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Walker NM, Ibuki Y, McLinden AP, Misumi K, Mitchell DC, Kleer GG, Lock AM, Vittal R, Sonenberg N, Garner AL, Lama VN. MNK-driven eIF4E phosphorylation regulates the fibrogenic transformation of mesenchymal cells and chronic lung allograft dysfunction. J Clin Invest 2024; 134:e168393. [PMID: 39145446 PMCID: PMC11324311 DOI: 10.1172/jci168393] [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: 01/09/2023] [Accepted: 06/25/2024] [Indexed: 08/16/2024] Open
Abstract
Tissue fibrosis remains unamenable to meaningful therapeutic interventions and is the primary cause of chronic graft failure after organ transplantation. Eukaryotic translation initiation factor (eIF4E), a key translational regulator, serves as convergent target of multiple upstream profibrotic signaling pathways that contribute to mesenchymal cell (MC) activation. Here, we investigate the role of MAP kinase-interacting serine/threonine kinase-induced (MNK-induced) direct phosphorylation of eIF4E at serine 209 (Ser209) in maintaining fibrotic transformation of MCs and determine the contribution of the MNK/eIF4E pathway to the pathogenesis of chronic lung allograft dysfunction (CLAD). MCs from patients with CLAD demonstrated constitutively higher eIF4E phosphorylation at Ser209, and eIF4E phospho-Ser209 was found to be critical in regulating key fibrogenic protein autotaxin, leading to sustained β-catenin activation and profibrotic functions of CLAD MCs. MNK1 signaling was upregulated in CLAD MCs, and genetic or pharmacologic targeting of MNK1 activity inhibited eIF4E phospho-Ser209 and profibrotic functions of CLAD MCs in vitro. Treatment with an MNK1/2 inhibitor (eFT-508) abrogated allograft fibrosis in an orthotopic murine lung-transplant model. Together these studies identify what we believe is a previously unrecognized MNK/eIF4E/ATX/β-catenin signaling pathway of fibrotic transformation of MCs and present the first evidence, to our knowledge, for the utility of MNK inhibitors in fibrosis.
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Affiliation(s)
- Natalie M. Walker
- Department of Internal Medicine, University of Michigan, Ann Arbor, Michigan, USA
| | - Yuta Ibuki
- Department of Internal Medicine, University of Michigan, Ann Arbor, Michigan, USA
| | - A. Patrick McLinden
- Division of Pulmonary, Allergy, Critical Care, and Sleep Medicine, Department of Medicine, Emory University School of Medicine, Atlanta, Georgia, USA
| | - Keizo Misumi
- Division of Pulmonary, Allergy, Critical Care, and Sleep Medicine, Department of Medicine, Emory University School of Medicine, Atlanta, Georgia, USA
| | - Dylan C. Mitchell
- Department of Medicinal Chemistry, University of Michigan, Ann Arbor, Michigan, USA
| | - Gabriel G. Kleer
- Department of Internal Medicine, University of Michigan, Ann Arbor, Michigan, USA
| | - Alison M. Lock
- Department of Internal Medicine, University of Michigan, Ann Arbor, Michigan, USA
| | - Ragini Vittal
- Division of Pulmonary, Allergy, Critical Care, and Sleep Medicine, Department of Medicine, Emory University School of Medicine, Atlanta, Georgia, USA
| | - Nahum Sonenberg
- Department of Biochemistry and McGill Cancer Center, McGill University, Montreal, Quebec, Canada
| | - Amanda L. Garner
- Department of Medicinal Chemistry, University of Michigan, Ann Arbor, Michigan, USA
| | - Vibha N. Lama
- Department of Internal Medicine, University of Michigan, Ann Arbor, Michigan, USA
- Division of Pulmonary, Allergy, Critical Care, and Sleep Medicine, Department of Medicine, Emory University School of Medicine, Atlanta, Georgia, USA
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2
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Mir DA, Ma Z, Horrocks J, Rogers AN. Stress-induced Eukaryotic Translational Regulatory Mechanisms. ARXIV 2024:arXiv:2405.01664v1. [PMID: 38745702 PMCID: PMC11092689] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 05/16/2024]
Abstract
The eukaryotic protein synthesis process entails intricate stages governed by diverse mechanisms to tightly regulate translation. Translational regulation during stress is pivotal for maintaining cellular homeostasis, ensuring the accurate expression of essential proteins crucial for survival. This selective translational control mechanism is integral to cellular adaptation and resilience under adverse conditions. This review manuscript explores various mechanisms involved in selective translational regulation, focusing on mRNA-specific and global regulatory processes. Key aspects of translational control include translation initiation, which is often a rate-limiting step, and involves the formation of the eIF4F complex and recruitment of mRNA to ribosomes. Regulation of translation initiation factors, such as eIF4E, eIF4E2, and eIF2, through phosphorylation and interactions with binding proteins, modulates translation efficiency under stress conditions. This review also highlights the control of translation initiation through factors like the eIF4F complex and the ternary complex and also underscores the importance of eIF2α phosphorylation in stress granule formation and cellular stress responses. Additionally, the impact of amino acid deprivation, mTOR signaling, and ribosome biogenesis on translation regulation and cellular adaptation to stress is also discussed. Understanding the intricate mechanisms of translational regulation during stress provides insights into cellular adaptation mechanisms and potential therapeutic targets for various diseases, offering valuable avenues for addressing conditions associated with dysregulated protein synthesis.
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Affiliation(s)
- Dilawar Ahmad Mir
- Kathryn W. Davis Center for Regenerative Biology and Aging, Mount Desert Island Biological Laboratory, Bar Harbor, ME
| | - Zhengxin Ma
- Kathryn W. Davis Center for Regenerative Biology and Aging, Mount Desert Island Biological Laboratory, Bar Harbor, ME
| | - Jordan Horrocks
- Kathryn W. Davis Center for Regenerative Biology and Aging, Mount Desert Island Biological Laboratory, Bar Harbor, ME
| | - Aric N Rogers
- Kathryn W. Davis Center for Regenerative Biology and Aging, Mount Desert Island Biological Laboratory, Bar Harbor, ME
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Li N, Duan Y, Ye Q, Ma Y, Ma R, Zhao L, Zhu S, Yu F, Qi S, Wang Y. The Arabidopsis eIF4E1 regulates NRT1.1-mediated nitrate signaling at both translational and transcriptional levels. THE NEW PHYTOLOGIST 2023; 240:338-353. [PMID: 37424317 DOI: 10.1111/nph.19129] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/03/2023] [Accepted: 06/18/2023] [Indexed: 07/11/2023]
Abstract
Identifying new nitrate regulatory genes and illustrating their mechanisms in modulating nitrate signaling are of great significance for achieving the high yield and nitrogen use efficiency (NUE) of crops. Here, we screened a mutant with defects in nitrate response and mapped the mutation to the gene eIF4E1 in Arabidopsis. Our results showed that eIF4E1 regulated nitrate signaling and metabolism. Ribo-seq and polysome profiling analysis revealed that eIF4E1 modulated the amount of some nitrogen (N)-related mRNAs being translated, especially the mRNA of NRT1.1 was reduced in the eif4e1 mutant. RNA-Seq results enriched some N-related genes, supporting that eIF4E1 is involved in nitrate regulation. The genetic analysis indicated that eIF4E1 worked upstream of NRT1.1 in nitrate signaling. In addition, an eIF4E1-interacting protein GEMIN2 was identified and found to be involved in nitrate signaling. Further investigation showed that overexpression of eIF4E1 promoted plant growth and enhanced yield and NUE. These results demonstrate that eIF4E1 regulates nitrate signaling by modulating NRT1.1 at both translational and transcriptional levels, laying the foundation for future research on the regulation of mineral nutrition at the translational level.
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Affiliation(s)
- Na Li
- College of Life Sciences, National Key Laboratory of Wheat Improvement, Shandong Agricultural University, Tai'an, Shandong, 271018, China
| | - Yawen Duan
- College of Life Sciences, National Key Laboratory of Wheat Improvement, Shandong Agricultural University, Tai'an, Shandong, 271018, China
| | - Qing Ye
- College of Life Sciences, National Key Laboratory of Wheat Improvement, Shandong Agricultural University, Tai'an, Shandong, 271018, China
| | - Yuhan Ma
- College of Life Sciences, National Key Laboratory of Wheat Improvement, Shandong Agricultural University, Tai'an, Shandong, 271018, China
| | - Rongjie Ma
- College of Life Sciences, National Key Laboratory of Wheat Improvement, Shandong Agricultural University, Tai'an, Shandong, 271018, China
| | - Lufei Zhao
- Agricultural Science and Engineering School, Liaocheng University, Liaocheng, Shandong, 252000, China
| | - Sirui Zhu
- State Key Laboratory of Chemo/Biosensing and Chemometrics, College of Biology, Hunan Key Laboratory of Plant Functional Genomics and Developmental Regulation, Hunan University, Changsha, Hunan, 410082, China
| | - Feng Yu
- State Key Laboratory of Chemo/Biosensing and Chemometrics, College of Biology, Hunan Key Laboratory of Plant Functional Genomics and Developmental Regulation, Hunan University, Changsha, Hunan, 410082, China
| | - Shengdong Qi
- College of Life Sciences, National Key Laboratory of Wheat Improvement, Shandong Agricultural University, Tai'an, Shandong, 271018, China
| | - Yong Wang
- College of Life Sciences, National Key Laboratory of Wheat Improvement, Shandong Agricultural University, Tai'an, Shandong, 271018, China
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4
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Guo J, Zhao H, Zhang J, Lv X, Zhang S, Su R, Zheng W, Dai J, Meng F, Gong F, Lu G, Xue Y, Lin G. Selective Translation of Maternal mRNA by eIF4E1B Controls Oocyte to Embryo Transition. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2023; 10:e2205500. [PMID: 36755190 PMCID: PMC10104655 DOI: 10.1002/advs.202205500] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/22/2022] [Revised: 01/17/2023] [Indexed: 06/18/2023]
Abstract
Maternal messenger ribonucleic acids (mRNAs) are driven by a highly orchestrated scheme of recruitment to polysomes and translational activation. However, selecting and regulating individual mRNAs for the translation from a competitive pool of mRNAs are little-known processes. This research shows that the maternal eukaryotic translation initiation factor 4e1b (Eif4e1b) expresses during the oocyte-to-embryo transition (OET), and maternal deletion of Eif4e1b leads to multiple defects concerning oogenesis and embryonic developmental competence during OET. The linear amplification of complementary deoxyribonucleic acid (cDNA) ends, and sequencing (LACE-seq) is used to identify the distinct subset of mRNA and its CG-rich binding sites within the 5' untranslated region (UTR) targeted by eIF4E1B. The proteomics analyses indicate that eIF4E1B-specific bound genes show stronger downregulation at the protein level, which further verify a group of proteins that plays a crucial role in oocyte maturation and embryonic developmental competence is insufficiently synthesized in Eif4e1b-cKO oocytes during OET. Moreover, the biochemical results in vitro are combined to further confirm the maternal-specific translation activation model assembled by eIF4E1B and 3'UTR-associated mRNA binding proteins. The findings demonstrate the indispensability of eIF4E1B for selective translation activation in mammalian oocytes and provide a potential network regulated by eIF4E1B in OET.
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Affiliation(s)
- Jing Guo
- Clinical Research Center for Reproduction and Genetics in Hunan ProvinceReproductive and Genetic Hospital of CITIC‐XiangyaChangsha410078P. R. China
| | - Hailian Zhao
- Key Laboratory of RNA BiologyInstitute of BiophysicsChinese Academy of SciencesBeijing100101P. R. China
- University of Chinese Academy of SciencesBeijing100049P. R. China
| | - Jue Zhang
- Clinical Research Center for Reproduction and Genetics in Hunan ProvinceReproductive and Genetic Hospital of CITIC‐XiangyaChangsha410078P. R. China
| | - Xiangjiang Lv
- Laboratory of Reproductive and Stem Cell EngineeringNHC Key Laboratory of Human Stem Cell and Reproductive EngineeringCentral South UniversityChangsha410078P. R. China
| | - Shen Zhang
- Clinical Research Center for Reproduction and Genetics in Hunan ProvinceReproductive and Genetic Hospital of CITIC‐XiangyaChangsha410078P. R. China
| | - Ruibao Su
- Key Laboratory of RNA BiologyInstitute of BiophysicsChinese Academy of SciencesBeijing100101P. R. China
- University of Chinese Academy of SciencesBeijing100049P. R. China
| | - Wei Zheng
- Clinical Research Center for Reproduction and Genetics in Hunan ProvinceReproductive and Genetic Hospital of CITIC‐XiangyaChangsha410078P. R. China
| | - Jing Dai
- Clinical Research Center for Reproduction and Genetics in Hunan ProvinceReproductive and Genetic Hospital of CITIC‐XiangyaChangsha410078P. R. China
- Laboratory of Reproductive and Stem Cell EngineeringNHC Key Laboratory of Human Stem Cell and Reproductive EngineeringCentral South UniversityChangsha410078P. R. China
| | - Fei Meng
- Clinical Research Center for Reproduction and Genetics in Hunan ProvinceReproductive and Genetic Hospital of CITIC‐XiangyaChangsha410078P. R. China
| | - Fei Gong
- Clinical Research Center for Reproduction and Genetics in Hunan ProvinceReproductive and Genetic Hospital of CITIC‐XiangyaChangsha410078P. R. China
- Laboratory of Reproductive and Stem Cell EngineeringNHC Key Laboratory of Human Stem Cell and Reproductive EngineeringCentral South UniversityChangsha410078P. R. China
| | - Guangxiu Lu
- Clinical Research Center for Reproduction and Genetics in Hunan ProvinceReproductive and Genetic Hospital of CITIC‐XiangyaChangsha410078P. R. China
- Laboratory of Reproductive and Stem Cell EngineeringNHC Key Laboratory of Human Stem Cell and Reproductive EngineeringCentral South UniversityChangsha410078P. R. China
| | - Yuanchao Xue
- Key Laboratory of RNA BiologyInstitute of BiophysicsChinese Academy of SciencesBeijing100101P. R. China
- University of Chinese Academy of SciencesBeijing100049P. R. China
| | - Ge Lin
- Clinical Research Center for Reproduction and Genetics in Hunan ProvinceReproductive and Genetic Hospital of CITIC‐XiangyaChangsha410078P. R. China
- Laboratory of Reproductive and Stem Cell EngineeringNHC Key Laboratory of Human Stem Cell and Reproductive EngineeringCentral South UniversityChangsha410078P. R. China
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Chen H, Chen C, Huang S, Zhao M, Wang T, Jiang T, Wang C, Tao Z, Zhang Y, Wang Y, Wang W, Tang Q, Li P. Inactivation of RPX1 in Arabidopsis confers resistance to Plutella xylostella through the accumulation of the homoterpene DMNT. PLANT, CELL & ENVIRONMENT 2023; 46:946-961. [PMID: 36582057 PMCID: PMC10107731 DOI: 10.1111/pce.14528] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/08/2022] [Revised: 12/19/2022] [Accepted: 12/27/2022] [Indexed: 06/17/2023]
Abstract
The lepidopteran crop pest Plutella xylostella causes severe constraints on Brassica cultivation. Here, we report a novel role for RPX1 (resistance to P. xylostella) in resistance to this pest in Arabidopsis thaliana. The rpx1-1 mutant repels P. xylostella larvae, and feeding on the rpx1-1 mutant severely damages the peritrophic matrix structure in the midgut of the larvae, thereby negatively affecting larval growth and pupation. This resistance results from the accumulation of defence compounds, including the homoterpene (3E)-4,8-dimethyl-1,3,7-nonatriene (DMNT), due to the upregulation of PENTACYCLIC TRITERPENE SYNTHASE 1 (PEN1), which encodes a key DMNT biosynthetic enzyme. P. xylostella infestation and wounding induce RPX1 protein degradation, which may confer a rapid response to insect infestation. RPX1 inactivation and PEN1 overexpression are not associated with negative trade-offs for plant growth but have much higher seed production than the wild-type in the presence of P. xylostella infestation. This study offers a new strategy for plant molecular breeding against P. xylostella.
