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Mars JC, Culjkovic-Kraljacic B, Borden KL. eIF4E orchestrates mRNA processing, RNA export and translation to modify specific protein production. Nucleus 2024; 15:2360196. [PMID: 38880976 PMCID: PMC11185188 DOI: 10.1080/19491034.2024.2360196] [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: 02/12/2024] [Accepted: 05/22/2024] [Indexed: 06/18/2024] Open
Abstract
The eukaryotic translation initiation factor eIF4E acts as a multifunctional factor that simultaneously influences mRNA processing, export, and translation in many organisms. Its multifactorial effects are derived from its capacity to bind to the methyl-7-guanosine cap on the 5'end of mRNAs and thus can act as a cap chaperone for transcripts in the nucleus and cytoplasm. In this review, we describe the multifactorial roles of eIF4E in major mRNA-processing events including capping, splicing, cleavage and polyadenylation, nuclear export and translation. We discuss the evidence that eIF4E acts at two levels to generate widescale changes to processing, export and ultimately the protein produced. First, eIF4E alters the production of components of the mRNA processing machinery, supporting a widescale reprogramming of multiple mRNA processing events. In this way, eIF4E can modulate mRNA processing without physically interacting with target transcripts. Second, eIF4E also physically interacts with both capped mRNAs and components of the RNA processing or translation machineries. Further, specific mRNAs are sensitive to eIF4E only in particular mRNA processing events. This selectivity is governed by the presence of cis-acting elements within mRNAs known as USER codes that recruit relevant co-factors engaging the appropriate machinery. In all, we describe the molecular bases for eIF4E's multifactorial function and relevant regulatory pathways, discuss the basis for selectivity, present a compendium of ~80 eIF4E-interacting factors which play roles in these activities and provide an overview of the relevance of its functions to its oncogenic potential. Finally, we summarize early-stage clinical studies targeting eIF4E in cancer.
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Affiliation(s)
- Jean-Clément Mars
- Institute of Research in Immunology and Cancer, Department of Pathology and Cell Biology, Université de Montréal, Montréal, QC, Canada
| | - Biljana Culjkovic-Kraljacic
- Institute of Research in Immunology and Cancer, Department of Pathology and Cell Biology, Université de Montréal, Montréal, QC, Canada
| | - Katherine L.B. Borden
- Institute of Research in Immunology and Cancer, Department of Pathology and Cell Biology, Université de Montréal, Montréal, QC, Canada
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2
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Borden KLB. The eukaryotic translation initiation factor eIF4E unexpectedly acts in splicing thereby coupling mRNA processing with translation: eIF4E induces widescale splicing reprogramming providing system-wide connectivity between splicing, nuclear mRNA export and translation. Bioessays 2024; 46:e2300145. [PMID: 37926700 PMCID: PMC11021180 DOI: 10.1002/bies.202300145] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2023] [Revised: 10/17/2023] [Accepted: 10/24/2023] [Indexed: 11/07/2023]
Abstract
Recent findings position the eukaryotic translation initiation factor eIF4E as a novel modulator of mRNA splicing, a process that impacts the form and function of resultant proteins. eIF4E physically interacts with the spliceosome and with some intron-containing transcripts implying a direct role in some splicing events. Moreover, eIF4E drives the production of key components of the splicing machinery underpinning larger scale impacts on splicing. These drive eIF4E-dependent reprogramming of the splicing signature. This work completes a series of studies demonstrating eIF4E acts in all the major mRNA maturation steps whereby eIF4E drives production of the RNA processing machinery and escorts some transcripts through various maturation steps. In this way, eIF4E couples the mRNA processing-export-translation axis linking nuclear mRNA processing to cytoplasmic translation. eIF4E elevation is linked to worse outcomes in acute myeloid leukemia patients where these activities are dysregulated. Understanding these effects provides new insight into post-transcriptional control and eIF4E-driven cancers.
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Affiliation(s)
- Katherine L. B. Borden
- Institute for Research in Immunology and Cancer and Department of Pathology and Cell BiologyUniversity of MontrealMontrealQuebecCanada
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3
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Zha HL, Chen W, Shi W, Liao YY. Inhibition of Eukaryotic Initiating Factor eIF4E Overcomes Abemaciclib Resistance in Gastric Cancer. Curr Med Sci 2023; 43:927-934. [PMID: 37752406 DOI: 10.1007/s11596-023-2789-3] [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: 11/05/2022] [Accepted: 07/18/2023] [Indexed: 09/28/2023]
Abstract
OBJECTIVE Aberrant activating mutations in cyclin-dependent kinases 4 and 6 (CDK4/6) are common in various cancers, including gastroesophageal malignancies. Although CDK4/6 inhibitors, such as abemaciclib and palbociclib, have been approved for breast cancer treatment, their effectiveness as a monotherapy remains limited for gastroesophageal tumors. The present study explored the underlying mechanism of abemaciclib resistance. METHODS Abemaciclib-resistant gastric cancer cell lines were generated, and the phospho-eukaryotic translation initiation factor 4E (p-eIF4E) and eIF4E expression was compared between resistant and parental cell lines. In order to analyze the role of eIF4E in cell resistance, siRNA knockdown was employed. The effectiveness of ribavirin alone and its combination with abemaciclib was evaluated in the gastric cancer xenograft mouse model. RESULTS The upregulation of eIF4E was a common feature in gastric cancer cells exposed to prolonged abemaciclib treatment. Gastric cancer cells with increased eIF4E levels exhibited a better response to eIF4E inhibition, especially those that were resistant to abemaciclib. Ribavirin, which is an approved anti-viral drug, significantly improved the efficacy of abemaciclib, both in vitro and in vivo, by inhibiting eIF4E. Importantly, ribavirin effectively suppressed the abemaciclib-resistant gastric cancer growth in mice without causing toxicity. CONCLUSION These findings suggest that targeting eIF4E can enhance the abemaciclib treatment for gastric cancer, proposing the potential combination therapy of CDK4/6 inhibitors with ribavirin for advanced gastric cancer.
