the early block to gene expression in infected cells. J Cell Sci 2020; 133:jcs.232504. [PMID: 31822628 DOI: 10.1242/jcs.232504] [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: 03/29/2019] [Accepted: 12/02/2019] [Indexed: 11/20/2022] Open
Abstract
Human rhinoviruses (HRVs) express 2 cysteine proteases, 2A and 3C, that are responsible for viral polyprotein processing. Both proteases also suppress host gene expression by inhibiting mRNA transcription, nuclear export and cap-dependent translation. However, the relative contribution that each makes in achieving this goal remains unclear. In this study, we have compared both the combined and individual ability of the two proteases to shut down cellular gene expression using a novel dynamic reporter system. Our findings show that 2A inhibits host gene expression much more rapidly than 3C. By comparing the activities of a representative set of proteases from the three different HRV species, we also find variation in the speed at which host gene expression is suppressed. Our work highlights the key role that 2A plays in early suppression of the infected host cell response and shows that this can be influenced by natural variation in the activity of this enzyme.
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Affiliation(s)
- David Smart
- Clinical and Experimental Sciences, Faculty of Medicine, University of Southampton, Sir Henry Wellcome Laboratories, University Hospital Southampton, Southampton SO16 6YD, UK.,Southampton NIHR Respiratory Biomedical Research Centre, University Hospital Southampton, Southampton SO16 6YD, UK
| | - Irene Filippi
- Clinical and Experimental Sciences, Faculty of Medicine, University of Southampton, Sir Henry Wellcome Laboratories, University Hospital Southampton, Southampton SO16 6YD, UK.,Southampton NIHR Respiratory Biomedical Research Centre, University Hospital Southampton, Southampton SO16 6YD, UK
| | - Cornelia Blume
- Clinical and Experimental Sciences, Faculty of Medicine, University of Southampton, Sir Henry Wellcome Laboratories, University Hospital Southampton, Southampton SO16 6YD, UK.,Southampton NIHR Respiratory Biomedical Research Centre, University Hospital Southampton, Southampton SO16 6YD, UK
| | - Benjamin Smalley
- Clinical and Experimental Sciences, Faculty of Medicine, University of Southampton, Sir Henry Wellcome Laboratories, University Hospital Southampton, Southampton SO16 6YD, UK
| | - Donna Davies
- Clinical and Experimental Sciences, Faculty of Medicine, University of Southampton, Sir Henry Wellcome Laboratories, University Hospital Southampton, Southampton SO16 6YD, UK.,Southampton NIHR Respiratory Biomedical Research Centre, University Hospital Southampton, Southampton SO16 6YD, UK.,Institute for Life Sciences, University of Southampton, Southampton SO17 1BJ, UK
| | - Christopher J McCormick
- Clinical and Experimental Sciences, Faculty of Medicine, University of Southampton, Sir Henry Wellcome Laboratories, University Hospital Southampton, Southampton SO16 6YD, UK
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26
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Smolle MA, Czapiewski P, Lapińska-Szumczyk S, Majewska H, Supernat A, Zaczek A, Biernat W, Golob-Schwarzl N, Haybaeck J. The Prognostic Significance of Eukaryotic Translation Initiation Factors (eIFs) in Endometrial Cancer. Int J Mol Sci 2019; 20:E6169. [PMID: 31817792 PMCID: PMC6941158 DOI: 10.3390/ijms20246169] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2019] [Revised: 12/01/2019] [Accepted: 12/05/2019] [Indexed: 02/07/2023] Open
Abstract
Whilst the role of eukaryotic translation initiation factors (eIFs) has already been investigated in several human cancers, their role in endometrial cancer (EC) is relatively unknown. In the present retrospective study, 279 patients with EC (1180 samples) were included (mean age: 63.0 years, mean follow-up: 6.1 years). Samples were analysed for expression of 7 eIFs subunits (eIF2α, eIF3c, eIF3h, eIF4e, eIF4g, eIF5, eIF6) through immunohistochemistry and western blotting. Fifteen samples of healthy endometrium served as controls. Density and intensity were assessed and mean combined scores (CS) calculated for each patient. Upon immunohistochemistry, median eIF5 CS were significantly higher in EC as compared with non-neoplastic tissue (NNT, p < 0.001), whilst median eIF6 CS were significantly lower in EC (p < 0.001). Moreover, eIF5 (p = 0.002), eIF6 (p = 0.032) and eIF4g CS (p = 0.014) were significantly different when comparing NNT with EC grading types. Median eIF4g CS was higher in type II EC (p = 0.034). Upon western blot analysis, eIF4g (p < 0.001), peIF2α (p < 0.001) and eIF3h (p < 0.05) were significantly overexpressed in EC, while expression of eIF3c was significantly reduced in EC as compared with NNT (p < 0.001). The remaining eIFs were non-significant. Besides tumour stage (p < 0.001) and patient's age (p < 0.001), high eIF4g CS-levels were independently associated with poor prognosis (HR: 1.604, 95%CI: 1.037-2.483, p = 0.034). The other eIFs had no prognostic significance. Notably, the independent prognostic significance of eIF4g was lost when adding tumour type. Considering the difficulties in differentiating EC type I and II, eIF4g may serve as a novel prognostic marker indicating patient outcome.
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Affiliation(s)
- Maria Anna Smolle
- Department of Orthopaedics and Trauma, Medical University of Graz, Auenbruggerplatz 5, 8036 Graz, Austria;
- Area 2 Cancer, Center for Biomarker Research in Medicine, Stiftingtalstraße 5, 8010 Graz, Austria;
| | - Piotr Czapiewski
- Department of Pathomorphology, Medical University of Gdansk, Mariana Smoluchowskiego 17, 80-214 Gdańsk, Poland; (P.C.); (H.M.); (W.B.)
- Department of Pathology, Medical Faculty, Otto-von-Guericke University Magdeburg, Leipziger Straße 44, 39120 Magdeburg, Germany
| | - Sylwia Lapińska-Szumczyk
- Department of Gynaecology, Gynaecological Oncology and Gynaecological Endocrinology, Medical University of Gdańsk, M. Skłodowskiej-Curie 3a Street, 80-210 Gdańsk, Poland;
| | - Hanna Majewska
- Department of Pathomorphology, Medical University of Gdansk, Mariana Smoluchowskiego 17, 80-214 Gdańsk, Poland; (P.C.); (H.M.); (W.B.)
| | - Anna Supernat
- Department of Medical Biotechnology, Intercollegiate Faculty of Biotechnology, University of Gdańnsk and Medical University of Gdańsk, Bażyńskiego 1a, 80-952 Gdańsk, Poland; (A.S.); (A.Z.)
| | - Anna Zaczek
- Department of Medical Biotechnology, Intercollegiate Faculty of Biotechnology, University of Gdańnsk and Medical University of Gdańsk, Bażyńskiego 1a, 80-952 Gdańsk, Poland; (A.S.); (A.Z.)
| | - Wojciech Biernat
- Department of Pathomorphology, Medical University of Gdansk, Mariana Smoluchowskiego 17, 80-214 Gdańsk, Poland; (P.C.); (H.M.); (W.B.)