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Affiliation(s)
- Hongyi Chen
- The National Engineering Lab of Crop Stress Resistance Breeding, School of Life SciencesAnhui Agricultural UniversityHefeiChina
| | - Chen Chen
- The National Engineering Lab of Crop Stress Resistance Breeding, School of Life SciencesAnhui Agricultural UniversityHefeiChina
- Department of Microbiology, the Key Laboratory of Microbiology and Parasitology of Anhui Province, the Key Laboratory of Zoonoses of High Institutions in Anhui, School of Basic Medical SciencesAnhui Medical UniversityHefeiChina
| | - Shijie Huang
- The National Engineering Lab of Crop Stress Resistance Breeding, School of Life SciencesAnhui Agricultural UniversityHefeiChina
| | - Mengjie Zhao
- The National Engineering Lab of Crop Stress Resistance Breeding, School of Life SciencesAnhui Agricultural UniversityHefeiChina
| | - Tengyue Wang
- The National Engineering Lab of Crop Stress Resistance Breeding, School of Life SciencesAnhui Agricultural UniversityHefeiChina
| | - Taoshan Jiang
- The National Engineering Lab of Crop Stress Resistance Breeding, School of Life SciencesAnhui Agricultural UniversityHefeiChina
| | - Chuanhong Wang
- The National Engineering Lab of Crop Stress Resistance Breeding, School of Life SciencesAnhui Agricultural UniversityHefeiChina
| | - Zhen Tao
- The National Engineering Lab of Crop Stress Resistance Breeding, School of Life SciencesAnhui Agricultural UniversityHefeiChina
| | - Yan Zhang
- The National Engineering Lab of Crop Stress Resistance Breeding, School of Life SciencesAnhui Agricultural UniversityHefeiChina
| | - Yunhe Wang
- The National Engineering Lab of Crop Stress Resistance Breeding, School of Life SciencesAnhui Agricultural UniversityHefeiChina
| | - Wanyi Wang
- The National Engineering Lab of Crop Stress Resistance Breeding, School of Life SciencesAnhui Agricultural UniversityHefeiChina
| | - Qingfeng Tang
- Key Laboratory of Biology and Sustainable Management of Plant Diseases and Pests of Anhui Higher Education Institutes, School of Plant ProtectionAnhui Agricultural UniversityHefeiChina
| | - Peijin Li
- The National Engineering Lab of Crop Stress Resistance Breeding, School of Life SciencesAnhui Agricultural UniversityHefeiChina
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6
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Christie M, Igreja C. eIF4E-homologous protein (4EHP): a multifarious cap-binding protein. FEBS J 2023; 290:266-285. [PMID: 34758096 DOI: 10.1111/febs.16275] [Citation(s) in RCA: 11] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2021] [Revised: 10/29/2021] [Accepted: 11/09/2021] [Indexed: 02/05/2023]
Abstract
The cap-binding protein 4EHP/eIF4E2 has been a recent object of interest in the field of post-transcriptional gene regulation and translational control. From ribosome-associated quality control, to RNA decay and microRNA-mediated gene silencing, this member of the eIF4E protein family regulates gene expression through numerous pathways. Low in abundance but ubiquitously expressed, 4EHP interacts with different binding partners to form multiple protein complexes that regulate translation in a variety of biological contexts. Documented functions of 4EHP primarily relate to its role as a translational repressor, but recent findings indicate that it might also participate in the activation of translation in specific settings. In this review, we discuss the known functions, properties and mechanisms that involve 4EHP in the control of gene expression. We also discuss our current understanding of how 4EHP processes are regulated in eukaryotic cells, and the diseases implicated with dysregulation of 4EHP-mediated translational control.
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Affiliation(s)
- Mary Christie
- School of Life and Environmental Sciences, The University of Sydney, NSW, Australia
| | - Cátia Igreja
- Department for Integrative Evolutionary Biology, Max Planck Institute for Developmental Biology, Tübingen, Germany
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7
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Genome-Wide Identification and Expression Analysis of eIF Family Genes from Brassica rapa in Response to TuMV Resistance. PLANTS 2022; 11:plants11172248. [PMID: 36079630 PMCID: PMC9460045 DOI: 10.3390/plants11172248] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/18/2022] [Revised: 08/13/2022] [Accepted: 08/23/2022] [Indexed: 11/28/2022]
Abstract
Brassica rapa is one of the most important leafy vegetables worldwide, and has a long history of cultivation. However, it has not been possible to completely control the damage of turnip mosaic virus (TuMV), a serious virus in B. rapa, to production. In this study, the genome-wide identification and expression detection of eIF family genes from B. rapa in response to TuMV resistance were analyzed, including the identification of eIF family genes, chromosomal distribution, three-dimensional (3D) structure and sequence logo analyses, and the expression characterization as well as differential metabolite analysis of eIF family genes in resistant/susceptible lines, which may further prove the whole-genome tripling (WGT) event in B. rapa evolution and provide evidence for the functional redundancy and functional loss of multicopy eIF genes in evolution. A qRT-PCR analysis revealed that the relative expressions of eIF genes in a susceptible line (80461) were higher than those in a resistant line (80124), which may prove that, when TuMV infects host plants, the eIF genes can combine with the virus mRNA 5′ end cap structure and promote the initiation of virus mRNA translation in the susceptible B. rapa line. In addition, the metabolite substances were detected, the differences in metabolites between disease-resistant and disease-susceptible plants were mainly manifested by altered compounds such as flavonoids, jasmonic acid, salicylic acid, ketones, esters, etc., which inferred that the different metabolite regulations of eIF family genes and reveal the resistance mechanisms of eIF genes against TuMV in brassica crops. This study may lay a new theoretical foundation for revealing eIF family gene resistance to TuMV in B. rapa, as well as advancing our understanding of virus–host interactions.
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8
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Cruz A, Joseph S. Interaction of the Influenza A Virus NS1 Protein with the 5'-m7G-mRNA·eIF4E·eIF4G1 Complex. Biochemistry 2022; 61:1485-1494. [PMID: 35797022 PMCID: PMC10164398 DOI: 10.1021/acs.biochem.2c00019] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The influenza A virus (IAV) is responsible for seasonal epidemics that result in hundreds of thousands of deaths worldwide annually. The non-structural protein 1 (NS1) of the IAV inflicts various antagonistic processes on the host during infection. These processes include inhibition of the host interferon system, inhibition of the apoptotic response, and enhancement of viral mRNA translation, all of which contribute to the overall virulence of the IAV. Although the mechanism by which NS1 stimulates translation is unknown, NS1 has been shown to bind both poly-A binding Protein 1 and eukaryotic initiation factor 4 gamma 1 (eIF4G1), two proteins necessary for cap-dependent translation. We directly analyzed the interaction between NS1 and eIF4G1 within the context of the 5'-m7G-mRNA·eIF4E·eIF4G1 complex. Interestingly, our studies show that NS1 can bind this complex in the presence or absence of 5'-m7G-mRNA. Additionally, we were interested in investigating whether NS1 interacts with eIF4E directly. Our results indicate that NS1 can bind to eIF4E only in the absence of 5'-m7G-mRNA. Considering previous data, we propose that NS1 stimulates translation by binding to eIF4G1 and recruiting the 43S pre-translation initiation complex to the mRNA.
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Affiliation(s)
- Alejandro Cruz
- Department of Chemistry and Biochemistry, University of California at San Diego, 9500 Gilman Drive, La Jolla, California 92093-0314 United States
| | - Simpson Joseph
- Department of Chemistry and Biochemistry, University of California at San Diego, 9500 Gilman Drive, La Jolla, California 92093-0314 United States
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9
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Lewis V, Rodrigue B, Arsenault E, Zhang M, Taghavi-Abkuh FF, Silva WCC, Myers M, Matta-Camacho E, Aguilar-Valles A. Translational control by ketamine and its implications for comorbid cognitive deficits in depressive disorders. J Neurochem 2022. [PMID: 35680556 DOI: 10.1111/jnc.15652] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2022] [Revised: 05/19/2022] [Accepted: 05/26/2022] [Indexed: 11/29/2022]
Abstract
Ketamine has shown antidepressant effects in patients with major depressive disorder (MDD) resistant to first-line treatments and approved for use in this patient population. Ketamine induces several forms of synaptic plasticity, which are proposed to underlie its antidepressant effects. However, the molecular mechanism of action directly responsible for ketamine's antidepressant effects remains under active investigation. It was recently demonstrated that the effectors of the mammalian target of rapamycin complex 1 (mTORC1) signalling pathway, namely, eukaryotic initiation factor 4E (eIF4E) binding proteins 1 and 2 (4E-BP1 and 4E-BP2), are central in mediating ketamine-induced synaptic plasticity and behavioural antidepressant-like effect. 4E-BPs are a family of messenger ribonucleic acid (mRNA) translation repressors inactivated by mTORC1. We observed that their expression in inhibitory interneurons mediates ketamine's effects in the forced swim and novelty suppressed feeding tests and the long-lasting inhibition of GABAergic neurotransmission in the hippocampus. In addition, another effector pathway that regulates translation elongation downstream of mTORC1, the eukaryotic elongation factor 2 kinase (eEF2K), has been implicated in ketamine's behavioural effects. We will discuss how ketamine's rapid antidepressant effect depends on the activation of neuronal mRNA translation through 4E-BP1/2 and eEF2K. Furthermore, given that these pathways also regulate cognitive functions, we will discuss the evidence of ketamine's effect on cognitive function in MDD. Overall, the data accrued from pre-clinical research have implicated the mRNA translation pathways in treating mood symptoms of MDD. However, it is yet unclear whether the pro-cognitive potential of subanesthetic ketamine in rodents also engages these pathways and whether such an effect is consistently observed in the treatment-resistant MDD population.
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Affiliation(s)
- Vern Lewis
- Department of Neuroscience, Carleton University, Ottawa, Ontario, Canada
| | - Brandon Rodrigue
- Department of Neuroscience, Carleton University, Ottawa, Ontario, Canada
| | - Emily Arsenault
- Department of Neuroscience, Carleton University, Ottawa, Ontario, Canada
| | - Molly Zhang
- Department of Neuroscience, Carleton University, Ottawa, Ontario, Canada
| | | | | | - Mysa Myers
- Department of Neuroscience, Carleton University, Ottawa, Ontario, Canada
| | - Edna Matta-Camacho
- Department of Neuroscience, Carleton University, Ottawa, Ontario, Canada
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10
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Laseca N, Molina A, Ramón M, Valera M, Azcona F, Encina A, Demyda-Peyrás S. Fine-Scale Analysis of Runs of Homozygosity Islands Affecting Fertility in Mares. Front Vet Sci 2022; 9:754028. [PMID: 35252415 PMCID: PMC8891756 DOI: 10.3389/fvets.2022.754028] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2021] [Accepted: 01/10/2022] [Indexed: 11/16/2022] Open
Abstract
The loss of genetic variability in livestock populations bred under strict selection processes is a growing concern, as it may lead to increased inbreeding values and lower fertility, as a consequence of the “inbreeding depression” effect. This is particularly important in horses, where inbreeding levels tend to rise as individuals become more and more closely related. In this study, we evaluated the effect of increased inbreeding levels on mare fertility by combining an SNP-based genomic approach using runs of homozygosity and the estimation of genetic breeding values for reproductive traits in a large population of Pura Raza Española mares. Our results showed a negative correlation between whole-genome homozygosity and fertility estimated breeding values (EBVs) at the genome level (ρ = −0.144). However, the analysis at chromosome level revealed a wide variability, with some chromosomes showing higher correlations than others. Interestingly, the correlation was stronger (−0.241) when we repeated the analysis in a reduced dataset including the 10% most and least fertile individuals, where the latter showed an increase in average inbreeding values (FROH) of around 30%. We also found 41 genomic regions (ROHi, runs of homozygosity islands) where homozygosity increased 100-fold, 13 of which were significantly associated with fertility after cross-validation. These regions encompassed 17 candidate genes previously related to oocyte and embryo development in several species. Overall, we demonstrated the relationship between increased homozygosis at the genomic level and fertility in mares. Our findings may help to deal with the occurrence of inbreeding depression, as well as further our understanding of the mechanisms underlying fertility in mares.