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Affiliation(s)
- Huo-Long Zha
- Department of Gastroenterology, Renmin Hospital, Hubei University of Medicine, Shiyan, 442000, China
| | - Wei Chen
- Department of Critical Care Medicine, Taihe Hospital, Hubei University of Medicine, Shiyan, 442000, China
| | - Wei Shi
- Department of Gastroenterology, Renmin Hospital, Hubei University of Medicine, Shiyan, 442000, China.
| | - Ying-Ying Liao
- Department of Gastroenterology, Renmin Hospital, Hubei University of Medicine, Shiyan, 442000, China.
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4
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Li F, Sun H, Yu Y, Che N, Han J, Cheng R, Zhao N, Guo Y, Huang C, Zhang D. RIPK1-dependent necroptosis promotes vasculogenic mimicry formation via eIF4E in triple-negative breast cancer. Cell Death Dis 2023; 14:335. [PMID: 37217473 PMCID: PMC10203343 DOI: 10.1038/s41419-023-05841-w] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2022] [Revised: 04/27/2023] [Accepted: 04/28/2023] [Indexed: 05/24/2023]
Abstract
Necroptosis is a caspase-independent form of programmed cell death. Receptor interacting protein kinase 1 (RIPK1) is a key molecule in the initiation of necroptosis and the formation of the necrotic complex. Vasculogenic mimicry (VM) provides a blood supply to tumor cells that is not dependent on endothelial cells. However, the relationship between necroptosis and VM in triple-negative breast cancer (TNBC) is not fully understood. In this study, we found that RIPK1-dependent necroptosis promoted VM formation in TNBC. Knockdown of RIPK1 significantly suppressed the number of necroptotic cells and VM formation. Moreover, RIPK1 activated the p-AKT/eIF4E signaling pathway during necroptosis in TNBC. eIF4E was blocked by knockdown of RIPK1 or AKT inhibitors. Furthermore, we found that eIF4E promoted VM formation by promoting epithelial-mesenchymal transition (EMT) and the expression and activity of MMP2. In addition to its critical role in necroptosis-mediated VM, eIF4E was essential for VM formation. Knockdown of eIF4E significantly suppressed VM formation during necroptosis. Finally, through clinical significance, the results found that eIF4E expression in TNBC was positively correlated with the mesenchymal marker vimentin, the VM marker MMP2, and the necroptosis markers MLKL and AKT. In conclusion, RIPK1-dependent necroptosis promotes VM formation in TNBC. Necroptosis promotes VM formation by activating RIPK1/p-AKT/eIF4E signaling in TNBC. eIF4E promotes EMT and MMP2 expression and activity, leading to VM formation. Our study provides a rationale for necroptosis-mediated VM and also providing a potential therapeutic target for TNBC.
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Affiliation(s)
- Fan Li
- Department of Pathology, Tianjin Medical University, Tianjin 300070, Tianjin, China
| | - Huizhi Sun
- Tianjin Medical University Cancer Institute and Hospital, National Clinical Research Center for Cancer, Key Laboratory of Cancer Prevention and Therapy, Tianjin's Clinical Research Center for Cancer, 300060, Tianjin, China
| | - Yihui Yu
- Department of Pathology, Tianjin Medical University, Tianjin 300070, Tianjin, China
| | - Na Che
- Department of Pathology, Tianjin Medical University, Tianjin 300070, Tianjin, China
| | - Jiyuan Han
- Department of Pathology, Tianjin Medical University, Tianjin 300070, Tianjin, China
| | - Runfen Cheng
- Tianjin Medical University Cancer Institute and Hospital, National Clinical Research Center for Cancer, Key Laboratory of Cancer Prevention and Therapy, Tianjin's Clinical Research Center for Cancer, 300060, Tianjin, China
| | - Nan Zhao
- Department of Pathology, Tianjin Medical University, Tianjin 300070, Tianjin, China
| | - Yuhong Guo
- Tianjin Medical University Cancer Institute and Hospital, National Clinical Research Center for Cancer, Key Laboratory of Cancer Prevention and Therapy, Tianjin's Clinical Research Center for Cancer, 300060, Tianjin, China
| | - Chongbiao Huang
- Tianjin Medical University Cancer Institute and Hospital, National Clinical Research Center for Cancer, Key Laboratory of Cancer Prevention and Therapy, Tianjin's Clinical Research Center for Cancer, 300060, Tianjin, China.
| | - Danfang Zhang
- Department of Pathology, Tianjin Medical University, Tianjin 300070, Tianjin, China.