| | - Nicole Golob-Schwarzl
- Area 2 Cancer, Center for Biomarker Research in Medicine, Stiftingtalstraße 5, 8010 Graz, Austria;
- Institute of Pathology, Medical University of Graz, Auenbruggerplatz 25, 8036 Graz, Austria
| | - Johannes Haybaeck
- Area 2 Cancer, Center for Biomarker Research in Medicine, Stiftingtalstraße 5, 8010 Graz, Austria;
- Department of Pathology, Medical Faculty, Otto-von-Guericke University Magdeburg, Leipziger Straße 44, 39120 Magdeburg, Germany
- Institute of Pathology, Medical University of Graz, Auenbruggerplatz 25, 8036 Graz, Austria
- Department of Pathology, Neuropathology and Molecular Pathology, Medical University of Innsbruck, Müllerstraße 44, 6020 Innsbruck, Austria
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Marina D, Arnaud L, Paul Noel L, Felix S, Bernard R, Natacha C. Relevance of Translation Initiation in Diffuse Glioma Biology and its Therapeutic Potential. Cells 2019; 8:E1542. [PMID: 31795417 PMCID: PMC6953081 DOI: 10.3390/cells8121542] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2019] [Revised: 11/21/2019] [Accepted: 11/26/2019] [Indexed: 02/06/2023] Open
Abstract
Cancer cells are continually exposed to environmental stressors forcing them to adapt their protein production to survive. The translational machinery can be recruited by malignant cells to synthesize proteins required to promote their survival, even in times of high physiological and pathological stress. This phenomenon has been described in several cancers including in gliomas. Abnormal regulation of translation has encouraged the development of new therapeutics targeting the protein synthesis pathway. This approach could be meaningful for glioma given the fact that the median survival following diagnosis of the highest grade of glioma remains short despite current therapy. The identification of new targets for the development of novel therapeutics is therefore needed in order to improve this devastating overall survival rate. This review discusses current literature on translation in gliomas with a focus on the initiation step covering both the cap-dependent and cap-independent modes of initiation. The different translation initiation protagonists will be described in normal conditions and then in gliomas. In addition, their gene expression in gliomas will systematically be examined using two freely available datasets. Finally, we will discuss different pathways regulating translation initiation and current drugs targeting the translational machinery and their potential for the treatment of gliomas.
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Affiliation(s)
- Digregorio Marina
- Laboratory of Nervous System Disorders and Therapy, GIGA-Neurosciences Research Centre, University of Liège, 4000 Liège, Belgium; (D.M.); (L.A.); (L.P.N.); (S.F.); (R.B.)
| | - Lombard Arnaud
- Laboratory of Nervous System Disorders and Therapy, GIGA-Neurosciences Research Centre, University of Liège, 4000 Liège, Belgium; (D.M.); (L.A.); (L.P.N.); (S.F.); (R.B.)
- Department of Neurosurgery, CHU of Liège, 4000 Liège, Belgium
| | - Lumapat Paul Noel
- Laboratory of Nervous System Disorders and Therapy, GIGA-Neurosciences Research Centre, University of Liège, 4000 Liège, Belgium; (D.M.); (L.A.); (L.P.N.); (S.F.); (R.B.)
| | - Scholtes Felix
- Laboratory of Nervous System Disorders and Therapy, GIGA-Neurosciences Research Centre, University of Liège, 4000 Liège, Belgium; (D.M.); (L.A.); (L.P.N.); (S.F.); (R.B.)
- Department of Neurosurgery, CHU of Liège, 4000 Liège, Belgium
| | - Rogister Bernard
- Laboratory of Nervous System Disorders and Therapy, GIGA-Neurosciences Research Centre, University of Liège, 4000 Liège, Belgium; (D.M.); (L.A.); (L.P.N.); (S.F.); (R.B.)
- Department of Neurology, CHU of Liège, 4000 Liège, Belgium
| | - Coppieters Natacha
- Laboratory of Nervous System Disorders and Therapy, GIGA-Neurosciences Research Centre, University of Liège, 4000 Liège, Belgium; (D.M.); (L.A.); (L.P.N.); (S.F.); (R.B.)
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28
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Zhou ZD, Selvaratnam T, Lee JCT, Chao YX, Tan EK. Molecular targets for modulating the protein translation vital to proteostasis and neuron degeneration in Parkinson's disease. Transl Neurodegener 2019; 8:6. [PMID: 30740222 PMCID: PMC6360798 DOI: 10.1186/s40035-019-0145-0] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2018] [Accepted: 01/14/2019] [Indexed: 12/13/2022] Open
Abstract
Parkinson's disease (PD) is the most common neurodegenerative movement disorder, which is characterized by the progressive loss of dopaminergic neurons in the Substantia Nigra pars compacta concomitant with Lewy body formation in affected brain areas. The detailed pathogenic mechanisms underlying the selective loss of dopaminergic neurons in PD are unclear, and no drugs or treatments have been developed to alleviate progressive dopaminergic neuron degeneration in PD. However, the formation of α-synuclein-positive protein aggregates in Lewy body has been identified as a common pathological feature of PD, possibly stemming from the consequence of protein misfolding and dysfunctional proteostasis. Proteostasis is the mechanism for maintaining protein homeostasis via modulation of protein translation, enhancement of chaperone capacity and the prompt clearance of misfolded protein by the ubiquitin proteasome system and autophagy. Deregulated protein translation and impaired capacities of chaperone or protein degradation can disturb proteostasis processes, leading to pathological protein aggregation and neurodegeneration in PD. In recent years, multiple molecular targets in the modulation of protein translation vital to proteostasis and dopaminergic neuron degeneration have been identified. The potential pathophysiological and therapeutic significance of these molecular targets to neurodegeneration in PD is highlighted.
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Affiliation(s)
- Zhi Dong Zhou
- Department of Research, National Neuroscience Institute, 11 Jalan Tan Tock Seng, Singapore, 308433 Singapore
- Signature Research Program in Neuroscience and Behavioural Disorders, Duke-NUS Medical School Singapore, 8 College Road, Singapore, Singapore
| | - Thevapriya Selvaratnam
- Department of Research, National Neuroscience Institute, 11 Jalan Tan Tock Seng, Singapore, 308433 Singapore
| | - Ji Chao Tristan Lee
- Department of Research, National Neuroscience Institute, 11 Jalan Tan Tock Seng, Singapore, 308433 Singapore
| | - Yin Xia Chao
- Department of Research, National Neuroscience Institute, 11 Jalan Tan Tock Seng, Singapore, 308433 Singapore
| | - Eng-King Tan
- Department of Research, National Neuroscience Institute, 11 Jalan Tan Tock Seng, Singapore, 308433 Singapore
- Department of Neurology, Singapore General Hospital, Outram Road, Singapore, 169608 Singapore
- Signature Research Program in Neuroscience and Behavioural Disorders, Duke-NUS Medical School Singapore, 8 College Road, Singapore, Singapore
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29
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de la Parra C, Ernlund A, Alard A, Ruggles K, Ueberheide B, Schneider RJ. A widespread alternate form of cap-dependent mRNA translation initiation. Nat Commun 2018; 9:3068. [PMID: 30076308 PMCID: PMC6076257 DOI: 10.1038/s41467-018-05539-0] [Citation(s) in RCA: 103] [Impact Index Per Article: 17.2] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2018] [Accepted: 07/06/2018] [Indexed: 11/30/2022] Open
Abstract
Translation initiation of most mammalian mRNAs is mediated by a 5′ cap structure that binds eukaryotic initiation factor 4E (eIF4E). However, inactivation of eIF4E does not impair translation of many capped mRNAs, suggesting an unknown alternate mechanism may exist for cap-dependent but eIF4E-independent translation. We show that DAP5, an eIF4GI homolog that lacks eIF4E binding, utilizes eIF3d to facilitate cap-dependent translation of approximately 20% of mRNAs. Genome-wide transcriptomic and translatomic analyses indicate that DAP5 is required for translation of many transcription factors and receptor capped mRNAs and their mRNA targets involved in cell survival, motility, DNA repair and translation initiation, among other mRNAs. Mass spectrometry and crosslinking studies demonstrate that eIF3d is a direct binding partner of DAP5. In vitro translation and ribosome complex studies demonstrate that DAP5 and eIF3d are both essential for eIF4E-independent capped-mRNA translation. These studies disclose a widespread and previously unknown mechanism for cap-dependent mRNA translation by DAP5-eIF3d complexes. Binding of eIF4E to the 5′ cap of mRNAs is a key early step in canonical translation initiation, but the requirement for eIF4E is not universal. Here the authors show that the eIF4G homolog DAP5 interacts with eIF3 to promote cap-dependent translation of a significant number of mRNA in an eIF4E-independent manner.
