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Ben S, Ding Z, Xin J, Li F, Cheng Y, Chen S, Fan L, Zhang Q, Li S, Du M, Zhang Z, Wei GH, Cheng G, Wang M. piRNA PROPER Suppresses DUSP1 Translation by Targeting N 6-Methyladenosine-Mediated RNA Circularization to Promote Oncogenesis of Prostate Cancer. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2024:e2402954. [PMID: 38962952 DOI: 10.1002/advs.202402954] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/21/2024] [Revised: 06/19/2024] [Indexed: 07/05/2024]
Abstract
Genetic and epigenetic alterations occur in many physiological and pathological processes. The existing knowledge regarding the association of PIWI-interacting RNAs (piRNAs) and their genetic variants on risk and progression of prostate cancer (PCa) is limited. In this study, three genome-wide association study datasets are combined, including 85,707 PCa cases and 166,247 controls, to uncover genetic variants in piRNAs. Functional investigations involved manipulating piRNA expression in cellular and mouse models to study its oncogenetic role in PCa. A specific genetic variant, rs17201241 is identified, associated with increased expression of PROPER (piRNA overexpressed in prostate cancer) in tumors and are located within the gene, conferring an increased risk and malignant progression of PCa. Mechanistically, PROPER coupled with YTHDF2 to recognize N6-methyladenosine (m6A) and facilitated RNA-binding protein interactions between EIF2S3 at 5'-untranslated region (UTR) and YTHDF2/YBX3 at 3'-UTR to promote DUSP1 circularization. This m6A-dependent mRNA-looping pattern enhanced DUSP1 degradation and inhibited DUSP1 translation, ultimately reducing DUSP1 expression and promoting PCa metastasis via the p38 mitogen-activated protein kinase (MAPK) signaling pathway. Inhibition of PROPER expression using antagoPROPER effectively suppressed xenograft growth, suggesting its potential as a therapeutic target. Thus, targeting piRNA PROPER-mediated genetic and epigenetic fine control is a promising strategy for the concurrent prevention and treatment of PCa.
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Affiliation(s)
- Shuai Ben
- The Affiliated Suzhou Hospital of Nanjing Medical University, Suzhou Municipal Hospital, Gusu School, Nanjing Medical University, Suzhou, 215002, China
- Department of Environmental Genomics, Jiangsu Key Laboratory of Cancer Biomarkers, Prevention and Treatment, Collaborative Innovation Center for Cancer Personalized Medicine, School of Public Health, Nanjing Medical University, Nanjing, 211166, China
- Department of Genetic Toxicology, The Key Laboratory of Modern Toxicology of Ministry of Education, Center for Global Health, School of Public Health, Nanjing Medical University, Nanjing, 211166, China
- Department of Ophthalmology, Shanghai General Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, 200080, China
| | - Zhutao Ding
- Department of Environmental Genomics, Jiangsu Key Laboratory of Cancer Biomarkers, Prevention and Treatment, Collaborative Innovation Center for Cancer Personalized Medicine, School of Public Health, Nanjing Medical University, Nanjing, 211166, China
- Department of Genetic Toxicology, The Key Laboratory of Modern Toxicology of Ministry of Education, Center for Global Health, School of Public Health, Nanjing Medical University, Nanjing, 211166, China
| | - Junyi Xin
- Department of Bioinformatic, School of Biomedical Engineering and Informatics, Nanjing Medical University, Nanjing, Jiangsu, 211166, China
| | - Feng Li
- State Key Laboratory of Reproductive Medicine, Nanjing Medical University, Nanjing, Jiangsu, 211100, China
| | - Yifei Cheng
- Department of Environmental Genomics, Jiangsu Key Laboratory of Cancer Biomarkers, Prevention and Treatment, Collaborative Innovation Center for Cancer Personalized Medicine, School of Public Health, Nanjing Medical University, Nanjing, 211166, China
- Department of Genetic Toxicology, The Key Laboratory of Modern Toxicology of Ministry of Education, Center for Global Health, School of Public Health, Nanjing Medical University, Nanjing, 211166, China
| | - Silu Chen
- Department of Environmental Genomics, Jiangsu Key Laboratory of Cancer Biomarkers, Prevention and Treatment, Collaborative Innovation Center for Cancer Personalized Medicine, School of Public Health, Nanjing Medical University, Nanjing, 211166, China