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5
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Noren Hooten N, Torres S, Mode NA, Zonderman AB, Ghosh P, Ezike N, Evans MK. Association of extracellular vesicle inflammatory proteins and mortality. Sci Rep 2022; 12:14049. [PMID: 35982068 PMCID: PMC9386667 DOI: 10.1038/s41598-022-17944-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2022] [Accepted: 08/03/2022] [Indexed: 11/24/2022] Open
Abstract
Even before the COVID-19 pandemic declines in life expectancy in the United States were attributed to increased mortality rates in midlife adults across racial and ethnic groups, indicating a need for markers to identify individuals at risk for early mortality. Extracellular vesicles (EVs) are small, lipid-bound vesicles capable of shuttling functional proteins, nucleic acids, and lipids. Given their role as intercellular communicators and potential biomarkers of disease, we explored whether circulating EVs may be markers of mortality in a prospective, racially, and socioeconomically diverse middle-aged cohort. We isolated plasma EVs from 76 individuals (mean age = 59.6 years) who died within a 5 year period and 76 surviving individuals matched by age, race, and poverty status. There were no significant differences in EV concentration, size, or EV-associated mitochondrial DNA levels associated with mortality. We found that several EV-associated inflammatory proteins including CCL23, CSF-1, CXCL9, GDNF, MCP-1, STAMBP, and 4E-BP1 were significantly associated with mortality. IL-10RB and CDCP1 were more likely to be present in plasma EVs from deceased individuals than in their alive counterparts. We also report differences in EV-associated inflammatory proteins with poverty status, race, and sex. Our results suggest that plasma EV-associated inflammatory proteins are promising potential clinical biomarkers of mortality.
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Affiliation(s)
- Nicole Noren Hooten
- Laboratory of Epidemiology and Population Science, National Institute on Aging, National Institutes of Health, 251 Bayview Boulevard, Baltimore, MD, 21224, USA
| | - Stephanie Torres
- Laboratory of Epidemiology and Population Science, National Institute on Aging, National Institutes of Health, 251 Bayview Boulevard, Baltimore, MD, 21224, USA.,Edward Via College of Osteopathic Medicine at University of Louisiana Monroe, Monroe, LA, USA
| | - Nicolle A Mode
- Laboratory of Epidemiology and Population Science, National Institute on Aging, National Institutes of Health, 251 Bayview Boulevard, Baltimore, MD, 21224, USA
| | - Alan B Zonderman
- Laboratory of Epidemiology and Population Science, National Institute on Aging, National Institutes of Health, 251 Bayview Boulevard, Baltimore, MD, 21224, USA
| | - Paritosh Ghosh
- Laboratory of Clinical Investigation, National Institute on Aging, National Institutes of Health, 251 Bayview Boulevard, Baltimore, MD, 21224, USA
| | - Ngozi Ezike
- Laboratory of Epidemiology and Population Science, National Institute on Aging, National Institutes of Health, 251 Bayview Boulevard, Baltimore, MD, 21224, USA
| | - Michele K Evans
- Laboratory of Epidemiology and Population Science, National Institute on Aging, National Institutes of Health, 251 Bayview Boulevard, Baltimore, MD, 21224, USA.
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6
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Osborne MJ, Volpon L, Memarpooryazdi M, Pillay S, Thambipillai A, Czarnota S, Culjkovic-Kraljacic B, Trahan C, Oeffinger M, Cowling VH, L B Borden K. Identification and characterization of the interaction between the methyl-7-guanosine cap maturation enzyme RNMT and the cap-binding protein eIF4E. J Mol Biol 2022; 434:167451. [PMID: 35026230 DOI: 10.1016/j.jmb.2022.167451] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2021] [Revised: 01/04/2022] [Accepted: 01/05/2022] [Indexed: 12/20/2022]
Abstract
The control of RNA metabolism is an important aspect of molecular biology with wide-ranging impacts on cells. Central to processing of coding RNAs is the addition of the methyl-7 guanosine (m7G) "cap" on their 5' end. The eukaryotic translation initiation factor eIF4E directly binds the m7G cap and through this interaction plays key roles in many steps of RNA metabolism including nuclear RNA export and translation. eIF4E also stimulates capping of many transcripts through its ability to drive the production of the enzyme RNMT which methylates the G-cap to form the mature m7G cap. Here, we found that eIF4E also physically associated with RNMT in human cells. Moreover, eIF4E directly interacted with RNMT in vitro. eIF4E is only the second protein reported to directly bind the methyltransferase domain of RNMT, the first being its co-factor RAM. We combined high-resolution NMR methods with biochemical studies to define the binding interfaces for the RNMT-eIF4E complex. Further, we found that eIF4E competes for RAM binding to RNMT and conversely, RNMT competes for binding of well-established eIF4E-binding partners such as the 4E-BPs. RNMT uses novel structural means to engage eIF4E. Finally, we observed that m7G cap-eIF4E-RNMT trimeric complexes form, and thus RNMT-eIF4E complexes may be employed so that eIF4E captures newly capped RNA. In all, we show for the first time that the cap-binding protein eIF4E directly binds to the cap-maturation enzyme RNMT.