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Affiliation(s)
- Columba de la Parra
- Department of Microbiology, NYU School of Medicine, New York, NY, 10016, USA.,Perlmutter Cancer Center, NYU School of Medicine, New York, NY, 10016, USA
| | - Amanda Ernlund
- Department of Microbiology, NYU School of Medicine, New York, NY, 10016, USA
| | - Amandine Alard
- Department of Microbiology, NYU School of Medicine, New York, NY, 10016, USA
| | - Kelly Ruggles
- Department of Medicine, NYU School of Medicine, New York, NY, 10016, USA
| | - Beatrix Ueberheide
- Department of Biochemistry and Molecular Pharmacology, NYU School of Medicine, New York, NY, 10016, USA
| | - Robert J Schneider
- Department of Microbiology, NYU School of Medicine, New York, NY, 10016, USA. .,Perlmutter Cancer Center, NYU School of Medicine, New York, NY, 10016, USA.
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30
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Kumar R, Khandelwal N, Thachamvally R, Tripathi BN, Barua S, Kashyap SK, Maherchandani S, Kumar N. Role of MAPK/MNK1 signaling in virus replication. Virus Res 2018; 253:48-61. [PMID: 29864503 PMCID: PMC7114592 DOI: 10.1016/j.virusres.2018.05.028] [Citation(s) in RCA: 76] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2018] [Revised: 04/16/2018] [Accepted: 05/31/2018] [Indexed: 12/23/2022]
Abstract
Viruses are known to exploit cellular signaling pathways. MAPK is a major cell signaling pathway activated by diverse group of viruses. MNK1 regulates both cap-dependent and IRES-mediated mRNA translation. This review discuss the role of MAPK, particularly the role of MNK1 in virus replication.
Viruses are obligate intracellular parasites; they heavily depend on the host cell machinery to effectively replicate and produce new progeny virus particles. Following viral infection, diverse cell signaling pathways are initiated by the cells, with the major goal of establishing an antiviral state. However, viruses have been shown to exploit cellular signaling pathways for their own effective replication. Genome-wide siRNA screens have also identified numerous host factors that either support (proviral) or inhibit (antiviral) virus replication. Some of the host factors might be dispensable for the host but may be critical for virus replication; therefore such cellular factors may serve as targets for development of antiviral therapeutics. Mitogen activated protein kinase (MAPK) is a major cell signaling pathway that is known to be activated by diverse group of viruses. MAPK interacting kinase 1 (MNK1) has been shown to regulate both cap-dependent and internal ribosomal entry sites (IRES)-mediated mRNA translation. In this review we have discuss the role of MAPK in virus replication, particularly the role of MNK1 in replication and translation of viral genome.
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Affiliation(s)
- Ram Kumar
- Virology Laboratory, National Centre for Veterinary Type Cultures, ICAR-National Research Centre on Equines, Hisar, Haryana 125001, India; Department of Veterinary Microbiology and Biotechnology, Rajasthan University of Veterinary and Animal Sciences, Bikaner, Rajasthan 334001, India
| | - Nitin Khandelwal
- Virology Laboratory, National Centre for Veterinary Type Cultures, ICAR-National Research Centre on Equines, Hisar, Haryana 125001, India
| | - Riyesh Thachamvally
- Virology Laboratory, National Centre for Veterinary Type Cultures, ICAR-National Research Centre on Equines, Hisar, Haryana 125001, India
| | - Bhupendra Nath Tripathi
- Virology Laboratory, National Centre for Veterinary Type Cultures, ICAR-National Research Centre on Equines, Hisar, Haryana 125001, India
| | - Sanjay Barua
- Virology Laboratory, National Centre for Veterinary Type Cultures, ICAR-National Research Centre on Equines, Hisar, Haryana 125001, India
| | - Sudhir Kumar Kashyap
- Department of Veterinary Microbiology and Biotechnology, Rajasthan University of Veterinary and Animal Sciences, Bikaner, Rajasthan 334001, India
| | - Sunil Maherchandani
- Department of Veterinary Microbiology and Biotechnology, Rajasthan University of Veterinary and Animal Sciences, Bikaner, Rajasthan 334001, India
| | - Naveen Kumar
- Virology Laboratory, National Centre for Veterinary Type Cultures, ICAR-National Research Centre on Equines, Hisar, Haryana 125001, India.
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31
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Gao Z, Yuan T, Zhou X, Ni P, Sun G, Li P, Cheng Z, Wang X. Targeting BRD4 proteins suppresses the growth of NSCLC through downregulation of eIF4E expression. Cancer Biol Ther 2018; 19:407-415. [PMID: 29333921 DOI: 10.1080/15384047.2018.1423923] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022] Open
Abstract
Lung cancer is the leading cause of cancer-related death worldwide. Bromodomain and extraterminal domain (BET) proteins act as epigenome readers for gene transcriptional regulation. Among BET family members, BRD4 was well studied, but for its mechanism in non-small cell lung carcinoma has not been elucidated. eIF4E regulates gene translation and has been proved to play an important role in the progression of lung cancer. In this study, we first confirmed that BET inhibitors JQ1 and I-BET151 suppressed the growth of NSCLCs, in parallel with downregulated eIF4E expression. Then we found that knockdown of BRD4 expression using siRNAs inhibited the growth of NSCLCs as well as decreased eIF4E protein levels. Moreover, overexpression of eIF4E partially abrogated the growth inhibitory effect of JQ1, while knockdown of eIF4E enhanced the inhibitory effect of JQ1. Furthermore, JQ1 treatment or knockdown of BRD4 expression decreased eIF4E mRNA levels and inhibited its promoter activity by luciferase reporter assay. JQ1 treatment significantly decreased the binding of eIF4E promoter with BRD4. Finally, JQ1 inhibited the growth of H460 tumors in parallel with downregulated eIF4E mRNA and protein levels in a xenograft mouse model. These findings suggest that inhibition of BET by JQ1, I-BET151, or BRD4 silencing suppresses the growth of non-small cell lung carcinoma through decreasing eIF4E transcription and subsequent mRNA and protein expression. Considering that BET regulates gene transcription epigenetically, our findings not only reveal a new mechanism of BET-regulated eIF4E in lung cancer, but also indicate a novel strategy by co-targeting eIF4E for enhancing BET-targeted cancer therapy.
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Affiliation(s)
- Zhongyuan Gao
- a Department of Pharmacology , Nanjing Medical University , Nanjing , Jiangsu Province , China
| | - Ting Yuan
- b Department of Pain Management , The Second Affiliated Hospital, Nanjing Medical University , Nanjing , Jiangsu Province , China
| | - Xiao Zhou
- b Department of Pain Management , The Second Affiliated Hospital, Nanjing Medical University , Nanjing , Jiangsu Province , China
| | - Ping Ni
- a Department of Pharmacology , Nanjing Medical University , Nanjing , Jiangsu Province , China
| | - Geng Sun
- a Department of Pharmacology , Nanjing Medical University , Nanjing , Jiangsu Province , China
| | - Ping Li
- a Department of Pharmacology , Nanjing Medical University , Nanjing , Jiangsu Province , China
| | - Zhixiang Cheng
- b Department of Pain Management , The Second Affiliated Hospital, Nanjing Medical University , Nanjing , Jiangsu Province , China
| | - Xuerong Wang
- a Department of Pharmacology , Nanjing Medical University , Nanjing , Jiangsu Province , China.,c Key Laboratory of Human Functional Genomics of Jiangsu Province, Nanjing Medical University , Nanjing , Jiangsu Province , China
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Epstein-Barr Virus Protein EB2 Stimulates Translation Initiation of mRNAs through Direct Interactions with both Poly(A)-Binding Protein and Eukaryotic Initiation Factor 4G. J Virol 2018; 92:JVI.01917-17. [PMID: 29142127 DOI: 10.1128/jvi.01917-17] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2017] [Accepted: 11/06/2017] [Indexed: 02/06/2023] Open
Abstract
Epstein-Barr virus (EBV) expresses several mRNAs produced from intronless genes that could potentially be unfavorably translated compared to cellular spliced mRNAs. To overcome this situation, the virus encodes an RNA-binding protein (RBP) called EB2, which was previously found to both facilitate the export of nuclear mRNAs and increase their translational yield. Here, we show that EB2 binds both nuclear and cytoplasmic cap-binding complexes (CBC and eukaryotic initiation factor 4F [eIF4F], respectively) as well as the poly(A)-binding protein (PABP) to enhance translation initiation of a given messenger ribonucleoparticle (mRNP). Interestingly, such an effect can be obtained only if EB2 is initially bound to the native mRNPs in the nucleus. We also demonstrate that the EB2-eIF4F-PABP association renders translation of these mRNPs less sensitive to translation initiation inhibitors. Taken together, our data suggest that EB2 binds and stabilizes cap-binding complexes in order to increase mRNP translation and furthermore demonstrate the importance of the mRNP assembly process in the nucleus to promote protein synthesis in the cytoplasm.IMPORTANCE Most herpesvirus early and late genes are devoid of introns. However, it is now well documented that mRNA splicing facilitates recruitment on the mRNAs of cellular factors involved in nuclear mRNA export and translation efficiency. To overcome the absence of splicing of herpesvirus mRNAs, a viral protein, EB2 in the case of Epstein-Barr virus, is produced to facilitate the cytoplasmic accumulation of viral mRNAs. Although we previously showed that EB2 also specifically enhances translation of its target mRNAs, the mechanism was unknown. Here, we show that EB2 first is recruited to the mRNA cap structure in the nucleus and then interacts with the proteins eIF4G and PABP to enhance the initiation step of translation.