- Department of Genetic Toxicology, The Key Laboratory of Modern Toxicology of Ministry of Education, Center for Global Health, School of Public Health, Nanjing Medical University, Nanjing, 211166, China
| | - Lulu Fan
- Department of Environmental Genomics, Jiangsu Key Laboratory of Cancer Biomarkers, Prevention and Treatment, Collaborative Innovation Center for Cancer Personalized Medicine, School of Public Health, Nanjing Medical University, Nanjing, 211166, China
- Department of Genetic Toxicology, The Key Laboratory of Modern Toxicology of Ministry of Education, Center for Global Health, School of Public Health, Nanjing Medical University, Nanjing, 211166, China
| | - Qin Zhang
- Disease Networks Research Unit, Faculty of Biochemistry and Molecular Medicine & Biocenter Oulu, University of Oulu, Oulu, 90220, Finland
| | - Shuwei Li
- Department of Environmental Genomics, Jiangsu Key Laboratory of Cancer Biomarkers, Prevention and Treatment, Collaborative Innovation Center for Cancer Personalized Medicine, School of Public Health, Nanjing Medical University, Nanjing, 211166, China
- Department of Genetic Toxicology, The Key Laboratory of Modern Toxicology of Ministry of Education, Center for Global Health, School of Public Health, Nanjing Medical University, Nanjing, 211166, China
| | - Mulong Du
- Department of Biostatistics, Center for Global Health, School of Public Health, Nanjing Medical University, Nanjing, 211166, China
| | - Zhengdong Zhang
- Department of Environmental Genomics, Jiangsu Key Laboratory of Cancer Biomarkers, Prevention and Treatment, Collaborative Innovation Center for Cancer Personalized Medicine, School of Public Health, Nanjing Medical University, Nanjing, 211166, China
- Department of Genetic Toxicology, The Key Laboratory of Modern Toxicology of Ministry of Education, Center for Global Health, School of Public Health, Nanjing Medical University, Nanjing, 211166, China
| | - Gong-Hong Wei
- Disease Networks Research Unit, Faculty of Biochemistry and Molecular Medicine & Biocenter Oulu, University of Oulu, Oulu, 90220, Finland
- Fudan University Shanghai Cancer Center & MOE Key Laboratory of Metabolism and Molecular Medicine and Department of Biochemistry and Molecular Biology of School of Basic Medical Sciences, Shanghai Medical College of Fudan University, Shanghai, 200032, China
| | - Gong Cheng
- Department of Urology, The First Affiliated Hospital of Nanjing Medical University & Jiangsu Province People's Hospital, Nanjing, 210029, China
| | - Meilin Wang
- The Affiliated Suzhou Hospital of Nanjing Medical University, Suzhou Municipal Hospital, Gusu School, Nanjing Medical University, Suzhou, 215002, China
- Department of Environmental Genomics, Jiangsu Key Laboratory of Cancer Biomarkers, Prevention and Treatment, Collaborative Innovation Center for Cancer Personalized Medicine, School of Public Health, Nanjing Medical University, Nanjing, 211166, China
- Department of Genetic Toxicology, The Key Laboratory of Modern Toxicology of Ministry of Education, Center for Global Health, School of Public Health, Nanjing Medical University, Nanjing, 211166, China
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Zhao Y, Chen J, Zheng H, Luo Y, An M, Lin Y, Pang M, Li Y, Kong Y, He W, Lin T, Chen C. SUMOylation-Driven mRNA Circularization Enhances Translation and Promotes Lymphatic Metastasis of Bladder Cancer. Cancer Res 2024; 84:434-448. [PMID: 37991737 PMCID: PMC10831341 DOI: 10.1158/0008-5472.can-23-2278] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2023] [Revised: 10/10/2023] [Accepted: 11/17/2023] [Indexed: 11/23/2023]
Abstract