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Affiliation(s)
- Michael J Osborne
- Institute of Research in Immunology and Cancer, Department of Pathology and Cell Biology, Université de Montréal, Pavilion Marcelle-Coutu, Chemin Polytechnique, Montréal, QC H3T 1J4, Canada
| | - Laurent Volpon
- Institute of Research in Immunology and Cancer, Department of Pathology and Cell Biology, Université de Montréal, Pavilion Marcelle-Coutu, Chemin Polytechnique, Montréal, QC H3T 1J4, Canada
| | - Mina Memarpooryazdi
- Institute of Research in Immunology and Cancer, Department of Pathology and Cell Biology, Université de Montréal, Pavilion Marcelle-Coutu, Chemin Polytechnique, Montréal, QC H3T 1J4, Canada
| | - Subhadra Pillay
- Institute of Research in Immunology and Cancer, Department of Pathology and Cell Biology, Université de Montréal, Pavilion Marcelle-Coutu, Chemin Polytechnique, Montréal, QC H3T 1J4, Canada; Department of Biological Chemistry, Michigan Medicine, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - Aksharh Thambipillai
- Institute of Research in Immunology and Cancer, Department of Pathology and Cell Biology, Université de Montréal, Pavilion Marcelle-Coutu, Chemin Polytechnique, Montréal, QC H3T 1J4, Canada
| | - Sylwia Czarnota
- Institute of Research in Immunology and Cancer, Department of Pathology and Cell Biology, Université de Montréal, Pavilion Marcelle-Coutu, Chemin Polytechnique, Montréal, QC H3T 1J4, Canada
| | - Biljana Culjkovic-Kraljacic
- Institute of Research in Immunology and Cancer, Department of Pathology and Cell Biology, Université de Montréal, Pavilion Marcelle-Coutu, Chemin Polytechnique, Montréal, QC H3T 1J4, Canada
| | - Christian Trahan
- Department for Systems Biology, Institut de Recherches Cliniques de Montréal, Montréal, QC H2W 1R7, Canada; Département de Biochimie et Médecine Moléculaire, Université de Montréal, Montréal, QC H3T 1J4, Canada
| | - Marlene Oeffinger
- Department for Systems Biology, Institut de Recherches Cliniques de Montréal, Montréal, QC H2W 1R7, Canada; Département de Biochimie et Médecine Moléculaire, Université de Montréal, Montréal, QC H3T 1J4, Canada; Division of Experimental Medicine, McGill University, Montréal, QC, Canada
| | - Victoria H Cowling
- Centre for Gene Regulation and Expression, School of Life Sciences, University of Dundee, Dundee, UK, DD1 5EH
| | - Katherine L B Borden
- Institute of Research in Immunology and Cancer, Department of Pathology and Cell Biology, Université de Montréal, Pavilion Marcelle-Coutu, Chemin Polytechnique, Montréal, QC H3T 1J4, Canada.
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7
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Borden K, Culjkovic-Kraljacic B, Cowling VH. To cap it all off, again: dynamic capping and recapping of coding and non-coding RNAs to control transcript fate and biological activity. Cell Cycle 2021; 20:1347-1360. [PMID: 34241559 PMCID: PMC8344758 DOI: 10.1080/15384101.2021.1930929] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
The addition of the methyl-7-guanosine (m7G) “cap” on the 5' ends of coding and some non-coding RNAs is essential for their protein coding capacity and biochemical activity, respectively. It was previously considered that capping was a constitutive process that generates a complete cap on all transcripts at steady-state. However, development of new methodologies demonstrated that steady-state capping is a dynamic and regulatable feature of many coding and non-coding RNAs. Indeed, capping status of specific RNAs can flux during differentiation and development, thereby impacting on their protein-coding capacity and activity. Moreover, in some primary cancer specimens, capping can be elevated for transcripts encoding proteins involved in proliferation and survival corresponding to their increased protein levels. Overexpression of one of the capping enzymes (RNMT), the transcription factor MYC or the eukaryotic translation initiation factor eIF4E all led to increased levels of steady-state capping of selected transcripts. Additionally, transcripts can be decapped and recapped, allowing these to be sequestered until needed. This review provides a summary of the major advances in enzymatic and affinity-based approaches to quantify m7G capping. Further, we summarize the evidence for regulation of capping. Capping has emerged as a significant regulatory step in RNA metabolism which is poised to impact a myriad of biological processes.
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Affiliation(s)
- Klb Borden
- Department of Pathology and Cell Biology, Institute of Research in Immunology and Cancer, University of Montreal, Montreal, Canada
| | - B Culjkovic-Kraljacic
- Department of Pathology and Cell Biology, Institute of Research in Immunology and Cancer, University of Montreal, Montreal, Canada
| | - V H Cowling
- Centre for Gene Regulation and Expression, School of Life Sciences, University of Dundee, Dundee, UK, UK
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8
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de Lima GB, de Lima Cavalcanti TYV, de Brito ANALM, de Assis LA, Andrade-Vieira RP, Freire ER, da Silva Assunção TR, de Souza Reis CR, Zanchin NIT, Guimarães BG, de-Melo-Neto OP. The translation initiation factor EIF4E5 from Leishmania: crystal structure and interacting partners. RNA Biol 2021; 18:2433-2449. [PMID: 33945405 DOI: 10.1080/15476286.2021.1918919] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022] Open
Abstract
The mRNA cap-binding protein, eIF4E, mediates the recognition of the mRNA 5' end and, as part of the heterotrimeric eIF4F complex, facilitates the recruitment of the ribosomal subunits to initiate eukaryotic translation. Various regulatory events involving eIF4E and a second eIF4F subunit, eIF4G, are required for proper control of translation initiation. In pathogenic trypanosomatids, six eIF4Es and five eIF4Gs have been described, several forming different eIF4F-like complexes with yet unresolved roles. EIF4E5 is one of the least known of the trypanosomatid eIF4Es and has not been characterized in Leishmania species. Here, we used immunoprecipitation assays, combined with mass-spectrometry, to identify major EIF4E5 interacting proteins in L. infantum. A constitutively expressed, HA-tagged, EIF4E5 co-precipitated mainly with EIF4G1 and binding partners previously described in Trypanosoma brucei, EIF4G1-IP, RBP43 and the 14-3-3 proteins. In contrast, no clear co-precipitation with EIF4G2, also previously reported, was observed. EIF4E5 also co-precipitated with protein kinases, possibly associated with cell-cycle regulation, selected RNA binding proteins and histones. Phosphorylated residues were identified and mapped to the Leishmania-specific C-terminal end. Mutagenesis of the tryptophan residue (W53) postulated to mediate interactions with protein partners or of a neighbouring tryptophan conserved in Leishmania (W45) did not substantially impair the identified interactions. Finally, the crystal structure of Leishmania EIF4E5 evidences remarkable differences in the eIF4G interfacing region, when compared with human eIF4E-1 and with its Trypanosoma orthologue. Mapping of its C-terminal end near the cap-binding site also imply relevant differences in cap-binding function and/or regulation.