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Su MG, Weng JTY, Hsu JBK, Huang KY, Chi YH, Lee TY. Investigation and identification of functional post-translational modification sites associated with drug binding and protein-protein interactions. BMC SYSTEMS BIOLOGY 2017; 11:132. [PMID: 29322920 PMCID: PMC5763307 DOI: 10.1186/s12918-017-0506-1] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Background Protein post-translational modification (PTM) plays an essential role in various cellular processes that modulates the physical and chemical properties, folding, conformation, stability and activity of proteins, thereby modifying the functions of proteins. The improved throughput of mass spectrometry (MS) or MS/MS technology has not only brought about a surge in proteome-scale studies, but also contributed to a fruitful list of identified PTMs. However, with the increase in the number of identified PTMs, perhaps the more crucial question is what kind of biological mechanisms these PTMs are involved in. This is particularly important in light of the fact that most protein-based pharmaceuticals deliver their therapeutic effects through some form of PTM. Yet, our understanding is still limited with respect to the local effects and frequency of PTM sites near pharmaceutical binding sites and the interfaces of protein-protein interaction (PPI). Understanding PTM’s function is critical to our ability to manipulate the biological mechanisms of protein. Results In this study, to understand the regulation of protein functions by PTMs, we mapped 25,835 PTM sites to proteins with available three-dimensional (3D) structural information in the Protein Data Bank (PDB), including 1785 modified PTM sites on the 3D structure. Based on the acquired structural PTM sites, we proposed to use five properties for the structural characterization of PTM substrate sites: the spatial composition of amino acids, residues and side-chain orientations surrounding the PTM substrate sites, as well as the secondary structure, division of acidity and alkaline residues, and solvent-accessible surface area. We further mapped the structural PTM sites to the structures of drug binding and PPI sites, identifying a total of 1917 PTM sites that may affect PPI and 3951 PTM sites associated with drug-target binding. An integrated analytical platform (CruxPTM), with a variety of methods and online molecular docking tools for exploring the structural characteristics of PTMs, is presented. In addition, all tertiary structures of PTM sites on proteins can be visualized using the JSmol program. Conclusion Resolving the function of PTM sites is important for understanding the role that proteins play in biological mechanisms. Our work attempted to delineate the structural correlation between PTM sites and PPI or drug-target binding. CurxPTM could help scientists narrow the scope of their PTM research and enhance the efficiency of PTM identification in the face of big proteome data. CruxPTM is now available at http://csb.cse.yzu.edu.tw/CruxPTM/. Electronic supplementary material The online version of this article (10.1186/s12918-017-0506-1) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Min-Gang Su
- Department of Computer Science and Engineering, Yuan Ze University, Taoyuan, 320, Taiwan
| | - Julia Tzu-Ya Weng
- Department of Computer Science and Engineering, Yuan Ze University, Taoyuan, 320, Taiwan
| | - Justin Bo-Kai Hsu
- Department of Medical Research, Taipei Medical University Hospital, Taipei, 110, Taiwan
| | - Kai-Yao Huang
- Department of Computer Science and Engineering, Yuan Ze University, Taoyuan, 320, Taiwan.,Department of Medical Research, Hsinchu Mackay Memorial Hospital, Hsinchu City, 300, Taiwan
| | - Yu-Hsiang Chi
- Department of Computer Science and Engineering, Yuan Ze University, Taoyuan, 320, Taiwan
| | - Tzong-Yi Lee
- Department of Computer Science and Engineering, Yuan Ze University, Taoyuan, 320, Taiwan. .,Innovation Center for Big Data and Digital Convergence, Yuan Ze University, Taoyuan, 320, Taiwan.
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34
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Geter PA, Ernlund AW, Bakogianni S, Alard A, Arju R, Giashuddin S, Gadi A, Bromberg J, Schneider RJ. Hyperactive mTOR and MNK1 phosphorylation of eIF4E confer tamoxifen resistance and estrogen independence through selective mRNA translation reprogramming. Genes Dev 2017; 31:2235-2249. [PMID: 29269484 PMCID: PMC5769768 DOI: 10.1101/gad.305631.117] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2017] [Accepted: 11/20/2017] [Indexed: 01/04/2023]
Abstract
Geter et al. show that tamoxifen resistance involves selective mRNA translational reprogramming to an anti-estrogen state by Runx2 and other mRNAs. Tamoxifen-resistant translational reprogramming is shown to be mediated by increased expression of eIF4E and its increased availability by hyperactive mTOR and to require phosphorylation of eIF4E at Ser209 by increased MNK activity. The majority of breast cancers expresses the estrogen receptor (ER+) and is treated with anti-estrogen therapies, particularly tamoxifen in premenopausal women. However, tamoxifen resistance is responsible for a large proportion of breast cancer deaths. Using small molecule inhibitors, phospho-mimetic proteins, tamoxifen-sensitive and tamoxifen-resistant breast cancer cells, a tamoxifen-resistant patient-derived xenograft model, patient tumor tissues, and genome-wide transcription and translation studies, we show that tamoxifen resistance involves selective mRNA translational reprogramming to an anti-estrogen state by Runx2 and other mRNAs. Tamoxifen-resistant translational reprogramming is shown to be mediated by increased expression of eIF4E and its increased availability by hyperactive mTOR and to require phosphorylation of eIF4E at Ser209 by increased MNK activity. Resensitization to tamoxifen is restored only by reducing eIF4E expression or mTOR activity and also blocking MNK1 phosphorylation of eIF4E. mRNAs specifically translationally up-regulated with tamoxifen resistance include Runx2, which inhibits ER signaling and estrogen responses and promotes breast cancer metastasis. Silencing Runx2 significantly restores tamoxifen sensitivity. Tamoxifen-resistant but not tamoxifen-sensitive patient ER+ breast cancer specimens also demonstrate strongly increased MNK phosphorylation of eIF4E. eIF4E levels, availability, and phosphorylation therefore promote tamoxifen resistance in ER+ breast cancer through selective mRNA translational reprogramming
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Affiliation(s)
- Phillip A Geter
- Department of Microbiology, Alexandria Center for Life Science, New York University School of Medicine, New York, New York 10016, USA
| | - Amanda W Ernlund
- Department of Microbiology, Alexandria Center for Life Science, New York University School of Medicine, New York, New York 10016, USA
| | - Sofia Bakogianni
- Department of Microbiology, Alexandria Center for Life Science, New York University School of Medicine, New York, New York 10016, USA
| | - Amandine Alard
- Department of Microbiology, Alexandria Center for Life Science, New York University School of Medicine, New York, New York 10016, USA
| | - Rezina Arju
- Department of Microbiology, Alexandria Center for Life Science, New York University School of Medicine, New York, New York 10016, USA
| | - Shah Giashuddin
- New York Presbyterian-Brooklyn Methodist Hospital, Brooklyn, New York 11215, USA
| | - Abhilash Gadi
- Department of Microbiology, Alexandria Center for Life Science, New York University School of Medicine, New York, New York 10016, USA
| | - Jacqueline Bromberg
- Memorial Sloan Kettering Cancer Institute, New York, New York 10016 USA.,Perlmutter Cancer Center, New York University School of Medicine, New York, New York 10016 USA
| | - Robert J Schneider
- Department of Microbiology, Alexandria Center for Life Science, New York University School of Medicine, New York, New York 10016, USA.,Memorial Sloan Kettering Cancer Institute, New York, New York 10016 USA.,Perlmutter Cancer Center, New York University School of Medicine, New York, New York 10016 USA
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35
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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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Svitkin YV, Cheng YM, Chakraborty T, Presnyak V, John M, Sonenberg N. N1-methyl-pseudouridine in mRNA enhances translation through eIF2α-dependent and independent mechanisms by increasing ribosome density. Nucleic Acids Res 2017; 45:6023-6036. [PMID: 28334758 PMCID: PMC5449617 DOI: 10.1093/nar/gkx135] [Citation(s) in RCA: 149] [Impact Index Per Article: 21.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2017] [Accepted: 02/20/2017] [Indexed: 12/21/2022] Open
Abstract
Certain chemical modifications confer increased stability and low immunogenicity to in vitro transcribed mRNAs, thereby facilitating expression of therapeutically important proteins. Here, we demonstrate that N1-methyl-pseudouridine (N1mΨ) outperforms several other nucleoside modifications and their combinations in terms of translation capacity. Through extensive analysis of various modified transcripts in cell-free translation systems, we deconvolute the different components of the effect on protein expression independent of mRNA stability mechanisms. We show that in addition to turning off the immune/eIF2α phosphorylation-dependent inhibition of translation, the incorporated N1mΨ nucleotides dramatically alter the dynamics of the translation process by increasing ribosome pausing and density on the mRNA. Our results indicate that the increased ribosome loading of modified mRNAs renders them more permissive for initiation by favoring either ribosome recycling on the same mRNA or de novo ribosome recruitment.
