1
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Zeng J, Lu C, Huang X, Li Y. The human eIF4E:4E-BP2 complex structure for studying hyperphosphorylation. Phys Chem Chem Phys 2024; 26:10660-10672. [PMID: 38511550 DOI: 10.1039/d3cp05736d] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/22/2024]
Abstract
The cap-dependent mRNA translation is dysregulated in many kinds of cancers. The interaction between eIF4E and eIF4G through a canonical eIF4E-binding motif (CEBM) determines the efficacy of the cap-dependent mRNA translation. eIF4E-binding proteins (4E-BPs) share the CEBM and compete with eIF4G for the same binding surface of eIF4E and then inhibit the mRNA translation. 4E-BPs function as tumor repressors in nature. Hyperphosphorylation of 4E-BPs regulates the structure folding and causes the dissociation of 4E-BPs from eIF4E. However, until now, there has been no structure of the full-length 4E-BPs in complex with eIF4E. The regulation mechanism of phosphorylation is still unclear. In this work, we first investigate the interactions of human eIF4E with the CEBM and an auxiliary eIF4E-binding motif (AEBM) in eIF4G and 4E-BPs. The results unravel that the structure and interactions of the CEBM are highly conserved between eIF4G and 4E-BPs. However, the extended CEBM (ECEBM) in 4E-BPs forms a longer helix than that in eIF4G. The residue R62 in the ECEBM of 4E-BP2 forms salt bridges with E32 and E70 of eIF4E. The residue R63 of 4E-BP2 forms two special hydrogen bonds with N77 of eIF4E. Both of these interactions are missing in eIF4G. The AEBM of 4E-BPs folds into a β-sheet conformation, which protects V81 inside a hydrophobic core in 4E-BP2. In eIF4G, the AEBM exists in a random coil state. The hydrophilic residues S637 and D638 of eIF4G open the hydrophobic core for solvents. The results show that the ECEBM and AEBM may be responsible for the competing advantage of 4E-BP2. Finally, based on our previous work (J. Zeng, F. Jiang and Y. D. Wu, J. Chem. Theory Comput., 2017, 13, 320), the human eIF4E:4E-BP2 complex (eIF4E:BP2P18-I88) including all reported phosphorylation sites is predicted. The eIF4E:BP2P18-I88 complex is different from the existing experimental eIF4E:eIF4G complex and provides an important structure for further studying the regulation mechanism of phosphorylation in 4E-BPs.
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Affiliation(s)
- Juan Zeng
- School of Biomedical Engineering, Guangdong Medical University, Dongguan 523808, China.
| | - CuiMin Lu
- School of Biomedical Engineering, Guangdong Medical University, Dongguan 523808, China.
| | - Xuan Huang
- School of Biomedical Engineering, Guangdong Medical University, Dongguan 523808, China.
| | - Yang Li
- Department of Urology, Huaihe Hospital of Henan University, Kaifeng 475000, Henan, China.
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2
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Smith AB, Ganguly DR, Moore M, Bowerman AF, Janapala Y, Shirokikh NE, Pogson BJ, Crisp PA. Dynamics of mRNA fate during light stress and recovery: from transcription to stability and translation. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2024; 117:818-839. [PMID: 37947266 PMCID: PMC10952913 DOI: 10.1111/tpj.16531] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/22/2023] [Revised: 09/20/2023] [Accepted: 10/23/2023] [Indexed: 11/12/2023]
Abstract
Transcript stability is an important determinant of its abundance and, consequently, translational output. Transcript destabilisation can be rapid and is well suited for modulating the cellular response. However, it is unclear the extent to which RNA stability is altered under changing environmental conditions in plants. We previously hypothesised that recovery-induced transcript destabilisation facilitated a phenomenon of rapid recovery gene downregulation (RRGD) in Arabidopsis thaliana (Arabidopsis) following light stress, based on mathematical calculations to account for ongoing transcription. Here, we test this hypothesis and investigate processes regulating transcript abundance and fate by quantifying changes in transcription, stability and translation before, during and after light stress. We adapt syringe infiltration to apply a transcriptional inhibitor to soil-grown plants in combination with stress treatments. Compared with measurements in juvenile plants and cell culture, we find reduced stability across a range of transcripts encoding proteins involved in RNA binding and processing. We also observe light-induced destabilisation of transcripts, followed by their stabilisation during recovery. We propose that this destabilisation facilitates RRGD, possibly in combination with transcriptional shut-off that was confirmed for HSP101, ROF1 and GOLS1. We also show that translation remains highly dynamic over the course of light stress and recovery, with a bias towards transcript-specific increases in ribosome association, independent of changes in total transcript abundance, after 30 min of light stress. Taken together, we provide evidence for the combinatorial regulation of transcription and stability that occurs to coordinate translation during light stress and recovery in Arabidopsis.
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Affiliation(s)
- Aaron B. Smith
- Research School of BiologyThe Australian National UniversityCanberraAustralian Capital Territory2601Australia
| | - Diep R. Ganguly
- CSIRO Synthetic Biology Future Science PlatformCanberraAustralian Capital Territory2601Australia
- Department of BiologyUniversity of PennsylvaniaPhiladelphiaPennsylvania19104USA
| | - Marten Moore
- Research School of BiologyThe Australian National UniversityCanberraAustralian Capital Territory2601Australia
| | - Andrew F. Bowerman
- Research School of BiologyThe Australian National UniversityCanberraAustralian Capital Territory2601Australia
| | - Yoshika Janapala
- Department of Biochemistry and Molecular Biology, Monash Biomedicine Discovery InstituteMonash UniversityClaytonVictoria3800Australia
| | - Nikolay E. Shirokikh
- The John Curtin School of Medical Research, The Shine‐Dalgarno Centre for RNA InnovationThe Australian National UniversityCanberraAustralian Capital Territory2601Australia
| | - Barry J. Pogson
- Research School of BiologyThe Australian National UniversityCanberraAustralian Capital Territory2601Australia
| | - Peter A. Crisp
- School of Agriculture and Food SciencesThe University of QueenslandBrisbaneQueensland4072Australia
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3
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Wu S, Wagner G. Computational inference of eIF4F complex function and structure in human cancers. Proc Natl Acad Sci U S A 2024; 121:e2313589121. [PMID: 38266053 PMCID: PMC10835048 DOI: 10.1073/pnas.2313589121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2023] [Accepted: 12/18/2023] [Indexed: 01/26/2024] Open
Abstract
The canonical eukaryotic initiation factor 4F (eIF4F) complex, composed of eIF4G1, eIF4A1, and the cap-binding protein eIF4E, plays a crucial role in cap-dependent translation initiation in eukaryotic cells. An alternative cap-independent initiation can occur, involving only eIF4G1 and eIF4A1 through internal ribosome entry sites (IRESs). This mechanism is considered complementary to cap-dependent initiation, particularly in tumors under stress conditions. However, the selection and molecular mechanism of specific translation initiation remains poorly understood in human cancers. Thus, we analyzed gene copy number variations (CNVs) in TCGA tumor samples and found frequent amplification of genes involved in translation initiation. Copy number gains in EIF4G1 and EIF3E frequently co-occur across human cancers. Additionally, EIF4G1 expression strongly correlates with genes from cancer cell survival pathways including cell cycle and lipogenesis, in tumors with EIF4G1 amplification or duplication. Furthermore, we revealed that eIF4G1 and eIF4A1 protein levels strongly co-regulate with ribosomal subunits, eIF2, and eIF3 complexes, while eIF4E co-regulates with 4E-BP1, ubiquitination, and ESCRT proteins. Utilizing Alphafold predictions, we modeled the eIF4F structure with and without eIF4E binding. For cap-dependent initiation, our modeling reveals extensive interactions between the N-terminal eIF4E-binding domain of eIF4G1 and eIF4E. Furthermore, the eIF4G1 HEAT-2 domain positions eIF4E near the eIF4A1 N-terminal domain (NTD), resulting in the collaborative enclosure of the RNA binding cavity within eIF4A1. In contrast, during cap-independent initiation, the HEAT-2 domain directly binds the eIF4A1-NTD, leading to a stronger interaction between eIF4G1 and eIF4A1, thus closing the mRNA binding cavity without the involvement of eIF4E.
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Affiliation(s)
- Su Wu
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA02115
| | - Gerhard Wagner
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA02115
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4
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Lorenzo-Orts L, Strobl M, Steinmetz B, Leesch F, Pribitzer C, Roehsner J, Schutzbier M, Dürnberger G, Pauli A. eIF4E1b is a non-canonical eIF4E protecting maternal dormant mRNAs. EMBO Rep 2024; 25:404-427. [PMID: 38177902 PMCID: PMC10883267 DOI: 10.1038/s44319-023-00006-4] [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: 06/07/2023] [Revised: 10/31/2023] [Accepted: 11/08/2023] [Indexed: 01/06/2024] Open
Abstract
Maternal mRNAs are essential for protein synthesis during oogenesis and early embryogenesis. To adapt translation to specific needs during development, maternal mRNAs are translationally repressed by shortening the polyA tails. While mRNA deadenylation is associated with decapping and degradation in somatic cells, maternal mRNAs with short polyA tails are stable. Here we report that the germline-specific eIF4E paralog, eIF4E1b, is essential for zebrafish oogenesis. eIF4E1b localizes to P-bodies in zebrafish embryos and binds to mRNAs with reported short or no polyA tails, including histone mRNAs. Loss of eIF4E1b results in reduced histone mRNA levels in early gonads, consistent with a role in mRNA storage. Using mouse and human eIF4E1Bs (in vitro) and zebrafish eIF4E1b (in vivo), we show that unlike canonical eIF4Es, eIF4E1b does not interact with eIF4G to initiate translation. Instead, eIF4E1b interacts with the translational repressor eIF4ENIF1, which is required for eIF4E1b localization to P-bodies. Our study is consistent with an important role of eIF4E1b in regulating mRNA dormancy and provides new insights into fundamental post-transcriptional regulatory principles governing early vertebrate development.
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Affiliation(s)
- Laura Lorenzo-Orts
- Research Institute of Molecular Pathology (IMP), Vienna BioCenter (VBC), 1030, Vienna, Austria.
| | - Marcus Strobl
- Research Institute of Molecular Pathology (IMP), Vienna BioCenter (VBC), 1030, Vienna, Austria
| | - Benjamin Steinmetz
- Research Institute of Molecular Pathology (IMP), Vienna BioCenter (VBC), 1030, Vienna, Austria
- Department of Biology, Institute of Molecular Systems Biology, ETH Zürich, 8093, Zurich, Switzerland
| | - Friederike Leesch
- Research Institute of Molecular Pathology (IMP), Vienna BioCenter (VBC), 1030, Vienna, Austria
- Vienna BioCenter PhD Program, Doctoral School of the University of Vienna and Medical University of Vienna, Vienna, Austria
| | - Carina Pribitzer
- Research Institute of Molecular Pathology (IMP), Vienna BioCenter (VBC), 1030, Vienna, Austria
| | - Josef Roehsner
- Research Institute of Molecular Pathology (IMP), Vienna BioCenter (VBC), 1030, Vienna, Austria
- Vienna BioCenter PhD Program, Doctoral School of the University of Vienna and Medical University of Vienna, Vienna, Austria
| | - Michael Schutzbier
- Research Institute of Molecular Pathology (IMP), Vienna BioCenter (VBC), 1030, Vienna, Austria
| | - Gerhard Dürnberger
- Research Institute of Molecular Pathology (IMP), Vienna BioCenter (VBC), 1030, Vienna, Austria
| | - Andrea Pauli
- Research Institute of Molecular Pathology (IMP), Vienna BioCenter (VBC), 1030, Vienna, Austria.
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5
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Baron N, Purushotham R, Pullaiahgari D, Bose P, Zarivach R, Shapira M. LeishIF4E2 is a cap-binding protein that plays a role in Leishmania cell cycle progression. FASEB J 2024; 38:e23367. [PMID: 38095329 DOI: 10.1096/fj.202301665r] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2023] [Revised: 11/14/2023] [Accepted: 11/27/2023] [Indexed: 12/18/2023]
Abstract
Leishmania encode six paralogs of the cap-binding protein eIF4E and five eIF4G candidates, forming unique complexes. Two cap-binding proteins, LeishIF4E1 and LeishIF4E2, do not bind any identified LeishIF4Gs, thus their roles are intriguing. Here, we combine structural prediction, proteomic analysis, and interaction assays to shed light on LeishIF4E2 function. A nonconserved C-terminal extension was identified through structure prediction and sequence alignment. m7 GTP-binding assays involving both recombinant and transgenic LeishIF4E2 with and without the C-terminal extension revealed that this extension functions as a regulatory gate, modulating the cap-binding activity of LeishIF4E2. The interactomes of the two LeishIF4E2 versions were investigated, highlighting the role of the C-terminal extension in binding to SLBP2. SLBP2 is known to interact with a stem-loop structure in the 3' UTRs of histone mRNAs. Consistent with the predicted inhibitory effect of SLBP2 on histone expression in Xenopus laevis, a hemizygous deletion mutant of LeishIF4E2, exhibited an upregulation of several histones. We therefore propose that LeishIF4E2 is involved in histone expression, possibly through its interaction between SLBP2 and LeishIF4E2, thus affecting cell cycle progression. In addition, cell synchronization showed that LeishIF4E2 expression decreased during the S-phase, when histones are known to be synthesized. Previous studies in T. brucei also highlighted an association between TbEIF4E2 and SLBP2, and further reported on an interaction between TbIF4E2 and S-phase-abundant mRNAs. Our results show that overexpression of LeishIF4E2 correlates with upregulation of cell cycle and chromosome maintenance proteins. Along with its effect on histone expression, we propose that LeishIF4E2 is involved in cell cycle progression.