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Affiliation(s)
- Gustavo Barbosa de Lima
- Departamento de Microbiologia, Instituto Aggeu Magalhães, FIOCRUZ-PE, Av. Moraes Rego s/n, Recife-PE, Brazil
| | - Thaíse Yasmine Vasconcelos de Lima Cavalcanti
- Departamento de Microbiologia, Instituto Aggeu Magalhães, FIOCRUZ-PE, Av. Moraes Rego s/n, Recife-PE, Brazil.,Programa de Pós-Graduação em Genética, Universidade Federal de Pernambuco, Recife-PE, Brazil
| | - Adriana Neuman Albuquerque Lins Moura de Brito
- Departamento de Microbiologia, Instituto Aggeu Magalhães, FIOCRUZ-PE, Av. Moraes Rego s/n, Recife-PE, Brazil.,Programa de Pós-Graduação em Genética, Universidade Federal de Pernambuco, Recife-PE, Brazil
| | - Ludmilla Arruda de Assis
- Departamento de Microbiologia, Instituto Aggeu Magalhães, FIOCRUZ-PE, Av. Moraes Rego s/n, Recife-PE, Brazil
| | | | - Eden Ribeiro Freire
- Departamento de Microbiologia, Instituto Aggeu Magalhães, FIOCRUZ-PE, Av. Moraes Rego s/n, Recife-PE, Brazil.,Laboratório de Biologia Estrutural e Engenharia de Proteínas, Instituto Carlos Chagas, FIOCRUZ-PR, Curitiba-PR, Brazil
| | | | | | - Nilson Ivo Tonin Zanchin
- Laboratório de Biologia Estrutural e Engenharia de Proteínas, Instituto Carlos Chagas, FIOCRUZ-PR, Curitiba-PR, Brazil
| | - Beatriz Gomes Guimarães
- Laboratório de Biologia Estrutural e Engenharia de Proteínas, Instituto Carlos Chagas, FIOCRUZ-PR, Curitiba-PR, Brazil
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9
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Poornima G, Srivastava G, Roy B, Kuttanda IA, Kurbah I, Rajyaguru PI. RGG-motif containing mRNA export factor Gbp2 acts as a translation repressor. RNA Biol 2021; 18:2342-2353. [PMID: 33910495 DOI: 10.1080/15476286.2021.1910403] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Complex cascades of RNA-binding proteins regulate the mRNA metabolism and influence gene expression. Several distinct proteins act at different stages of mRNA life cycle. SR family proteins in yeast are implicated in mRNA processing and nuclear export. In this report, we uncover the role of an SR/RGG-motif containing mRNA export factor Gbp2 in mRNA translation regulation. We demonstrate that Gbp2 localizes to cytoplasmic granules upon heat shock and oxidative stress. Our pull-down assays demonstrate that Gbp2 directly binds to the conserved translation factor eIF4G1 via its RGG motif. We further mapped the region on eIF4G1 to which Gbp2 binds and observed that the binding region overlaps with another translation repressor Sbp1. We found that the RGG-motif deletion mutant is defective in localizing to polysome fractions. Upon tethering Gbp2 to a GFP reporter mRNA in vivo, translation of GFP reporter decreased significantly indicating that Gbp2 acts as a translation repressor. Consistent with these results, we show that Gbp2 can directly repress mRNA translation in the in vitro translation systems in an RGG-motif dependent manner. Taken together, our results establish that the mRNA export factor Gbp2 has a vital role in repressing translation of mRNA. We propose that Gbp2 is a multifaceted RGG-motif protein responsible for translational repression without affecting mRNA levels.
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Affiliation(s)
| | - Gaurav Srivastava
- Department of Biochemistry, Indian Institute of Science, Bangalore, India
| | - Brinta Roy
- Department of Biochemistry, Indian Institute of Science, Bangalore, India
| | | | - Iladeiti Kurbah
- Department of Biochemistry, Indian Institute of Science, Bangalore, India
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10
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Hernández-Alvarez L, Oliveira AB, Hernández-González JE, Chahine J, Pascutti PG, de Araujo AS, de Souza FP. Computational study on the allosteric mechanism of Leishmania major IF4E-1 by 4E-interacting protein-1: Unravelling the determinants of m 7GTP cap recognition. Comput Struct Biotechnol J 2021; 19:2027-2044. [PMID: 33995900 PMCID: PMC8085901 DOI: 10.1016/j.csbj.2021.03.036] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2020] [Revised: 03/25/2021] [Accepted: 03/29/2021] [Indexed: 02/07/2023] Open
Abstract
Atomistic details on perturbations induced by Lm4E-IP1 binding are described. The modulation of LmIF4E-1 affinity for the cap is confirmed by energetic analyses. Signaling paths between the allosteric and othosteric sites of LmIF4E-1 are predicted. Lm4E-IP1 binding increases the side-chain entropy of W83 and R172 of LmIF4E-1. A mechanism of dynamic allostery is proposed for the regulation mediated by Lm4E-IP1.