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Affiliation(s)
- Yuri V Svitkin
- Department of Biochemistry, McGill University, Montréal, Québec H3A 1A3, Canada.,Rosalind and Morris Goodman Cancer Research Centre, Montréal, Québec H3A 1A3, Canada
| | | | | | | | | | - Nahum Sonenberg
- Department of Biochemistry, McGill University, Montréal, Québec H3A 1A3, Canada.,Rosalind and Morris Goodman Cancer Research Centre, Montréal, Québec H3A 1A3, Canada
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37
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Hou JN, Chen TH, Chiang YH, Peng JY, Yang TH, Cheng CC, Sofiyatun E, Chiu CH, Chiang-Ni C, Chen WJ. PERK Signal-Modulated Protein Translation Promotes the Survivability of Dengue 2 Virus-Infected Mosquito Cells and Extends Viral Replication. Viruses 2017; 9:v9090262. [PMID: 28930151 PMCID: PMC5618028 DOI: 10.3390/v9090262] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2017] [Revised: 09/15/2017] [Accepted: 09/17/2017] [Indexed: 01/03/2023] Open
Abstract
Survival of mosquitoes from dengue virus (DENV) infection is a prerequisite of viral transmission to the host. This study aimed to see how mosquito cells can survive the infection during prosperous replication of the virus. In C6/36 cells, global protein translation was shut down after infection by DENV type 2 (DENV2). However, it returned to a normal level when infected cells were treated with an inhibitor of the protein kinase RNA (PKR)-like ER kinase (PERK) signaling pathway. Based on a 7-Methylguanosine 5′-triphosphate (m7GTP) pull-down assay, the eukaryotic translation initiation factor 4F (eIF4F) complex was also identified in DENV2-infected cells. This suggests that most mosquito proteins are synthesized via canonical cap-dependent translation. When the PERK signal pathway was inhibited, both accumulation of reactive oxygen species and changes in the mitochondrial membrane potential increased. This suggested that ER stress response was alleviated through the PERK-mediated shutdown of global proteins in DENV2-infected C6/36 cells. In the meantime, the activities of caspases-9 and -3 and the apoptosis-related cell death rate increased in C6/36 cells with PERK inhibition. This reflected that the PERK-signaling pathway is involved in determining cell survival, presumably by reducing DENV2-induced ER stress. Looking at the PERK downstream target, α-subunit of eukaryotic initiation factor 2 (eIF2α), an increased phosphorylation status was only shown in infected C6/36 cells. This indicated that recruitment of ribosome binding to the mRNA 5′-cap structure could have been impaired in cap-dependent translation. It turned out that shutdown of cellular protein translation resulted in a pro-survival effect on mosquito cells in response to DENV2 infection. As synthesis of viral proteins was not affected by the PERK signal pathway, an alternate mode other than cap-dependent translation may be utilized. This finding provides insights into elucidating how the PERK signal pathway modulates dynamic translation of proteins and helps mosquito cells survive continuous replication of the DENV2. It was ecologically important for virus amplification in mosquitoes and transmission to humans.
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Affiliation(s)
- Jiun-Nan Hou
- Graduate Institute of Biomedical Sciences, Chang Gung University, Kwei-San, Tao-Yuan 33332, Taiwan.
| | - Tien-Huang Chen
- Department of Public Health and Parasitology, Chang Gung University, Kwei-San, Tao-Yuan 33332, Taiwan.
| | - Yi-Hsuan Chiang
- Department of Public Health and Parasitology, Chang Gung University, Kwei-San, Tao-Yuan 33332, Taiwan.
| | - Jing-Yun Peng
- Graduate Institute of Biomedical Sciences, Chang Gung University, Kwei-San, Tao-Yuan 33332, Taiwan.
| | - Tsong-Han Yang
- Department of Public Health and Parasitology, Chang Gung University, Kwei-San, Tao-Yuan 33332, Taiwan.
| | - Chih-Chieh Cheng
- Graduate Institute of Biomedical Sciences, Chang Gung University, Kwei-San, Tao-Yuan 33332, Taiwan.
| | - Eny Sofiyatun
- Graduate Institute of Biomedical Sciences, Chang Gung University, Kwei-San, Tao-Yuan 33332, Taiwan.
- Environmental Health Department, Banjarnegara Polytechnic, Central Java 53482, Indonesia.
| | - Cheng-Hsun Chiu
- Molecular Infectious Disease Research Center, Chang Gung Memorial Hospital, Kwei-San, Tao-Yuan 33332, Taiwan.
- Division of Pediatric Infectious Diseases, Department of Pediatrics, Chang Gung Children's Hospital, Chang Gung University College of Medicine, Kwei-San, Tao-Yuan 33305, Taiwan.
| | - Chuan Chiang-Ni
- Graduate Institute of Biomedical Sciences, Chang Gung University, Kwei-San, Tao-Yuan 33332, Taiwan.
- Department of Microbiology and Immunology, Chang Gung University, Kwei-San, Tao-Yuan 33332, Taiwan.
| | - Wei-June Chen
- Graduate Institute of Biomedical Sciences, Chang Gung University, Kwei-San, Tao-Yuan 33332, Taiwan.
- Department of Public Health and Parasitology, Chang Gung University, Kwei-San, Tao-Yuan 33332, Taiwan.
- Molecular Infectious Disease Research Center, Chang Gung Memorial Hospital, Kwei-San, Tao-Yuan 33332, Taiwan.