Aberrant gene expression is a prominent feature of metastatic cancer. Translational initiation is a vital step in fine-tuning gene expression. Thus, exploring translation initiation regulators may identify therapeutic targets for preventing and treating metastasis. Herein, we identified that DHCR24 was overexpressed in lymph node (LN) metastatic bladder cancer and correlated with poor prognosis of patients. DHCR24 promoted lymphangiogenesis and LN metastasis of bladder cancer in vitro and in vivo. Mechanistically, DHCR24 mediated and recognized the SUMO2 modification at lysine 108 of hnRNPA2B1 to foster TBK1 mRNA circularization and eIF4F initiation complex assembly by enhancing hnRNPA2B1-eIF4G1 interaction. Moreover, DHCR24 directly anchored to TBK1 mRNA 3'-untranslated region to increase its stability, thus forming a feed forward loop to elevate TBK1 expression. TBK1 activated PI3K/Akt signaling to promote VEGFC secretion, resulting in lymphangiogenesis and LN metastasis. DHCR24 silencing significantly impeded bladder cancer lymphangiogenesis and lymphatic metastasis in a patient-derived xenograft model. Collectively, these findings elucidate DHCR24-mediated translation machinery that promotes lymphatic metastasis of bladder cancer and supports the potential application of DHCR24-targeted therapy for LN-metastatic bladder cancer. SIGNIFICANCE DHCR24 is a SUMOylation regulator that controls translation initiation complex assembly and orchestrates TBK1 mRNA circularization to activate Akt/VEGFC signaling, which stimulates lymphangiogenesis and promotes lymph node metastasis in bladder cancer.
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Affiliation(s)
- Yue Zhao
- Department of Interventional Oncology, The First Affiliated Hospital of Sun Yat-sen University, Guangzhou, Guangdong, P. R. China
| | - Jiancheng Chen
- Department of Urology, Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou, Guangdong, P. R. China
- Guangdong Provincial Key Laboratory of Malignant Tumor Epigenetics and Gene Regulation, Sun Yat-sen Memorial Hospital, State Key Laboratory of Oncology in South China, Guangzhou, Guangdong, P. R. China
| | - Hanhao Zheng
- Department of Urology, Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou, Guangdong, P. R. China
- Guangdong Provincial Key Laboratory of Malignant Tumor Epigenetics and Gene Regulation, Sun Yat-sen Memorial Hospital, State Key Laboratory of Oncology in South China, Guangzhou, Guangdong, P. R. China
| | - Yuming Luo
- Department of General Surgery, Guangdong Provincial People's Hospital, Guangdong Academy of Medical Sciences, Guangzhou, Guangdong, P. R. China
| | - Mingjie An
- Department of Urology, Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou, Guangdong, P. R. China
- Guangdong Provincial Key Laboratory of Malignant Tumor Epigenetics and Gene Regulation, Sun Yat-sen Memorial Hospital, State Key Laboratory of Oncology in South China, Guangzhou, Guangdong, P. R. China
| | - Yan Lin
- Department of Urology, Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou, Guangdong, P. R. China
- Guangdong Provincial Key Laboratory of Malignant Tumor Epigenetics and Gene Regulation, Sun Yat-sen Memorial Hospital, State Key Laboratory of Oncology in South China, Guangzhou, Guangdong, P. R. China
| | - Mingrui Pang
- Department of Urology, Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou, Guangdong, P. R. China
- Guangdong Provincial Key Laboratory of Malignant Tumor Epigenetics and Gene Regulation, Sun Yat-sen Memorial Hospital, State Key Laboratory of Oncology in South China, Guangzhou, Guangdong, P. R. China
| | - Yuanlong Li
- Department of Urology, Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou, Guangdong, P. R. China
- Guangdong Provincial Key Laboratory of Malignant Tumor Epigenetics and Gene Regulation, Sun Yat-sen Memorial Hospital, State Key Laboratory of Oncology in South China, Guangzhou, Guangdong, P. R. China
| | - Yao Kong
- Department of General Surgery, Guangdong Provincial People's Hospital, Guangdong Academy of Medical Sciences, Guangzhou, Guangdong, P. R. China
| | - Wang He
- Department of Urology, Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou, Guangdong, P. R. China
- Guangdong Provincial Key Laboratory of Malignant Tumor Epigenetics and Gene Regulation, Sun Yat-sen Memorial Hospital, State Key Laboratory of Oncology in South China, Guangzhou, Guangdong, P. R. China
| | - Tianxin Lin
- Department of Urology, Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou, Guangdong, P. R. China
- Guangdong Provincial Key Laboratory of Malignant Tumor Epigenetics and Gene Regulation, Sun Yat-sen Memorial Hospital, State Key Laboratory of Oncology in South China, Guangzhou, Guangdong, P. R. China
| | - Changhao Chen
- Department of Urology, Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou, Guangdong, P. R. China