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Affiliation(s)
- Nora Laseca
- Laboratorio de Diagnóstico Genético Veterinario, Departamento de Genética, Universidad de Córdoba, Córdoba, Spain
| | - Antonio Molina
- Laboratorio de Diagnóstico Genético Veterinario, Departamento de Genética, Universidad de Córdoba, Córdoba, Spain
| | - Manuel Ramón
- Cersyra de Valdepeñas, Instituto Regional de Investigación y Desarrollo Agroalimentario y Forestal Castilla La Mancha, Tomelloso, Spain
| | - Mercedes Valera
- Departamento de Agronomía, Escuela Técnica Superior de Ingeniería Agronómica, Universidad de Sevilla, Sevilla, Spain
| | - Florencia Azcona
- IGEVET (UNLP-CONICET LA PLATA), Facultad de Ciencias Veterinarias, Universidad Nacional de La Plata, La Plata, Argentina
| | - Ana Encina
- Departamento de Agronomía, Escuela Técnica Superior de Ingeniería Agronómica, Universidad de Sevilla, Sevilla, Spain
- Asociación Nacional de Criadores de Caballos de Pura Raza Española, Sevilla, Spain
| | - Sebastián Demyda-Peyrás
- Departamento de Producción Animal, Facultad de Ciencias Veterinarias, Universidad Nacional de La Plata, Buenos Aires, Argentina
- Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET LA PLATA), La Plata, Argentina
- *Correspondence: Sebastián Demyda-Peyrás
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11
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Chen BR, Wei TW, Tang CP, Sun JT, Shan TK, Fan Y, Yang TT, Li YF, Ma Y, Wang SB, Wang ZM, Wang H, Shi JZ, Liu L, Chen JW, Zhou LH, Du C, Sun R, Wang QM, Wang LS. MNK2-eIF4E axis promotes cardiac repair in the infarcted mouse heart by activating cyclin D1. J Mol Cell Cardiol 2022; 166:91-106. [DOI: 10.1016/j.yjmcc.2022.02.006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/12/2021] [Revised: 02/15/2022] [Accepted: 02/23/2022] [Indexed: 10/19/2022]
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12
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Control of the eIF4E activity: structural insights and pharmacological implications. Cell Mol Life Sci 2021; 78:6869-6885. [PMID: 34541613 PMCID: PMC8558276 DOI: 10.1007/s00018-021-03938-z] [Citation(s) in RCA: 27] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2021] [Revised: 08/28/2021] [Accepted: 09/08/2021] [Indexed: 12/17/2022]
Abstract
The central role of eukaryotic translation initiation factor 4E (eIF4E) in controlling mRNA translation has been clearly assessed in the last decades. eIF4E function is essential for numerous physiological processes, such as protein synthesis, cellular growth and differentiation; dysregulation of its activity has been linked to ageing, cancer onset and progression and neurodevelopmental disorders, such as autism spectrum disorder (ASD) and Fragile X Syndrome (FXS). The interaction between eIF4E and the eukaryotic initiation factor 4G (eIF4G) is crucial for the assembly of the translational machinery, the initial step of mRNA translation. A well-characterized group of proteins, named 4E-binding proteins (4E-BPs), inhibits the eIF4E–eIF4G interaction by competing for the same binding site on the eIF4E surface. 4E-BPs and eIF4G share a single canonical motif for the interaction with a conserved hydrophobic patch of eIF4E. However, a second non-canonical and not conserved binding motif was recently detected for eIF4G and several 4E-BPs. Here, we review the structural features of the interaction between eIF4E and its molecular partners eIF4G and 4E-BPs, focusing on the implications of the recent structural and biochemical evidence for the development of new therapeutic strategies. The design of novel eIF4E-targeting molecules that inhibit translation might provide new avenues for the treatment of several conditions.
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13
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Xu W, Kannan S, Verma CS, Nacro K. Update on the Development of MNK Inhibitors as Therapeutic Agents. J Med Chem 2021; 65:983-1007. [PMID: 34533957 DOI: 10.1021/acs.jmedchem.1c00368] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Mitogen-activated protein kinase-interacting kinases 1 and 2 (MNK1/2) represent a central class of enzymes that are activated by extracellular signal-regulated kinase (ERK) or p38 mitogen-activated protein (MAP) kinases. MNK1 and MNK2 coordinate cellular signaling, control production of inflammatory chemokines, and regulate cell proliferation and survival. MNK1/2 are referred to as serine/threonine kinases as they phosphorylate serine or threonine residues on their substrates. Upon activation, MNK1/2 phosphorylate eukaryotic translation initiation factor 4E (eIF4E) at Ser209, which in turn initiates ribosome assembly and protein translation. Deleterious overexpression of MNK1/2 and/or eIF4E have been reported in several diseases including cancers, neurological disorders, autism, and inflammation. Recently, there have been intense efforts toward the development of potent and selective inhibitors of MNK1/2 in both academia and industry. Herein, we review the current understanding of the structural and biological aspects of MNK1/2 and provide an update of pharmacological inhibitors of MNK1/2 including candidates in clinical trials.
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Affiliation(s)
- Weijun Xu
- Experimental Drug Development Centre (EDDC), A*STAR, 10 Biopolis Road, Chromos #05-01, 138670, Singapore
| | | | - Chandra S Verma
- Bioinformatics Institute (BII), A*STAR, 30 Biopolis Street, #07-01 Matrix, 138671, Singapore.,Department of Biological Sciences, National University of Singapore, 16 Science Drive 4, 117558, Singapore.,School of Biological Sciences, Nanyang Technological University, 60 Nanyang Drive, 637551, Singapore
| | - Kassoum Nacro
- Experimental Drug Development Centre (EDDC), A*STAR, 10 Biopolis Road, Chromos #05-01, 138670, Singapore
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14
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Jensen KB, Dredge BK, Toubia J, Jin X, Iadevaia V, Goodall GJ, Proud CG. capCLIP: a new tool to probe translational control in human cells through capture and identification of the eIF4E-mRNA interactome. Nucleic Acids Res 2021; 49:e105. [PMID: 34255842 PMCID: PMC8501963 DOI: 10.1093/nar/gkab604] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2021] [Revised: 06/16/2021] [Accepted: 07/06/2021] [Indexed: 12/21/2022] Open
Abstract
Translation of eukaryotic mRNAs begins with binding of their m7G cap to eIF4E, followed by recruitment of other translation initiation factor proteins. We describe capCLIP, a novel method to comprehensively capture and quantify the eIF4E (eukaryotic initiation factor 4E) 'cap-ome' and apply it to examine the biological consequences of eIF4E-cap binding in distinct cellular contexts. First, we use capCLIP to identify the eIF4E cap-omes in human cells with/without the mTORC1 (mechanistic target of rapamycin, complex 1) inhibitor rapamycin, there being an emerging consensus that rapamycin inhibits translation of TOP (terminal oligopyrimidine) mRNAs by displacing eIF4E from their caps. capCLIP reveals that the representation of TOP mRNAs in the cap-ome is indeed systematically reduced by rapamycin, thus validating our new methodology. capCLIP also refines the requirements for a functional TOP sequence. Second, we apply capCLIP to probe the consequences of phosphorylation of eIF4E. We show eIF4E phosphorylation reduces overall eIF4E-mRNA association and, strikingly, causes preferential dissociation of mRNAs with short 5'-UTRs. capCLIP is a valuable new tool to probe the function of eIF4E and of other cap-binding proteins such as eIF4E2/eIF4E3.
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Affiliation(s)
- Kirk B Jensen
- Lifelong Health, South Australian Health and Medical Research Institute, North Terrace, Adelaide, SA 5000, Australia.,School of Biological Sciences, Faculty of Sciences, University of Adelaide, Adelaide, SA 5005, Australia
| | - B Kate Dredge
- Centre for Cancer Biology, SA Pathology and University of South Australia, Adelaide, SA 5000, Australia
| | - John Toubia
- Centre for Cancer Biology, SA Pathology and University of South Australia, Adelaide, SA 5000, Australia.,ACRF Cancer Genomics Facility, Centre for Cancer Biology, SA Pathology and University of South Australia, Frome Road, Adelaide, SA 5000, Australia
| | - Xin Jin
- Lifelong Health, South Australian Health and Medical Research Institute, North Terrace, Adelaide, SA 5000, Australia.,School of Medicine and Pharmacy, Ocean University of China, 5 Yushan Road, Qingdao 266003, China
| | - Valentina Iadevaia
- School of Biosciences and Medicine, University of Surrey, Guildford, Surrey GU2 7XH, UK
| | - Gregory J Goodall
- School of Biological Sciences, Faculty of Sciences, University of Adelaide, Adelaide, SA 5005, Australia.,Centre for Cancer Biology, SA Pathology and University of South Australia, Adelaide, SA 5000, Australia.,Adelaide Medical School, Faculty of Health and Medical Sciences, University of Adelaide, Adelaide, SA 5005, Australia
| | - Christopher G Proud
- Lifelong Health, South Australian Health and Medical Research Institute, North Terrace, Adelaide, SA 5000, Australia.,School of Biological Sciences, Faculty of Sciences, University of Adelaide, Adelaide, SA 5005, Australia
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15
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Das S. Taking a re-look at cap-binding signatures of the mRNA cap-binding protein eIF4E orthologues in trypanosomatids. Mol Cell Biochem 2020; 476:1037-1049. [PMID: 33169189 DOI: 10.1007/s11010-020-03970-w] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2020] [Accepted: 10/31/2020] [Indexed: 01/04/2023]
Abstract
Protein translation leading to polypeptide synthesis involves three distinct events, namely, initiation, elongation, and termination. Translation initiation is a multi-step process that is carried out by ribosomes on the mRNA with the assistance of a large number of proteins called translation initiation factors. Trypanosomatids are kinetoplastidas (flagellated protozoans), some of which cause acute disease syndromes in humans. Vector-borne transmission of protozoan parasites like Leishmania and Trypanosoma causes diseases that affect a large section of the world population and lead to significant morbidity and mortality. The mechanisms of translation initiation in higher eukaryotes are relatively well understood. However, structural and functional conservation of initiation factors in trypanosomatids are only beginning to be understood. Studies carried out so far suggests that at least in Leishmania and Trypanosoma eIF4E function may not be restricted to canonical translation initiation and some of the homologues may have alternate/non-canonical functions. Nonetheless, all of them bind the cap analogs, albeit with different efficiencies, indicating that this property may play an important role in the functionality of eIF4Es. Here, I give a brief background of trypanosomatid eIF4Es and revisit the cap-binding signatures of eIF4E orthologues in trypanosomatids, whose genome sequences are available, in detail, in comparison to human eIF4E1 and Trypanosoma cruzi eIF4E5, with an expanded list of members of this group in light of newer findings. The group 1 and 2 eIF4Es may use either a variation of heIF4E1 or T. cruzi eIF4E5 cap-4-binding signatures, while eIF4E5 and eIF4E6 use distinct amino acid contacts.
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Affiliation(s)
- Supratik Das
- Translational Health Science and Technology Institute, NCR Biotech Science Cluster, 3rd Milestone, Faridabad-Gurgaon Expressway, PO Box #04, Faridabad, Haryana, 121001, India.
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16
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Abstract
The stage at which ribosomes are recruited to messenger RNAs (mRNAs) is an elaborate and highly regulated phase of protein synthesis. Upon completion of this step, a ribosome is positioned at an appropriate initiation codon and primed to synthesize the encoded polypeptide product. In most circumstances, this step commits the ribosome to translate the mRNA. We summarize the knowledge regarding the initiation factors implicated in this activity as well as review different mechanisms by which this process is conducted.
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Affiliation(s)
- Jerry Pelletier
- Department of Biochemistry, McGill University, Montreal, Quebec H3G 1Y6, Canada; , .,Rosalind and Morris Goodman Cancer Research Center, McGill University, Montreal, Quebec H3A 1A3, Canada.,Department of Oncology, McGill University, Montreal, Quebec H4A 3T2, Canada
| | - Nahum Sonenberg
- Department of Biochemistry, McGill University, Montreal, Quebec H3G 1Y6, Canada; , .,Rosalind and Morris Goodman Cancer Research Center, McGill University, Montreal, Quebec H3A 1A3, Canada
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17
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Translation initiation factors GleIF4E2 and GleIF4A can interact directly with the components of the pre-initiation complex to facilitate translation initiation in Giardia lamblia. Mol Biochem Parasitol 2020; 236:111258. [DOI: 10.1016/j.molbiopara.2020.111258] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2019] [Revised: 12/31/2019] [Accepted: 01/13/2020] [Indexed: 01/20/2023]
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18
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Saha S, Mäkinen K. Insights into the Functions of eIF4E-Biding Motif of VPg in Potato Virus A Infection. Viruses 2020; 12:E197. [PMID: 32053987 PMCID: PMC7077193 DOI: 10.3390/v12020197] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2020] [Revised: 02/05/2020] [Accepted: 02/07/2020] [Indexed: 12/14/2022] Open
Abstract
The interaction between the viral protein genome-linked (VPg) and eukaryotic initiation factor 4E (eIF4E) or eIF(iso)4E of the host plays a crucial role in potyvirus infection. The VPg of potato virus A (PVA) contains the Tyr-X-X-X-X-Leu-phi (YXXXLΦ) binding motif for eIF(iso)4E. In order to investigate its role in PVA infection, we substituted the conserved tyrosine and leucine residues of the motif with alanine residues in the infectious cDNA of PVA (PVAVPgmut). PVAVPgmut RNA replicated in infiltrated leaves, but RNA accumulation remained low. Systemic infection occurred only if a reversion to wild type PVA occurred. VPg was able to stabilize PVA RNA and enhance the expression of Renilla luciferase (3'RLUC) from the 3' end of the PVA genome. VPgmut could not support either PVA RNA stabilization or enhanced 3'RLUC expression. The RNA silencing suppressor helper-component proteinase (HCPro) is responsible for the formation of PVA-induced RNA granules (PGs) during infection. While VPgmut increased the number of PG-like foci, the percentage of PVA RNA co-localization with PGs was reduced from 86% to 20%. A testable hypothesis for future studies based on these results is that the binding of eIF(iso)4E to PVA VPg via the YXXXLΦ motif is required for PVA RNA stabilization, as well as the transfer to the RNA silencing suppression pathway and, further, to polysomes for viral protein synthesis.
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Affiliation(s)
| | - Kristiina Mäkinen
- Department of Microbiology and Viikki Plant Science Centre, University of Helsinki, 00014 Helsinki, Finland;
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19
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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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20
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Reolon LW, Vichier-Guerre S, de Matos BM, Dugué L, Assunção TRDS, Zanchin NIT, Pochet S, Guimarães BG. Crystal structure of the Trypanosoma cruzi EIF4E5 translation factor homologue in complex with mRNA cap-4. Nucleic Acids Res 2019; 47:5973-5987. [PMID: 31066441 PMCID: PMC6582342 DOI: 10.1093/nar/gkz339] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2019] [Revised: 04/18/2019] [Accepted: 04/24/2019] [Indexed: 12/20/2022] Open
Abstract
Association of the initiation factor eIF4E with the mRNA cap structure is a key step for translation. Trypanosomatids present six eIF4E homologues, showing a low conservation and also differing significantly from the IF4Es of multicellular eukaryotes. On the mRNA side, while in most eukaryotes the mRNA contains cap-0 (7-methyl-GTP), the trypanosomatid mRNA features a cap-4, which is formed by a cap-0, followed by the AACU sequence containing 2′-O-ribose methylations and base methylations on nucleotides 1 and 4. The studies on eIF4E-cap-4 interaction have been hindered by the difficulty to synthesize this rather elaborated cap-4 sequence. To overcome this problem, we applied a liquid-phase oligonucleotide synthesis strategy and describe for the first time the crystal structure of a trypanosomatid eIF4E (T. cruzi EIF4E5) in complex with cap-4. The TcEIF4E5-cap-4 structure allowed a detailed description of the binding mechanism, revealing the interaction mode for the AACU sequence, with the bases packed in a parallel stacking conformation and involved, together with the methyl groups, in hydrophobic contacts with the protein. This binding mechanism evidences a distinct cap interaction mode in comparison with previously described eIF4E structures and may account for the difference of TcEIF4E5-cap-4 dissociation constant in comparison with other eIF4E homologues.