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Affiliation(s)
- Nofar Baron
- Department of Life Sciences, Ben-Gurion University of the Negev, Beer Sheva, Israel
| | - Rajaram Purushotham
- Department of Life Sciences, Ben-Gurion University of the Negev, Beer Sheva, Israel
| | | | - Priyanka Bose
- Department of Life Sciences, Ben-Gurion University of the Negev, Beer Sheva, Israel
| | - Raz Zarivach
- Department of Life Sciences, Ben-Gurion University of the Negev, Beer Sheva, Israel
| | - Michal Shapira
- Department of Life Sciences, Ben-Gurion University of the Negev, Beer Sheva, Israel
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6
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Wang N, Zhou K, Liang Z, Sun R, Tang H, Yang Z, Zhao W, Peng Y, Song P, Zheng S, Xie H. RapaLink-1 outperforms rapamycin in alleviating allogeneic graft rejection by inhibiting the mTORC1-4E-BP1 pathway in mice. Int Immunopharmacol 2023; 125:111172. [PMID: 37951193 DOI: 10.1016/j.intimp.2023.111172] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2023] [Revised: 10/16/2023] [Accepted: 10/31/2023] [Indexed: 11/13/2023]
Abstract
Inhibition of mammalian target of rapamycin (mTOR), which is a component of both mTORC1 and mTORC2, leads to clinical benefits for organ transplant recipients. Pathways to inhibit mTOR include strengthening the association of FKBP12-mTOR or competing with ATP at the active site of mTOR, which have been applied to the design of first- and second-generation mTOR inhibitors, respectively. However, the clinical efficacy of these mTOR inhibitors may be limited by side effects, compensatory activation of kinases and attenuation of feedback inhibition of receptor expression. A new generation of mTOR inhibitors possess a core structure similar to rapamycin and covalently link to mTOR kinase inhibitors, resulting in moderate selectivity and potent inhibition of mTORC1. Since the immunosuppressive potential of this class of compounds remains unknown, our goal is to examine the therapeutic efficacy of a third-generation mTOR inhibitor in organ transplantation. In this study, RapaLink-1 outperformed rapamycin in inhibiting T-cell proliferation and significantly prolonged graft survival time. Mechanistically, the ameliorated rejection induced by RapaLink-1 is associated with a reduction in p-4E-BP1 in T cells, resulting in an elevation in Treg cells alongside a decline in Th1 and Th17 cells. For the first time, these studies demonstrate the effectiveness of third-generation mTOR inhibitors in inhibiting allograft rejection, highlighting the potential of this novel class of mTOR inhibitors for further investigation.
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Affiliation(s)
- Ning Wang
- Division of Hepatobiliary and Pancreatic Surgery, Department of Surgery, The First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou 310003, China
| | - Ke Zhou
- Division of Lung Transplantation and Thoracic Surgery, Department of Surgery, The First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou 310003, China
| | - Zhi Liang
- Division of Hepatobiliary and Pancreatic Surgery, Department of Surgery, The First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou 310003, China
| | - Ruiqi Sun
- Division of Hepatobiliary and Pancreatic Surgery, Department of Surgery, The First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou 310003, China
| | - Hong Tang
- Division of Hepatobiliary and Pancreatic Surgery, Department of Surgery, The First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou 310003, China
| | - Zhentao Yang
- Division of Hepatobiliary and Pancreatic Surgery, Department of Surgery, The First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou 310003, China
| | - Wentao Zhao
- Division of Hepatobiliary and Pancreatic Surgery, Department of Surgery, The First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou 310003, China
| | - Yiyang Peng
- College of Pharmaceutical Sciences, Zhejiang University, 310058 Hangzhou, China
| | - Penghong Song
- Division of Hepatobiliary and Pancreatic Surgery, Department of Surgery, The First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou 310003, China
| | - Shusen Zheng
- Division of Hepatobiliary and Pancreatic Surgery, Department of Surgery, The First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou 310003, China; Key Laboratory of the Diagnosis and Treatment of Organ Transplantation, Research Unit of Collaborative Diagnosis and Treatment for Hepatobiliary and Pancreatic Cancer, Chinese Academy of Medical Sciences (2019RU019), Hangzhou 310003, China; NHC Key Laboratory of Combined Multi-organ Transplantation, Hangzhou 310003, China; Key Laboratory of Organ Transplantation, State Key Laboratory for The Diagnosis and Treatment of Infectious Diseases, Hangzhou, Zhejiang Province 310003, China.
| | - Haiyang Xie
- Division of Hepatobiliary and Pancreatic Surgery, Department of Surgery, The First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou 310003, China; Key Laboratory of the Diagnosis and Treatment of Organ Transplantation, Research Unit of Collaborative Diagnosis and Treatment for Hepatobiliary and Pancreatic Cancer, Chinese Academy of Medical Sciences (2019RU019), Hangzhou 310003, China; NHC Key Laboratory of Combined Multi-organ Transplantation, Hangzhou 310003, China; Key Laboratory of Organ Transplantation, State Key Laboratory for The Diagnosis and Treatment of Infectious Diseases, Hangzhou, Zhejiang Province 310003, China.
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7
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Wittenstein A, Caspi M, Rippin I, Elroy-Stein O, Eldar-Finkelman H, Thoms S, Rosin-Arbesfeld R. Nonsense mutation suppression is enhanced by targeting different stages of the protein synthesis process. PLoS Biol 2023; 21:e3002355. [PMID: 37943958 PMCID: PMC10684085 DOI: 10.1371/journal.pbio.3002355] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2023] [Revised: 11/28/2023] [Accepted: 09/29/2023] [Indexed: 11/12/2023] Open
Abstract
The introduction of premature termination codons (PTCs), as a result of splicing defects, insertions, deletions, or point mutations (also termed nonsense mutations), lead to numerous genetic diseases, ranging from rare neuro-metabolic disorders to relatively common inheritable cancer syndromes and muscular dystrophies. Over the years, a large number of studies have demonstrated that certain antibiotics and other synthetic molecules can act as PTC suppressors by inducing readthrough of nonsense mutations, thereby restoring the expression of full-length proteins. Unfortunately, most PTC readthrough-inducing agents are toxic, have limited effects, and cannot be used for therapeutic purposes. Thus, further efforts are required to improve the clinical outcome of nonsense mutation suppressors. Here, by focusing on enhancing readthrough of pathogenic nonsense mutations in the adenomatous polyposis coli (APC) tumor suppressor gene, we show that disturbing the protein translation initiation complex, as well as targeting other stages of the protein translation machinery, enhances both antibiotic and non-antibiotic-mediated readthrough of nonsense mutations. These findings strongly increase our understanding of the mechanisms involved in nonsense mutation readthrough and facilitate the development of novel therapeutic targets for nonsense suppression to restore protein expression from a large variety of disease-causing mutated transcripts.
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Affiliation(s)
- Amnon Wittenstein
- Department of Clinical Microbiology and Immunology, Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Michal Caspi
- Department of Clinical Microbiology and Immunology, Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Ido Rippin
- The Department of Human Molecular Genetics & Biochemistry School of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Orna Elroy-Stein
- Shmunis School of Biomedicine and Cancer Research, George S. Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv, Israel
| | - Hagit Eldar-Finkelman
- The Department of Human Molecular Genetics & Biochemistry School of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Sven Thoms
- Biochemistry and Molecular Medicine, Medical School EWL, Bielefeld University, Bielefeld, Germany
| | - Rina Rosin-Arbesfeld
- Department of Clinical Microbiology and Immunology, Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
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8
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Evans JF, McCormack FX, Sonenberg N, Krymskaya VP. Lost in translation: a neglected mTOR target for lymphangioleiomyomatosis. Eur Respir Rev 2023; 32:230100. [PMID: 37758276 PMCID: PMC10523142 DOI: 10.1183/16000617.0100-2023] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2023] [Accepted: 07/24/2023] [Indexed: 09/30/2023] Open
Abstract
Lymphangioleiomyomatosis (LAM) is a cystic lung disease of women resulting from mutations in tuberous sclerosis complex (TSC) genes that suppress the mammalian target of rapamycin complex 1 (mTORC1) pathway. mTORC1 activation enhances a plethora of anabolic cellular functions, mainly via the activation of mRNA translation through stimulation of ribosomal protein S6 kinase (S6K1)/ribosomal protein S6 (S6) and eukaryotic initiation factor 4E-binding protein 1 (4E-BP1)/eukaryotic translation initiation factor 4E (eIF4E). Rapamycin (sirolimus), an allosteric inhibitor of mTORC1, stabilises lung function in many but not all LAM patients and, upon cessation of the drug, disease progression resumes. At clinically tolerable concentrations, rapamycin potently inhibits the ribosomal S6K1/S6 translation ribosome biogenesis and elongation axis, but not the translation 4E-BP1/eIF4E initiation axis. In this mini-review, we propose that inhibition of mTORC1-driven translation initiation is an obvious but underappreciated therapeutic strategy in LAM, TSC and other mTORC1-driven diseases.
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Affiliation(s)
- Jilly F Evans
- Division of Pulmonary, Allergy, and Critical Care Medicine, Department of Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
- Lung Biology Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Francis X McCormack
- Division of Pulmonary, Critical Care and Sleep Medicine, University of Cincinnati, Cincinnati, OH, USA
| | - Nahum Sonenberg
- Department of Biochemistry and Goodman Cancer Institute, McGill University, Montreal, QC, Canada
| | - Vera P Krymskaya
- Division of Pulmonary, Allergy, and Critical Care Medicine, Department of Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
- Lung Biology Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
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9
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Meena NK, Randazzo D, Raben N, Puertollano R. AAV-mediated delivery of secreted acid α-glucosidase with enhanced uptake corrects neuromuscular pathology in Pompe mice. JCI Insight 2023; 8:e170199. [PMID: 37463048 PMCID: PMC10543735 DOI: 10.1172/jci.insight.170199] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2023] [Accepted: 07/11/2023] [Indexed: 08/23/2023] Open
Abstract
Gene therapy is under advanced clinical development for several lysosomal storage disorders. Pompe disease, a debilitating neuromuscular illness affecting infants, children, and adults with different severity, is caused by a deficiency of lysosomal glycogen-degrading enzyme acid α-glucosidase (GAA). Here, we demonstrated that adeno-associated virus-mediated (AAV-mediated) systemic gene transfer reversed glycogen storage in all key therapeutic targets - skeletal and cardiac muscles, the diaphragm, and the central nervous system - in both young and severely affected old Gaa-knockout mice. Furthermore, the therapy reversed secondary cellular abnormalities in skeletal muscle, such as those in autophagy and mTORC1/AMPK signaling. We used an AAV9 vector encoding a chimeric human GAA protein with enhanced uptake and secretion to facilitate efficient spread of the expressed protein among multiple target tissues. These results lay the groundwork for a future clinical development strategy in Pompe disease.
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Affiliation(s)
- Naresh K. Meena
- Cell and Developmental Biology Center, National Heart, Lung, and Blood Institute, NIH, Bethesda, Maryland, USA
| | - Davide Randazzo
- Light Imaging Section, Office of Science and Technology, National Institute of Arthritis and Musculoskeletal and Skin Diseases, NIH, Bethesda, Maryland, USA
| | - Nina Raben
- Cell and Developmental Biology Center, National Heart, Lung, and Blood Institute, NIH, Bethesda, Maryland, USA
| | - Rosa Puertollano
- Cell and Developmental Biology Center, National Heart, Lung, and Blood Institute, NIH, Bethesda, Maryland, USA
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10
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Wu S, Wagner G. Computational inference of eIF4F complex function and structure in human cancers. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.08.10.552450. [PMID: 37609226 PMCID: PMC10441403 DOI: 10.1101/2023.08.10.552450] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/24/2023]
Abstract
The canonical eukaryotic initiation factor 4F (eIF4F) complex, composed of eIF4G1, eIF4A1, and the cap-binding protein eIF4E, plays a crucial role in cap-dependent translation initiation in eukaryotic cells (1). However, cap-independent initiation can occur through internal ribosomal entry sites (IRESs), involving only eIF4G1 and eIF4A1 present, which is considered to be a complementary process to cap-dependent initiation in tumors under stress conditions (2). The selection and molecular mechanism of specific translation initiation in human cancers remains poorly understood. Thus, we analyzed gene copy number variations (CNVs) in TCGA tumor samples and found frequent amplification of genes involved in translation initiation. Copy number gains in EIF4G1 and EIF3E frequently co-occur across human cancers. Additionally, EIF4G1 expression strongly correlates with genes from cancer cell survival pathways including cell cycle and lipogenesis, in tumors with EIF4G1 amplification or duplication. Furthermore, we revealed that eIF4G1 and eIF4A1 protein levels strongly co-regulate with ribosomal subunits, eIF2, and eIF3 complexes, while eIF4E co-regulates with 4E-BP1, ubiquitination, and ESCRT proteins. Using Alphafold predictions, we modeled the eIF4F structure with and without eIF4G1-eIF4E binding. The modeling for cap-dependent initiation suggests that eIF4G1 interacts with eIF4E through its N-terminal eIF4E-binding domain, bringing eIF4E near the eIF4A1 mRNA binding cavity and closing the cavity with both eIF4G1 HEAT-2 domain and eIF4E. In the cap-independent mechanism, α-helix 5 of eIF4G1 HEAT-2 domain instead directly interacts with the eIF4A1 N-terminal domain to close the mRNA binding cavity without eIF4E involvement, resulting in a stronger interaction between eIF4G1 and eIF4A1. Significance Statement Translation initiation is primarily governed by eIF4F, employing a "cap-dependent" mechanism, but eIF4F dysregulation may lead to a "cap-independent" mechanism in stressed cancer cells. We found frequent amplification of translation initiation genes, and co-occurring copy number gains of EIF4G1 and EIF3E genes in human cancers. EIF4G1 amplification or duplication may be positively selected for its beneficial impact on the overexpression of cancer survival genes. The co-regulation of eIF4G1 and eIF4A1, distinctly from eIF4E, reveals eIF4F dysregulation favoring cap-independent initiation. Alphafold predicts changes in the eIF4F complex assembly to accommodate both initiation mechanisms. These findings have significant implications for evaluating cancer cell vulnerability to eIF4F inhibition and developing treatments that target cancer cells with dependency on the translation initiation mechanism.
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11
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Lucchesi CA, Zhang J, Gao M, Shaw J, Chen X. Identification of a First-in-Class Small-Molecule Inhibitor of the EIF4E-RBM38 Complex That Enhances Wild-type TP53 Protein Translation for Tumor Growth Suppression. Mol Cancer Ther 2023; 22:726-736. [PMID: 36940176 PMCID: PMC10866396 DOI: 10.1158/1535-7163.mct-22-0627] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2022] [Revised: 12/19/2022] [Accepted: 03/15/2023] [Indexed: 03/21/2023]
Abstract
EIF4E, an mRNA cap-binding protein, is necessary for cap-dependent translation. Overexpression of EIF4E is known to promote cancer development by preferentially translating a group of oncogenic mRNAs. Thus, 4EGI-1, a disruptor of EIF4E-EIF4G1 interaction, was developed to inhibit oncoprotein expression for cancer therapy. Interestingly, RBM38, an RNA-binding protein, interacts with EIF4E on TP53 mRNA, prevents EIF4E from binding to TP53 mRNA cap, and inhibits TP53 expression. Thus, Pep8, an eight amino acid peptide derived from RBM38, was developed to disrupt the EIF4E-RBM38 complex, leading to increased TP53 expression and decreased tumor cell growth. Herein, we have developed a first-in-class small-molecule compound 094, which interacts with EIF4E via the same pocket as does Pep8, dissociates RBM38 from EIF4E, and enhances TP53 translation in RBM38- and EIF4E-dependent manners. Structure-activity relationship studies identified that both the fluorobenzene and ethyl benzamide are necessary for compound 094 to interact with EIF4E. Furthermore, we showed that compound 094 is capable of suppressing three-dimensional tumor spheroid growth in RBM38- and TP53-dependent manners. In addition, we found that compound 094 cooperates with the chemotherapeutic agent doxorubicin and EIF4E inhibitor 4EGI-1 to suppress tumor cell growth. Collectively, we showed that two distinct approaches can be used together to target EIF4E for cancer therapy by enhancing wild-type TP53 expression (094) and by suppressing oncoprotein expression (4EGI-1).