- Guangdong Provincial Key Laboratory of Malignant Tumor Epigenetics and Gene Regulation, Sun Yat-sen Memorial Hospital, State Key Laboratory of Oncology in South China, Guangzhou, Guangdong, P. R. China
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3
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Baymukhametov TN, Lyabin DN, Chesnokov YM, Sorokin II, Pechnikova E, Vasiliev A, Afonina Z. Polyribosomes of circular topology are prevalent in mammalian cells. Nucleic Acids Res 2022; 51:908-918. [PMID: 36583341 PMCID: PMC9881139 DOI: 10.1093/nar/gkac1208] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2022] [Revised: 12/02/2022] [Accepted: 12/06/2022] [Indexed: 12/31/2022] Open
Abstract
Polyribosomes, the groups of ribosomes simultaneously translating a single mRNA molecule, are very common in both, prokaryotic and eukaryotic cells. Even in early EM studies, polyribosomes have been shown to possess various spatial conformations, including a ring-shaped configuration which was considered to be functionally important. However, a recent in situ cryo-ET analysis of predominant regular inter-ribosome contacts did not confirm the abundance of ring-shaped polyribosomes in a cell cytoplasm. To address this discrepancy, here we analyzed the cryo-ET structure of polyribosomes in diluted lysates of HeLa cells. It was shown that the vast majority of the ribosomes were combined into polysomes and were proven to be translationally active. Tomogram analysis revealed that circular polyribosomes are indeed very common in the cytoplasm, but they mostly possess pseudo-regular structures without specific inter-ribosomal contacts. Although the size of polyribosomes varied widely, most circular polysomes were relatively small in size (4-8 ribosomes). Our results confirm the recent data that it is cellular mRNAs with short ORF that most commonly form circular structures providing an enhancement of translation.
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Affiliation(s)
- Timur N Baymukhametov
- Structural biology department, National Research Center ‘Kurchatov Institute’, Moscow 123182, Russia
| | - Dmitry N Lyabin
- Institute of Protein Research RAS, Pushchino, Moscow Region 142290, Russia
| | - Yury M Chesnokov
- Probe and Electron Microscopy Resource Center, National Research Center ‘Kurchatov Institute’, Moscow 123182, Russia
| | - Ivan I Sorokin
- Institute of Protein Research RAS, Pushchino, Moscow Region 142290, Russia
| | - Evgeniya V Pechnikova
- Probe and Electron Microscopy Resource Center, National Research Center ‘Kurchatov Institute’, Moscow 123182, Russia,Electron Microscopy Laboratory, Shubnikov Institute of Crystallography of Federal Scientific Research Centre ‘Crystallography and Photonics’ RAS, Moscow 119333, Russia
| | - Alexander L Vasiliev
- Probe and Electron Microscopy Resource Center, National Research Center ‘Kurchatov Institute’, Moscow 123182, Russia,Electron Microscopy Laboratory, Shubnikov Institute of Crystallography of Federal Scientific Research Centre ‘Crystallography and Photonics’ RAS, Moscow 119333, Russia
| | - Zhanna A Afonina
- To whom correspondence should be addressed. Tel: +7 985 7232812; Fax: +7 4967 318435;
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4
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Tran TM, Rao DS. RNA binding proteins in MLL-rearranged leukemia. Exp Hematol Oncol 2022; 11:80. [PMID: 36307883 PMCID: PMC9615162 DOI: 10.1186/s40164-022-00343-5] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2022] [Accepted: 10/18/2022] [Indexed: 11/10/2022] Open
Abstract
AbstractRNA binding proteins (RBPs) have recently emerged as important post-transcriptional gene expression regulators in both normal development and disease. RBPs influence the fate of mRNAs through multiple mechanisms of action such as RNA modifications, alternative splicing, and miR-mediated regulation. This complex and, often, combinatorial regulation by RBPs critically impacts the expression of oncogenic transcripts and, thus, the activation of pathways that drive oncogenesis. Here, we focus on the major features of RBPs, their mechanisms of action, and discuss the current progress in investigating the function of important RBPs in MLL-rearranged leukemia.