During their life cycle, Leishmania parasites display a fine-tuned regulation of the mRNA translation through the differential expression of isoforms of eukaryotic translation initiation factor 4E (LeishIF4Es). The interaction between allosteric modulators such as 4E-interacting proteins (4E-IPs) and LeishIF4E affects the affinity of this initiation factor for the mRNA cap. Here, several computational approaches were employed to elucidate the molecular bases of the previously-reported allosteric modulation in L. major exerted by 4E-IP1 (Lm4E-IP1) on eukaryotic translation initiation factor 4E 1 (LmIF4E-1). Molecular dynamics (MD) simulations and accurate binding free energy calculations (ΔGbind) were combined with network-based modeling of residue-residue correlations. We also describe the differences in internal motions of LmIF4E-1 apo form, cap-bound, and Lm4E-IP1-bound systems. Through community network calculations, the differences in the allosteric pathways of allosterically-inhibited and active forms of LmIF4E-1 were revealed. The ΔGbind values show significant differences between the active and inhibited systems, which are in agreement with the available experimental data. Our study thoroughly describes the dynamical perturbations of LmIF4E-1 cap-binding site triggered by Lm4E-IP1. These findings are not only essential for the understanding of a critical process of trypanosomatids’ gene expression but also for gaining insight into the allostery of eukaryotic IF4Es, which could be useful for structure-based design of drugs against this protein family.
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Affiliation(s)
- Lilian Hernández-Alvarez
- Department of Physics, Instituto de Biociências, Letras e Ciências Exatas, Universidade Estadual Paulista Julio de Mesquita Filho, São José do Rio Preto, São Paulo, Brazil
| | - Antonio B Oliveira
- Department of Physics, Instituto de Biociências, Letras e Ciências Exatas, Universidade Estadual Paulista Julio de Mesquita Filho, São José do Rio Preto, São Paulo, Brazil.,Center for Theoretical Biological Physics, Rice University, Huston, TX, United States
| | - Jorge Enrique Hernández-González
- Department of Physics, Instituto de Biociências, Letras e Ciências Exatas, Universidade Estadual Paulista Julio de Mesquita Filho, São José do Rio Preto, São Paulo, Brazil.,Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
| | - Jorge Chahine
- Department of Physics, Instituto de Biociências, Letras e Ciências Exatas, Universidade Estadual Paulista Julio de Mesquita Filho, São José do Rio Preto, São Paulo, Brazil
| | - Pedro Geraldo Pascutti
- Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
| | - Alexandre Suman de Araujo
- Department of Physics, Instituto de Biociências, Letras e Ciências Exatas, Universidade Estadual Paulista Julio de Mesquita Filho, São José do Rio Preto, São Paulo, Brazil
| | - Fátima Pereira de Souza
- Department of Physics, Instituto de Biociências, Letras e Ciências Exatas, Universidade Estadual Paulista Julio de Mesquita Filho, São José do Rio Preto, São Paulo, Brazil
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11
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Leroux LP, Chaparro V, Jaramillo M. Infection by the Protozoan Parasite Toxoplasma gondii Inhibits Host MNK1/2-eIF4E Axis to Promote Its Survival. Front Cell Infect Microbiol 2020; 10:488. [PMID: 33014898 PMCID: PMC7509071 DOI: 10.3389/fcimb.2020.00488] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2020] [Accepted: 08/06/2020] [Indexed: 11/13/2022] Open
Abstract
The obligate intracellular parasite Toxoplasma gondii reprograms host gene expression through multiple mechanisms that promote infection, including the up-regulation of mTOR-dependent host mRNA translation. In addition to the mTOR-4E-BP1/2 axis, MAPK-interacting kinases 1 and 2 (MNK1/2) control the activity of the mRNA cap-binding protein eIF4E. Herein, we show that T. gondii inhibits the phosphorylation of MNK1/2 and their downstream target eIF4E in murine and human macrophages. Exposure to soluble T. gondii antigens (STAg) failed to fully recapitulate this phenotype indicating the requirement of live infection. Treatment with okadaic acid, a potent phosphatase inhibitor, restored phosphorylation of MNK1/2 and eIF4E regardless of infection. T. gondii replication was higher in macrophages isolated from mice mutated at the residue where eIF4E is phosphorylated (eIF4E S209A knock-in) than in wild-type (WT) control cells despite no differences in infection rates. Similarly, parasitemia in the mesenteric lymph nodes and spleen, as well as brain cyst burden were significantly augmented in infected eIF4E S209A knock-in mice compared to their WT counterparts. Of note, mutant mice were more susceptible to acute toxoplasmosis and displayed exacerbated levels of IFNγ. In all, these data suggest that the MNK1/2-eIF4E axis is required to control T. gondii infection and that its inactivation represents a strategy exploited by the parasite to promote its survival.