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38
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Cellular cap-binding protein, eIF4E, promotes picornavirus genome restructuring and translation. Proc Natl Acad Sci U S A 2017; 114:9611-9616. [PMID: 28827335 DOI: 10.1073/pnas.1704390114] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Picornaviruses use internal ribosome entry sites (IRESs) to translate their genomes into protein. A typical feature of these IRESs is their ability to bind directly to the eukaryotic initiation factor (eIF) 4G component of the eIF4F cap-binding complex. Remarkably, the hepatitis A virus (HAV) IRES requires eIF4E for its translation, but no mechanism has been proposed to explain this. Here we demonstrate that eIF4E regulates HAV IRES-mediated translation by two distinct mechanisms. First, eIF4E binding to eIF4G generates a high-affinity binding conformation of the eIF4F complex for the IRES. Second, eIF4E binding to eIF4G strongly stimulates the rate of duplex unwinding by eIF4A on the IRES. Our data also reveal that eIF4E promotes eIF4F binding and increases the rate of restructuring of the poliovirus (PV) IRES. This provides a mechanism to explain why PV IRES-mediated translation is stimulated by eIF4E availability in nuclease-treated cell-free extracts. Using a PV replicon and purified virion RNA, we also show that eIF4E promotes the rate of eIF4G cleavage by the 2A protease. Finally, we show that cleavage of eIF4G by the poliovirus 2A protease generates a high-affinity IRES binding truncation of eIF4G that stimulates eIF4A duplex unwinding independently of eIF4E. Therefore, our data reveal how picornavirus IRESs use eIF4E-dependent and -independent mechanisms to promote their translation.
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39
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Yamamoto H, Unbehaun A, Spahn CMT. Ribosomal Chamber Music: Toward an Understanding of IRES Mechanisms. Trends Biochem Sci 2017; 42:655-668. [PMID: 28684008 DOI: 10.1016/j.tibs.2017.06.002] [Citation(s) in RCA: 58] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2017] [Revised: 06/05/2017] [Accepted: 06/06/2017] [Indexed: 12/31/2022]
Abstract
Internal initiation is a 5'-end-independent mode of translation initiation engaged by many virus- and putatively some cell-encoded templates. Internal initiation is facilitated by specific RNA tertiary folds, called internal ribosomal entry sites (IRESs), in the 5' untranslated region (UTR) of the respective transcripts. In this review we discuss recent structural insight into how established IRESs first capture and then manipulate the eukaryotic translation machinery through non-canonical interactions and by guiding the intrinsic conformational flexibility of the eukaryotic ribosome. Because IRESs operate with reduced complexity and constitute minimal systems of initiation, comparison with canonical initiation may allow common mechanistic principles of the ribosome to be delineated.
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Affiliation(s)
- Hiroshi Yamamoto
- Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Institut für Medizinische Physik und Biophysik, Charitéplatz 1, 10117 Berlin, Germany
| | - Anett Unbehaun
- Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Institut für Medizinische Physik und Biophysik, Charitéplatz 1, 10117 Berlin, Germany
| | - Christian M T Spahn
- Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Institut für Medizinische Physik und Biophysik, Charitéplatz 1, 10117 Berlin, Germany.
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40
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Wu S, Yang L, Wu D, Gao Z, Li P, Huang W, Wang X. AEG-1 induces gastric cancer metastasis by upregulation of eIF4E expression. J Cell Mol Med 2017; 21:3481-3493. [PMID: 28661037 PMCID: PMC5706588 DOI: 10.1111/jcmm.13258] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2017] [Accepted: 04/26/2017] [Indexed: 12/19/2022] Open
Abstract
Gastric cancer is the third leading cause of cancer-related deaths worldwide, and patients with lymph node, peritoneal and distant metastasis have a poor prognosis. Overexpression of Astrocyte-elevated gene-1 (AEG-1) has been reported to be correlated with the progression and metastasis of gastric cancer. However, its mechanisms are quite unclear. In this study, we found that elevated expression of AEG-1 was correlated with metastasis in human gastric cancer tissues. Moreover, gain- or loss-of-function of AEG-1, respectively, promoted or suppressed epithelial-mesenchymal transition (EMT), migration and invasion of gastric cancer cells. AEG-1 positively regulated eIF4E, MMP-9 and Twist expression. Manipulating eIF4E expression by transfection of overexpression constructs or siRNAs partially eliminated AEG-1-regulated EMT, cell migration and invasion. In addition, overexpression or knockdown of eIF4E promoted or suppressed EMT, cell migration and invasion in parallel with upregulation of MMP-9 and Twist expression, while manipulating eIF4E expression partially abrogated AEG-1-induced MMP-9 and Twist. Finally, silencing of AEG-1 expression not only inhibited tumour growth in parallel with downregulation of eIF4E, MMP-9 and Twist expression in a xenograft nude mouse model, but also suppressed lymph node and peritoneal metastasis of gastric cancer in an orthotopic nude mouse model. These findings suggest that AEG-1 promotes gastric cancer metastasis through upregulation of eIF4E-mediated MMP-9 and Twist, which provides new diagnostic markers and therapeutic targets for cancer metastasis.
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Affiliation(s)
- Shengjie Wu
- Department of Pharmacology, Nanjing Medical University, Nanjing, Jiangsu, China
| | - Li Yang
- Department of General Surgery, Medical Oncology and Pathology, the First Affiliated Hospital of Nanjing Medical University, Nanjing, Jiangsu, China
| | - Dandan Wu
- Department of Pharmacology, Nanjing Medical University, Nanjing, Jiangsu, China.,Department of Basic Medicine, Kangda College of Nanjing Medical University, Lianyungang, Jiangsu, China
| | - Zhongyuan Gao
- Department of Pharmacology, Nanjing Medical University, Nanjing, Jiangsu, China
| | - Ping Li
- Department of Pharmacology, Nanjing Medical University, Nanjing, Jiangsu, China
| | - Wenbin Huang
- Department of Pathology, Nanjing Medical University Affiliated Nanjing Hospital (Nanjing First Hospital), Nanjing, Jiangsu, China
| | - Xuerong Wang
- Department of Pharmacology, Nanjing Medical University, Nanjing, Jiangsu, China
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41
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Kratzke RA. Targeting eukaryotic protein translation in mesothelioma. Transl Lung Cancer Res 2017; 6:343-349. [PMID: 28713679 PMCID: PMC5504115 DOI: 10.21037/tlcr.2017.06.07] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2017] [Accepted: 05/29/2017] [Indexed: 12/29/2022]
Abstract
The default mechanism for protein translation in eukaryotes involves activation of the eIF4 complex at the 5' end of mRNA. This activity is upregulated in cancers, resulting in the expression of a variety of proteins necessary for the development and maintenance of the neoplastic state. Not surprisingly, mesothelioma demonstrates this same reliance on activation of 5' cap mediated translation. Efforts are ongoing to target and exploit our knowledge of this key molecular switch for cancer therapy. Agents targeting the critical eIF4E cap binding protein, disruption of the eIF4 complex, and exploitation for oncolytic virotherapy are some of the important areas of current research in mesothelioma protein translational research.
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Affiliation(s)
- Robert A Kratzke
- Division of Hematology-Oncology Transplant, University of Minnesota, Minneapolis, MN, USA
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42
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Terenin IM, Smirnova VV, Andreev DE, Dmitriev SE, Shatsky IN. A researcher's guide to the galaxy of IRESs. Cell Mol Life Sci 2017; 74:1431-1455. [PMID: 27853833 PMCID: PMC11107752 DOI: 10.1007/s00018-016-2409-5] [Citation(s) in RCA: 38] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2016] [Revised: 11/01/2016] [Accepted: 11/02/2016] [Indexed: 12/25/2022]
Abstract
The idea of internal initiation is frequently exploited to explain the peculiar translation properties or unusual features of some eukaryotic mRNAs. In this review, we summarize the methods and arguments most commonly used to address cases of translation governed by internal ribosome entry sites (IRESs). Frequent mistakes are revealed. We explain why "cap-independent" does not readily mean "IRES-dependent" and why the presence of a long and highly structured 5' untranslated region (5'UTR) or translation under stress conditions cannot be regarded as an argument for appealing to internal initiation. We carefully describe the known pitfalls and limitations of the bicistronic assay and artefacts of some commercially available in vitro translation systems. We explain why plasmid DNA transfection should not be used in IRES studies and which control experiments are unavoidable if someone decides to use it anyway. Finally, we propose a workflow for the validation of IRES activity, including fast and simple experiments based on a single genetic construct with a sequence of interest.
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Affiliation(s)
- Ilya M Terenin
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, 119234, Russia.