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5
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Biziaev NS, Egorova TV, Alkalaeva EZ. Dynamics of Eukaryotic mRNA Structure during Translation. Mol Biol 2022. [DOI: 10.1134/s0026893322030037] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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6
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George J, Li Y, Kadamberi IP, Parashar D, Tsaih SW, Gupta P, Geethadevi A, Chen C, Ghosh C, Sun Y, Mittal S, Ramchandran R, Rui H, Lopez-Berestein G, Rodriguez-Aguayo C, Leone G, Rader JS, Sood AK, Dey M, Pradeep S, Chaluvally-Raghavan P. RNA-binding protein FXR1 drives cMYC translation by recruiting eIF4F complex to the translation start site. Cell Rep 2021; 37:109934. [PMID: 34731628 PMCID: PMC8675433 DOI: 10.1016/j.celrep.2021.109934] [Citation(s) in RCA: 29] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2020] [Revised: 08/02/2021] [Accepted: 10/12/2021] [Indexed: 11/17/2022] Open
Abstract
Fragile X-related protein-1 (FXR1) gene is highly amplified in patients with ovarian cancer, and this amplification is associated with increased expression of both FXR1 mRNA and protein. FXR1 expression directly associates with the survival and proliferation of cancer cells. Surface sensing of translation (SUnSET) assay demonstrates that FXR1 enhances the overall translation in cancer cells. Reverse-phase protein array (RPPA) reveals that cMYC is the key target of FXR1. Mechanistically, FXR1 binds to the AU-rich elements (ARE) present within the 3' untranslated region (3'UTR) of cMYC and stabilizes its expression. In addition, the RGG domain in FXR1 interacts with eIF4A1 and eIF4E proteins. These two interactions of FXR1 result in the circularization of cMYC mRNA and facilitate the recruitment of eukaryotic translation initiation factors to the translation start site. In brief, we uncover a mechanism by which FXR1 promotes cMYC levels in cancer cells.