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Affiliation(s)
- Christopher A. Lucchesi
- Comparative Oncology Laboratory, Schools of Veterinary Medicine and Medicine, University of California at Davis, Davis, California
| | - Jin Zhang
- Comparative Oncology Laboratory, Schools of Veterinary Medicine and Medicine, University of California at Davis, Davis, California
| | - Mingchun Gao
- Department of Chemistry, University of California, Davis, Davis, California
| | - Jared Shaw
- Department of Chemistry, University of California, Davis, Davis, California
| | - Xinbin Chen
- Comparative Oncology Laboratory, Schools of Veterinary Medicine and Medicine, University of California at Davis, Davis, California
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12
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Ma J, Dong C, Cao YZ, Ma BL. Dual Target of EGFR and mTOR Suppresses Triple-Negative Breast Cancer Cell Growth by Regulating the Phosphorylation of mTOR Downstream Proteins. BREAST CANCER (DOVE MEDICAL PRESS) 2023; 15:11-24. [PMID: 36691572 PMCID: PMC9864233 DOI: 10.2147/bctt.s390017] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/15/2022] [Accepted: 12/20/2022] [Indexed: 01/19/2023]
Abstract
Objective To detect the activation of the EGFR and mTOR signaling pathways in the triple negative breast cancer cell line MDA-MB-468 and investigate the inhibitory effect of gefitinib, an epidermal growth factor receptor inhibitor, and everolimus, a target protein inhibitor of rapamycin, on triple negative breast cancer cells. Methods Triple negative human breast cancer MDA-MB-468 cells were cultured and blank control group, single EGFR inhibitor gefitinib group, single mTOR inhibitor everolimus group, and two drug combination group were set up respectively to detect the effects of single and combined drugs on cell proliferation activity, cell cycle and apoptosis, and the expression of EGFR and mTOR signal pathway proteins in cell lines after single and combined drug intervention was detected again by Western blot. Results The level of EGFR and p-mTOR protein in triple negative breast cancer was higher than in non triple negative breast cancer (P<0.05). The level of mTOR, S6K1, p-EGFR, p-S6K1 was significantly increased when treated with EGF (0ng/mL, 10ng/mL, 100ng/mL) for 1h, compared to without EGF stimulation (P<0.05). The level of p-EGFR, p-mTOR, p-S6K1 protein increased significantly when the cells were exposed to EGF for 2h, respectively (P<0.05). EGFR inhibitor gefitinib alone and the mTOR inhibitor everolimus alone could significantly inhibit the proliferation of human triple negative breast cancer MDA-MB-468 cells in a dose-dependent manner (P<0.05). The level of p-4EBP1 protein in EGFR and mTOR signal pathway was significantly increased after the intervention of gefitinib alone, everolimus alone, and the combination of two drugs (P<0.05). Conclusion EGFR and mTOR signaling pathways can be activated in triple negative breast cancer; Both the EGFR inhibitor gefitinib alone and the mTOR inhibitor everolimus alone can significantly inhibit the proliferation of human triple negative breast cancer MDA-MB-468 cells. The combination of the EGFR inhibitor gefitinib and the mTOR inhibitor everolimus may achieve anti-tumor effect similar to that of single drug by reducing the drug dose.
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Affiliation(s)
- Jing Ma
- Department of Breast and Thyroid Surgery, Affiliated Cancer Hospital of Xinjiang Medical University, Urumqi, 830000, People’s Republic of China
| | - Chao Dong
- Department of Breast and Thyroid Surgery, Affiliated Cancer Hospital of Xinjiang Medical University, Urumqi, 830000, People’s Republic of China
| | - Yan-Zhen Cao
- Pathology Center, Affiliated Cancer Hospital of Xinjiang Medical University, Urumqi, 830000, People’s Republic of China
| | - Bin-Lin Ma
- Department of Breast and Thyroid Surgery, Affiliated Cancer Hospital of Xinjiang Medical University, Urumqi, 830000, People’s Republic of China,Correspondence: Bin-Lin Ma, Department of Breast and Thyroid Surgery, Affiliated Cancer Hospital of Xinjiang Medical University, No. 789, Suzhou East Street, Xinshi District, Urumqi, 830000, People’s Republic of China, Tel/Fax +86 991 7819082, Email
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13
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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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14
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Targeting anti-apoptotic pathways eliminates senescent melanocytes and leads to nevi regression. Nat Commun 2022; 13:7923. [PMID: 36564381 PMCID: PMC9789033 DOI: 10.1038/s41467-022-35657-9] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2022] [Accepted: 12/16/2022] [Indexed: 12/24/2022] Open
Abstract
Human melanocytic nevi (moles) result from a brief period of clonal expansion of melanocytes. As a cellular defensive mechanism against oncogene-induced hyperplasia, nevus-resident melanocytes enter a senescent state of stable cell cycle arrest. Senescent melanocytes can persist for months in mice and years in humans with a risk to escape the senescent state and progress to melanoma. The mechanisms providing prolonged survival of senescent melanocytes remain poorly understood. Here, we show that senescent melanocytes in culture and in nevi express high level of the anti-apoptotic BCL-2 family member BCL-W but remain insensitive to the pan-BCL-2 inhibitor ABT-263. We demonstrate that resistance to ABT-263 is driven by mTOR-mediated enhanced translation of another anti-apoptotic member, MCL-1. Strikingly, the combination of ABT-263 and MCL-1 inhibitors results in synthetic lethality to senescent melanocytes, and its topical application sufficient to eliminate nevi in male mice. These data highlight the important role of redundant anti-apoptotic mechanisms for the survival advantage of senescent melanocytes, and the proof-of-concept for a non-invasive combination therapy for nevi removal.
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15
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A noncanonical function of EIF4E limits ALDH1B1 activity and increases susceptibility to ferroptosis. Nat Commun 2022; 13:6318. [PMID: 36274088 PMCID: PMC9588786 DOI: 10.1038/s41467-022-34096-w] [Citation(s) in RCA: 40] [Impact Index Per Article: 20.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2022] [Accepted: 10/13/2022] [Indexed: 12/25/2022] Open
Abstract
Ferroptosis is a type of lipid peroxidation-dependent cell death that is emerging as a therapeutic target for cancer. However, the mechanisms of ferroptosis during the generation and detoxification of lipid peroxidation products remain rather poorly defined. Here, we report an unexpected role for the eukaryotic translation initiation factor EIF4E as a determinant of ferroptotic sensitivity by controlling lipid peroxidation. A drug screening identified 4EGI-1 and 4E1RCat (previously known as EIF4E-EIF4G1 interaction inhibitors) as powerful inhibitors of ferroptosis. Genetic and functional studies showed that EIF4E (but not EIF4G1) promotes ferroptosis in a translation-independent manner. Using mass spectrometry and subsequent protein-protein interaction analysis, we identified EIF4E as an endogenous repressor of ALDH1B1 in mitochondria. ALDH1B1 belongs to the family of aldehyde dehydrogenases and may metabolize the aldehyde substrate 4-hydroxynonenal (4HNE) at high concentrations. Supraphysiological levels of 4HNE triggered ferroptosis, while low concentrations of 4HNE increased the cell susceptibility to classical ferroptosis inducers by activating the NOX1 pathway. Accordingly, EIF4E-dependent ALDH1B1 inhibition enhanced the anticancer activity of ferroptosis inducers in vitro and in vivo. Our results support a key function of EIF4E in orchestrating lipid peroxidation to ignite ferroptosis.
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16
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Patel PS, Pérez-Baos S, Walters B, Orlen M, Volkova A, Ruggles K, Park CY, Schneider RJ. Translational regulation of TFH cell differentiation and autoimmune pathogenesis. SCIENCE ADVANCES 2022; 8:eabo1782. [PMID: 35749506 PMCID: PMC9232117 DOI: 10.1126/sciadv.abo1782] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/18/2022] [Accepted: 05/09/2022] [Indexed: 06/15/2023]
Abstract
Little is known regarding T cell translational regulation. We demonstrate that T follicular helper (TFH) cells use a previously unknown mechanism of selective messenger RNA (mRNA) translation for their differentiation, role in B cell maturation, and in autoimmune pathogenesis. We show that TFH cells have much higher levels of translation factor eIF4E than non-TFH CD4+ T cells, which is essential for translation of TFH cell fate-specification mRNAs. Genome-wide translation studies indicate that modest down-regulation of eIF4E activity by a small-molecule inhibitor or short hairpin RN impairs TFH cell development and function. In mice, down-regulation of eIF4E activity specifically reduces TFH cells among T helper subtypes, germinal centers, B cell recruitment, and antibody production. In experimental autoimmune encephalomyelitis, eIF4E activity down-regulation blocks TFH cell participation in disease pathogenesis while promoting rapid remission and spinal cord remyelination. TFH cell development and its role in autoimmune pathogenesis involve selective mRNA translation that is highly druggable.
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Affiliation(s)
- Preeyam S. Patel
- Department of Microbiology, New York University School of Medicine, New York, NY 10016, USA
| | - Sandra Pérez-Baos
- Department of Microbiology, New York University School of Medicine, New York, NY 10016, USA
| | - Beth Walters
- Department of Microbiology, New York University School of Medicine, New York, NY 10016, USA
| | - Margo Orlen
- Department of Microbiology, New York University School of Medicine, New York, NY 10016, USA
| | - Angelina Volkova
- Department of Medicine, New York University School of Medicine, New York, NY 10016, USA
| | - Kelly Ruggles
- Department of Medicine, New York University School of Medicine, New York, NY 10016, USA
| | - Christopher Y. Park
- Department of Pathology, New York University School of Medicine, New York, NY 10016, USA
| | - Robert J. Schneider
- Department of Microbiology, New York University School of Medicine, New York, NY 10016, USA
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17
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Zhao Y, Li C, Zhang Y, Li Z. CircTMTC1 contributes to nasopharyngeal carcinoma progression through targeting miR-495-MET-eIF4G1 translational regulation axis. Cell Death Dis 2022; 13:250. [PMID: 35301291 PMCID: PMC8930977 DOI: 10.1038/s41419-022-04686-z] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2021] [Revised: 12/20/2021] [Accepted: 02/24/2022] [Indexed: 02/07/2023]
Abstract
Nasopharyngeal carcinoma (NPC) is the most common primary malignancy arising from the epithelial cells of nasopharynx. CircTMTC1 is upregulated in NPC patients, but its role and molecular mechanism in NPC are unknown. Normal nasopharyngeal epithelium and tumor tissues were collected. The expression of circTMTC1, miR-495, MET/eIF4G1 pathway-related molecules were examined. Colony formation and transwell assays were used to assess cell proliferation, migration, and invasion. Cell apoptosis was analyzed by annexin V and propidium iodide (PI) staining. Gene interaction was examined by RNA immunoprecipitation (RIP) and luciferase activity assays. Subcutaneous and intravenous xenograft mouse models were established to analyze NPC growth and metastasis in vivo. CircTMTC1 was highly expressed and miR-495 was downregulated in NPC, which were associated with poor prognosis of NPC. Both circTMTC1 knockdown and miR-495 overexpression inhibited NPC cell proliferation, migration, invasion, and epithelial–mesenchymal transition (EMT) and promoted cell apoptosis. CircTMTC1 directly targeted miR-495 to promote the expression of its downstream target gene MET. miR-495 knockdown enhanced the expression of c-Myc, Cyclin D1, and survivin and accelerated NPC cell proliferation, migration, invasion, and EMT through targeting MET and activating the MET-eIF4G1 axis. CircTMTC1 silence inhibited NPC growth and lung metastasis by targeting the miR-495-MET-eIF4G1 translational regulation axis in vivo. CircTMTC1 accelerates NPC progression through targeting miR-495 and consequently activating the MET-eIF4G1 translational regulation axis, suggesting potential therapeutic targets for NPC treatment.
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Affiliation(s)
- Yajie Zhao
- Department of Nuclear Medicine, Xiangya Hospital, Central South University, Changsha, 410008, Hunan Province, P. R. China
| | - Chao Li
- Department of Oncology, Xiangya Hospital, Central South University, Changsha, 410008, Hunan Province, P. R. China
| | - Yan Zhang
- Department of Pathology, The Second Affiliated Hospital of Zhengzhou University, Zhengzhou, 450014, Henan Province, P. R. China
| | - Zhanzhan Li
- Department of Oncology, Xiangya Hospital, Central South University, Changsha, 410008, Hunan Province, P. R. China. .,National Clinical Research Center for Geriatric Disorders, Xiangya Hospital, Central South University, Changsha, 410008, Hunan Province, P. R. China.
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18
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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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19
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Keane L, Antignano I, Riechers SP, Zollinger R, Dumas AA, Offermann N, Bernis ME, Russ J, Graelmann F, McCormick PN, Esser J, Tejera D, Nagano A, Wang J, Chelala C, Biederbick Y, Halle A, Salomoni P, Heneka MT, Capasso M. mTOR-dependent translation amplifies microglia priming in aging mice. J Clin Invest 2021; 131:132727. [PMID: 33108356 DOI: 10.1172/jci132727] [Citation(s) in RCA: 32] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2019] [Accepted: 10/14/2020] [Indexed: 12/20/2022] Open
Abstract
Microglia maintain homeostasis in the brain. However, with age, they become primed and respond more strongly to inflammatory stimuli. We show here that microglia from aged mice had upregulated mTOR complex 1 signaling controlling translation, as well as protein levels of inflammatory mediators. Genetic ablation of mTOR signaling showed a dual yet contrasting effect on microglia priming: it caused an NF-κB-dependent upregulation of priming genes at the mRNA level; however, mice displayed reduced cytokine protein levels, diminished microglia activation, and milder sickness behavior. The effect on translation was dependent on reduced phosphorylation of 4EBP1, resulting in decreased binding of eIF4E to eIF4G. Similar changes were present in aged human microglia and in damage-associated microglia, indicating that upregulation of mTOR-dependent translation is an essential aspect of microglia priming in aging and neurodegeneration.