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Affiliation(s)
- Lidia Watanabe Reolon
- Carlos Chagas Institute, Oswaldo Cruz Foundation, FIOCRUZ-PR, Curitiba, Paraná 81350-010, Brazil.,Biochemistry Postgraduate Program, Federal University of Parana, Curitiba, Paraná 81530-000, Brazil
| | | | - Bruno Moisés de Matos
- Carlos Chagas Institute, Oswaldo Cruz Foundation, FIOCRUZ-PR, Curitiba, Paraná 81350-010, Brazil.,Biochemistry Postgraduate Program, Federal University of Parana, Curitiba, Paraná 81530-000, Brazil
| | - Laurence Dugué
- Unité de Chimie et Biocatalyse, Institut Pasteur, UMR3523 CNRS, Paris 75015, France
| | | | - Nilson Ivo Tonin Zanchin
- Carlos Chagas Institute, Oswaldo Cruz Foundation, FIOCRUZ-PR, Curitiba, Paraná 81350-010, Brazil
| | - Sylvie Pochet
- Unité de Chimie et Biocatalyse, Institut Pasteur, UMR3523 CNRS, Paris 75015, France
| | - Beatriz Gomes Guimarães
- Carlos Chagas Institute, Oswaldo Cruz Foundation, FIOCRUZ-PR, Curitiba, Paraná 81350-010, Brazil.,Biochemistry Postgraduate Program, Federal University of Parana, Curitiba, Paraná 81530-000, Brazil
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21
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Kim HJ. Cell Fate Control by Translation: mRNA Translation Initiation as a Therapeutic Target for Cancer Development and Stem Cell Fate Control. Biomolecules 2019; 9:biom9110665. [PMID: 31671902 PMCID: PMC6921038 DOI: 10.3390/biom9110665] [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: 10/10/2019] [Revised: 10/28/2019] [Accepted: 10/28/2019] [Indexed: 12/11/2022] Open
Abstract
Translation of mRNA is an important process that controls cell behavior and gene regulation because proteins are the functional molecules that determine cell types and function. Cancer develops as a result of genetic mutations, which lead to the production of abnormal proteins and the dysregulation of translation, which in turn, leads to aberrant protein synthesis. In addition, the machinery that is involved in protein synthesis plays critical roles in stem cell fate determination. In the current review, recent advances in the understanding of translational control, especially translational initiation in cancer development and stem cell fate control, are described. Therapeutic targets of mRNA translation such as eIF4E, 4EBP, and eIF2, for cancer treatment or stem cell fate regulation are reviewed. Upstream signaling pathways that regulate and affect translation initiation were introduced. It is important to regulate the expression of protein for normal cell behavior and development. mRNA translation initiation is a key step to regulate protein synthesis, therefore, identifying and targeting molecules that are critical for protein synthesis is necessary and beneficial to develop cancer therapeutics and stem cells fate regulation.
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Affiliation(s)
- Hyun-Jung Kim
- Laboratory of Molecular Stem Cell Pharmacology, College of Pharmacy, Chung-Ang University, Seoul 156-756, Korea.
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22
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Santos Pereira-Dutra F, Cancela M, Valandro Meneghetti B, Bunselmeyer Ferreira H, Mariante Monteiro K, Zaha A. Functional characterization of the translation initiation factor eIF4E of Echinococcus granulosus. Parasitol Res 2019; 118:2843-2855. [PMID: 31401657 DOI: 10.1007/s00436-019-06421-8] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2019] [Accepted: 08/02/2019] [Indexed: 01/24/2023]
Abstract
The eukaryotic initiation factor 4E (eIF4E) specifically recognizes the 5' mRNA cap, a rate-limiting step in the translation initiation process. Although the 7-methylguanosine cap (MMGcap) is the most common 5' cap structure in eukaryotes, the trans-splicing process that occurs in several organism groups, including nematodes and flatworms, leads to the addition of a trimethylguanosine cap (TMGcap) to some RNA transcripts. In some helminths, eIF4E can have a dual capacity to bind both MMGcap and TMGcap. In the present work, we evaluated the distribution of eIF4E protein sequences in platyhelminths and we showed that only one gene coding for eIF4E is present in most parasitic flatworms. Based on this result, we cloned the Echinococcus granulosus cDNA sequence encoding eIF4E in Escherichia coli, expressed the recombinant eIF4E as a fusion protein to GST, and tested its ability to capture mRNAs through the 5' cap using pull-down assay and qPCR. Our results indicate that the recombinant eIF4E was able to bind preferentially 5'-capped mRNAs compared with rRNAs from total RNA preparations of E. granulosus. By qPCR, we observed an enrichment in MMG-capped mRNA compared with TMG-capped mRNAs among Eg-eIF4E-GST pull-down RNAs. Eg-eIF4E structural model using the Schistosoma mansoni eIF4E as template showed to be well preserved with only a few differences between chemically similar amino acid residues at the binding sites. These data showed that E. granulosus eIF4E can be used as a potential tool to study full-length 5'-capped mRNA, besides being a potential drug target against parasitic flatworms.
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Affiliation(s)
- Filipe Santos Pereira-Dutra
- Laboratório de Biologia Molecular de Cestodeos, Centro de Biotecnologia, Universidade Federal do Rio Grande do Sul, UFRGS, Avenida Bento Gonçalves, 9500, Caixa Postal 15053, Porto Alegre, RS, CEP 91501-970, Brazil.,Programa de Pós-Graduação em Biologia Celular e Molecular, Centro de Biotecnologia, UFRGS, Porto Alegre, Brazil
| | - Martin Cancela
- Laboratório de Biologia Molecular de Cestodeos, Centro de Biotecnologia, Universidade Federal do Rio Grande do Sul, UFRGS, Avenida Bento Gonçalves, 9500, Caixa Postal 15053, Porto Alegre, RS, CEP 91501-970, Brazil.,Programa de Pós-Graduação em Biologia Celular e Molecular, Centro de Biotecnologia, UFRGS, Porto Alegre, Brazil
| | - Bruna Valandro Meneghetti
- Laboratório de Biologia Molecular de Cestodeos, Centro de Biotecnologia, Universidade Federal do Rio Grande do Sul, UFRGS, Avenida Bento Gonçalves, 9500, Caixa Postal 15053, Porto Alegre, RS, CEP 91501-970, Brazil.,Programa de Pós-Graduação em Biologia Celular e Molecular, Centro de Biotecnologia, UFRGS, Porto Alegre, Brazil
| | - Henrique Bunselmeyer Ferreira
- Laboratório de Biologia Molecular de Cestodeos, Centro de Biotecnologia, Universidade Federal do Rio Grande do Sul, UFRGS, Avenida Bento Gonçalves, 9500, Caixa Postal 15053, Porto Alegre, RS, CEP 91501-970, Brazil.,Programa de Pós-Graduação em Biologia Celular e Molecular, Centro de Biotecnologia, UFRGS, Porto Alegre, Brazil.,Departamento de Biologia Molecular e Biotecnologia, Instituto de Biociências, UFRGS, Porto Alegre, Brazil
| | - Karina Mariante Monteiro
- Laboratório de Biologia Molecular de Cestodeos, Centro de Biotecnologia, Universidade Federal do Rio Grande do Sul, UFRGS, Avenida Bento Gonçalves, 9500, Caixa Postal 15053, Porto Alegre, RS, CEP 91501-970, Brazil.,Programa de Pós-Graduação em Biologia Celular e Molecular, Centro de Biotecnologia, UFRGS, Porto Alegre, Brazil.,Departamento de Biologia Molecular e Biotecnologia, Instituto de Biociências, UFRGS, Porto Alegre, Brazil
| | - Arnaldo Zaha
- Laboratório de Biologia Molecular de Cestodeos, Centro de Biotecnologia, Universidade Federal do Rio Grande do Sul, UFRGS, Avenida Bento Gonçalves, 9500, Caixa Postal 15053, Porto Alegre, RS, CEP 91501-970, Brazil. .,Programa de Pós-Graduação em Biologia Celular e Molecular, Centro de Biotecnologia, UFRGS, Porto Alegre, Brazil. .,Departamento de Biologia Molecular e Biotecnologia, Instituto de Biociências, UFRGS, Porto Alegre, Brazil.
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23
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Abstract
BACKGROUND Molecular switches in phosphatidylinositol 3-kinase (PI3K)-AKT signaling pathway may serve as potential targets for the treatment of colorectal cancer (CRC). This study aims to profile the gene alterations involved in PI3K-AKT signaling pathway in patients with CRC. METHODS Tumoral and matched peritumoral tissues were collected from 15 CRC patients who went routine surgery. A human PI3K-AKT signaling pathway polymerase chain reaction (PCR) array, which profiled the transcriptional changes of a total number of 84 genes involved in the PI3K-AKT pathway, was then applied to determine the gene alterations in CRC tumoral tissue with matched peritumoral tissue as a healthy control. Subsequent real-time reverse transcription PCR and western blot (WB) with different subgroups of CRC patients were then performed to further validate the array findings. RESULTS The PCR array identified 14 aberrantly expressed genes involved in the PI3K-AKT signaling pathway in CRC tumoral tissue, among which 12 genes, CCND1, CSNK2A1, EIF4E, EIF4EBP1, EIF4G1, FOS, GRB10, GSK3B, ILK, PTK2, PTPN11, and PHEB were significantly up-modulated (> two fold) while the remaining two, PDK1 and PIK3CG, were down-regulated (> two fold). These genes involve in the regulation of gene transcription and translation, cell cycle, and cell growth, proliferation, and differentiation. The real-time reverse transcription PCR validation agreed with the array data towards the tested genes, CCND1, EIF4E, FOS, and PIK3CG, while it failed to obtain similar result for PDK1. Interestingly, the WB analyses were further consistent with the PCR results that the protein levels of CCND1, EIF4E, and FOS were apparently up-regulated and that protein PIK3CG was down-modulated. CONCLUSION Taken together, the present study identified a deregulated PI3K-AKT signaling pathway in CRC patients, which might serve as therapeutic target(s).
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24
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Hu J, Sun F, Handel MA. Nuclear localization of EIF4G3 suggests a role for the XY body in translational regulation during spermatogenesis in mice. Biol Reprod 2019; 98:102-114. [PMID: 29161344 DOI: 10.1093/biolre/iox150] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2017] [Accepted: 11/16/2017] [Indexed: 12/28/2022] Open
Abstract
Eukaryotic translation initiation factor 4G (EIF4G) is an important scaffold protein in the translation initiation complex. In mice, mutation of the Eif4g3 gene causes male infertility, with arrest of meiosis at the end of meiotic prophase. This study documents features of the developmental expression and subcellular localization of EIF4G3 that might contribute to its highly specific role in meiosis and spermatogenesis. Quite unexpectedly, EIF4G3 is located in the nucleus of spermatocytes, where it is highly enriched in the XY body, the chromatin domain formed by the transcriptionally inactive sex chromosomes. Moreover, many other, but not all, translation-related proteins are also localized in the XY body. These unanticipated observations implicate roles for the XY body in controlling mRNA metabolism and/or "poising" protein translation complexes before the meiotic division phase in spermatocytes.
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Affiliation(s)
| | - Fengyun Sun
- The Jackson Laboratory, Bar Harbor, Maine, USA
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25
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Lu H, Mazumder M, Jaikaran ASI, Kumar A, Leis EK, Xu X, Altmann M, Cochrane A, Woolley GA. A Yeast System for Discovering Optogenetic Inhibitors of Eukaryotic Translation Initiation. ACS Synth Biol 2019; 8:744-757. [PMID: 30901519 DOI: 10.1021/acssynbio.8b00386] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
The precise spatiotemporal regulation of protein synthesis is essential for many complex biological processes such as memory formation, embryonic development, and tumor formation. Current methods used to study protein synthesis offer only a limited degree of spatiotemporal control. Optogenetic methods, in contrast, offer the prospect of controlling protein synthesis noninvasively within minutes and with a spatial scale as small as a single synapse. Here, we present a hybrid yeast system where growth depends on the activity of human eukaryotic initiation factor 4E (eIF4E) that is suitable for screening optogenetic designs for the down-regulation of protein synthesis. We used this system to screen a diverse initial panel of 15 constructs designed to couple a light switchable domain (PYP, RsLOV, AsLOV, Dronpa) to 4EBP2 (eukaryotic initiation factor 4E binding protein 2), a native inhibitor of translation initiation. We identified cLIPS1 (circularly permuted LOV inhibitor of protein synthesis 1), a fusion of a segment of 4EBP2 and a circularly permuted version of the LOV2 domain from Avena sativa, as a photoactivated inhibitor of translation. Adapting the screen for higher throughput, we tested small libraries of cLIPS1 variants and found cLIPS2, a construct with an improved degree of optical control. We show that these constructs can both inhibit translation in yeast harboring a human eIF4E in vivo, and bind human eIF4E in vitro in a light-dependent manner. This hybrid yeast system thus provides a convenient way for discovering optogenetic constructs that can regulate human eIF4E-dependent translation initiation in a mechanistically defined manner.