- Engelhardt Institute of Molecular Biology, Russian Academy of Sciences, Moscow, 119334, Russia.
| | - Victoria V Smirnova
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, 119234, Russia
- Department of Bioengineering and Bioinformatics, Lomonosov Moscow State University, Moscow, 119234, Russia
| | - Dmitri E Andreev
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, 119234, Russia
| | - Sergey E Dmitriev
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, 119234, Russia
- Engelhardt Institute of Molecular Biology, Russian Academy of Sciences, Moscow, 119334, Russia
- Department of Biochemistry, Biological Faculty, Lomonosov Moscow State University, Moscow, 119234, Russia
| | - Ivan N Shatsky
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, 119234, Russia.
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43
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Khurana R, Ranches G, Schafferer S, Lukasser M, Rudnicki M, Mayer G, Hüttenhofer A. Identification of urinary exosomal noncoding RNAs as novel biomarkers in chronic kidney disease. RNA (NEW YORK, N.Y.) 2017; 23:142-152. [PMID: 27872161 PMCID: PMC5238789 DOI: 10.1261/rna.058834.116] [Citation(s) in RCA: 101] [Impact Index Per Article: 14.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/23/2016] [Accepted: 11/08/2016] [Indexed: 06/06/2023]
Abstract
In chronic kidney disease (CKD), the decline in the glomerular filtration rate is associated with increased morbidity and mortality and thus poses a major challenge for healthcare systems. While the contribution of tissue-derived miRNAs and mRNAs to CKD progression has been extensively studied, little is known about the role of urinary exosomes and their association with CKD. Exosomes are small, membrane-derived endocytic vesicles that contribute to cell-to-cell communication and are present in various body fluids, such as blood or urine. Next-generation sequencing approaches have revealed that exosomes are enriched in noncoding RNAs and thus exhibit great potential for sensitive nucleic acid biomarkers in various human diseases. Therefore, in this study we aimed to identify urinary exosomal ncRNAs as novel biomarkers for diagnosis of CKD. Since up to now most approaches have focused on the class of miRNAs, we extended our analysis to several other noncoding RNA classes, such as tRNAs, tRNA fragments (tRFs), mitochondrial tRNAs, or lincRNAs. For their computational identification from RNA-seq data, we developed a novel computational pipeline, designated as ncRNASeqScan. By these analyses, in CKD patients we identified 30 differentially expressed ncRNAs, derived from urinary exosomes, as suitable biomarkers for early diagnosis. Thereby, miRNA-181a appeared as the most robust and stable potential biomarker, being significantly decreased by about 200-fold in exosomes of CKD patients compared to healthy controls. Using a cell culture system for CKD indicated that urinary exosomes might indeed originate from renal proximal tubular epithelial cells.
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MESH Headings
- Adult
- Aged
- Aged, 80 and over
- Biomarkers/urine
- Case-Control Studies
- Early Diagnosis
- Epithelial Cells/metabolism
- Epithelial Cells/pathology
- Exosomes/chemistry
- Exosomes/metabolism
- Female
- Glomerular Filtration Rate
- High-Throughput Nucleotide Sequencing
- Humans
- Kidney Tubules, Proximal/metabolism
- Kidney Tubules, Proximal/pathology
- Male
- MicroRNAs/urine
- Middle Aged
- Molecular Sequence Annotation
- RNA/urine
- RNA, Long Noncoding/urine
- RNA, Mitochondrial
- RNA, Transfer/urine
- Renal Insufficiency, Chronic/diagnosis
- Renal Insufficiency, Chronic/pathology
- Renal Insufficiency, Chronic/urine
- Sequence Analysis, RNA
- Severity of Illness Index
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Affiliation(s)
- Rimpi Khurana
- Division of Genomics and RNomics, Biocenter, Medical University Innsbruck, 6020 Innsbruck, Austria
| | - Glory Ranches
- Division of Genomics and RNomics, Biocenter, Medical University Innsbruck, 6020 Innsbruck, Austria
| | - Simon Schafferer
- Division of Genomics and RNomics, Biocenter, Medical University Innsbruck, 6020 Innsbruck, Austria
| | - Melanie Lukasser
- Division of Genomics and RNomics, Biocenter, Medical University Innsbruck, 6020 Innsbruck, Austria
| | - Michael Rudnicki
- Department of Internal Medicine IV, Nephrology and Hypertension, Medical University Innsbruck, 6020 Innsbruck, Austria
| | - Gert Mayer
- Department of Internal Medicine IV, Nephrology and Hypertension, Medical University Innsbruck, 6020 Innsbruck, Austria
| | - Alexander Hüttenhofer
- Division of Genomics and RNomics, Biocenter, Medical University Innsbruck, 6020 Innsbruck, Austria
- i-med GenomeSeq Core, 6020 Innsbruck, Austria
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Kanda T, Ozawa M, Tsukiyama-Kohara K. IRES-mediated translation of foot-and-mouth disease virus (FMDV) in cultured cells derived from FMDV-susceptible and -insusceptible animals. BMC Vet Res 2016; 12:66. [PMID: 27036295 PMCID: PMC4815274 DOI: 10.1186/s12917-016-0694-8] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2015] [Accepted: 03/23/2016] [Indexed: 01/17/2023] Open
Abstract
BACKGROUND Foot-and-mouth disease virus (FMDV) possess a positive sense, single stranded RNA genome. Internal ribosomal entry site (IRES) element exists within its 5' untranslated region (5'UTR) of the viral RNA. Translation of the viral RNA is initiated by internal entry of the 40S ribosome within the IRES element. This process is facilitated by cellular factors known as IRES trans-acting factors (ITAFs). Foot-and-mouth disease (FMD) is host-restricted disease for cloven-hoofed animals such as cattle and pigs, but the factors determining the host range have not been identified yet. Although, ITAFs are known to promote IRES-mediated translation, these findings were confirmed only in cells derived from FMDV-insusceptible animals so far. We evaluated and compared the IRES-mediated translation activities among cell lines derived from four different animal species using bicistronic luciferase reporter plasmid, which possesses an FMDV-IRES element between Renilla and Firefly luciferase genes. Furthermore, we analyzed the effect of the cellular factors on IRES-mediated translation by silencing the cellular factors using siRNA in both FMDV-susceptible and -insusceptible animal cells. RESULTS Our data indicated that IRES-mediated translational activity was not linked to FMDV host range. ITAF45 promoted IRES-mediated translation in all cell lines, and the effects of poly-pyrimidine tract binding protein (PTB) and eukaryotic initiation factor 4E-binding protein 1 (4E-BP1) were observed only in FMDV-susceptible cells. Thus, PTB and 4E-BP1 may influence the host range of FMDV. CONCLUSIONS IRES-mediated translation activity of FMDV was not predictive of its host range. ITAF45 promoted IRES-mediated translation in all cells, and the effects of PTB and 4E-BP1 were observed only in FMDV-susceptible cells.
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Affiliation(s)
- Takehiro Kanda
- Department of Animal Hygiene, Joint Facility of Veterinary Medicine, Kagoshima University, Kagoshima, Kagoshima, Japan
| | - Makoto Ozawa
- Department of Animal Hygiene, Joint Facility of Veterinary Medicine, Kagoshima University, Kagoshima, Kagoshima, Japan.,Transboundary Animal Disease Center, Joint Facility of Veterinary Medicine, Kagoshima University, Kagoshima, Kagoshima, Japan
| | - Kyoko Tsukiyama-Kohara
- Department of Animal Hygiene, Joint Facility of Veterinary Medicine, Kagoshima University, Kagoshima, Kagoshima, Japan. .,Transboundary Animal Disease Center, Joint Facility of Veterinary Medicine, Kagoshima University, Kagoshima, Kagoshima, Japan.