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Affiliation(s)
- Lily Keane
- German Center for Neurodegenerative Diseases (DZNE), Bonn, Germany.,Centre for Tumour Microenvironment and
| | | | | | | | | | - Nina Offermann
- German Center for Neurodegenerative Diseases (DZNE), Bonn, Germany
| | - Maria E Bernis
- German Center for Neurodegenerative Diseases (DZNE), Bonn, Germany
| | - Jenny Russ
- German Center for Neurodegenerative Diseases (DZNE), Bonn, Germany
| | | | | | - Julia Esser
- German Center for Neurodegenerative Diseases (DZNE), Bonn, Germany
| | - Dario Tejera
- German Center for Neurodegenerative Diseases (DZNE), Bonn, Germany
| | - Ai Nagano
- Centre for Cancer Genomics and Computational Biology, Barts Cancer Institute, Queen Mary University of London, London, United Kingdom
| | - Jun Wang
- Centre for Cancer Genomics and Computational Biology, Barts Cancer Institute, Queen Mary University of London, London, United Kingdom
| | - Claude Chelala
- Centre for Cancer Genomics and Computational Biology, Barts Cancer Institute, Queen Mary University of London, London, United Kingdom
| | | | - Annett Halle
- German Center for Neurodegenerative Diseases (DZNE), Bonn, Germany
| | - Paolo Salomoni
- German Center for Neurodegenerative Diseases (DZNE), Bonn, Germany
| | - Michael T Heneka
- German Center for Neurodegenerative Diseases (DZNE), Bonn, Germany
| | - Melania Capasso
- German Center for Neurodegenerative Diseases (DZNE), Bonn, Germany.,Centre for Tumour Microenvironment and
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20
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Fang C, Xie H, Zhao J, Wang W, Hou H, Zhang B, Zhou D, Geng X. eIF4E-eIF4G complex inhibition synergistically enhances the effect of sorafenib in hepatocellular carcinoma. Anticancer Drugs 2021; 32:822-828. [PMID: 33783376 PMCID: PMC8366763 DOI: 10.1097/cad.0000000000001074] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2020] [Revised: 03/04/2021] [Indexed: 12/29/2022]
Abstract
The clinical efficacy of sorafenib in hepatocellular carcinoma (HCC) is disappointing due to its low response rate and high rates of adverse effects. The eukaryotic translation initiation factor 4F (eIF4F) complex, mainly consisting of eIF4E-eukaryotic translation initiation factor 4G (eIF4G) interaction, is involved in the induction of drug resistance. Herein, we aimed to demonstrate that eIF4E-eIF4G complex inhibition enhanced the effect of sorafenib. The antiproliferation effect of combined treatment was evaluated by MTT assay and colony formation assay. Flow cytometry was used to detect the early cell apoptosis and cell cycle. The specific mechanism was demonstrated using western blot and lentivirus transfection. The combination of sorafenib with eIF4E-eIF4G inhibitors 4E1RCat (structural) or 4EGI-1 (competitive) synergistically inhibited the cell viability and colony formation ability of HCC cells. Moreover, the combined treatment induced more early apoptosis than sorafenib alone through downregulating the Bcl-2 expression. Besides, the coadministration of sorafenib and 4E1RCat or 4EGI-1 synergistically inhibited the expressions of eIF4E, eIF4G and phospho-4E-BP1 in HCC cells while blocking the phosphorylation of 4E-BP1 with lentiviral transfection failed to increase the sensitivity of HCC cells to sorafenib treatment. PI3K-AKT-mTOR signaling was also inhibited by the combined treatment. In a word, eIF4E-eIF4G complex inhibition synergistically enhances the effect of sorafenib in HCC treatment.
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Affiliation(s)
- Chao Fang
- Department of Hepatobiliary Surgery, The Second Affiliated Hospital of Anhui Medical University
| | - Haishen Xie
- Department of Hepatobiliary Surgery, The Second Affiliated Hospital of Anhui Medical University
| | - Jun Zhao
- Department of Hepatobiliary Surgery, The Second Affiliated Hospital of Anhui Medical University
| | - Weichen Wang
- Department of Hepatobiliary Surgery, The Second Affiliated Hospital of Anhui Medical University
| | - Hui Hou
- Department of Hepatobiliary Surgery, The Second Affiliated Hospital of Anhui Medical University
| | - Bin Zhang
- Department of Hepatobiliary Surgery, The Second Affiliated Hospital of Anhui Medical University
| | - Dachen Zhou
- Department of Hepatobiliary Surgery, The Second Affiliated Hospital of Anhui Medical University
| | - Xiaoping Geng
- Department of Hepatobiliary Surgery, The Second Affiliated Hospital of Anhui Medical University
- Department of Hepatobiliary Surgery, The First Affiliated Hospital of Anhui Medical University, Hefei, Anhui, PR China
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21
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Wu S, Wagner G. Deep computational analysis details dysregulation of eukaryotic translation initiation complex eIF4F in human cancers. Cell Syst 2021; 12:907-923.e6. [PMID: 34358439 DOI: 10.1016/j.cels.2021.07.002] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2020] [Revised: 04/22/2021] [Accepted: 07/09/2021] [Indexed: 12/28/2022]
Abstract
eIF4F plays diverse roles in human cancers, which complicate the development of an overarching understanding of its functional and regulatory impacts across tumor types. Typically, eIF4F drives initiation from the mRNA 5' end (cap) and is composed of eIF4G1, eIF4A1, and cap-binding eIF4E. Cap-independent initiation is possible without eIF4E, from internal ribosomal entry sites (IRESs). By analyzing large public datasets, we found that cancers selectively overexpress EIF4G1 more than EIF4E. That expression imbalance supports EIF4G1 as a prognostic indicator in patients with cancer. It also attenuates "housekeeping" pathways that are usually regulated in a tissue-specific manner via cap-dependent initiation in healthy tissues and reinforce regulation of cancer-preferred pathways in cap-independent contexts. Cap-independent initiation is mechanistically attributable to eIF4G1 hyperphosphorylation that promotes binding to eIF4A1 and reduced eIF4E availability. Collectively, these findings reveal a novel model of dysregulated eIF4F function and highlight the clinical relevance of cap-(in)dependent initiation in cancer.
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Affiliation(s)
- Su Wu
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02115, USA.
| | - Gerhard Wagner
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02115, USA.
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22
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Tiu GC, Kerr CH, Forester CM, Krishnarao PS, Rosenblatt HD, Raj N, Lantz TC, Zhulyn O, Bowen ME, Shokat L, Attardi LD, Ruggero D, Barna M. A p53-dependent translational program directs tissue-selective phenotypes in a model of ribosomopathies. Dev Cell 2021; 56:2089-2102.e11. [PMID: 34242585 PMCID: PMC8319123 DOI: 10.1016/j.devcel.2021.06.013] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2020] [Revised: 03/26/2021] [Accepted: 06/11/2021] [Indexed: 12/13/2022]
Abstract
In ribosomopathies, perturbed expression of ribosome components leads to tissue-specific phenotypes. What accounts for such tissue-selective manifestations as a result of mutations in the ribosome, a ubiquitous cellular machine, has remained a mystery. Combining mouse genetics and in vivo ribosome profiling, we observe limb-patterning phenotypes in ribosomal protein (RP) haploinsufficient embryos, and we uncover selective translational changes of transcripts that controlling limb development. Surprisingly, both loss of p53, which is activated by RP haploinsufficiency, and augmented protein synthesis rescue these phenotypes. These findings are explained by the finding that p53 functions as a master regulator of protein synthesis, at least in part, through transcriptional activation of 4E-BP1. 4E-BP1, a key translational regulator, in turn, facilitates selective changes in the translatome downstream of p53, and this thereby explains how RP haploinsufficiency may elicit specificity to gene expression. These results provide an integrative model to help understand how in vivo tissue-specific phenotypes emerge in ribosomopathies.
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Affiliation(s)
- Gerald C Tiu
- Department of Genetics, Stanford University School of Medicine, Stanford, CA 94305, USA; Department of Developmental Biology, Stanford University, Stanford, CA 94305, USA; Stanford Medical Scientist Training Program, Stanford University, Stanford, CA 94305, USA
| | - Craig H Kerr
- Department of Genetics, Stanford University School of Medicine, Stanford, CA 94305, USA; Department of Developmental Biology, Stanford University, Stanford, CA 94305, USA
| | - Craig M Forester
- Helen Diller Family Comprehensive Cancer Center, University of California, San Francisco, San Francisco, CA 94143, USA; Division of Pediatric Allergy, Immunology and Bone Marrow Transplantation, University of California, San Francisco, San Francisco, CA 94143, USA; Children's Hospital Colorado, Division of Pediatric Hematology/Oncology/Bone Marrow Transplant, Colorado, University of Colorado Anschutz Medical Campus, Aurora, CO 80045, USA
| | - Pallavi S Krishnarao
- Department of Genetics, Stanford University School of Medicine, Stanford, CA 94305, USA; Department of Developmental Biology, Stanford University, Stanford, CA 94305, USA
| | - Hannah D Rosenblatt
- Department of Genetics, Stanford University School of Medicine, Stanford, CA 94305, USA; Department of Developmental Biology, Stanford University, Stanford, CA 94305, USA
| | - Nitin Raj
- Division of Radiation and Cancer Biology, Department of Radiation Oncology, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Travis C Lantz
- Department of Genetics, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Olena Zhulyn
- Department of Genetics, Stanford University School of Medicine, Stanford, CA 94305, USA; Department of Developmental Biology, Stanford University, Stanford, CA 94305, USA
| | - Margot E Bowen
- Division of Radiation and Cancer Biology, Department of Radiation Oncology, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Leila Shokat
- Department of Genetics, Stanford University School of Medicine, Stanford, CA 94305, USA; Department of Developmental Biology, Stanford University, Stanford, CA 94305, USA
| | - Laura D Attardi
- Department of Genetics, Stanford University School of Medicine, Stanford, CA 94305, USA; Division of Radiation and Cancer Biology, Department of Radiation Oncology, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Davide Ruggero
- Department of Urology, University of California, San Francisco, San Francisco, CA 94143, USA; Helen Diller Family Comprehensive Cancer Center, University of California, San Francisco, San Francisco, CA 94143, USA; Department of Cellular and Molecular Pharmacology, University of California, San Francisco, San Francisco, CA 94143, USA.
| | - Maria Barna
- Department of Genetics, Stanford University School of Medicine, Stanford, CA 94305, USA; Department of Developmental Biology, Stanford University, Stanford, CA 94305, USA.
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23
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Plasmalogens regulate the AKT-ULK1 signaling pathway to control the position of the axon initial segment. Prog Neurobiol 2021; 205:102123. [PMID: 34302896 DOI: 10.1016/j.pneurobio.2021.102123] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2021] [Revised: 06/11/2021] [Accepted: 07/14/2021] [Indexed: 01/04/2023]
Abstract
The axon initial segment (AIS) is a specialized region in neurons that encompasses two essential functions, the generation of action potentials and the regulation of the axodendritic polarity. The mechanism controlling the position of the axon initial segment to allow plasticity and regulation of neuron excitability is unclear. Here we demonstrate that plasmalogens, the most abundant ether-phospholipid, are essential for the homeostatic positioning of the AIS. Plasmalogen deficiency is a hallmark of Rhizomelic Chondrodysplasia Punctata (RCDP) and Zellweger spectrum disorders, but Alzheimer's and Parkinson's disease, are also characterized by plasmalogen defects. Neurons lacking plasmalogens displaced the AIS to more distal positions and were characterized by reduced excitability. Treatment with a short-chain alkyl glycerol was able to rescue AIS positioning. Plasmalogen deficiency impaired AKT activation, and we show that inhibition of AKT phosphorylation at Ser473 and Thr308 is sufficient to induce a distal relocation of the AIS. Pathway analysis revealed that downstream of AKT, overtly active ULK1 mediates AIS repositioning. Rescuing the impaired AKT signaling pathway was able to normalize AIS position independently of the biochemical defect. These results unveil a previously unknown mechanism that couples the phospholipid composition of the neuronal membrane to the positional assembly of the AIS.
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24
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Dmitriev SE, Vladimirov DO, Lashkevich KA. A Quick Guide to Small-Molecule Inhibitors of Eukaryotic Protein Synthesis. BIOCHEMISTRY (MOSCOW) 2021; 85:1389-1421. [PMID: 33280581 PMCID: PMC7689648 DOI: 10.1134/s0006297920110097] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Eukaryotic ribosome and cap-dependent translation are attractive targets in the antitumor, antiviral, anti-inflammatory, and antiparasitic therapies. Currently, a broad array of small-molecule drugs is known that specifically inhibit protein synthesis in eukaryotic cells. Many of them are well-studied ribosome-targeting antibiotics that block translocation, the peptidyl transferase center or the polypeptide exit tunnel, modulate the binding of translation machinery components to the ribosome, and induce miscoding, premature termination or stop codon readthrough. Such inhibitors are widely used as anticancer, anthelmintic and antifungal agents in medicine, as well as fungicides in agriculture. Chemicals that affect the accuracy of stop codon recognition are promising drugs for the nonsense suppression therapy of hereditary diseases and restoration of tumor suppressor function in cancer cells. Other compounds inhibit aminoacyl-tRNA synthetases, translation factors, and components of translation-associated signaling pathways, including mTOR kinase. Some of them have antidepressant, immunosuppressive and geroprotective properties. Translation inhibitors are also used in research for gene expression analysis by ribosome profiling, as well as in cell culture techniques. In this article, we review well-studied and less known inhibitors of eukaryotic protein synthesis (with the exception of mitochondrial and plastid translation) classified by their targets and briefly describe the action mechanisms of these compounds. We also present a continuously updated database (http://eupsic.belozersky.msu.ru/) that currently contains information on 370 inhibitors of eukaryotic protein synthesis.
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Affiliation(s)
- S E Dmitriev
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, 119234, Russia. .,Faculty of Bioengineering and Bioinformatics, Lomonosov Moscow State University, Moscow, 119234, Russia.,Engelhardt Institute of Molecular Biology, Russian Academy of Sciences, Moscow, 119991, Russia
| | - D O Vladimirov
- Faculty of Bioengineering and Bioinformatics, Lomonosov Moscow State University, Moscow, 119234, Russia
| | - K A Lashkevich
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, 119234, Russia
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25
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Li Y, Tang J, Ji X, Hua MM, Liu M, Chang L, Gu Y, Shi C, Ni W, Liu J, Shi HJ, Huang X, O'Neill C, Jin X. Regulation of the mammalian maternal-to-embryonic transition by eukaryotic translation initiation factor 4E. Development 2021; 148:268308. [PMID: 34013332 PMCID: PMC8254863 DOI: 10.1242/dev.190793] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2020] [Accepted: 05/12/2021] [Indexed: 12/24/2022]
Abstract
Eukaryotic translation initiation factor 4E (eIF4E) mediates cap-dependent translation. Genetic and inhibitor studies show that eIF4E expression is required for the successful transition from maternal to embryonic control of mouse embryo development. eIF4E was present in the oocyte and in the cytoplasm soon after fertilization and during each stage of early development. Functional knockout (Eif4e−/−) by PiggyBac [Act-RFP] transposition resulted in peri-implantation embryonic lethality because of the failure of normal epiblast formation. Maternal stores of eIF4E supported development up to the two- to four-cell stage, after which new expression occurred from both maternal and paternal inherited alleles. Inhibition of the maternally acquired stores of eIF4E (using the inhibitor 4EGI-1) resulted in a block at the two-cell stage. eIF4E activity was required for new protein synthesis in the two-cell embryo and Eif4e−/− embryos had lower translational activity compared with wild-type embryos. eIF4E-binding protein 1 (4E-BP1) is a hypophosphorylation-dependent negative regulator of eIF4E. mTOR activity was required for 4E-BP1 phosphorylation and inhibiting mTOR retarded embryo development. Thus, this study shows that eIF4E activity is regulated at key embryonic transitions in the mammalian embryo and is essential for the successful transition from maternal to embryonic control of development. Summary: Combined use of a PB [Act-RFP] transgenesis model, selective pharmacological inhibition and expression analyses verified the essential role of eIF4E in the transition from maternal to embryonic control of mouse development.