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Affiliation(s)
- Huixin Lu
- Department of Chemistry, University of Toronto, 80 St. George Street, Toronto, ON M5S 3H6, Canada
| | - Mostafizur Mazumder
- Department of Chemistry, University of Toronto, 80 St. George Street, Toronto, ON M5S 3H6, Canada
| | - Anna S. I. Jaikaran
- Department of Chemistry, University of Toronto, 80 St. George Street, Toronto, ON M5S 3H6, Canada
| | - Anil Kumar
- Department of Chemistry, University of Toronto, 80 St. George Street, Toronto, ON M5S 3H6, Canada
| | - Eric K. Leis
- Department of Chemistry, University of Toronto, 80 St. George Street, Toronto, ON M5S 3H6, Canada
| | - Xiuling Xu
- Department of Chemistry, University of Toronto, 80 St. George Street, Toronto, ON M5S 3H6, Canada
| | - Michael Altmann
- Institut für Biochemie und Molekulare Medizin, Universität Bern, Bühlstr. 28, CH-3012 Bern, Switzerland
| | - Alan Cochrane
- Department of Molecular Genetics, University of Toronto, 1 King’s College Circle, Toronto, ON M5S 1A8, Canada
| | - G. Andrew Woolley
- Department of Chemistry, University of Toronto, 80 St. George Street, Toronto, ON M5S 3H6, Canada
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26
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Pazo A, Pérez-González A, Oliveros JC, Huarte M, Chavez JP, Nieto A. hCLE/RTRAF-HSPC117-DDX1-FAM98B: A New Cap-Binding Complex That Activates mRNA Translation. Front Physiol 2019; 10:92. [PMID: 30833903 PMCID: PMC6388641 DOI: 10.3389/fphys.2019.00092] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2018] [Accepted: 01/25/2019] [Indexed: 11/29/2022] Open
Abstract
hCLE/C14orf166/RTRAF, DDX1, and HSPC117 are components of cytoplasmic mRNA-transporting granules kinesin-associated in dendrites. They have also been found in cytoplasmic ribosome-containing RNA granules that transport specific mRNAs halted for translation until specific neuronal signals renders them accessible to the translation machinery. hCLE associates to DDX1, HSPC117, and FAM98B in HEK293T cells and all four proteins bind to cap analog-containing resins. Competition and elution experiments indicate that binding of hCLE complex to cap resins is independent of eIF4E; the cap-binding factor needed for translation. Purified hCLE free of its associated proteins binds cap with low affinity suggesting that its interacting proteins modulate its cap association. hCLE silencing reduces hCLE accumulation and that of its interacting proteins and decreases mRNA translation. hCLE-associated RNAs have been isolated and sequenced; RNAs involved in mRNA translation are specifically associated. The data suggest that RNA granules may co-transport RNAs encoding proteins involved in specific functions together with RNAs that encode proteins needed for the translation of these specific RNAs and indicate an important role for hCLE modulating mRNA translation.
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Affiliation(s)
- Alejandra Pazo
- Centro Nacional de Biotecnología (CSIC), Madrid, Spain.,CIBER de Enfermedades Respiratorias, Madrid, Spain
| | - Alicia Pérez-González
- Centro Nacional de Biotecnología (CSIC), Madrid, Spain.,CIBER de Enfermedades Respiratorias, Madrid, Spain
| | | | - Maite Huarte
- Department of Gene Therapy and Regulation of Gene Expression, Center for Applied Medical Research (CIMA), University of Navarra, Pamplona, Spain
| | - Juan Pablo Chavez
- Centro Nacional de Biotecnología (CSIC), Madrid, Spain.,CIBER de Enfermedades Respiratorias, Madrid, Spain
| | - Amelia Nieto
- Centro Nacional de Biotecnología (CSIC), Madrid, Spain.,CIBER de Enfermedades Respiratorias, Madrid, Spain
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27
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Lama D, Liberatore AM, Frosi Y, Nakhle J, Tsomaia N, Bashir T, Lane DP, Brown CJ, Verma CS, Auvin S. Structural insights reveal a recognition feature for tailoring hydrocarbon stapled-peptides against the eukaryotic translation initiation factor 4E protein. Chem Sci 2019; 10:2489-2500. [PMID: 30881679 PMCID: PMC6385854 DOI: 10.1039/c8sc03759k] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2018] [Accepted: 12/21/2018] [Indexed: 11/21/2022] Open
Abstract
Stapled-peptides have emerged as an exciting class of molecules which can modulate protein-protein interactions. We have used a structure-guided approach to rationally develop a set of hydrocarbon stapled-peptides with high binding affinities and residence times against the oncogenic eukaryotic translation initiation factor 4E (eIF4E) protein. Crystal structures of these peptides in complex with eIF4E show that they form specific interactions with a region on the protein-binding interface of eIF4E which is distinct from the other well-established canonical interactions. This recognition element is a major molecular determinant underlying the improved binding kinetics of these peptides with eIF4E. The interactions were further exploited by designing features in the peptides to attenuate disorder and increase helicity which collectively resulted in the generation of a distinct class of hydrocarbon stapled-peptides targeting eIF4E. This study details new insights into the molecular basis of stapled-peptide: eIF4E interactions and their exploitation to enhance promising lead molecules for the development of stapled-peptide compounds for oncology.
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Affiliation(s)
- Dilraj Lama
- Bioinformatics Institute , ASTAR (Agency for Science, Technology and Research) , 30 Biopolis Street, #07-01 Matrix , Singapore 138671 . ; Tel: +65 6478 8273
| | - Anne-Marie Liberatore
- Ipsen Innovation , 5, Avenue du Canada , Les Ulis , France 91940 . ; Tel: +33 160 922481
| | - Yuri Frosi
- p53 Laboratory , ASTAR (Agency for Science, Technology and Research) , 8A Biomedical Grove, #06-04/05, Neuros/Immunos , Singapore 138648 . ; Tel: +65 6478 8273
| | - Jessica Nakhle
- Ipsen Innovation , 5, Avenue du Canada , Les Ulis , France 91940 . ; Tel: +33 160 922481
| | - Natia Tsomaia
- Ipsen Bioscience , 650 East Kendall Street , Cambridge , MA 02142 , USA
| | - Tarig Bashir
- Ipsen Innovation , 5, Avenue du Canada , Les Ulis , France 91940 . ; Tel: +33 160 922481
| | - David P Lane
- p53 Laboratory , ASTAR (Agency for Science, Technology and Research) , 8A Biomedical Grove, #06-04/05, Neuros/Immunos , Singapore 138648 . ; Tel: +65 6478 8273
| | - Christopher J Brown
- p53 Laboratory , ASTAR (Agency for Science, Technology and Research) , 8A Biomedical Grove, #06-04/05, Neuros/Immunos , Singapore 138648 . ; Tel: +65 6478 8273
| | - Chandra S Verma
- Bioinformatics Institute , ASTAR (Agency for Science, Technology and Research) , 30 Biopolis Street, #07-01 Matrix , Singapore 138671 . ; Tel: +65 6478 8273.,Department of Biological Sciences , National University of Singapore , 14 Science Drive 4 , Singapore 117543.,School of Biological Sciences , Nanyang Technological University , 50 Nanyang Drive , Singapore 637551
| | - Serge Auvin
- Ipsen Innovation , 5, Avenue du Canada , Les Ulis , France 91940 . ; Tel: +33 160 922481
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28
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Patrick RM, Lee JCH, Teetsel JRJ, Yang SH, Choy GS, Browning KS. Discovery and characterization of conserved binding of eIF4E 1 (CBE1), a eukaryotic translation initiation factor 4E-binding plant protein. J Biol Chem 2018; 293:17240-17247. [PMID: 30213859 DOI: 10.1074/jbc.ra118.003945] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2018] [Revised: 08/08/2018] [Indexed: 12/23/2022] Open
Abstract
In many eukaryotes, translation initiation is regulated by proteins that bind to the mRNA cap-binding protein eukaryotic translation initiation factor 4E (eIF4E). These proteins commonly prevent association of eIF4E with eIF4G or form repressive messenger ribonucleoproteins that exclude the translation machinery. Such gene-regulatory mechanisms in plants, and even the presence of eIF4E-interacting proteins other than eIF4G (and the plant-specific isoform eIFiso4G, which binds eIFiso4E), are unknown. Here, we report the discovery of a plant-specific protein, conserved binding of eIF4E 1 (CBE1). We found that CBE1 has an evolutionarily conserved eIF4E-binding motif in its N-terminal domain and binds eIF4E or eIFiso4E in vitro CBE1 thereby forms cap-binding complexes and is an eIF4E-dependent constituent of these complexes in vivo Of note, plant mutants lacking CBE1 exhibited dysregulation of cell cycle-related transcripts and accumulated higher levels of mRNAs encoding proteins involved in mitosis than did WT plants. Our findings indicate that CBE1 is a plant protein that can form mRNA cap-binding complexes having the potential for regulating gene expression. Because mammalian translation factors are known regulators of cell cycle progression, we propose that CBE1 may represent such first translation factor-associated plant-specific cell cycle regulator.
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Affiliation(s)
- Ryan M Patrick
- From the Department of Molecular Biosciences and Institute for Cell and Molecular Biology, The University of Texas at Austin, Austin, Texas 78712
| | - Jessica C H Lee
- From the Department of Molecular Biosciences and Institute for Cell and Molecular Biology, The University of Texas at Austin, Austin, Texas 78712
| | - Jade R J Teetsel
- From the Department of Molecular Biosciences and Institute for Cell and Molecular Biology, The University of Texas at Austin, Austin, Texas 78712
| | - Soo-Hyun Yang
- From the Department of Molecular Biosciences and Institute for Cell and Molecular Biology, The University of Texas at Austin, Austin, Texas 78712
| | - Grace S Choy
- From the Department of Molecular Biosciences and Institute for Cell and Molecular Biology, The University of Texas at Austin, Austin, Texas 78712
| | - Karen S Browning
- From the Department of Molecular Biosciences and Institute for Cell and Molecular Biology, The University of Texas at Austin, Austin, Texas 78712
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29
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Moore KS, von Lindern M. RNA Binding Proteins and Regulation of mRNA Translation in Erythropoiesis. Front Physiol 2018; 9:910. [PMID: 30087616 PMCID: PMC6066521 DOI: 10.3389/fphys.2018.00910] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2018] [Accepted: 06/21/2018] [Indexed: 12/12/2022] Open
Abstract
Control of gene expression in erythropoiesis has to respond to signals that may emerge from intracellular processes or environmental factors. Control of mRNA translation allows for relatively rapid modulation of protein synthesis from the existing transcriptome. For instance, the protein synthesis rate needs to be reduced when reactive oxygen species or unfolded proteins accumulate in the cells, but also when iron supply is low or when growth factors are lacking in the environment. In addition, regulation of mRNA translation can be important as an additional layer of control on top of gene transcription, in which RNA binding proteins (RBPs) can modify translation of a set of transcripts to the cell’s actual protein requirement. The 5′ and 3′ untranslated regions of mRNA (5′UTR, 3′UTR) contain binding sites for general and sequence specific translation factors. They also contain secondary structures that may hamper scanning of the 5′UTR by translation complexes or may help to recruit translation factors. In addition, the term 5′UTR is not fully correct because many transcripts contain small open reading frames in their 5′UTR that are translated and contribute to regulation of mRNA translation. It is becoming increasingly clear that the transcriptome only partly predicts the proteome. The aim of this review is (i) to summarize how the availability of general translation initiation factors can selectively regulate transcripts because the 5′UTR contains secondary structures or short translated sequences, (ii) to discuss mechanisms that control the length of the mRNA poly(A) tail in relation to mRNA translation, and (iii) to give examples of sequence specific RBPs and their targets. We focused on transcripts and RBPs required for erythropoiesis. Whereas differentiation of erythroblasts to erythrocytes is orchestrated by erythroid transcription factors, the production of erythrocytes needs to respond to the availability of growth factors and nutrients, particularly the availability of iron.
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Affiliation(s)
- Kat S Moore
- Department of Hematopoiesis, Sanquin Research, and Landsteiner Laboratory, Amsterdam UMC, Amsterdam, Netherlands
| | - Marieke von Lindern
- Department of Hematopoiesis, Sanquin Research, and Landsteiner Laboratory, Amsterdam UMC, Amsterdam, Netherlands
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30
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Roy S, Jagus R, Morse D. Translation and Translational Control in Dinoflagellates. Microorganisms 2018; 6:microorganisms6020030. [PMID: 29642465 PMCID: PMC6027434 DOI: 10.3390/microorganisms6020030] [Citation(s) in RCA: 17] [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: 02/23/2018] [Revised: 04/03/2018] [Accepted: 04/05/2018] [Indexed: 12/24/2022] Open
Abstract
Dinoflagellates are unicellular protists that feature a multitude of unusual nuclear features, including large genomes, packaging of DNA without histones, and multiple gene copies organized as tandem gene arrays. Furthermore, all dinoflagellate mRNAs experience trans-splicing with a common 22-nucleotide splice leader (SL) sequence. These features challenge some of the concepts and assumptions about the regulation of gene expression derived from work on model eukaryotes such as yeasts and mammals. Translational control in the dinoflagellates, based on extensive study of circadian bioluminescence and by more recent microarray and transcriptome analyses, is now understood to be a crucial element in regulating gene expression. A picture of the translation machinery of dinoflagellates is emerging from the recent availability of transcriptomes of multiple dinoflagellate species and the first complete genome sequences. The components comprising the translational control toolkit of dinoflagellates are beginning to take shape and are outlined here.
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Affiliation(s)
- Sougata Roy
- Institut de Recherche en Biologie Végétale, Département de Sciences Biologiques, Université de Montréal, 4101 Sherbrooke East, Montréal, QC H1X 2B2, Canada.
| | - Rosemary Jagus
- Institute of Marine & Environmental Technology, University of Maryland Center for Environmental Science701 E. Pratt St., Baltimore, MD 21202, USA.
| | - David Morse
- Institut de Recherche en Biologie Végétale, Département de Sciences Biologiques, Université de Montréal, 4101 Sherbrooke East, Montréal, QC H1X 2B2, Canada.
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31
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Erben ED. High-throughput Methods for Dissection of Trypanosome Gene Regulatory Networks. Curr Genomics 2018; 19:78-86. [PMID: 29491736 PMCID: PMC5814965 DOI: 10.2174/1389202918666170815125336] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2016] [Revised: 12/22/2016] [Accepted: 02/03/2017] [Indexed: 12/24/2022] Open
Abstract
From synthesis to decay, mRNA associates with RNA-binding proteins (RBPs) establishing dynamic ribonucleoprotein particles (RNPs). Understanding the composition and function of RNPs is fundamental to understanding how eukaryotic mRNAs are controlled. This is especially relevant for trypanosomes and related kinetoplastid parasites, which mostly rely on post-transcriptional mechanisms to control gene expression. Crucial for trypanosome differentiation, development, or even response to heat shock, RBPs are known to be essential modulators of diverse molecular processes. The recent application of large-scale quantitative methods, such as Next-Generation Sequencing (NGS) and quantitative mass spectrometry, has revealed new exciting features about the parasite RNA-related metabolism. Novel proteins carrying RNA-binding activity, including many proteins without RNA-related ontology were discovered setting a necessary groundwork to get in insights into RNA biology. Conclusion: This review aims to give the reader an understanding of current trypanosome RNP research, highlighting the progress made using high-throughput approaches.