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Affiliation(s)
- Louis-Philippe Leroux
- Institut National de la Recherche Scientifique (INRS)-Centre Armand-Frappier Santé Biotechnologie (CAFSB), Laval, QC, Canada
| | - Visnu Chaparro
- Institut National de la Recherche Scientifique (INRS)-Centre Armand-Frappier Santé Biotechnologie (CAFSB), Laval, QC, Canada
| | - Maritza Jaramillo
- Institut National de la Recherche Scientifique (INRS)-Centre Armand-Frappier Santé Biotechnologie (CAFSB), Laval, QC, Canada
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12
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Borden KLB, Volpon L. The diversity, plasticity, and adaptability of cap-dependent translation initiation and the associated machinery. RNA Biol 2020; 17:1239-1251. [PMID: 32496897 PMCID: PMC7549709 DOI: 10.1080/15476286.2020.1766179] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Translation initiation is a critical facet of gene expression with important impacts that underlie cellular responses to stresses and environmental cues. Its dysregulation in many diseases position this process as an important area for the development of new therapeutics. The gateway translation factor eIF4E is typically considered responsible for ‘global’ or ‘canonical’ m7G cap-dependent translation. However, eIF4E impacts translation of specific transcripts rather than the entire translatome. There are many alternative cap-dependent translation mechanisms that also contribute to the translation capacity of the cell. We review the diversity of these, juxtaposing more recently identified mechanisms with eIF4E-dependent modalities. We also explore the multiplicity of functions played by translation factors, both within and outside protein synthesis, and discuss how these differentially contribute to their ultimate physiological impacts. For comparison, we discuss some modalities for cap-independent translation. In all, this review highlights the diverse mechanisms that engage and control translation in eukaryotes.
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Affiliation(s)
- Katherine L B Borden
- Institute of Research in Immunology and Cancer (IRIC), Department of Pathology and Cell Biology, Université de Montréal , Montreal, Québec, Canada
| | - Laurent Volpon
- Institute of Research in Immunology and Cancer (IRIC), Department of Pathology and Cell Biology, Université de Montréal , Montreal, Québec, Canada
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13
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Batool A, Majeed ST, Aashaq S, Majeed R, Andrabi KI. Eukaryotic Initiation Factor 4E phosphorylation acts a switch for its binding to 4E-BP1 and mRNA cap assembly. Biochem Biophys Res Commun 2020; 527:489-495. [PMID: 32336547 DOI: 10.1016/j.bbrc.2020.04.086] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2020] [Accepted: 04/16/2020] [Indexed: 11/28/2022]
Abstract
Translational regulation has invited considerable interest consequent of its circumstantial dysregulation during cancer genesis. eIF4E (Eukaryotic Initiation Factor 4E) has been identified as an important factor involved in tumor progression by way of instrumenting the convergence of oncogenic signals for up-regulation of Cap-dependent translation. In the backdrop of dramatic eIF4E over-expression in a large population of human cancers, we suggest that the tumorigenic property of eIF4E is strictly attributed to its phosphorylation state. We provide evidence that while phosphorylated eIF4E fails to be sequestered by 4E-BP1, its dephosphorylated form shows overwhelming binding with 4E-BP1 without any consideration to the state of 4E-BP1 phosphorylation to suggest that eIF4E-4EBP1 binding is governed by eIF4E phosphorylation instead of 4E-BP1. We also show that eIF4E engages in Cap-assembly formation preferably in a phosphorylation-dependent manner to suggest that eIF4E phosphorylation rather than 4E-BP1 regulates its availability for Cap-assembly.
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Affiliation(s)
- Asiya Batool
- Department of Biotechnology, Science Block, University of Kashmir, Srinagar, 190006, J&K, India
| | - Sheikh Tahir Majeed
- Department of Biotechnology, Science Block, University of Kashmir, Srinagar, 190006, J&K, India
| | - Sabreena Aashaq
- Department of Biotechnology, Science Block, University of Kashmir, Srinagar, 190006, J&K, India
| | - Rabiya Majeed
- Department of Biotechnology, Science Block, University of Kashmir, Srinagar, 190006, J&K, India
| | - Khurshid Iqbal Andrabi
- Department of Biotechnology, Science Block, University of Kashmir, Srinagar, 190006, J&K, India.
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14
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eIF4E and Interactors from Unicellular Eukaryotes. Int J Mol Sci 2020; 21:ijms21062170. [PMID: 32245232 PMCID: PMC7139794 DOI: 10.3390/ijms21062170] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2020] [Revised: 03/12/2020] [Accepted: 03/18/2020] [Indexed: 12/22/2022] Open
Abstract
eIF4E, the mRNA cap-binding protein, is well known as a general initiation factor allowing for mRNA-ribosome interaction and cap-dependent translation in eukaryotic cells. In this review we focus on eIF4E and its interactors in unicellular organisms such as yeasts and protozoan eukaryotes. In a first part, we describe eIF4Es from yeast species such as Saccharomyces cerevisiae, Candida albicans, and Schizosaccharomyces pombe. In the second part, we will address eIF4E and interactors from parasite unicellular species—trypanosomatids and marine microorganisms—dinoflagellates. We propose that different strategies have evolved during evolution to accommodate cap-dependent translation to differing requirements. These evolutive “adjustments” involve various forms of eIF4E that are not encountered in all microorganismic species. In yeasts, eIF4E interactors, particularly p20 and Eap1 are found exclusively in Saccharomycotina species such as S. cerevisiae and C. albicans. For protozoan parasites of the Trypanosomatidae family beside a unique cap4-structure located at the 5′UTR of all mRNAs, different eIF4Es and eIF4Gs are active depending on the life cycle stage of the parasite. Additionally, an eIF4E-interacting protein has been identified in Leishmania major which is important for switching from promastigote to amastigote stages. For dinoflagellates, little is known about the structure and function of the multiple and diverse eIF4Es that have been identified thanks to widespread sequencing in recent years.