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Affiliation(s)
- Jasmine George
- Department of Obstetrics and Gynecology, Medical College of Wisconsin, Milwaukee, WI 53226, USA
| | - Yongsheng Li
- Key Laboratory of Tropical Translational Medicine of Ministry of Education, College of Biomedical Information and Engineering, Hainan Medical University, Haikou 571199, China
| | - Ishaque P Kadamberi
- Department of Obstetrics and Gynecology, Medical College of Wisconsin, Milwaukee, WI 53226, USA
| | - Deepak Parashar
- Department of Obstetrics and Gynecology, Medical College of Wisconsin, Milwaukee, WI 53226, USA
| | - Shirng-Wern Tsaih
- Department of Obstetrics and Gynecology, Medical College of Wisconsin, Milwaukee, WI 53226, USA
| | - Prachi Gupta
- Department of Obstetrics and Gynecology, Medical College of Wisconsin, Milwaukee, WI 53226, USA
| | - Anjali Geethadevi
- Department of Obstetrics and Gynecology, Medical College of Wisconsin, Milwaukee, WI 53226, USA
| | - Changliang Chen
- Department of Obstetrics and Gynecology, Medical College of Wisconsin, Milwaukee, WI 53226, USA
| | - Chandrima Ghosh
- Department of Biological Sciences, University of Wisconsin, Milwaukee, WI 53211, USA
| | - Yunguang Sun
- Department of Pathology, Medical College of Wisconsin, Milwaukee, WI 53226, USA
| | - Sonam Mittal
- Department of Obstetrics and Gynecology, Medical College of Wisconsin, Milwaukee, WI 53226, USA
| | - Ramani Ramchandran
- Department of Pediatrics, Medical College of Wisconsin, Milwaukee, WI 53226, USA
| | - Hallgeir Rui
- Department of Pathology, Medical College of Wisconsin, Milwaukee, WI 53226, USA
| | - Gabriel Lopez-Berestein
- Department of Experimental Therapeutics, University of Texas MD Anderson Cancer Center, 1515 Holcombe Blvd., Houston, TX 77030, USA; Center for RNA Interference and Non-Coding RNA, University of Texas MD Anderson Cancer Center, 1515 Holcombe Blvd., Houston, TX 77030, USA
| | - Cristian Rodriguez-Aguayo
- Department of Experimental Therapeutics, University of Texas MD Anderson Cancer Center, 1515 Holcombe Blvd., Houston, TX 77030, USA; Center for RNA Interference and Non-Coding RNA, University of Texas MD Anderson Cancer Center, 1515 Holcombe Blvd., Houston, TX 77030, USA
| | - Gustavo Leone
- Department of Biochemistry, Medical College of Wisconsin, Milwaukee, WI 53226, USA; Medical College of Wisconsin Cancer Center, Milwaukee, WI 53226, USA
| | - Janet S Rader
- Department of Obstetrics and Gynecology, Medical College of Wisconsin, Milwaukee, WI 53226, USA
| | - Anil K Sood
- Center for RNA Interference and Non-Coding RNA, University of Texas MD Anderson Cancer Center, 1515 Holcombe Blvd., Houston, TX 77030, USA; Department of Gynecologic Oncology and Reproductive Medicine and Cancer Biology, University of Texas MD Anderson Cancer Center, 1515 Holcombe Blvd., Houston, TX 77030, USA
| | - Madhusudan Dey
- Department of Biological Sciences, University of Wisconsin, Milwaukee, WI 53211, USA
| | - Sunila Pradeep
- Department of Obstetrics and Gynecology, Medical College of Wisconsin, Milwaukee, WI 53226, USA; Department of Physiology, Medical College of Wisconsin, Milwaukee, WI 53226, USA; Center of Systems Molecular Medicine, Medical College of Wisconsin, Milwaukee, WI 53226, USA; Medical College of Wisconsin Cancer Center, Milwaukee, WI 53226, USA
| | - Pradeep Chaluvally-Raghavan
- Department of Obstetrics and Gynecology, Medical College of Wisconsin, Milwaukee, WI 53226, USA; Department of Physiology, Medical College of Wisconsin, Milwaukee, WI 53226, USA; Center of Systems Molecular Medicine, Medical College of Wisconsin, Milwaukee, WI 53226, USA; Medical College of Wisconsin Cancer Center, Milwaukee, WI 53226, USA.
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7
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Jang S, Shin H, Lee Y. Functional Analysis of RNA Motifs Essential for BC200 RNA-mediated Translational Regulation. BMB Rep 2020. [PMID: 31234958 PMCID: PMC7061212 DOI: 10.5483/bmbrep.2020.53.2.153] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Brain cytoplasmic 200 RNA (BC200 RNA) is proposed to act as a local translational modulator by inhibiting translation after being targeted to neuronal dendrites. However, the mechanism by which BC200 RNA inhibits translation is not fully understood. Although a detailed functional analysis of RNA motifs is essential for understanding the BC200 RNA-mediated translation-inhibition mechanism, there is little relevant research on the subject. Here, we performed a systematic domain-dissection analysis of BC200 RNA to identify functional RNA motifs responsible for its translational-inhibition activity. Various RNA variants were assayed for their ability to inhibit translation of luciferase mRNA in vitro. We found that the 111–200-nucleotide region consisting of part of the Alu domain as well as the A/C-rich domain (consisting of both the A-rich and C-rich domains) is most effective for translation inhibition. Surprisingly, we also found that individual A-rich, A/C-rich, and Alu domains can enhance translation but at different levels for each domain, and that these enhancing effects manifest as cap-dependent translation.