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Affiliation(s)
- Yan Li
- Reproductive Medicine Center, The First Affiliated Hospital of Wenzhou Medical University, Wenzhou, Zhejiang Province, 325000, China
| | - Jianan Tang
- NHC Key Lab of Reproduction Regulation, Shanghai Institute of Planned Parenthood Research, Fudan University, Shanghai, 200032, China
| | - Xu Ji
- Department of Pharmacology, School of Pharmaceutical Sciences, Nanjing Tech University, Nanjing, Jiangsu Province, 211816, China
| | - Min-Min Hua
- NHC Key Lab of Reproduction Regulation, Shanghai Institute of Planned Parenthood Research, Fudan University, Shanghai, 200032, China
| | - Miao Liu
- Reproductive Medical Center, Zhongshan Hospital, Fudan University, Shanghai, 200032, China
| | - Lu Chang
- Department of Pharmacology, School of Pharmaceutical Sciences, Nanjing Tech University, Nanjing, Jiangsu Province, 211816, China
| | - Yihua Gu
- NHC Key Lab of Reproduction Regulation, Shanghai Institute of Planned Parenthood Research, Fudan University, Shanghai, 200032, China
| | - Changgen Shi
- NHC Key Lab of Reproduction Regulation, Shanghai Institute of Planned Parenthood Research, Fudan University, Shanghai, 200032, China
| | - Wuhua Ni
- Reproductive Medicine Center, The First Affiliated Hospital of Wenzhou Medical University, Wenzhou, Zhejiang Province, 325000, China
| | - Jing Liu
- Department of Pharmacology, School of Pharmaceutical Sciences, Nanjing Tech University, Nanjing, Jiangsu Province, 211816, China
| | - Hui-Juan Shi
- NHC Key Lab of Reproduction Regulation, Shanghai Institute of Planned Parenthood Research, Fudan University, Shanghai, 200032, China
| | - Xuefeng Huang
- Reproductive Medicine Center, The First Affiliated Hospital of Wenzhou Medical University, Wenzhou, Zhejiang Province, 325000, China
| | - Christopher O'Neill
- Human Reproduction Unit, Sydney Center for Regenerative and Developmental Medicine, Kolling Institute for Medical Research, Sydney Medical School, University of Sydney, St. Leonards, New South Wales, 2065, Australia
| | - Xingliang Jin
- Reproductive Medicine Center, The First Affiliated Hospital of Wenzhou Medical University, Wenzhou, Zhejiang Province, 325000, China.,Human Reproduction Unit, Sydney Center for Regenerative and Developmental Medicine, Kolling Institute for Medical Research, Sydney Medical School, University of Sydney, St. Leonards, New South Wales, 2065, Australia
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26
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Inhibitory effects of Tomivosertib in acute myeloid leukemia. Oncotarget 2021; 12:955-966. [PMID: 34012509 PMCID: PMC8121614 DOI: 10.18632/oncotarget.27952] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2021] [Accepted: 04/19/2021] [Indexed: 12/26/2022] Open
Abstract
The MAPK-interacting kinases 1 and 2 (MNK1/2) have generated increasing interest as therapeutic targets for acute myeloid leukemia (AML). We evaluated the therapeutic potential of the highly-selective MNK1/2 inhibitor Tomivosertib on AML cells. Tomivosertib was highly effective at blocking eIF4E phosphorylation on serine 209 in AML cells. Such inhibitory effects correlated with dose-dependent suppression of cellular viability and leukemic progenitor colony formation. Moreover, combination of Tomivosertib and Venetoclax resulted in synergistic anti-leukemic responses in AML cell lines. Mass spectrometry studies identified novel putative MNK1/2 interactors, while in parallel studies we demonstrated that MNK2 - RAPTOR - mTOR complexes are not disrupted by Tomivosertib. Overall, these findings demonstrate that Tomivosertib exhibits potent anti-leukemic properties on AML cells and support the development of clinical translational efforts involving the use of this drug, alone or in combination with other therapies for the treatment of AML.
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27
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Böhm R, Imseng S, Jakob RP, Hall MN, Maier T, Hiller S. The dynamic mechanism of 4E-BP1 recognition and phosphorylation by mTORC1. Mol Cell 2021; 81:2403-2416.e5. [PMID: 33852892 DOI: 10.1016/j.molcel.2021.03.031] [Citation(s) in RCA: 30] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2020] [Revised: 02/22/2021] [Accepted: 03/18/2021] [Indexed: 10/21/2022]
Abstract
The activation of cap-dependent translation in eukaryotes requires multisite, hierarchical phosphorylation of 4E-BP by the 1 MDa kinase mammalian target of rapamycin complex 1 (mTORC1). To resolve the mechanism of this hierarchical phosphorylation at the atomic level, we monitored by NMR spectroscopy the interaction of intrinsically disordered 4E binding protein isoform 1 (4E-BP1) with the mTORC1 subunit regulatory-associated protein of mTOR (Raptor). The N-terminal RAIP motif and the C-terminal TOR signaling (TOS) motif of 4E-BP1 bind separate sites in Raptor, resulting in avidity-based tethering of 4E-BP1. This tethering orients the flexible central region of 4E-BP1 toward the mTORC1 kinase site for phosphorylation. The structural constraints imposed by the two tethering interactions, combined with phosphorylation-induced conformational switching of 4E-BP1, explain the hierarchy of 4E-BP1 phosphorylation by mTORC1. Furthermore, we demonstrate that mTORC1 recognizes both free and eIF4E-bound 4E-BP1, allowing rapid phosphorylation of the entire 4E-BP1 pool and efficient activation of translation. Finally, our findings provide a mechanistic explanation for the differential rapamycin sensitivity of the 4E-BP1 phosphorylation sites.
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Affiliation(s)
- Raphael Böhm
- Biozentrum, University of Basel, 4056 Basel, Switzerland
| | - Stefan Imseng
- Biozentrum, University of Basel, 4056 Basel, Switzerland
| | - Roman P Jakob
- Biozentrum, University of Basel, 4056 Basel, Switzerland
| | - Michael N Hall
- Biozentrum, University of Basel, 4056 Basel, Switzerland.
| | - Timm Maier
- Biozentrum, University of Basel, 4056 Basel, Switzerland.
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28
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Fischer PD, Papadopoulos E, Dempersmier JM, Wang ZF, Nowak RP, Donovan KA, Kalabathula J, Gorgulla C, Junghanns PPM, Kabha E, Dimitrakakis N, Petrov OI, Mitsiades C, Ducho C, Gelev V, Fischer ES, Wagner G, Arthanari H. A biphenyl inhibitor of eIF4E targeting an internal binding site enables the design of cell-permeable PROTAC-degraders. Eur J Med Chem 2021; 219:113435. [PMID: 33892272 DOI: 10.1016/j.ejmech.2021.113435] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2020] [Revised: 03/23/2021] [Accepted: 04/01/2021] [Indexed: 12/15/2022]
Abstract
The eukaryotic translation initiation factor 4E (eIF4E) is the master regulator of cap-dependent protein synthesis. Overexpression of eIF4E is implicated in diseases such as cancer, where dysregulation of oncogenic protein translation is frequently observed. eIF4E has been an attractive target for cancer treatment. Here we report a high-resolution X-ray crystal structure of eIF4E in complex with a novel inhibitor (i4EG-BiP) that targets an internal binding site, in contrast to the previously described inhibitor, 4EGI-1, which binds to the surface. We demonstrate that i4EG-BiP is able to displace the scaffold protein eIF4G and inhibit the proliferation of cancer cells. We provide insights into how i4EG-BiP is able to inhibit cap-dependent translation by increasing the eIF4E-4E-BP1 interaction while diminishing the interaction of eIF4E with eIF4G. Leveraging structural details, we designed proteolysis targeted chimeras (PROTACs) derived from 4EGI-1 and i4EG-BiP and characterized these on biochemical and cellular levels. We were able to design PROTACs capable of binding eIF4E and successfully engaging Cereblon, which targets proteins for proteolysis. However, these initial PROTACs did not successfully stimulate degradation of eIF4E, possibly due to competitive effects from 4E-BP1 binding. Our results highlight challenges of targeted proteasomal degradation of eIF4E that must be addressed by future efforts.
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Affiliation(s)
- Patrick D Fischer
- Department of Cancer Biology, Dana-Farber Cancer Institute, Boston, MA, 02215, USA; Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA, 02115, USA; Department of Pharmacy, Pharmaceutical and Medicinal Chemistry, Saarland University, Saarbrücken, 66123, Germany
| | - Evangelos Papadopoulos
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA, 02115, USA; Medical Oncology, Dana-Farber Cancer Institute, Boston, MA, 02215, USA.
| | - Jon M Dempersmier
- Department of Cancer Biology, Dana-Farber Cancer Institute, Boston, MA, 02215, USA; Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA, 02115, USA
| | - Zi-Fu Wang
- Department of Cancer Biology, Dana-Farber Cancer Institute, Boston, MA, 02215, USA; Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA, 02115, USA
| | - Radosław P Nowak
- Department of Cancer Biology, Dana-Farber Cancer Institute, Boston, MA, 02215, USA; Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA, 02115, USA
| | - Katherine A Donovan
- Department of Cancer Biology, Dana-Farber Cancer Institute, Boston, MA, 02215, USA; Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA, 02115, USA
| | - Joann Kalabathula
- Department of Cancer Biology, Dana-Farber Cancer Institute, Boston, MA, 02215, USA
| | - Christoph Gorgulla
- Department of Cancer Biology, Dana-Farber Cancer Institute, Boston, MA, 02215, USA; Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA, 02115, USA
| | - Pierre P M Junghanns
- Department of Pharmacy, Pharmaceutical and Medicinal Chemistry, Saarland University, Saarbrücken, 66123, Germany
| | - Eihab Kabha
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA, 02115, USA
| | - Nikolaos Dimitrakakis
- Wyss Institute for Biologically Inspired Engineering at Harvard University, Boston, MA, 02115, USA
| | - Ognyan I Petrov
- Faculty of Chemistry and Pharmacy, Sofia University, 1 James Bourchier Blvd., 1164, Sofia, Bulgaria
| | | | - Christian Ducho
- Department of Pharmacy, Pharmaceutical and Medicinal Chemistry, Saarland University, Saarbrücken, 66123, Germany
| | - Vladimir Gelev
- Faculty of Chemistry and Pharmacy, Sofia University, 1 James Bourchier Blvd., 1164, Sofia, Bulgaria
| | - Eric S Fischer
- Department of Cancer Biology, Dana-Farber Cancer Institute, Boston, MA, 02215, USA; Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA, 02115, USA
| | - Gerhard Wagner
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA, 02115, USA
| | - Haribabu Arthanari
- Department of Cancer Biology, Dana-Farber Cancer Institute, Boston, MA, 02215, USA; Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA, 02115, USA.
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29
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Hernández-Alvarez L, Oliveira AB, Hernández-González JE, Chahine J, Pascutti PG, de Araujo AS, de Souza FP. Computational study on the allosteric mechanism of Leishmania major IF4E-1 by 4E-interacting protein-1: Unravelling the determinants of m 7GTP cap recognition. Comput Struct Biotechnol J 2021; 19:2027-2044. [PMID: 33995900 PMCID: PMC8085901 DOI: 10.1016/j.csbj.2021.03.036] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2020] [Revised: 03/25/2021] [Accepted: 03/29/2021] [Indexed: 02/07/2023] Open
Abstract
Atomistic details on perturbations induced by Lm4E-IP1 binding are described. The modulation of LmIF4E-1 affinity for the cap is confirmed by energetic analyses. Signaling paths between the allosteric and othosteric sites of LmIF4E-1 are predicted. Lm4E-IP1 binding increases the side-chain entropy of W83 and R172 of LmIF4E-1. A mechanism of dynamic allostery is proposed for the regulation mediated by Lm4E-IP1.
During their life cycle, Leishmania parasites display a fine-tuned regulation of the mRNA translation through the differential expression of isoforms of eukaryotic translation initiation factor 4E (LeishIF4Es). The interaction between allosteric modulators such as 4E-interacting proteins (4E-IPs) and LeishIF4E affects the affinity of this initiation factor for the mRNA cap. Here, several computational approaches were employed to elucidate the molecular bases of the previously-reported allosteric modulation in L. major exerted by 4E-IP1 (Lm4E-IP1) on eukaryotic translation initiation factor 4E 1 (LmIF4E-1). Molecular dynamics (MD) simulations and accurate binding free energy calculations (ΔGbind) were combined with network-based modeling of residue-residue correlations. We also describe the differences in internal motions of LmIF4E-1 apo form, cap-bound, and Lm4E-IP1-bound systems. Through community network calculations, the differences in the allosteric pathways of allosterically-inhibited and active forms of LmIF4E-1 were revealed. The ΔGbind values show significant differences between the active and inhibited systems, which are in agreement with the available experimental data. Our study thoroughly describes the dynamical perturbations of LmIF4E-1 cap-binding site triggered by Lm4E-IP1. These findings are not only essential for the understanding of a critical process of trypanosomatids’ gene expression but also for gaining insight into the allostery of eukaryotic IF4Es, which could be useful for structure-based design of drugs against this protein family.