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Affiliation(s)
- Esteban D Erben
- Zentrum fur Molekulare Biologie der Universitet Heidelberg (ZMBH), Im Neuenheimer Feld 282, 69120Heidelberg, Germany
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32
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Piserà A, Campo A, Campo S. Structure and functions of the translation initiation factor eIF4E and its role in cancer development and treatment. J Genet Genomics 2018; 45:13-24. [DOI: 10.1016/j.jgg.2018.01.003] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2017] [Revised: 01/12/2018] [Accepted: 01/15/2018] [Indexed: 12/22/2022]
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33
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Kozarski M, Kubacka D, Wojtczak BA, Kasprzyk R, Baranowski MR, Kowalska J. 7-Methylguanosine monophosphate analogues with 5'-(1,2,3-triazoyl) moiety: Synthesis and evaluation as the inhibitors of cNIIIB nucleotidase. Bioorg Med Chem 2017; 26:191-199. [PMID: 29195795 DOI: 10.1016/j.bmc.2017.11.032] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2017] [Revised: 11/16/2017] [Accepted: 11/20/2017] [Indexed: 12/26/2022]
Abstract
The hydrolysis of nucleoside 5'-monophosphates to the corresponding nucleosides and inorganic phosphate is catalysed by 5'-nucleotidases, thereby contributing to the control of endogenous nucleotide turnover and affecting the fate of exogenously delivered nucleotide- and nucleoside-derived therapeutics in cells. A recently identified nucleotidase cNIIIB shows preference towards 7-methylguanosine monophosphate (m7GMP) as a substrate, which suggests its potential involvement in mRNA degradation. However, the extent of biological functions and the significance of cNIIIB remains to be elucidated. Here, we synthesised a series of m7GMP analogues carrying a 1,2,3-triazole moiety at the 5' position as the potential inhibitors of human cNIIIB. The compounds were synthesised by using the copper-catalysed azide-alkyne cycloaddition (CuAAC) between 5'-azido-5'-deoxy-7-methylguanosine and different phosphate or phosphonate derivatives carrying terminal alkyne. The analogues were evaluated as cNIIIB inhibitors using HPLC and malachite green assays, demonstrating that compound 1a, carrying a 1,2,3-triazoylphosphonate moiety, inhibits cNIIIB activity at micromolar concentrations (IC50 87.8 ± 7.5 µM), while other analogues showed no activity. In addition, compound 1d was identified as an artifical substrate for HscNIIIB. Further characterization of inhibitor 1a revealed that it is poorly recognised by other m7G-binding proteins, eIF4E and DcpS, indicating its selectivity towards cNIIIB. The first inhibitor (1a) and unnatural substrate (1d) of cNIIIB, identified here, can be used as molecular probes for the elucidation of biological roles of cNIIIB, including the verification of its proposed function in mRNA metabolism.
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Affiliation(s)
- Mateusz Kozarski
- University of Warsaw, Faculty of Physics, Institute of Experimental Physics, Division of Biophysics, Pasteura 5, 02-093 Warsaw, Poland
| | - Dorota Kubacka
- University of Warsaw, Faculty of Physics, Institute of Experimental Physics, Division of Biophysics, Pasteura 5, 02-093 Warsaw, Poland
| | - Blazej A Wojtczak
- University of Warsaw, Centre of New Technologies, Banacha 2c, 02-097 Warsaw, Poland
| | - Renata Kasprzyk
- University of Warsaw, Centre of New Technologies, Banacha 2c, 02-097 Warsaw, Poland; University of Warsaw, College of Inter-Faculty Individual Studies in Mathematics and Natural Sciences, Banacha 2c, 02-097 Warsaw, Poland
| | - Marek R Baranowski
- University of Warsaw, Faculty of Physics, Institute of Experimental Physics, Division of Biophysics, Pasteura 5, 02-093 Warsaw, Poland
| | - Joanna Kowalska
- University of Warsaw, Faculty of Physics, Institute of Experimental Physics, Division of Biophysics, Pasteura 5, 02-093 Warsaw, Poland.
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The Role of Cytoplasmic mRNA Cap-Binding Protein Complexes in Trypanosoma brucei and Other Trypanosomatids. Pathogens 2017; 6:pathogens6040055. [PMID: 29077018 PMCID: PMC5750579 DOI: 10.3390/pathogens6040055] [Citation(s) in RCA: 44] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2017] [Revised: 10/21/2017] [Accepted: 10/22/2017] [Indexed: 11/16/2022] Open
Abstract
Trypanosomatid protozoa are unusual eukaryotes that are well known for having unusual ways of controlling their gene expression. The lack of a refined mode of transcriptional control in these organisms is compensated by several post-transcriptional control mechanisms, such as control of mRNA turnover and selection of mRNA for translation, that may modulate protein synthesis in response to several environmental conditions found in different hosts. In other eukaryotes, selection of mRNA for translation is mediated by the complex eIF4F, a heterotrimeric protein complex composed by the subunits eIF4E, eIF4G, and eIF4A, where the eIF4E binds to the 5'-cap structure of mature mRNAs. In this review, we present and discuss the characteristics of six trypanosomatid eIF4E homologs and their associated proteins that form multiple eIF4F complexes. The existence of multiple eIF4F complexes in trypanosomatids evokes exquisite mechanisms for differential mRNA recognition for translation.
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35
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Shi S, Zhang X, Mandel MA, Zhang P, Zhang Y, Ferguson M, Amuge T, Rounsley S, Liu Z, Xiong Z. Variations of five eIF4E genes across cassava accessions exhibiting tolerant and susceptible responses to cassava brown streak disease. PLoS One 2017; 12:e0181998. [PMID: 28771520 PMCID: PMC5542559 DOI: 10.1371/journal.pone.0181998] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2017] [Accepted: 07/11/2017] [Indexed: 11/19/2022] Open
Abstract
Cassava (Manihot esculenta) is an important tropical subsistence crop that is severely affected by cassava brown streak disease (CBSD) in East Africa. The disease is caused by Cassava brown streak virus (CBSV) and Ugandan cassava brown streak virus (UCBSV). Both have a (+)-sense single-stranded RNA genome with a 5' covalently-linked viral protein, which functionally resembles the cap structure of mRNA, binds to eukaryotic translation initiation factor 4E (eIF4E) or its analogues, and then enable the translation of viral genomic RNA in host cells. To characterize cassava eIF4Es and their potential role in CBSD tolerance and susceptibility, we cloned five eIF4E transcripts from cassava (accession TMS60444). Sequence analysis indicated that the cassava eIF4E family of proteins consisted of one eIF4E, two eIF(iso)4E, and two divergent copies of novel cap-binding proteins (nCBPs). Our data demonstrated experimentally the coding of these five genes as annotated in the published cassava genome and provided additional evidence for refined annotations. Illumina resequencing data of the five eIF4E genes were analyzed from 14 cassava lines tolerant or susceptible to CBSD. Abundant single nucleotide polymorphisms (SNP) and biallelic variations were observed in the eIF4E genes; however, most of the SNPs were located in the introns and non-coding regions of the exons. Association studies of non-synonymous SNPs revealed no significant association between any SNP of the five eIF4E genes and the tolerance or susceptibility to CBSD. However, two SNPs in two genes were weakly associated with the CBSD responses but had no direct causal-effect relationship. SNPs in an intergenic region upstream of eIF4E_me showed a surprising strong association with CBSD responses. Digital expression profile analysis showed differential expression of different eIF4E genes but no significant difference in gene expression was found between susceptible and tolerant cassava accessions despite the association of the intergenic SNPs with CBSD responses.
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Affiliation(s)
- Shanshan Shi
- Institute of Tropical biology and biotechnology, Chinese Academy of Tropical Agricultural Sciences, Haikou, China
- School of Plant Sciences and BIO5 Institute, University of Arizona, Tucson, Arizona, United States of America
| | - Xiuchun Zhang
- Institute of Tropical biology and biotechnology, Chinese Academy of Tropical Agricultural Sciences, Haikou, China
| | - M. Alejandra Mandel
- School of Plant Sciences and BIO5 Institute, University of Arizona, Tucson, Arizona, United States of America
| | - Peng Zhang
- National Key Laboratory of Plant Molecular Genetics, CAS Center for Excellence in Molecular Plant Sciences, Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai, China
| | - Yuliang Zhang
- Institute of Tropical biology and biotechnology, Chinese Academy of Tropical Agricultural Sciences, Haikou, China
| | - Morag Ferguson
- International Institute of Tropical Agriculture (IITA), Nairobi, Kenya
| | - Teddy Amuge
- International Institute of Tropical Agriculture (IITA), Nairobi, Kenya
| | - Steve Rounsley
- Genus plc, DeForest, Wisconsin, United States of America
| | - Zhixin Liu
- Institute of Tropical biology and biotechnology, Chinese Academy of Tropical Agricultural Sciences, Haikou, China
- * E-mail: (ZX); (ZL)
| | - Zhongguo Xiong
- School of Plant Sciences and BIO5 Institute, University of Arizona, Tucson, Arizona, United States of America
- * E-mail: (ZX); (ZL)
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36
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Golob-Schwarzl N, Krassnig S, Toeglhofer AM, Park YN, Gogg-Kamerer M, Vierlinger K, Schröder F, Rhee H, Schicho R, Fickert P, Haybaeck J. New liver cancer biomarkers: PI3K/AKT/mTOR pathway members and eukaryotic translation initiation factors. Eur J Cancer 2017; 83:56-70. [PMID: 28715695 DOI: 10.1016/j.ejca.2017.06.003] [Citation(s) in RCA: 75] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2017] [Accepted: 06/01/2017] [Indexed: 12/14/2022]
Abstract
Hepatocellular carcinoma (HCC) is the third leading cause of cancer-related deaths worldwide. The initiation of protein translation is an important rate-limiting step in eukaryotes and is crucial in many viral infections. Eukaryotic translation initiation factors (eIFs) are involved in the initiation step of protein translation and are linked to the phosphatidylinositol-3-kinases PI3K/AKT/mTOR pathway. Therefore we aimed to investigate a potential role of eIFs in HCC. We herein report on the immunohistochemical expression of the various eIF subunits in 235 cases of virus-related human HCC. Additionally, we used immunoblot analysis to investigate the expression of virus-related HCC and non-virus-related HCC in comparison to controls. Mammalian target of rapamycin (or mechanistic target of rapamycin as it is known now (mTOR) and activated mTOR were significantly increased in chronic hepatitis C (HCV)-associated HCC, in HCC without a viral background, in alcoholic liver disease and Wilson disease. pPTEN, phosphatase and tensin homologue (PTEN) and pAKT showed a significant increase in HBV- and HCV-associated HCC, chronic hepatitis B, HCC without a viral background, alcoholic steatohepatitis (ASH) and Wilson disease. Phosphorylated (p)-eIF2α, eIF2α, eiF3B, eIF3D, eIF3J, p-eIF4B, eIF4G and eIF6 were upregulated in HCV-associated HCC. eIF2α, p-eIF4B, eIF5 and various eIF3 subunits were significantly increased in chronic hepatitis B (HBV)-associated HCC. HCC without viral background displayed a significant increase for the eIF subunits p-2α, 3C, 3I, 4E and 4G. We noticed engraved differences in the expression pattern between chronic hepatitis B and C, HBV- and HCV-associated HCC and non-virus-related HCC.
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Affiliation(s)
- Nicole Golob-Schwarzl
- Department of Pathology, Medical University of Graz, Austria; Center for Biomarker Research in Medicine, Graz, Austria
| | | | | | - Young Nyun Park
- Department of Pathology, Yonsei University, College of Medicine, Seoul, South Korea
| | | | | | | | - Hyungjn Rhee
- Department of Pathology, Yonsei University, University College of Medicine, Seoul, South Korea
| | - Rudolf Schicho
- Institute of Experimental and Clinical Pharmacology, Medical University of Graz, Austria
| | - Peter Fickert
- Division of Gastroenterology and Hepatology, Medical University of Graz, Austria
| | - Johannes Haybaeck
- Department of Pathology, Medical University of Graz, Austria; Center for Biomarker Research in Medicine, Graz, Austria; Department of Pathology, Otto-von-Guericke-University Magdeburg, Germany.
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Tate AT, Andolfatto P, Demuth JP, Graham AL. The within-host dynamics of infection in trans-generationally primed flour beetles. Mol Ecol 2017; 26:3794-3807. [PMID: 28277618 DOI: 10.1111/mec.14088] [Citation(s) in RCA: 49] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2016] [Revised: 02/17/2017] [Accepted: 02/21/2017] [Indexed: 12/19/2022]
Abstract
Many taxa exhibit plastic immune responses initiated after primary microbial exposure that provide increased protection against disease-induced mortality and the fitness costs of infection. In several arthropod species, this protection can even be passed from parents to offspring through a phenomenon called trans-generational immune priming. Here, we first demonstrate that trans-generational priming is a repeatable phenomenon in flour beetles (Tribolium castaneum) primed and infected with Bacillus thuringiensis (Bt). We then quantify the within-host dynamics of microbes and host physiological responses in infected offspring from primed and unprimed mothers by monitoring bacterial density and using mRNA-seq to profile host gene expression, respectively, over the acute infection period. We find that priming increases inducible resistance against Bt around a critical temporal juncture where host septicaemic trajectories, and consequently survival, may be determined in unprimed individuals. Our results identify a highly differentially expressed biomarker of priming, containing an EIF4-e domain, in uninfected individuals, as well as several other candidate genes. Moreover, the induction and decay dynamics of gene expression over time suggest a metabolic shift in primed individuals. The identified bacterial and gene expression dynamics are likely to influence patterns of bacterial fitness and disease transmission in natural populations.
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Affiliation(s)
- Ann T Tate
- Department of Ecology and Evolutionary Biology, Princeton University, Princeton, NJ, 08544, USA
| | - Peter Andolfatto
- Department of Ecology and Evolutionary Biology, Princeton University, Princeton, NJ, 08544, USA
| | - Jeffery P Demuth
- Department of Biology, University of Texas, Arlington, TX, 76010, USA
| | - Andrea L Graham
- Department of Ecology and Evolutionary Biology, Princeton University, Princeton, NJ, 08544, USA
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38
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Sesma A, Castresana C, Castellano MM. Regulation of Translation by TOR, eIF4E and eIF2α in Plants: Current Knowledge, Challenges and Future Perspectives. FRONTIERS IN PLANT SCIENCE 2017; 8:644. [PMID: 28491073 PMCID: PMC5405063 DOI: 10.3389/fpls.2017.00644] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/21/2017] [Accepted: 04/10/2017] [Indexed: 05/06/2023]
Abstract
An important step in eukaryotic gene expression is the synthesis of proteins from mRNA, a process classically divided into three stages, initiation, elongation, and termination. Translation is a precisely regulated and conserved process in eukaryotes. The presence of plant-specific translation initiation factors and the lack of well-known translational regulatory pathways in this kingdom nonetheless indicate how a globally conserved process can diversify among organisms. The control of protein translation is a central aspect of plant development and adaptation to environmental stress, but the mechanisms are still poorly understood. Here we discuss current knowledge of the principal mechanisms that regulate translation initiation in plants, with special attention to the singularities of this eukaryotic kingdom. In addition, we highlight the major recent breakthroughs in the field and the main challenges to address in the coming years.