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15
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Ala-Poikela M, Rajamäki ML, Valkonen JP. A Novel Interaction Network Used by Potyviruses in Virus-Host Interactions at the Protein Level. Viruses 2019; 11:E1158. [PMID: 31847316 PMCID: PMC6950583 DOI: 10.3390/v11121158] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2019] [Revised: 12/10/2019] [Accepted: 12/11/2019] [Indexed: 12/30/2022] Open
Abstract
Host proteins that are central to infection of potyviruses (genus Potyvirus; family Potyviridae) include the eukaryotic translation initiation factors eIF4E and eIF(iso)4E. The potyviral genome-linked protein (VPg) and the helper component proteinase (HCpro) interact with each other and with eIF4E and eIF(iso)4E and proteins are involved in the same functions during viral infection. VPg interacts with eIF4E/eIF(iso)4E via the 7-methylguanosine cap-binding region, whereas HCpro interacts with eIF4E/eIF(iso)4E via the 4E-binding motif YXXXXLΦ, similar to the motif in eIF4G. In this study, HCpro and VPg were found to interact in the nucleus, nucleolus, and cytoplasm in cells infected with the potyvirus potato virus A (PVA). In the cytoplasm, interactions between HCpro and VPg occurred in punctate bodies not associated with viral replication vesicles. In addition to HCpro, the 4E-binding motif was recognized in VPg of PVA. Mutations in the 4E-binding motif of VPg from PVA weakened interactions with eIF4E and heavily reduced PVA virulence. Furthermore, mutations in the 4G-binding domain of eIF4E reduced interactions with VPg and abolished interactions with HCpro. Thus, HCpro and VPg can both interact with eIF4E using the 4E-binding motif. Our results suggest a novel interaction network used by potyviruses to interact with host plants via translation initiation factors.
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Affiliation(s)
| | - Minna-Liisa Rajamäki
- Department of Agricultural Sciences, University of Helsinki, P.O. Box 27, FI-00014 Helsinki, Finland;
| | - Jari P.T. Valkonen
- Department of Agricultural Sciences, University of Helsinki, P.O. Box 27, FI-00014 Helsinki, Finland;
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16
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Structural studies of the eIF4E-VPg complex reveal a direct competition for capped RNA: Implications for translation. Proc Natl Acad Sci U S A 2019; 116:24056-24065. [PMID: 31712417 DOI: 10.1073/pnas.1904752116] [Citation(s) in RCA: 36] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Viruses have transformed our understanding of mammalian RNA processing, including facilitating the discovery of the methyl-7-guanosine (m7G) cap on the 5' end of RNAs. The m7G cap is required for RNAs to bind the eukaryotic translation initiation factor eIF4E and associate with the translation machinery across plant and animal kingdoms. The potyvirus-derived viral genome-linked protein (VPg) is covalently bound to the 5' end of viral genomic RNA (gRNA) and associates with host eIF4E for successful infection. Divergent models to explain these observations proposed either an unknown mode of eIF4E engagement or a competition of VPg for the m7G cap-binding site. To dissect these possibilities, we resolved the structure of VPg, revealing a previously unknown 3-dimensional (3D) fold, and characterized the VPg-eIF4E complex using NMR and biophysical techniques. VPg directly bound the cap-binding site of eIF4E and competed for m7G cap analog binding. In human cells, VPg inhibited eIF4E-dependent RNA export, translation, and oncogenic transformation. Moreover, VPg formed trimeric complexes with eIF4E-eIF4G, eIF4E bound VPg-luciferase RNA conjugates, and these VPg-RNA conjugates were templates for translation. Informatic analyses revealed structural similarities between VPg and the human kinesin EG5. Consistently, EG5 directly bound eIF4E in a similar manner to VPg, demonstrating that this form of engagement is relevant beyond potyviruses. In all, we revealed an unprecedented modality for control and engagement of eIF4E and show that VPg-RNA conjugates functionally engage eIF4E. As such, potyvirus VPg provides a unique model system to interrogate eIF4E.
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17
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Batool A, Aashaq S, Andrabi KI. Eukaryotic initiation factor 4E (eIF4E): A recap of the cap-binding protein. J Cell Biochem 2019; 120:14201-14212. [PMID: 31074051 DOI: 10.1002/jcb.28851] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2019] [Revised: 04/09/2019] [Accepted: 04/11/2019] [Indexed: 12/29/2022]
Abstract
Eukaryotic initiation factor 4E (eIF4E), a fundamental effector and rate limiting element of protein synthesis, binds the 7-methylguanosine cap at the 5' end of eukaryotic messenger RNA (mRNA) specifically as a constituent of eIF4F translation initiation complex thus facilitating the recruitment of mRNA to the ribosomes. This review focusses on the engagement of signals contributing to growth factor originated maxim and their role in the activation of eIF4E to achieve a collective influence on cellular growth, with a key focus on conjuring vital processes like protein synthesis. The review invites considerable interest in elevating the appeal of eIF4E beyond its role in regulating translation viz a viz cancer genesis, attributed to its phosphorylation state that improves the prospect for the growth of the cancerous cell. This review highlights the latest studies that have envisioned to target these pathways and ultimately the translational machinery for therapeutic intervention. The review also brings forward the prospect of eIF4E to act as a converging juncture for signaling pathways like mTOR/PI3K and Mnk/MAPK to promote tumorigenesis.
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Affiliation(s)
- Asiya Batool
- Department of Biotechnology and Bioinformatics, University of Kashmir, Srinagar, Jammu and Kashmir, India
| | - Sabreena Aashaq
- Department of Biotechnology and Bioinformatics, University of Kashmir, Srinagar, Jammu and Kashmir, India
| | - Khurshid I Andrabi
- Department of Biotechnology and Bioinformatics, University of Kashmir, Srinagar, Jammu and Kashmir, India
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