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Affiliation(s)
- Lilian Hernández-Alvarez
- Department of Physics, Instituto de Biociências, Letras e Ciências Exatas, Universidade Estadual Paulista Julio de Mesquita Filho, São José do Rio Preto, São Paulo, Brazil
| | - Antonio B Oliveira
- Department of Physics, Instituto de Biociências, Letras e Ciências Exatas, Universidade Estadual Paulista Julio de Mesquita Filho, São José do Rio Preto, São Paulo, Brazil.,Center for Theoretical Biological Physics, Rice University, Huston, TX, United States
| | - Jorge Enrique Hernández-González
- Department of Physics, Instituto de Biociências, Letras e Ciências Exatas, Universidade Estadual Paulista Julio de Mesquita Filho, São José do Rio Preto, São Paulo, Brazil.,Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
| | - Jorge Chahine
- Department of Physics, Instituto de Biociências, Letras e Ciências Exatas, Universidade Estadual Paulista Julio de Mesquita Filho, São José do Rio Preto, São Paulo, Brazil
| | - Pedro Geraldo Pascutti
- Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
| | - Alexandre Suman de Araujo
- Department of Physics, Instituto de Biociências, Letras e Ciências Exatas, Universidade Estadual Paulista Julio de Mesquita Filho, São José do Rio Preto, São Paulo, Brazil
| | - Fátima Pereira de Souza
- Department of Physics, Instituto de Biociências, Letras e Ciências Exatas, Universidade Estadual Paulista Julio de Mesquita Filho, São José do Rio Preto, São Paulo, Brazil
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30
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Abstract
Inhibiting eukaryotic protein translation with small molecules is emerging as a powerful therapeutic strategy. The advantage of targeting cellular translational machinery is that it is required for the highly proliferative state of many neoplastic cells, replication of certain viruses, and ultimately the expression of a wide variety of protein targets. Although, this approach has been exploited to develop clinical agents, such as homoharringtonine (HHT, 1), used to treat chronic myeloid leukemia (CML), inhibiting components of the translational machinery is often associated with cytotoxic phenotypes. However, recent studies have demonstrated that certain small molecules can inhibit the translation of specific subsets of proteins, leading to lower cytotoxicity, and opening-up therapeutic opportunities for translation inhibitors to be deployed in indications beyond oncology and infectious disease. This review summarizes efforts to develop inhibitors of the eukaryotic translational machinery as therapeutic agents and highlights emerging opportunities for translation inhibitors in the future.
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Affiliation(s)
- Angela Fan
- Department of Discovery Chemistry, Merck & Co., Inc., South San Francisco, California 94080, United States
| | - Phillip P Sharp
- Department of Discovery Chemistry, Merck & Co., Inc., South San Francisco, California 94080, United States
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31
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MNK1 and MNK2 enforce expression of E2F1, FOXM1, and WEE1 to drive soft tissue sarcoma. Oncogene 2021; 40:1851-1867. [PMID: 33564073 PMCID: PMC7946644 DOI: 10.1038/s41388-021-01661-4] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2020] [Revised: 12/25/2020] [Accepted: 01/15/2021] [Indexed: 01/31/2023]
Abstract
Soft tissue sarcoma (STS) is a heterogeneous disease that arises from connective tissues. Clinical outcome of patients with advanced tumors especially de-differentiated liposarcoma and uterine leiomyosarcoma remains unsatisfactory, despite intensive treatment regimens including maximal surgical resection, radiation, and chemotherapy. MAP kinase-interacting serine/threonine-protein kinase 1 and 2 (MNK1/2) have been shown to contribute to oncogenic translation via phosphorylation of eukaryotic translation initiation factor 4E (eIF4E). However, little is known about the role of MNK1/2 and their downstream targets in STS. In this study, we show that depletion of either MNK1 or MNK2 suppresses cell viability, anchorage-independent growth, and tumorigenicity of STS cells. We also identify a compelling antiproliferative efficacy of a novel, selective MNK inhibitor ETC-168. Cellular responsiveness of STS cells to ETC-168 correlates positively with that of phosphorylated ribosomal protein S6 (RPS6). Mirroring MNK1/2 silencing, ETC-168 treatment strongly blocks eIF4E phosphorylation and represses expression of sarcoma-driving onco-proteins including E2F1, FOXM1, and WEE1. Moreover, combination of ETC-168 and MCL1 inhibitor S63845 exerts a synergistic antiproliferative activity against STS cells. In summary, our study reveals crucial roles of MNK1/2 and their downstream targets in STS tumorigenesis. Our data encourage further clinical translation of MNK inhibitors for STS treatment.
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32
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Oxidative Damage of Mussels Living in Seawater Enriched with Trace Metals, from the Viewpoint of Proteins Expression and Modification. TOXICS 2020; 8:toxics8040089. [PMID: 33081042 PMCID: PMC7711521 DOI: 10.3390/toxics8040089] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/25/2020] [Revised: 10/13/2020] [Accepted: 10/15/2020] [Indexed: 12/20/2022]
Abstract
The impact of metals bioaccumulation in marine organisms is a subject of intense investigation. This study was designed to determine the association between oxidative stress induced by seawater enriched with trace metals and protein synthesis using as a model the mussels Mytilus galloprovincialis. Mussels were exposed to 40 μg/L Cu, 30 μg/L Hg, or 100 μg/L Cd for 5 and 15 days, and the pollution effect was evaluated by measuring established oxidative biomarkers. The results showed damage on the protein synthesis machine integrity and specifically on translation factors and ribosomal proteins expression and modifications. The exposure of mussels to all metals caused oxidative damage that was milder in the cases of Cu and Hg and more pronounced for Cd. However, after prolonged exposure of mussels to Cd (15 days), the effects receded. These changes that perturb protein biosynthesis can serve as a great tool for elucidating the mechanisms of toxicity and could be integrated in biomonitoring programs.
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33
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Belfetmi A, Léger-Abraham M. 1H, 13C, and 15N backbone chemical shift assignments of m 7GTP cap-bound Leishmania initiation factor 4E-1. BIOMOLECULAR NMR ASSIGNMENTS 2020; 14:259-263. [PMID: 32519295 PMCID: PMC7462832 DOI: 10.1007/s12104-020-09958-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 04/29/2020] [Accepted: 06/02/2020] [Indexed: 06/11/2023]
Abstract
Most of the translational control of gene expression in higher eukaryotes occurs during the initiation step of protein synthesis. While this process is well characterized in mammalian cells, it is less defined in parasites, including the ones that cause human Leishmaniasis. The Leishmania cap-binding isoform 1 (LeishIF4E-1) is the only isoform that binds the specific trypanosomatids-specific hypermethylated 5' cap, called cap-4, in the human stage of the parasite life cycle. We report here the extensive NMR resonance assignment of LeishIF4E-1 bound to a cap analog, m7GTP. The chemical shift data constitute a prerequisite to understanding specific translation initiation mechanisms used in Leishmania parasites and to developing antiparasitic drugs targeting their translation initiation factors.
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Affiliation(s)
- Anissa Belfetmi
- Department of Microbiology, Blavatnik Institute, Harvard Medical School, Boston, MA, 02115, USA
| | - Mélissa Léger-Abraham
- Department of Microbiology, Blavatnik Institute, Harvard Medical School, Boston, MA, 02115, USA.
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34
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5'-Cap‒Dependent Translation as a Potent Therapeutic Target for Lethal Human Squamous Cell Carcinoma. J Invest Dermatol 2020; 141:742-753.e10. [PMID: 32971126 DOI: 10.1016/j.jid.2020.08.021] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2020] [Revised: 08/10/2020] [Accepted: 08/26/2020] [Indexed: 01/12/2023]
Abstract
Skin squamous cell carcinomas (SCCs) are a major cause of death in patients who have undergone or will undergo organ transplantation. Moreover, these neoplasms cause significant disease and economic burden and diminish patients' life quality. However, no effective treatment or intervention strategies are available. In this study, we investigated the pathologic role of 5'-cap translation, which is regulated by the formation of a ternary initiation factor complex involving eIF4E, eIF4G, and eIF4A1. We detected increased expression of phosphorylated eIF4E, eIF4G, and eIF4A1 in human and murine skin SCCs. The increase in these ternary initiation factor complex proteins was associated with enhanced eIF4E translation targets cyclin D1 and c-Myc. Conversely, small interfering RNA-mediated depletion of eIF4E in human SCC cells (A431 and SCC-13) reduced eIF4G and proteins that regulate the cell cycle and proliferation. Notably, inhibition of Raf/MAPK/extracellular signal-regulated kinase signaling decreased eIF4E and phosphorylated eIF4E accumulation and significantly diminished cell-cycle gene expression and tumor volume of A431-derived xenograft tumors. Furthermore, disrupting the eIF4E with an allosteric inhibitor of eIF4E and eIF4G binding, 4EGI-1, decreased the eIF4E/eIF4G expression and reduced the proliferation. Finally, combined inhibition of the Raf/MAPK/extracellular signal-regulated kinase axis and eIF4E impaired 5'-cap‒dependent translation and abrogated tumor cell proliferation. These data demonstrate that 5'-cap‒dependent translation is a potential therapeutic target for abrogating lethal skin SCCs in patients who have undergone or will undergo organ transplantation.
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Tupperwar N, Meleppattu S, Shrivastava R, Baron N, Gilad A, Wagner G, Léger-Abraham M, Shapira M. A newly identified Leishmania IF4E-interacting protein, Leish4E-IP2, modulates the activity of cap-binding protein paralogs. Nucleic Acids Res 2020; 48:4405-4417. [PMID: 32232353 PMCID: PMC7192595 DOI: 10.1093/nar/gkaa173] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2020] [Revised: 03/04/2020] [Accepted: 03/16/2020] [Indexed: 01/06/2023] Open
Abstract
Translation of most cellular mRNAs in eukaryotes proceeds through a cap-dependent pathway, whereby the cap-binding complex, eIF4F, anchors the preinitiation complex at the 5′ end of mRNAs and regulates translation initiation. The requirement of Leishmania to survive in changing environments can explain why they encode multiple eIF4E (LeishIF4Es) and eIF4G (LeishIF4Gs) paralogs, as each could be assigned a discrete role during their life cycle. Here we show that the expression and activity of different LeishIF4Es change during the growth of cultured promastigotes, urging a search for regulatory proteins. We describe a novel LeishIF4E-interacting protein, Leish4E-IP2, which contains a conserved Y(X)4LΦ IF4E-binding-motif. Despite its capacity to bind several LeishIF4Es, Leish4E-IP2 was not detected in m7GTP-eluted cap-binding complexes, suggesting that it could inhibit the cap-binding activity of LeishIF4Es. Using a functional assay, we show that a recombinant form of Leish4E-IP2 inhibits the cap-binding activity of LeishIF4E-1 and LeishIF4E-3. Furthermore, we show that transgenic parasites expressing a tagged version of Leish4E-IP2 also display reduced cap-binding activities of tested LeishIF4Es, and decreased global translation. Given its ability to bind more than a single LeishIF4E, we suggest that Leish4E-IP2 could serve as a broad-range repressor of Leishmania protein synthesis.
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Affiliation(s)
- Nitin Tupperwar
- Department of Life Sciences, Ben-Gurion University of the Negev, Beer Sheva 84105, Israel
| | - Shimi Meleppattu
- Department of Microbiology, Blavatnik Institute, Harvard Medical School, Boston, MA 02115, USA.,Department of Biological Chemistry and Molecular Pharmacology, Blavatnik Institute, Harvard Medical School, Boston, MA 02138, USA
| | - Rohit Shrivastava
- Department of Life Sciences, Ben-Gurion University of the Negev, Beer Sheva 84105, Israel
| | - Nofar Baron
- Department of Life Sciences, Ben-Gurion University of the Negev, Beer Sheva 84105, Israel
| | - Ayelet Gilad
- Department of Life Sciences, Ben-Gurion University of the Negev, Beer Sheva 84105, Israel
| | - Gerhard Wagner
- Department of Biological Chemistry and Molecular Pharmacology, Blavatnik Institute, Harvard Medical School, Boston, MA 02138, USA
| | - Mélissa Léger-Abraham
- Department of Microbiology, Blavatnik Institute, Harvard Medical School, Boston, MA 02115, USA
| | - Michal Shapira
- Department of Life Sciences, Ben-Gurion University of the Negev, Beer Sheva 84105, Israel
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36
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Haizel SA, Bhardwaj U, Gonzalez RL, Mitra S, Goss DJ. 5'-UTR recruitment of the translation initiation factor eIF4GI or DAP5 drives cap-independent translation of a subset of human mRNAs. J Biol Chem 2020; 295:11693-11706. [PMID: 32571876 DOI: 10.1074/jbc.ra120.013678] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2020] [Revised: 06/16/2020] [Indexed: 01/04/2023] Open
Abstract
During unfavorable conditions (e.g. tumor hypoxia or viral infection), canonical, cap-dependent mRNA translation is suppressed in human cells. Nonetheless, a subset of physiologically important mRNAs (e.g. hypoxia-inducible factor 1α [HIF-1α], fibroblast growth factor 9 [FGF-9], and p53) is still translated by an unknown, cap-independent mechanism. Additionally, expression levels of eukaryotic translation initiation factor 4GI (eIF4GI) and of its homolog, death-associated protein 5 (DAP5), are elevated. By examining the 5' UTRs of HIF-1α, FGF-9, and p53 mRNAs and using fluorescence anisotropy binding studies, luciferase reporter-based in vitro translation assays, and mutational analyses, we demonstrate here that eIF4GI and DAP5 specifically bind to the 5' UTRs of these cap-independently translated mRNAs. Surprisingly, we found that the eIF4E-binding domain of eIF4GI increases not only the binding affinity but also the selectivity among these mRNAs. We further demonstrate that the affinities of eIF4GI and DAP5 binding to these 5' UTRs correlate with the efficiency with which these factors drive cap-independent translation of these mRNAs. Integrating the results of our binding and translation assays, we conclude that eIF4GI or DAP5 is critical for recruitment of a specific subset of mRNAs to the ribosome, providing mechanistic insight into their cap-independent translation.
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Affiliation(s)
- Solomon A Haizel
- Ph.D. Program in Biochemistry, The Graduate Center of the City University of New York, New York, New York, USA.,Department of Chemistry, Hunter College, New York, New York, USA
| | - Usha Bhardwaj
- Department of Chemistry, Hunter College, New York, New York, USA
| | - Ruben L Gonzalez
- Department of Chemistry, Columbia University, New York, New York, USA
| | - Somdeb Mitra
- Department of Chemistry, New York University, New York, New York, USA
| | - Dixie J Goss
- Ph.D. Program in Biochemistry, The Graduate Center of the City University of New York, New York, New York, USA .,Department of Chemistry, Hunter College, New York, New York, USA.,Ph.D. Program in Chemistry, The Graduate Center of the City University of New York, New York, New York, USA
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Non-cooperative 4E-BP2 folding with exchange between eIF4E-binding and binding-incompatible states tunes cap-dependent translation inhibition. Nat Commun 2020; 11:3146. [PMID: 32561718 PMCID: PMC7305185 DOI: 10.1038/s41467-020-16783-8] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2019] [Accepted: 05/15/2020] [Indexed: 12/24/2022] Open
Abstract
Phosphorylation of intrinsically disordered eIF4E binding proteins (4E-BPs) regulates cap-dependent translation by weakening their ability to compete with eIF4G for eIF4E binding within the translation initiation complex. We previously showed that phosphorylation of T37 and T46 in 4E-BP2 induces folding of a four-stranded beta-fold domain, partially sequestering the canonical eIF4E-binding helix. The C-terminal intrinsically disordered region (C-IDR), remaining disordered after phosphorylation, contains the secondary eIF4E-binding site and three other phospho-sites, whose mechanisms in inhibiting binding are not understood. Here we report that the domain is non-cooperatively folded, with exchange between beta strands and helical conformations. C-IDR phosphorylation shifts the conformational equilibrium, controlling access to eIF4E binding sites. The hairpin turns formed by pT37/pT46 are remarkably stable and function as transplantable units for phospho-regulation of stability. These results demonstrate how non-cooperative folding and conformational exchange leads to graded inhibition of 4E-BP2:eIF4E binding, shifting 4E-BP2 into an eIF4E binding-incompatible conformation and regulating translation initiation. Phosphorylation of eIF4E binding proteins (4E-BPs) controls their folding and regulates cap-dependent translation. Here, the authors show that phosphorylation of the C-terminal disordered region stabilizes the non-cooperatively folded 4E-BP domain to an eIF4E binding-incompatible state to control translation.