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Affiliation(s)
- Ane Sesma
- Centro de Biotecnología y Genómica de Plantas, Universidad Politécnica de Madrid – Instituto Nacional de Investigación y Tecnología Agraria y AlimentariaMadrid, Spain
- Departamento Biotecnología y Biología Vegetal, Universidad Politécnica de MadridMadrid, Spain
| | - Carmen Castresana
- Centro Nacional de Biotecnología – Consejo Superior de Investigaciones Científicas (CSIC)Madrid, Spain
| | - M. Mar Castellano
- Centro de Biotecnología y Genómica de Plantas, Universidad Politécnica de Madrid – Instituto Nacional de Investigación y Tecnología Agraria y AlimentariaMadrid, Spain
- *Correspondence: M. Mar Castellano,
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39
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Ayuso MI, Martínez-Alonso E, Regidor I, Alcázar A. Stress Granule Induction after Brain Ischemia Is Independent of Eukaryotic Translation Initiation Factor (eIF) 2α Phosphorylation and Is Correlated with a Decrease in eIF4B and eIF4E Proteins. J Biol Chem 2016; 291:27252-27264. [PMID: 27836976 DOI: 10.1074/jbc.m116.738989] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2016] [Revised: 11/10/2016] [Indexed: 11/06/2022] Open
Abstract
Stress granules (SGs) are cytoplasmic ribonucleoprotein aggregates that are directly connected with the translation initiation arrest response to cellular stresses. Translation inhibition (TI) is observed in transient brain ischemia, a condition that induces persistent TI even after reperfusion, i.e. when blood flow is restored, and causes delayed neuronal death (DND) in selective vulnerable regions. We previously described a connection between TI and DND in the hippocampal cornu ammonis 1 (CA1) in an animal model of transient brain ischemia. To link the formation of SGs to TI and DND after brain ischemia, we investigated SG induction in brain regions with differential vulnerabilities to ischemia-reperfusion (IR) in this animal model. SG formation is triggered by both eukaryotic translation initiation factor (eIF) 2α phosphorylation and eIF4F complex dysfunction. We analyzed SGs by immunofluorescence colocalization of granule-associated protein T-cell internal antigen-1 with eIF3b, eIF4E, and ribosomal protein S6 and studied eIF2 and eIF4F complex. The results showed that IR stress induced SG formation in the CA1 region after 3-day reperfusion, consistent with TI and DND in CA1. SGs were formed independently of eIF2α phosphorylation, and their appearance was correlated with a decrease in the levels of eIF4F compounds, the cap-binding protein eIF4E, and eIF4B, suggesting that remodeling of the eIF4F complex was required for SG formation. Finally, pharmacological protection of CA1 ischemic neurons with cycloheximide decreased the formation of SGs and restored eIF4E and eIF4B levels in CA1. These findings link changes in eIF4B and eIF4E to SG induction in regions vulnerable to death after IR.
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Affiliation(s)
| | | | - Ignacio Regidor
- Neurophysiology, Hospital Ramón y Cajal, Instituto Ramón y Cajal de Investigación Sanitaria, E-28034 Madrid, Spain
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Strenkowska M, Grzela R, Majewski M, Wnek K, Kowalska J, Lukaszewicz M, Zuberek J, Darzynkiewicz E, Kuhn AN, Sahin U, Jemielity J. Cap analogs modified with 1,2-dithiodiphosphate moiety protect mRNA from decapping and enhance its translational potential. Nucleic Acids Res 2016; 44:9578-9590. [PMID: 27903882 PMCID: PMC5175369 DOI: 10.1093/nar/gkw896] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2016] [Revised: 09/24/2016] [Accepted: 09/28/2016] [Indexed: 11/30/2022] Open
Abstract
Along with a growing interest in mRNA-based gene therapies, efforts are increasingly focused on reaching the full translational potential of mRNA, as a major obstacle for in vivo applications is sufficient expression of exogenously delivered mRNA. One method to overcome this limitation is chemically modifying the 7-methylguanosine cap at the 5′ end of mRNA (m7Gppp-RNA). We report a novel class of cap analogs designed as reagents for mRNA modification. The analogs carry a 1,2-dithiodiphosphate moiety at various positions along a tri- or tetraphosphate bridge, and thus are termed 2S analogs. These 2S analogs have high affinities for translation initiation factor 4E, and some exhibit remarkable resistance against the SpDcp1/2 decapping complex when introduced into RNA. mRNAs capped with 2S analogs combining these two features exhibit high translation efficiency in cultured human immature dendritic cells. These properties demonstrate that 2S analogs are potentially beneficial for mRNA-based therapies such as anti-cancer immunization.
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Affiliation(s)
- Malwina Strenkowska
- Division of Biophysics, Institute of Experimental Physics, Faculty of Physics, University of Warsaw, Zwirki i Wigury 93 Warsaw 02-089, Poland
| | - Renata Grzela
- Centre of New Technologies, University of Warsaw, S. Banacha 2c, 02-097 Warsaw, Poland
| | - Maciej Majewski
- Division of Biophysics, Institute of Experimental Physics, Faculty of Physics, University of Warsaw, Zwirki i Wigury 93 Warsaw 02-089, Poland
| | - Katarzyna Wnek
- Division of Biophysics, Institute of Experimental Physics, Faculty of Physics, University of Warsaw, Zwirki i Wigury 93 Warsaw 02-089, Poland
| | - Joanna Kowalska
- Division of Biophysics, Institute of Experimental Physics, Faculty of Physics, University of Warsaw, Zwirki i Wigury 93 Warsaw 02-089, Poland
| | - Maciej Lukaszewicz
- Division of Biophysics, Institute of Experimental Physics, Faculty of Physics, University of Warsaw, Zwirki i Wigury 93 Warsaw 02-089, Poland
| | - Joanna Zuberek
- Division of Biophysics, Institute of Experimental Physics, Faculty of Physics, University of Warsaw, Zwirki i Wigury 93 Warsaw 02-089, Poland
| | - Edward Darzynkiewicz
- Division of Biophysics, Institute of Experimental Physics, Faculty of Physics, University of Warsaw, Zwirki i Wigury 93 Warsaw 02-089, Poland.,Centre of New Technologies, University of Warsaw, S. Banacha 2c, 02-097 Warsaw, Poland
| | - Andreas N Kuhn
- BioNTech RNA Pharmaceuticals GmbH, An der Goldgrube 12, 55131 Mainz, Germany.,Translational Oncology (TRON), Freiligrathstraße 12, 55131 Mainz, Germany
| | - Ugur Sahin
- BioNTech RNA Pharmaceuticals GmbH, An der Goldgrube 12, 55131 Mainz, Germany.,Translational Oncology (TRON), Freiligrathstraße 12, 55131 Mainz, Germany
| | - Jacek Jemielity
- Centre of New Technologies, University of Warsaw, S. Banacha 2c, 02-097 Warsaw, Poland
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41
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Beyond the survival and death of the deltamethrin-threatened pollen beetle Meligethes aeneus: An in-depth proteomic study employing a transcriptome database. J Proteomics 2016; 150:281-289. [PMID: 27705816 DOI: 10.1016/j.jprot.2016.09.016] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2016] [Revised: 09/10/2016] [Accepted: 09/28/2016] [Indexed: 12/18/2022]
Abstract
Insecticide resistance is an increasingly global problem that hampers pest control. We sought the mechanism responsible for survival following pyrethroid treatment and the factors connected to paralysis/death of the pollen beetle Meligethes aeneus through a proteome-level analysis using nanoLC coupled with Orbitrap Fusion™ Tribrid™ mass spectrometry. A tolerant field population of beetles was treated with deltamethrin, and the ensuing proteome changes were observed in the survivors (resistant), dead (paralyzed) and control-treated beetles. The protein database consisted of the translated transcriptome, and the resulting changes were manually annotated via BLASTP. We identified a number of high-abundance changes in which there were several dominant proteins, e.g., the electron carrier cytochrome b5, ribosomal proteins 60S RPL28, 40S RPS23 and RPS26, eIF4E-transporter, anoxia up-regulated protein, 2 isoforms of vitellogenin and pathogenesis-related protein 5. Deltamethrin detoxification was influenced by different cytochromes P450, which were likely boosted by increased cytochrome b5, but glutathione-S-transferase ε and UDP-glucuronosyltransferases also contributed. Moreover, we observed changes in proteins related to RNA interference, RNA binding and epigenetic modifications. The high changes in ribosomal proteins and associated factors suggest specific control of translation. Overall, we showed modulation of expression processes by epigenetic markers, alternative splicing and translation. Future functional studies will benefit. BIOLOGICAL SIGNIFICANCE Insects develop pesticide resistance, which has become one of the key issues in plant protection. This growing resistance increases the demand for pesticide applications and the development of new substances. Knowledge in the field regarding the resistance mechanism and its responses to pesticide treatment provides us the opportunity to propose a solution for this issue. Although the pollen beetle Meligethes aeneus was effectively controlled with pyrethroids for many years, there have been reports of increasing resistance. We show protein changes including production of isoforms in response to deltamethrin at the protein level. These results illustrate the insect's survival state as a resistant beetle and in its paralyzed state (evaluated as dead) relative to resistant individuals.
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42
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Frydryskova K, Masek T, Borcin K, Mrvova S, Venturi V, Pospisek M. Distinct recruitment of human eIF4E isoforms to processing bodies and stress granules. BMC Mol Biol 2016; 17:21. [PMID: 27578149 PMCID: PMC5006505 DOI: 10.1186/s12867-016-0072-x] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2016] [Accepted: 08/16/2016] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Eukaryotic translation initiation factor 4E (eIF4E) plays a pivotal role in the control of cap-dependent translation initiation, modulates the fate of specific mRNAs, occurs in processing bodies (PBs) and is required for formation of stress granules (SGs). In this study, we focused on the subcellular localization of a representative compendium of eIF4E protein isoforms, particularly on the less studied members of the human eIF4E protein family, eIF4E2 and eIF4E3. RESULTS We showed that unlike eIF4E1, its less studied isoform eIF4E3_A, encoded by human chromosome 3, localized to stress granules but not PBs upon both heat shock and arsenite stress. Furthermore, we found that eIF4E3_A interacts with human translation initiation factors eIF4G1, eIF4G3 and PABP1 in vivo and sediments into the same fractions as canonical eIF4E1 during polysome analysis in sucrose gradients. Contrary to this finding, the truncated human eIF4E3 isoform, eIF4E3_B, showed no localization to SGs and no binding to eIF4G. We also highlighted that eIF4E2 may exhibit distinct functions under different stresses as it readily localizes to P-bodies during arsenite and heat stresses, whereas it is redirected to stress granules only upon heat shock. We extended our study to a number of protein variants, arising from alternative mRNA splicing, of each of the three eIF4E isoforms. Our results surprisingly uncovered differences in the ability of eIF4E1_1 and eIF4E1_3 to form stress granules in response to cellular stresses. CONCLUSION Our comparison of all three human eIF4E isoforms and their protein variants enriches the intriguing spectrum of roles attributed to the eukaryotic initiation translation factors of the 4E family, which exhibit a distinctive localization within different RNA granules under different stresses. The localization of eIF4E3_A to stress granules, but not to processing bodies, along with its binding to eIF4G and PABP1 suggests a role of human eIF4E3_A in translation initiation rather than its involvement in a translational repression and mRNA decay and turnover. The localization of eIF4E2 to stress granules under heat shock but not arsenite stress indicates its distinct function in cellular response to these stresses and points to the variable protein content of SGs as a consequence of different stress insults.
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Affiliation(s)
- Klara Frydryskova
- Laboratory of RNA Biochemistry, Department of Genetics and Microbiology, Faculty of Science, Charles University in Prague, Viničná 5, 128 00, Prague 2, Czech Republic
| | - Tomas Masek
- Laboratory of RNA Biochemistry, Department of Genetics and Microbiology, Faculty of Science, Charles University in Prague, Viničná 5, 128 00, Prague 2, Czech Republic.
| | - Katerina Borcin
- Laboratory of RNA Biochemistry, Department of Genetics and Microbiology, Faculty of Science, Charles University in Prague, Viničná 5, 128 00, Prague 2, Czech Republic
| | - Silvia Mrvova
- Laboratory of RNA Biochemistry, Department of Genetics and Microbiology, Faculty of Science, Charles University in Prague, Viničná 5, 128 00, Prague 2, Czech Republic
| | - Veronica Venturi
- Laboratory of RNA Biochemistry, Department of Genetics and Microbiology, Faculty of Science, Charles University in Prague, Viničná 5, 128 00, Prague 2, Czech Republic.,Centre for Genomic Regulation (CRG), The Barcelona Institute of Science and Technology, Dr. Aiguader 88, 08003, Barcelona, Spain
| | - Martin Pospisek
- Laboratory of RNA Biochemistry, Department of Genetics and Microbiology, Faculty of Science, Charles University in Prague, Viničná 5, 128 00, Prague 2, Czech Republic.
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43
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Kamenska A, Simpson C, Vindry C, Broomhead H, Bénard M, Ernoult-Lange M, Lee BP, Harries LW, Weil D, Standart N. The DDX6-4E-T interaction mediates translational repression and P-body assembly. Nucleic Acids Res 2016; 44:6318-34. [PMID: 27342281 PMCID: PMC5291280 DOI: 10.1093/nar/gkw565] [Citation(s) in RCA: 75] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2016] [Revised: 06/10/2016] [Accepted: 06/14/2016] [Indexed: 12/13/2022] Open
Abstract
4E-Transporter binds eIF4E via its consensus sequence YXXXXLΦ, shared with eIF4G, and is a nucleocytoplasmic shuttling protein found enriched in P-(rocessing) bodies. 4E-T inhibits general protein synthesis by reducing available eIF4E levels. Recently, we showed that 4E-T bound to mRNA however represses its translation in an eIF4E-independent manner, and contributes to silencing of mRNAs targeted by miRNAs. Here, we address further the mechanism of translational repression by 4E-T by first identifying and delineating the interacting sites of its major partners by mass spectrometry and western blotting, including DDX6, UNR, unrip, PAT1B, LSM14A and CNOT4. Furthermore, we document novel binding between 4E-T partners including UNR-CNOT4 and unrip-LSM14A, altogether suggesting 4E-T nucleates a complex network of RNA-binding protein interactions. In functional assays, we demonstrate that joint deletion of two short conserved motifs that bind UNR and DDX6 relieves repression of 4E-T-bound mRNA, in part reliant on the 4E-T-DDX6-CNOT1 axis. We also show that the DDX6-4E-T interaction mediates miRNA-dependent translational repression and de novo P-body assembly, implying that translational repression and formation of new P-bodies are coupled processes. Altogether these findings considerably extend our understanding of the role of 4E-T in gene regulation, important in development and neurogenesis.