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Affiliation(s)
- Seonghui Jang
- Department of Chemistry, KAIST, Daejeon 34141, Korea
- Korea Food Research Institute, Wanju 55365, Korea
| | - Heegwon Shin
- Department of Chemistry, KAIST, Daejeon 34141, Korea
| | - Younghoon Lee
- Department of Chemistry, KAIST, Daejeon 34141, Korea
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8
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Communication Is Key: 5'-3' Interactions that Regulate mRNA Translation and Turnover. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2019; 1203:149-164. [PMID: 31811634 DOI: 10.1007/978-3-030-31434-7_6] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Most eukaryotic mRNAs maintain a 5' cap structure and 3' poly(A) tail, cis-acting elements that are often separated by thousands of nucleotides. Nevertheless, multiple paradigms exist where mRNA 5' and 3' termini interact with each other in order to regulate mRNA translation and turnover. mRNAs recruit translation initiation factors to their termini, which in turn physically interact with each other. This physical bridging of the mRNA termini is known as the "closed loop" model, with years of genetic and biochemical evidence supporting the functional synergy between the 5' cap and 3' poly(A) tail to enhance mRNA translation initiation. However, a number of examples exist of "non-canonical" 5'-3' communication for cellular and viral RNAs that lack 5' cap structures and/or poly(A) tails. Moreover, in several contexts, mRNA 5'-3' communication can function to repress translation. Overall, we detail how various mRNA 5'-3' interactions play important roles in posttranscriptional regulation, wherein depending on the protein factors involved can result in translational stimulation or repression.
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9
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Kats IR, Klann E. Translating from cancer to the brain: regulation of protein synthesis by eIF4F. ACTA ACUST UNITED AC 2019; 26:332-342. [PMID: 31416906 PMCID: PMC6699409 DOI: 10.1101/lm.050047.119] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2019] [Accepted: 07/03/2019] [Indexed: 12/27/2022]
Abstract
Formation of eukaryotic initiation factor 4F (eIF4F) is widely considered to be the rate-limiting step in cap-dependent translation initiation. Components of eIF4F are often up-regulated in various cancers, and much work has been done to elucidate the role of each of the translation initiation factors in cancer cell growth and survival. In fact, many of the basic mechanisms describing how eIF4F is assembled and how it functions to regulate translation initiation were first investigated in cancer cell lines. These same eIF4F translational control pathways also are relevant for neuronal signaling that underlies long-lasting synaptic plasticity and memory, and in neurological diseases where eIF4F and its upstream regulators are dysregulated. Although eIF4F is important in cancer and for brain function, there is not always a clear path to use the results of studies performed in cancer models to inform one of the roles that the same translation factors have in neuronal signaling. Issues arise when extrapolating from cell lines to tissue, and differences are likely to exist in how eIF4F and its upstream regulatory pathways are expressed in the diverse neuronal subtypes found in the brain. This review focuses on summarizing the role of eIF4F and its accessory proteins in cancer, and how this information has been utilized to investigate neuronal signaling, synaptic function, and animal behavior. Certain aspects of eIF4F regulation are consistent across cancer and neuroscience, whereas some results are more complicated to interpret, likely due to differences in the complexity of the brain, its billions of neurons and synapses, and its diverse cell types.