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Schmidt S, Denk S, Wiegering A. Targeting Protein Synthesis in Colorectal Cancer. Cancers (Basel) 2020; 12:cancers12051298. [PMID: 32455578 PMCID: PMC7281195 DOI: 10.3390/cancers12051298] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2020] [Revised: 05/15/2020] [Accepted: 05/19/2020] [Indexed: 12/19/2022] Open
Abstract
Under physiological conditions, protein synthesis controls cell growth and survival and is strictly regulated. Deregulation of protein synthesis is a frequent event in cancer. The majority of mutations found in colorectal cancer (CRC), including alterations in the WNT pathway as well as activation of RAS/MAPK and PI3K/AKT and, subsequently, mTOR signaling, lead to deregulation of the translational machinery. Besides mutations in upstream signaling pathways, deregulation of global protein synthesis occurs through additional mechanisms including altered expression or activity of initiation and elongation factors (e.g., eIF4F, eIF2α/eIF2B, eEF2) as well as upregulation of components involved in ribosome biogenesis and factors that control the adaptation of translation in response to stress (e.g., GCN2). Therefore, influencing mechanisms that control mRNA translation may open a therapeutic window for CRC. Over the last decade, several potential therapeutic strategies targeting these alterations have been investigated and have shown promising results in cell lines, intestinal organoids, and mouse models. Despite these encouraging in vitro results, patients have not clinically benefited from those advances so far. In this review, we outline the mechanisms that lead to deregulated mRNA translation in CRC and highlight recent progress that has been made in developing therapeutic strategies that target these mechanisms for tumor therapy.
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Affiliation(s)
- Stefanie Schmidt
- Department of Biochemistry and Molecular Biology, Theodor Boveri Institute, Biocenter, University of Würzburg, 97074 Würzburg, Germany; (S.S.); (S.D.)
- Department of General, Visceral, Transplant, Vascular and Pediatric Surgery, University Hospital Würzburg, 97074 Würzburg, Germany
| | - Sarah Denk
- Department of Biochemistry and Molecular Biology, Theodor Boveri Institute, Biocenter, University of Würzburg, 97074 Würzburg, Germany; (S.S.); (S.D.)
- Department of General, Visceral, Transplant, Vascular and Pediatric Surgery, University Hospital Würzburg, 97074 Würzburg, Germany
| | - Armin Wiegering
- Department of Biochemistry and Molecular Biology, Theodor Boveri Institute, Biocenter, University of Würzburg, 97074 Würzburg, Germany; (S.S.); (S.D.)
- Department of General, Visceral, Transplant, Vascular and Pediatric Surgery, University Hospital Würzburg, 97074 Würzburg, Germany
- Department of Biochemistry and Molecular Biology, Comprehensive Cancer Center Mainfranken, University of Würzburg, 97074 Würzburg, Germany
- Correspondence: ; Tel.: +49-931-20138714
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Manne BK, Bhatlekar S, Middleton EA, Weyrich AS, Borst O, Rondina MT. Phospho-inositide-dependent kinase 1 regulates signal dependent translation in megakaryocytes and platelets. J Thromb Haemost 2020; 18:1183-1196. [PMID: 31997536 PMCID: PMC7192796 DOI: 10.1111/jth.14748] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2019] [Revised: 12/19/2019] [Accepted: 01/27/2020] [Indexed: 12/19/2022]
Abstract
BACKGROUND Regulated protein synthesis is essential for megakaryocyte (MK) and platelet functions, including platelet production and activation. PDK1 (phosphoinositide-dependent kinase 1) regulates platelet functional responses and has been associated with circulating platelet counts. Whether PDK1 also directly regulates protein synthetic responses in MKs and platelets, and platelet production by MKs, remains unknown. OBJECTIVE To determine if PDK1 regulates protein synthesis in MKs and platelets. METHODS Pharmacologic PDK1 inhibitors (BX-795) and mice where PDK1 was selectively ablated in MKs and platelets (PDK1-/- ) were used. PDK1 signaling in MKs and platelets (human and murine) were assessed by immunoblots. Activation-dependent translation initiation and protein synthesis in MKs and platelets was assessed by probing for dissociation of eIF4E from 4EBP1, and using m7-GTP pulldowns and S35 methionine incorporation assays. Proplatelet formation by MKs, synthesis of Bcl-3 and MARCKs protein, and clot retraction were employed for functional assays. RESULTS Inhibiting or ablating PDK1 in MKs and platelets abolished the phosphorylation of 4EBP1 and eIF4E by preventing activation of the PI3K and MAPK pathways. Inhibiting PDK1 also prevented dissociation of eIF4E from 4EBP1, decreased binding of eIF4E to m7GTP (required for translation initiation), and significantly reduced de novo protein synthesis. Inhibiting PDK1 reduced proplatelet formation by human MKs and blocked MARCKs protein synthesis. In both human and murine platelets, PDK1 controlled Bcl-3 synthesis. Inhibition of PDK1 led to complete failure of clot retraction in vitro. CONCLUSIONS PDK1 is a previously unidentified translational regulator in MKs and platelets, controlling protein synthetic responses, proplatelet formation, and clot retraction.
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Affiliation(s)
- Bhanu Kanth Manne
- Department of Internal Medicine & The Molecular Medicine Program, University of Utah, Salt Lake City, UT, 84112 USA
| | - Seema Bhatlekar
- Department of Internal Medicine & The Molecular Medicine Program, University of Utah, Salt Lake City, UT, 84112 USA
| | - Elizabeth A. Middleton
- Department of Internal Medicine & The Molecular Medicine Program, University of Utah, Salt Lake City, UT, 84112 USA
| | - Andrew S. Weyrich
- Department of Internal Medicine & The Molecular Medicine Program, University of Utah, Salt Lake City, UT, 84112 USA
- Department of Pathology, University of Utah, Salt Lake City, UT, 84112 USA
| | - Oliver Borst
- Department of Cardiology and Cardiovascular Medicine, University of Tübingen, Tübingen, 72076 Germany
| | - Matthew T. Rondina
- Department of Internal Medicine & The Molecular Medicine Program, University of Utah, Salt Lake City, UT, 84112 USA
- Department of Internal Medicine, GRECC, George E. Wahlen VAMC, Salt Lake City, UT, 84148
- Department of Pathology, University of Utah, Salt Lake City, UT, 84112 USA
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40
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Guo B, Wu S, Zhu X, Zhang L, Deng J, Li F, Wang Y, Zhang S, Wu R, Lu J, Zhou Y. Micropeptide CIP2A-BP encoded by LINC00665 inhibits triple-negative breast cancer progression. EMBO J 2020; 39:e102190. [PMID: 31755573 PMCID: PMC6939193 DOI: 10.15252/embj.2019102190] [Citation(s) in RCA: 136] [Impact Index Per Article: 34.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2019] [Revised: 10/10/2019] [Accepted: 10/15/2019] [Indexed: 01/22/2023] Open
Abstract
TGF-β signaling pathway plays a key role in breast cancer metastasis. Recent studies suggest that TGF-β regulates tumor progression and invasion not only via transcriptional regulation, but also via translational regulation. Using both bioinformatics and experimental tools, we identified a micropeptide CIP2A-BP encoded by LINC00665, whose translation was downregulated by TGF-β in breast cancer cell lines. Using TNBC cell lines, we showed that TGF-β-activated Smad signaling pathway induced the expression of translation inhibitory protein 4E-BP1, which inhibited eukaryote translation initiation factor elF4E, leading to reduced translation of CIP2A-BP from LINC00665. CIP2A-BP directly binds tumor oncogene CIP2A to replace PP2A's B56γ subunit, thus releasing PP2A activity, which inhibits PI3K/AKT/NFκB pathway, resulting in decreased expression levels of MMP-2, MMP-9, and Snail. Downregulation of CIP2A-BP in TNBC patients was significantly associated with metastasis and poor overall survival. In the MMTV-PyMT model, either introducing CIP2A-BP gene or direct injection of CIP2A-BP micropeptide significantly reduced lung metastases and improved overall survival. In conclusion, we provide evidence that CIP2A-BP is both a prognostic marker and a novel therapeutic target for TNBC.
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Affiliation(s)
- Binbin Guo
- Department of GeneticsMedical College of Soochow UniversitySuzhouChina
| | - Siqi Wu
- Department of GeneticsMedical College of Soochow UniversitySuzhouChina
| | - Xun Zhu
- Department of General SurgeryThe Second Affiliated Hospital of Soochow UniversitySuzhouChina
| | - Liyuan Zhang
- Department of Radiotherapy & OncologyThe Second Affiliated Hospital of Soochow UniversitySuzhouChina
| | - Jieqiong Deng
- Department of GeneticsMedical College of Soochow UniversitySuzhouChina
| | - Fang Li
- Department of GeneticsMedical College of Soochow UniversitySuzhouChina
| | - Yirong Wang
- Department of GeneticsMedical College of Soochow UniversitySuzhouChina
| | - Shenghua Zhang
- Department of GeneticsMedical College of Soochow UniversitySuzhouChina
| | - Rui Wu
- Department of GeneticsMedical College of Soochow UniversitySuzhouChina
| | - Jiachun Lu
- The State Key Lab of Respiratory DiseaseThe First Affiliated HospitalThe School of Public HealthGuangzhou Medical UniversityGuangzhouChina
| | - Yifeng Zhou
- Department of GeneticsMedical College of Soochow UniversitySuzhouChina
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41
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Burakova E, Vasa SK, Klein A, Linser R. Non-uniform sampling in quantitative assessment of heterogeneous solid-state NMR line shapes. JOURNAL OF BIOMOLECULAR NMR 2020; 74:71-82. [PMID: 31834579 DOI: 10.1007/s10858-019-00291-z] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/03/2019] [Accepted: 11/26/2019] [Indexed: 06/10/2023]
Abstract
Non-uniform sampling has been successfully used for solution and solid-state NMR of homogeneous samples. In the solid state, protein samples are often dominated by inhomogeneous contributions to the homogeneous line widths. In spite of different technical strategies for peak reconstruction by different methods, we validate that NUS can generally be used also for such situations where spectra are made up of complex peak shapes rather than Lorentian lines. Using the RMSD between subsampled and reconstructed data and those spectra obtained with uniform sampling for a sample comprising a wide conformational distribution, we quantitatively evaluate the identity of inhomogeneous peak patterns. The evaluation comprises Iterative Soft Thresholding (hmsIST implementation) as a method explicitly not assuming Lorentian lineshapes, as well as Sparse Multidimensional Iterative Lineshape Enhanced (SMILE) algorithm and Signal Separation Algorithm (SSA) reconstruction, which do work on the basis of Lorentian lineshape models, with different sampling densities. Even though individual peculiarities are apparent, all methods turn out principally viable to reconstruct the heterogeneously broadened peak shapes.
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Affiliation(s)
- Ekaterina Burakova
- Faculty for Chemistry and Pharmacy, Ludwig-Maximilians-University Munich, Butenandtstr. 5-13, 81377, Munich, Germany
- Faculty of Chemistry and Chemical Biology, Technical University Dortmund, Otto-Hahn-Straße 4a, 44227, Dortmund, Germany
| | - Suresh K Vasa
- Faculty for Chemistry and Pharmacy, Ludwig-Maximilians-University Munich, Butenandtstr. 5-13, 81377, Munich, Germany
- Faculty of Chemistry and Chemical Biology, Technical University Dortmund, Otto-Hahn-Straße 4a, 44227, Dortmund, Germany
| | - Alexander Klein
- Faculty for Chemistry and Pharmacy, Ludwig-Maximilians-University Munich, Butenandtstr. 5-13, 81377, Munich, Germany
- Faculty of Chemistry and Chemical Biology, Technical University Dortmund, Otto-Hahn-Straße 4a, 44227, Dortmund, Germany
| | - Rasmus Linser
- Faculty for Chemistry and Pharmacy, Ludwig-Maximilians-University Munich, Butenandtstr. 5-13, 81377, Munich, Germany.
- Faculty of Chemistry and Chemical Biology, Technical University Dortmund, Otto-Hahn-Straße 4a, 44227, Dortmund, Germany.
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Mishra RK, Datey A, Hussain T. mRNA Recruiting eIF4 Factors Involved in Protein Synthesis and Its Regulation. Biochemistry 2019; 59:34-46. [DOI: 10.1021/acs.biochem.9b00788] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Affiliation(s)
- Rishi Kumar Mishra
- Department of Molecular Reproduction, Development and Genetics, Division of Biological Sciences, Indian Institute of Science, Bangalore 560012, India
| | - Ayushi Datey
- Department of Molecular Reproduction, Development and Genetics, Division of Biological Sciences, Indian Institute of Science, Bangalore 560012, India
| | - Tanweer Hussain
- Department of Molecular Reproduction, Development and Genetics, Division of Biological Sciences, Indian Institute of Science, Bangalore 560012, India
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Spatio-temporal expression of ANK2 promotes cytokinesis in oocytes. Sci Rep 2019; 9:13121. [PMID: 31511568 PMCID: PMC6739377 DOI: 10.1038/s41598-019-49483-5] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2019] [Accepted: 08/21/2019] [Indexed: 01/01/2023] Open
Abstract
In the absence of transcription, the regulation of gene expression in oocytes is controlled almost exclusively at the level of transcriptome and proteome stabilization, and translation. A subset of maternal transcripts is stored in a translationally dormant state in the oocyte, and temporally driven translation of specific mRNAs propel meiotic progression, oocyte-to-embryo transition and early embryo development. We identified Ank2.3 as the only transcript variant present in the mouse oocyte and discovered that it is translated after nuclear envelope breakdown. Here we show that Ank2.3 mRNA is localized in higher concentration in the oocyte nucleoplasm and, after nuclear envelope breakdown, in the newly forming spindle where its translation occurs. Furthermore, we reveal that Ank2.3 mRNA contains an oligo-pyrimidine motif at 5'UTR that predetermines its translation through a cap-dependent pathway. Lastly, we show that prevention of ANK2 translation leads to abnormalities in oocyte cytokinesis.