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Smirnova VV, Terenin IM, Khutornenko AA, Andreev DE, Dmitriev SE, Shatsky IN. Does HIV-1 mRNA 5'-untranslated region bear an internal ribosome entry site? Biochimie 2016; 121:228-37. [DOI: 10.1016/j.biochi.2015.12.004] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2015] [Accepted: 12/11/2015] [Indexed: 12/18/2022]
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Eukaryotic initiation factor 4E-binding protein 1 (4E-BP1): a master regulator of mRNA translation involved in tumorigenesis. Oncogene 2016; 35:4675-88. [DOI: 10.1038/onc.2015.515] [Citation(s) in RCA: 80] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2015] [Revised: 12/11/2015] [Accepted: 12/11/2015] [Indexed: 01/17/2023]
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Komar AA, Hatzoglou M. Exploring Internal Ribosome Entry Sites as Therapeutic Targets. Front Oncol 2015; 5:233. [PMID: 26539410 PMCID: PMC4611151 DOI: 10.3389/fonc.2015.00233] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2015] [Accepted: 10/05/2015] [Indexed: 12/12/2022] Open
Abstract
Initiation of eukaryotic mRNA translation may proceed via several different routes, each requiring a different subset of factors and relying on different and specific interactions between the mRNA and the ribosome. Two modes predominate: (i) so-called cap-dependent initiation, which requires all canonical initiation factors and is responsible for about 95–97% of all initiation events in eukaryotic cells; and (ii) cap-independent internal initiation, which requires a reduced subset of initiation factors and accounts for up to 5% of the remaining initiation events. Internal initiation relies on the presence of so-called internal ribosome entry site (IRES) elements in the 5′ UTRs of some viral and cellular mRNAs. These elements (often possessing complex secondary and tertiary structures) promote efficient interaction of the mRNA with the 40S ribosome and allow for internal ribosome entry. Internal initiation of translation of specific mRNAs may contribute to development of severe disease and pathological states, such as hepatitis C and cancer. Therefore, this cellular mechanism represents an attractive target for pharmacological modulation. The purpose of this review is to provide insight into current strategies used to target viral and cellular IRESs and discuss the physiological consequences (and potential therapeutic implications) of abrogation/modulation of IRES-mediated translation.
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Affiliation(s)
- Anton A Komar
- Department of Biological, Geological and Environmental Sciences, Center for Gene Regulation in Health and Disease, Cleveland State University , Cleveland, OH , USA
| | - Maria Hatzoglou
- Department of Pharmacology, School of Medicine, Case Western Reserve University , Cleveland, OH , USA
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Abstract
The original purification of the heterotrimeric eIF4F was published over 30 years ago (Grifo, J. A., Tahara, S. M., Morgan, M. A., Shatkin, A. J., and Merrick, W. C. (1983) J. Biol. Chem. 258, 5804-5810). Since that time, numerous studies have been performed with the three proteins specifically required for the translation initiation of natural mRNAs, eIF4A, eIF4B, and eIF4F. These have involved enzymatic and structural studies of the proteins and a number of site-directed mutagenesis studies. The regulation of translation exhibited through the mammalian target of rapamycin (mTOR) pathway is predominately seen as the phosphorylation of 4E-BP, an inhibitor of protein synthesis that functions by binding to the cap binding subunit of eIF4F (eIF4E). A hypothesis that requires the disassembly of eIF4F during translation initiation to yield free subunits (eIF4A, eIF4E, and eIF4G) is presented.
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Affiliation(s)
- William C Merrick
- From the Department of Biochemistry, School of Medicine, Case Western Reserve University, Cleveland, Ohio 44106-4935
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49
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Tsai BP, Jimenez J, Lim S, Fitzgerald KD, Zhang M, Chuah CTH, Axelrod H, Wilson L, Ong ST, Semler BL, Waterman ML. A novel Bcr-Abl-mTOR-eIF4A axis regulates IRES-mediated translation of LEF-1. Open Biol 2015; 4:140180. [PMID: 25392452 PMCID: PMC4248067 DOI: 10.1098/rsob.140180] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
Internal ribosome entry sites (IRESs) in cellular mRNAs direct expression of growth-promoting factors through an alternative translation mechanism that has yet to be fully defined. Lymphoid enhancer factor-1 (LEF-1), a Wnt-mediating transcription factor important for cell survival and metastasis in cancer, is produced via IRES-directed translation, and its mRNA is frequently upregulated in malignancies, including chronic myeloid leukaemia (CML). In this study, we determined that LEF1 expression is regulated by Bcr-Abl, the oncogenic protein that drives haematopoietic cell transformation to CML. We have previously shown that the LEF1 5′ untranslated region recruits a complex of proteins to its IRES, including the translation initiation factor eIF4A. In this report, we use two small molecule inhibitors, PP242 (dual mTOR (mammalian target of rapamycin) kinase inhibitor) and hippuristanol (eIF4A inhibitor), to define IRES regulation via a Bcr-Abl–mTOR–eIF4A axis in CML cell lines and primary patient leukaemias. We found that LEF1 and other IRESs are uniquely sensitive to the activities of Bcr-Abl/mTOR. Most notably, we discovered that eIF4A, an RNA helicase, elicits potent non-canonical effects on the LEF1 IRES. Hippuristanol inhibition of eIF4A stalls translation of IRES mRNA and triggers dissociation from polyribosomes. We propose that a combination drug strategy which targets mTOR and IRES-driven translation disrupts key factors that contribute to growth and proliferation in CML.
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Affiliation(s)
- Becky Pinjou Tsai
- Department of Microbiology and Molecular Genetics, School of Medicine, University of California, Irvine, CA, USA
| | - Judith Jimenez
- Department of Microbiology and Molecular Genetics, School of Medicine, University of California, Irvine, CA, USA
| | - Sharon Lim
- Cancer and Stem Cell Biology Signature Research Program, Duke-NUS Graduate Medical School, Singapore Department of Haematology, Singapore General Hospital, Singapore
| | - Kerry D Fitzgerald
- Department of Microbiology and Molecular Genetics, School of Medicine, University of California, Irvine, CA, USA
| | - Min Zhang
- Division of Hematology/Oncology, Department of Medicine, School of Medicine, University of California, Irvine, CA, USA
| | - Charles T H Chuah
- Cancer and Stem Cell Biology Signature Research Program, Duke-NUS Graduate Medical School, Singapore Department of Haematology, Singapore General Hospital, Singapore
| | - Haley Axelrod
- Department of Microbiology and Molecular Genetics, School of Medicine, University of California, Irvine, CA, USA
| | - Luke Wilson
- Department of Microbiology and Molecular Genetics, School of Medicine, University of California, Irvine, CA, USA
| | - S Tiong Ong
- Cancer and Stem Cell Biology Signature Research Program, Duke-NUS Graduate Medical School, Singapore Department of Haematology, Singapore General Hospital, Singapore Department of Medical Oncology, National Cancer Centre, Singapore Department of Medicine, Duke University Medical Center, Durham, NC, USA
| | - Bert L Semler
- Department of Microbiology and Molecular Genetics, School of Medicine, University of California, Irvine, CA, USA
| | - Marian L Waterman
- Department of Microbiology and Molecular Genetics, School of Medicine, University of California, Irvine, CA, USA
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de Las Heras-Rubio A, Perucho L, Paciucci R, Vilardell J, LLeonart ME. Ribosomal proteins as novel players in tumorigenesis. Cancer Metastasis Rev 2015; 33:115-41. [PMID: 24375388 DOI: 10.1007/s10555-013-9460-6] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Ribosome biogenesis is the most demanding energetic and metabolic expenditure of the cell. The nucleolus, a nuclear compartment, coordinates rRNA transcription, maturation, and assembly into ribosome subunits. The transcription process is highly coordinated with ribosome biogenesis. In this context, ribosomal proteins (RPs) play a crucial role. In the last decade, an increasing number of studies have associated RPs with extraribosomal functions related to proliferation. Importantly, the expression of RPs appears to be deregulated in several human disorders due, at least in part, to genetic mutations. Although the deregulation of RPs in human malignancies is commonly observed, a more complex mechanism is believed to be involved, favoring the tumorigenic process, its progression and metastasis. This review explores the roles of the most frequently mutated oncogenes and tumor suppressor genes in human cancer that modulate ribosome biogenesis, including their interaction with RPs. In this regard, we propose a new focus for novel therapies.
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Affiliation(s)
- A de Las Heras-Rubio
- Oncology and Pathology Group, Institut de Recerca Hospital Vall d'Hebron, Passeig Vall d'Hebron 119-129, 08035, Barcelona, Spain
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