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Affiliation(s)
- Anastasiia Kamenska
- Department of Biochemistry, University of Cambridge, Tennis Court Road, Cambridge CB21QW, UK
| | - Clare Simpson
- Department of Biochemistry, University of Cambridge, Tennis Court Road, Cambridge CB21QW, UK
| | - Caroline Vindry
- Department of Biochemistry, University of Cambridge, Tennis Court Road, Cambridge CB21QW, UK
| | - Helen Broomhead
- Department of Biochemistry, University of Cambridge, Tennis Court Road, Cambridge CB21QW, UK
| | - Marianne Bénard
- Sorbonne Universités, UPMC, CNRS, IBPS, Developmental Biology Laboratory, 75005 Paris, France
| | - Michèle Ernoult-Lange
- Sorbonne Universités, UPMC, CNRS, IBPS, Developmental Biology Laboratory, 75005 Paris, France
| | - Benjamin P Lee
- Institute of Biomedical and Clinical Sciences, University of Exeter Medical School, Barrack Road, Exeter EX2 5DW
| | - Lorna W Harries
- Institute of Biomedical and Clinical Sciences, University of Exeter Medical School, Barrack Road, Exeter EX2 5DW
| | - Dominique Weil
- Sorbonne Universités, UPMC, CNRS, IBPS, Developmental Biology Laboratory, 75005 Paris, France
| | - Nancy Standart
- Department of Biochemistry, University of Cambridge, Tennis Court Road, Cambridge CB21QW, UK
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44
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Zuberek J, Kuchta K, Hernández G, Sonenberg N, Ginalski K. Diverse cap-binding properties of Drosophila eIF4E isoforms. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2016; 1864:1292-303. [PMID: 27374989 DOI: 10.1016/j.bbapap.2016.06.015] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 06/07/2016] [Accepted: 06/28/2016] [Indexed: 10/21/2022]
Abstract
The majority of eukaryotic mRNAs are translated in a cap-dependent manner, which requires recognition of the mRNA 5' cap by eIF4E protein. Multiple eIF4E family members have been identified in most eukaryotic organisms. Drosophila melanogaster (Dm) has eight eIF4E related proteins; seven of them belong to Class I and one to Class II. Their biological roles with the exception of Dm eIF4E-1, Dm eIF4E-3 and Dm 4EHP, remain unknown. Here, we compare the molecular basis of Dm eIF4E's interactions with cap and eIF4G peptide by using homology modelling and fluorescence binding assays with various cap analogues. We found that despite the presence of conserved key residues responsible for cap recognition, the differences in binding different cap analogues among Class I Dm eIF4E isoforms are up to 14-fold. The highest affinity for cap analogues was observed for Dm eIF4E-3. We suggest that Dm eIF4E-3 and Dm eIF4E-5 bind the second nucleoside of the cap in an unusual manner via stacking interactions with a histidine or a phenylalanine residue, respectively. Moreover, the analysis of ternary complexes of eIF4G peptide-eIF4E-cap analogue showed cooperativity between eIF4G and cap binding only for Dm eIF4E-4, which exhibits the lowest affinity for cap analogues among all Dm eIF4Es.
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Affiliation(s)
- Joanna Zuberek
- Division of Biophysics, Institute of Experimental Physics, Faculty of Physics, University of Warsaw, Warsaw 02-089, Poland.
| | - Krzysztof Kuchta
- Laboratory of Bioinformatics and Systems Biology, Centre of New Technologies, University of Warsaw, Warsaw 02-097, Poland; College of Inter-Faculty Individual Studies in Mathematics and Natural Sciences, University of Warsaw, Warsaw 02-089, Poland.
| | - Greco Hernández
- Division of Basic Research, National Institute of Cancer (INCan), Tlalpan, Mexico City 14080, Mexico.
| | - Nahum Sonenberg
- Department of Biochemistry and Goodman Cancer Research Centre, McGill University, Montreal, QC H3A 1A3, Canada.
| | - Krzysztof Ginalski
- Laboratory of Bioinformatics and Systems Biology, Centre of New Technologies, University of Warsaw, Warsaw 02-097, Poland.
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Kowalska J, Martin F, Jemielity J. Synthetic Capped mRNAs for Cap-Specific Photo-Cross-Linking Experiments. Methods Mol Biol 2016; 1428:31-43. [PMID: 27236790 DOI: 10.1007/978-1-4939-3625-0_2] [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] [Indexed: 06/05/2023]
Abstract
The 7-methylguanosine triphosphate cap present at the 5' ends of eukaryotic mRNAs plays numerous roles in mRNA expression and metabolism. The identification and studies on cap-binding partners can be significantly advanced using tailored chemical tools such as synthetic cap analogues or RNAs carrying modified cap structures. Here we provide protocols for the production of mRNAs specifically labeled within the 5' cap with a nucleoside capable of being photo-activated, either 6-thioguanosine or 7-methyl-6-thioguanosine, which can be used in photo-cross-linking experiments to identify or characterize cap-binding biomolecules. We also describe a protocol for the cross-linking experiments with capped RNAs to map histone H4 cap-binding pocket.
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Affiliation(s)
- Joanna Kowalska
- Division of Biophysics, Institute of Experimental Physics, Faculty of Physics, University of Warsaw, Zwirki i Wigury 93, Warsaw, 02-089, Poland
| | - Franck Martin
- Architecture et Réactivité de l'ARN, Université de Strasbourg, CNRS, Institut de Biologie Moléculaire et Cellulaire, 15 rue René Descartes, 67084, Strasbourg CEDEX, France.
| | - Jacek Jemielity
- Center of New Technologies, University of Warsaw, Banacha 2c, 02-097, Warsaw, Poland.
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46
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Lama D, Brown CJ, Lane DP, Verma CS. Gating by Tryptophan 73 Exposes a Cryptic Pocket at the Protein-Binding Interface of the Oncogenic eIF4E Protein. Biochemistry 2015; 54:6535-44. [DOI: 10.1021/acs.biochem.5b00812] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Affiliation(s)
- Dilraj Lama
- Bioinformatics
Institute, A*STAR (Agency for Science, Technology and Research), 30 Biopolis
Street, #07-01 Matrix, Singapore 138671
| | - Christopher J. Brown
- p53
Laboratory, A*STAR (Agency for Science, Technology and Research), 8A Biomedical Grove, #06-04/05, Neuros/Immunos, Singapore 138648
| | - David P. Lane
- p53
Laboratory, A*STAR (Agency for Science, Technology and Research), 8A Biomedical Grove, #06-04/05, Neuros/Immunos, Singapore 138648
| | - Chandra S. Verma
- Bioinformatics
Institute, A*STAR (Agency for Science, Technology and Research), 30 Biopolis
Street, #07-01 Matrix, Singapore 138671
- Department
of Biological Sciences, National University of Singapore, 14 Science
Drive 4, Singapore 117543
- School
of Biological Sciences, Nanyang Technological University, 50 Nanyang
Drive, Singapore 637551
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47
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An integrated approach for discovery of highly potent and selective Mnk inhibitors: Screening, synthesis and SAR analysis. Eur J Med Chem 2015; 103:539-50. [DOI: 10.1016/j.ejmech.2015.09.008] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2014] [Revised: 10/07/2014] [Accepted: 09/05/2015] [Indexed: 02/02/2023]
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Tristetraprolin Recruits Eukaryotic Initiation Factor 4E2 To Repress Translation of AU-Rich Element-Containing mRNAs. Mol Cell Biol 2015; 35:3921-32. [PMID: 26370510 DOI: 10.1128/mcb.00845-15] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2015] [Accepted: 09/06/2015] [Indexed: 11/20/2022] Open
Abstract
Tristetraprolin (TTP) regulates the expression of AU-rich element-containing mRNAs through promoting the degradation and repressing the translation of target mRNA. While the mechanism for promoting target mRNA degradation has been extensively studied, the mechanism underlying translational repression is not well established. Here, we show that TTP recruits eukaryotic initiation factor 4E2 (eIF4E2) to repress target mRNA translation. TTP interacted with eIF4E2 but not with eIF4E. Overexpression of eIF4E2 enhanced TTP-mediated translational repression, and downregulation of endogenous eIF4E2 or overexpression of a truncation mutant of eIF4E2 impaired TTP-mediated translational repression. Overexpression of an eIF4E2 mutant that lost the cap-binding activity also impaired TTP's activity, suggesting that the cap-binding activity of eIF4E2 is important in TTP-mediated translational repression. We further show that TTP promoted eIF4E2 binding to target mRNA. These results imply that TTP recruits eIF4E2 to compete with eIF4E to repress the translation of target mRNA. This notion is supported by the finding that downregulation of endogenous eIF4E2 increased the production of tumor necrosis factor alpha (TNF-α) protein without affecting the mRNA levels in THP-1 cells. Collectively, these results uncover a novel mechanism by which TTP represses target mRNA translation.
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de Melo Neto OP, da Costa Lima TDC, Xavier CC, Nascimento LM, Romão TP, Assis LA, Pereira MMC, Reis CRS, Papadopoulou B. The unique Leishmania EIF4E4 N-terminus is a target for multiple phosphorylation events and participates in critical interactions required for translation initiation. RNA Biol 2015; 12:1209-21. [PMID: 26338184 DOI: 10.1080/15476286.2015.1086865] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
The eukaryotic initiation factor 4E (eIF4E) recognizes the mRNA cap structure and, together with eIF4G and eIF4A, form the eIF4F complex that regulates translation initiation in eukaryotes. In trypanosomatids, 2 eIF4E homologues (EIF4E3 and EIF4E4) have been shown to be part of eIF4F-like complexes with presumed roles in translation initiation. Both proteins possess unique N-terminal extensions, which can be targeted for phosphorylation. Here, we provide novel insights on the Leishmania infantum EIF4E4 function and regulation. We show that EIF4E4 is constitutively expressed throughout the parasite development but is preferentially phosphorylated in exponentially grown promastigote and amastigote life stages, hence correlating with high levels of translation. Phosphorylation targets multiple serine-proline or threonine-proline residues within the N-terminal extension of EIF4E4 but does not require binding to the EIF4E4's partner, EIF4G3, or to the cap structure. We also report that EIF4E4 interacts with PABP1 through 3 conserved boxes at the EIF4E4 N-terminus and that this interaction is a prerequisite for efficient EIF4E4 phosphorylation. EIF4E4 is essential for Leishmania growth and an EIF4E4 null mutant was only obtained in the presence of an ectopically provided wild type gene. Complementation for the loss of EIF4E4 with several EIF4E4 mutant proteins affecting either phosphorylation or binding to mRNA or to EIF4E4 protein partners revealed that, in contrast to other eukaryotes, only the EIF4E4-PABP1 interaction but neither the binding to EIF4G3 nor phosphorylation is essential for translation. These studies also demonstrated that the lack of both EIF4E4 phosphorylation and EIF4G3 binding leads to a non-functional protein. Altogether, these findings further highlight the unique features of the translation initiation process in trypanosomatid protozoa.
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Affiliation(s)
- Osvaldo P de Melo Neto
- a Departamento de Microbiologia ; Centro de Pesquisas Aggeu Magalhães-FIOCRUZ ; Recife , PE , Brazil
| | - Tamara D C da Costa Lima
- a Departamento de Microbiologia ; Centro de Pesquisas Aggeu Magalhães-FIOCRUZ ; Recife , PE , Brazil
| | - Camila C Xavier
- a Departamento de Microbiologia ; Centro de Pesquisas Aggeu Magalhães-FIOCRUZ ; Recife , PE , Brazil
| | - Larissa M Nascimento
- a Departamento de Microbiologia ; Centro de Pesquisas Aggeu Magalhães-FIOCRUZ ; Recife , PE , Brazil.,b CHU de Quebec Research Center and Department of Microbiology ; Infectious Disease and Immunology; Laval University ; Quebec, QC , Canada
| | - Tatiany P Romão
- a Departamento de Microbiologia ; Centro de Pesquisas Aggeu Magalhães-FIOCRUZ ; Recife , PE , Brazil
| | - Ludmila A Assis
- a Departamento de Microbiologia ; Centro de Pesquisas Aggeu Magalhães-FIOCRUZ ; Recife , PE , Brazil
| | - Mariana M C Pereira
- a Departamento de Microbiologia ; Centro de Pesquisas Aggeu Magalhães-FIOCRUZ ; Recife , PE , Brazil
| | - Christian R S Reis
- a Departamento de Microbiologia ; Centro de Pesquisas Aggeu Magalhães-FIOCRUZ ; Recife , PE , Brazil
| | - Barbara Papadopoulou
- b CHU de Quebec Research Center and Department of Microbiology ; Infectious Disease and Immunology; Laval University ; Quebec, QC , Canada
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Zytek M, Kowalska J, Lukaszewicz M, Wojtczak BA, Zuberek J, Ferenc-Mrozek A, Darzynkiewicz E, Niedzwiecka A, Jemielity J. Towards novel efficient and stable nuclear import signals: synthesis and properties of trimethylguanosine cap analogs modified within the 5',5'-triphosphate bridge. Org Biomol Chem 2015; 12:9184-99. [PMID: 25296894 DOI: 10.1039/c4ob01579g] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
A trimethylguanosine (TMG) cap is present at the 5' end of several small nuclear and nucleolar RNAs. Recently, it has been reported that the TMG cap is a potential nuclear import signal for nucleus-targeting therapeutic nucleic acids and proteins. The import is mediated by recognition of the TMG cap by the snRNA transporting protein, snurportin1. This work describes the synthesis and properties of a series of dinucleotide TMG cap (m3(2,2,7)GpppG) analogs modified in the 5',5'-triphosphate bridge as tools to study TMG cap-dependent biological processes. The bridge was altered at different positions by introducing either bridging (imidodiphosphate, O to NH and methylenebisphosphonate, O to CH2) or non-bridging (phosphorothioate, O to S and boranophosphate, O to BH3) modifications, or by elongation to tetraphosphate. The stability of novel analogs in blood serum was studied to reveal that the α,β-bridging O to NH substitution (m3(2,2,7)GppNHpG) confers the highest resistance. Short RNAs capped with analogs containing α,β-bridging (m3(2,2,7)GppNHpG) or β-non-bridging (m3(2,2,7)GppSpG D2) modifications were resistant to decapping pyrophosphatase, hNudt16. Preliminary studies on binding by human snurportin1 revealed that both O to NH and O to S substitutions support this binding. Due to favorable properties in all three assays, m3(2,2,7)GppNHpG was selected as a promising candidate for further studies on the efficiency of the TMG cap as a nuclear import signal.
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Affiliation(s)
- Malgorzata Zytek
- Division of Biophysics, Institute of Experimental Physics, Faculty of Physics, University of Warsaw, Zwirki i Wigury 93, 02-089 Warsaw, Poland.
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