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44
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Huang JX, Lee G, Cavanaugh KE, Chang JW, Gardel ML, Moellering RE. High throughput discovery of functional protein modifications by Hotspot Thermal Profiling. Nat Methods 2019; 16:894-901. [PMID: 31384043 PMCID: PMC7238970 DOI: 10.1038/s41592-019-0499-3] [Citation(s) in RCA: 78] [Impact Index Per Article: 15.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2018] [Accepted: 06/21/2019] [Indexed: 12/29/2022]
Abstract
Mass spectrometry has revolutionized the ability to study posttranslationally modified proteoforms from biologic samples, yet we still lack methods to systematically predict, or even prioritize, which modification sites may perturb protein function. Here we describe a proteomic method to detect the effects of site-specific protein phosphorylation on the thermal stability of thousands of native proteins in live cells. This massively parallel biophysical assay unveiled shifts in overall protein stability in response to site-specific phosphorylation sites, as well as trends related to protein function and structure. This method can detect both intrinsic changes to protein structure as well as extrinsic changes to protein-protein, and protein-metabolite interactions resulting from the diminutive introduction of a phosphate onto large proteins. Finally, we show that functional “hotspot” protein modification sites can be discovered and prioritized for study in a high-throughput and unbiased fashion. This approach is applicable to diverse organisms, cell types and posttranslational modifications.
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Affiliation(s)
- Jun X Huang
- Department of Chemistry, The University of Chicago, Chicago, IL, USA.,Institute for Genomics and Systems Biology, The University of Chicago, Chicago, IL, USA
| | - Gihoon Lee
- Department of Chemistry, The University of Chicago, Chicago, IL, USA.,Institute for Genomics and Systems Biology, The University of Chicago, Chicago, IL, USA
| | - Kate E Cavanaugh
- Department of Physics, The University of Chicago, Chicago, IL, USA.,Institute for Biophysical Dynamics, The University of Chicago, Chicago, IL, USA.,James Franck Institute, The University of Chicago, Chicago, IL, USA
| | - Jae W Chang
- Department of Chemistry, The University of Chicago, Chicago, IL, USA.,Institute for Genomics and Systems Biology, The University of Chicago, Chicago, IL, USA
| | - Margaret L Gardel
- Department of Physics, The University of Chicago, Chicago, IL, USA.,Institute for Biophysical Dynamics, The University of Chicago, Chicago, IL, USA.,James Franck Institute, The University of Chicago, Chicago, IL, USA
| | - Raymond E Moellering
- Department of Chemistry, The University of Chicago, Chicago, IL, USA. .,Institute for Genomics and Systems Biology, The University of Chicago, Chicago, IL, USA.
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45
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Meleppattu S, Arthanari H, Zinoviev A, Boeszoermenyi A, Wagner G, Shapira M, Léger-Abraham M. Structural basis for LeishIF4E-1 modulation by an interacting protein in the human parasite Leishmania major. Nucleic Acids Res 2019; 46:3791-3801. [PMID: 29562352 PMCID: PMC5909430 DOI: 10.1093/nar/gky194] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2018] [Accepted: 03/06/2018] [Indexed: 01/06/2023] Open
Abstract
Leishmania parasites are unicellular pathogens that are transmitted to humans through the bite of infected sandflies. Most of the regulation of their gene expression occurs post-transcriptionally, and the different patterns of gene expression required throughout the parasites’ life cycle are regulated at the level of translation. Here, we report the X-ray crystal structure of the Leishmania cap-binding isoform 1, LeishIF4E-1, bound to a protein fragment of previously unknown function, Leish4E-IP1, that binds tightly to LeishIF4E-1. The molecular structure, coupled to NMR spectroscopy experiments and in vitro cap-binding assays, reveal that Leish4E-IP1 allosterically destabilizes the binding of LeishIF4E-1 to the 5′ mRNA cap. We propose mechanisms through which Leish4E-IP1-mediated LeishIF4E-1 inhibition could regulate translation initiation in the human parasite.
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Affiliation(s)
- Shimi Meleppattu
- Department of Microbiology and Immunobiology, Harvard Medical School, Boston, MA 02115, USA.,Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02115, USA
| | - Haribabu Arthanari
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02115, USA.,Department of Cancer Biology, Dana-Farber Cancer Institute, Boston, MA 02115, USA
| | - Alexandra Zinoviev
- Department of Life Sciences, Ben-Gurion University of the Negev, Beer Sheva 84105, Israel
| | - Andras Boeszoermenyi
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02115, USA.,Department of Cancer Biology, Dana-Farber Cancer Institute, Boston, MA 02115, USA
| | - Gerhard Wagner
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02115, USA
| | - Michal Shapira
- Department of Life Sciences, Ben-Gurion University of the Negev, Beer Sheva 84105, Israel
| | - Mélissa Léger-Abraham
- Department of Microbiology and Immunobiology, Harvard Medical School, Boston, MA 02115, USA.,Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02115, USA
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Grüner S, Weber R, Peter D, Chung MY, Igreja C, Valkov E, Izaurralde E. Structural motifs in eIF4G and 4E-BPs modulate their binding to eIF4E to regulate translation initiation in yeast. Nucleic Acids Res 2019; 46:6893-6908. [PMID: 30053226 PMCID: PMC6061780 DOI: 10.1093/nar/gky542] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2018] [Accepted: 06/02/2018] [Indexed: 12/13/2022] Open
Abstract
The interaction of the eukaryotic initiation factor 4G (eIF4G) with the cap-binding protein eIF4E initiates cap-dependent translation and is regulated by the 4E-binding proteins (4E-BPs), which compete with eIF4G to repress translation. Metazoan eIF4G and 4E-BPs interact with eIF4E via canonical and non-canonical motifs that bind to the dorsal and lateral surface of eIF4E in a bipartite recognition mode. However, previous studies pointed to mechanistic differences in how fungi and metazoans regulate protein synthesis. We present crystal structures of the yeast eIF4E bound to two yeast 4E-BPs, p20 and Eap1p, as well as crystal structures of a fungal eIF4E–eIF4G complex. We demonstrate that the core principles of molecular recognition of eIF4E are in fact highly conserved among translational activators and repressors in eukaryotes. Finally, we reveal that highly specialized structural motifs do exist and serve to modulate the affinity of protein-protein interactions that regulate cap-dependent translation initiation in fungi.
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Affiliation(s)
- Stefan Grüner
- Department of Biochemistry, Max Planck Institute for Developmental Biology, Max-Planck-Ring 5, D-72076 Tübingen, Germany
| | - Ramona Weber
- Department of Biochemistry, Max Planck Institute for Developmental Biology, Max-Planck-Ring 5, D-72076 Tübingen, Germany
| | - Daniel Peter
- Department of Biochemistry, Max Planck Institute for Developmental Biology, Max-Planck-Ring 5, D-72076 Tübingen, Germany
| | - Min-Yi Chung
- Department of Biochemistry, Max Planck Institute for Developmental Biology, Max-Planck-Ring 5, D-72076 Tübingen, Germany
| | - Cátia Igreja
- Department of Biochemistry, Max Planck Institute for Developmental Biology, Max-Planck-Ring 5, D-72076 Tübingen, Germany
| | - Eugene Valkov
- Department of Biochemistry, Max Planck Institute for Developmental Biology, Max-Planck-Ring 5, D-72076 Tübingen, Germany
| | - Elisa Izaurralde
- Department of Biochemistry, Max Planck Institute for Developmental Biology, Max-Planck-Ring 5, D-72076 Tübingen, Germany
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47
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Sun R, Cheng E, Velásquez C, Chang Y, Moore PS. Mitosis-related phosphorylation of the eukaryotic translation suppressor 4E-BP1 and its interaction with eukaryotic translation initiation factor 4E (eIF4E). J Biol Chem 2019; 294:11840-11852. [PMID: 31201269 PMCID: PMC6682726 DOI: 10.1074/jbc.ra119.008512] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2019] [Revised: 06/10/2019] [Indexed: 11/22/2022] Open
Abstract
Eukaryotic translation initiation factor 4E (eIF4E)–binding protein 1 (4E-BP1) inhibits cap-dependent translation in eukaryotes by competing with eIF4G for an interaction with eIF4E. Phosphorylation at Ser-83 of 4E-BP1 occurs during mitosis through the activity of cyclin-dependent kinase 1 (CDK1)/cyclin B rather than through canonical mTOR kinase activity. Here, we investigated the interaction of eIF4E with 4E-BP1 or eIF4G during interphase and mitosis. We observed that 4E-BP1 and eIF4G bind eIF4E at similar levels during interphase and mitosis. The most highly phosphorylated mitotic 4E-BP1 isoform (δ) did not interact with eIF4E, whereas a distinct 4E-BP1 phospho-isoform, EB-γ, phosphorylated at Thr-70, Ser-83, and Ser-101, bound to eIF4E during mitosis. Two-dimensional gel electrophoretic analysis corroborated the identity of the phosphorylation marks on the eIF4E-bound 4E-BP1 isoforms and uncovered a population of phosphorylated 4E-BP1 molecules lacking Thr-37/Thr-46–priming phosphorylation. Moreover, proximity ligation assays for phospho-4E-BP1 and eIF4E revealed different in situ interactions during interphase and mitosis. The eIF4E:eIF4G interaction was not inhibited but rather increased in mitotic cells, consistent with active translation initiation during mitosis. Phosphodefective substitution of 4E-BP1 at Ser-83 did not change global translation or individual mRNA translation profiles as measured by single-cell nascent protein synthesis and eIF4G RNA immunoprecipitation sequencing. Mitotic 5′-terminal oligopyrimidine RNA translation was active and, unlike interphase translation, resistant to mTOR inhibition. Our findings reveal the phosphorylation profiles of 4E-BP1 isoforms and their interactions with eIF4E throughout the cell cycle and indicate that 4E-BP1 does not specifically inhibit translation initiation during mitosis.
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Affiliation(s)
- Rui Sun
- Department of Microbiology and Molecular Genetics, University of Pittsburgh, Pittsburgh, Pennsylvania 15213.,Cancer Virology Program, UPMC Hillman Cancer Center, Pittsburgh, Pennsylvania 15213
| | - Erdong Cheng
- Department of Microbiology and Molecular Genetics, University of Pittsburgh, Pittsburgh, Pennsylvania 15213.,Cancer Virology Program, UPMC Hillman Cancer Center, Pittsburgh, Pennsylvania 15213
| | - Celestino Velásquez
- Department of Microbiology and Molecular Genetics, University of Pittsburgh, Pittsburgh, Pennsylvania 15213.,Cancer Virology Program, UPMC Hillman Cancer Center, Pittsburgh, Pennsylvania 15213
| | - Yuan Chang
- Cancer Virology Program, UPMC Hillman Cancer Center, Pittsburgh, Pennsylvania 15213 .,Department of Pathology, University of Pittsburgh, Pittsburgh, Pennsylvania 15213
| | - Patrick S Moore
- Department of Microbiology and Molecular Genetics, University of Pittsburgh, Pittsburgh, Pennsylvania 15213 .,Cancer Virology Program, UPMC Hillman Cancer Center, Pittsburgh, Pennsylvania 15213
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48
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Correddu D, Leung IK. Targeting mRNA translation in Parkinson’s disease. Drug Discov Today 2019; 24:1295-1303. [DOI: 10.1016/j.drudis.2019.04.003] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2019] [Revised: 03/23/2019] [Accepted: 04/02/2019] [Indexed: 01/22/2023]
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49
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Batool A, Aashaq S, Andrabi KI. Eukaryotic initiation factor 4E (eIF4E): A recap of the cap-binding protein. J Cell Biochem 2019; 120:14201-14212. [PMID: 31074051 DOI: 10.1002/jcb.28851] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2019] [Revised: 04/09/2019] [Accepted: 04/11/2019] [Indexed: 12/29/2022]
Abstract
Eukaryotic initiation factor 4E (eIF4E), a fundamental effector and rate limiting element of protein synthesis, binds the 7-methylguanosine cap at the 5' end of eukaryotic messenger RNA (mRNA) specifically as a constituent of eIF4F translation initiation complex thus facilitating the recruitment of mRNA to the ribosomes. This review focusses on the engagement of signals contributing to growth factor originated maxim and their role in the activation of eIF4E to achieve a collective influence on cellular growth, with a key focus on conjuring vital processes like protein synthesis. The review invites considerable interest in elevating the appeal of eIF4E beyond its role in regulating translation viz a viz cancer genesis, attributed to its phosphorylation state that improves the prospect for the growth of the cancerous cell. This review highlights the latest studies that have envisioned to target these pathways and ultimately the translational machinery for therapeutic intervention. The review also brings forward the prospect of eIF4E to act as a converging juncture for signaling pathways like mTOR/PI3K and Mnk/MAPK to promote tumorigenesis.
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Affiliation(s)
- Asiya Batool
- Department of Biotechnology and Bioinformatics, University of Kashmir, Srinagar, Jammu and Kashmir, India
| | - Sabreena Aashaq
- Department of Biotechnology and Bioinformatics, University of Kashmir, Srinagar, Jammu and Kashmir, India
| | - Khurshid I Andrabi
- Department of Biotechnology and Bioinformatics, University of Kashmir, Srinagar, Jammu and Kashmir, India
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50
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Johnson OT, Kaur T, Garner AL. A Conditionally Fluorescent Peptide Reporter of Secondary Structure Modulation. Chembiochem 2019; 20:40-45. [PMID: 30137694 PMCID: PMC6482830 DOI: 10.1002/cbic.201800377] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2018] [Indexed: 12/12/2022]
Abstract
Proteins containing intrinsic disorder often form secondary structure upon interaction with a binding partner. Modulating such structures presents an approach for manipulating the resultant functional outcomes. Translational repressor protein 4E-BP1 is an example of an intrinsically disordered protein that forms an α-helix upon binding to its protein ligand, eIF4E. Current biophysical methods for analyzing binding-induced structural changes are low-throughput, require large amounts of sample, or are extremely sensitive to signal interference by the ligand itself. Herein, we describe the discovery and development of a conditionally fluorescent 4E-BP1 peptide that reports structural changes of its helix in high-throughput format. This reporter peptide is based on conditional quenching of fluorescein by thioamides. In this case, fluorescence signal increases as the peptide becomes more ordered. Conversely, destabilization of the α-helix results in decreased fluorescence signal. The low concentration and low volume of peptide required make this approach amenable for high-throughput screening to discover ligands that alter peptide secondary structure.
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Affiliation(s)
- Oleta T. Johnson
- Program in Chemical Biology, University of Michigan, 210 Washtenaw Avenue, Ann Arbor, MI 48109 (USA),
| | - Tanpreet Kaur
- Department of Medicinal Chemistry, College of Pharmacy, University of Michigan, 1600 Huron Parkway, NCRC B520, Ann Arbor, MI 48109 (USA)
| | - Amanda L. Garner
- Program in Chemical Biology, University of Michigan, 210 Washtenaw Avenue, Ann Arbor, MI 48109 (USA),
- Department of Medicinal Chemistry, College of Pharmacy, University of Michigan, 1600 Huron Parkway, NCRC B520, Ann Arbor, MI 48109 (USA)
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