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Affiliation(s)
- Ilona R Kats
- Sackler Graduate Program, New York University School of Medicine, New York, New York 10016, USA.,Center for Neural Science, New York University, New York, New York 10003, USA
| | - Eric Klann
- Center for Neural Science, New York University, New York, New York 10003, USA.,NYU Neuroscience Institute, New York University School of Medicine, New York, New York 10016, USA
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10
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mRNA circularization by METTL3-eIF3h enhances translation and promotes oncogenesis. Nature 2018; 561:556-560. [PMID: 30232453 PMCID: PMC6234840 DOI: 10.1038/s41586-018-0538-8] [Citation(s) in RCA: 477] [Impact Index Per Article: 79.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2017] [Accepted: 08/14/2018] [Indexed: 12/01/2022]
Abstract
N6-Methyladenosine (m6A) modification of messenger RNA (mRNA) is emerging as an important regulator of gene expression that impacts different developmental and biological processes, and altered m6A homeostasis is linked to cancer1-5. m6A is catalyzed by METTL3 and enriched in the 3’ untranslated region (3’ UTR) of a large subset of mRNAs at sites close to the stop codon5. METTL3 can promote translation but the mechanism and widespread relevance remain unknown1. Here we show that METTL3 enhances translation only when tethered to reporter mRNA at sites close to the stop codon supporting a mRNA looping mechanism for ribosome recycling and translational control. Electron microscopy reveals the topology of individual polyribosomes with single METTL3 foci found in close proximity to 5’ cap-binding proteins. We identify a direct physical and functional interaction between METTL3 and the eukaryotic translation initiation factor 3 subunit h (eIF3h). METTL3 promotes translation of a large subset of oncogenic mRNAs, including Bromodomain-containing protein 4 (BRD4) that are also m6A-modified in human primary lung tumors. The METTL3-eIF3h interaction is required for enhanced translation, formation of densely packed polyribosomes, and oncogenic transformation. METTL3 depletion inhibits tumorigenicity and sensitizes lung cancer cells to BRD4 inhibition. These findings uncover a mRNA looping mechanism of translation control and identify METTL3-eIF3h as a potential cancer therapeutic target.
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11
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Afonina ZA, Shirokov VA. Three-Dimensional Organization of Polyribosomes–A Modern Approach. BIOCHEMISTRY (MOSCOW) 2018; 83:S48-S55. [DOI: 10.1134/s0006297918140055] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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12
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mRNA length-sensing in eukaryotic translation: reconsidering the "closed loop" and its implications for translational control. Curr Genet 2016; 63:613-620. [PMID: 28028558 DOI: 10.1007/s00294-016-0674-3] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2016] [Revised: 12/14/2016] [Accepted: 12/15/2016] [Indexed: 01/01/2023]
Abstract
Most eukaryotic mRNAs are recruited to the ribosome by recognition of a 5' m7GpppN cap. 30 years of genetic and biochemical evidence point to a role for interaction between the 5' cap-interacting factors and the 3' poly(A)-binding protein in bringing the ends of the mRNA into close proximity and promoting both translation and stability of the mRNA, in a form known as the "closed loop". However, the results of recent RNA-protein interaction studies suggest that not all mRNAs have equal access to the closed loop factors. Furthermore, association with closed loop factors appears to be highly biased towards mRNAs with short open reading frames, echoing the trend for higher translation of short mRNAs that has been observed in many eukaryotes. We recently reported that the ribosomal signaling scaffold protein RACK1 promotes the efficient translation of short mRNAs that strongly associate with the closed loop factors. Here, we discuss the implications of these observations with respect to translational control and suggest avenues through which the universality of the closed loop in eukaryotic translation could be revisited.
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Design of nucleotide-mimetic and non-nucleotide inhibitors of the translation initiation factor eIF4E: Synthesis, structural and functional characterisation. Eur J Med Chem 2016; 124:200-217. [PMID: 27592390 PMCID: PMC5111791 DOI: 10.1016/j.ejmech.2016.08.047] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2016] [Revised: 08/03/2016] [Accepted: 08/21/2016] [Indexed: 12/02/2022]
Abstract
Eukaryotic translation initiation factor 4E (eIF4E) is considered as the corner stone in the cap-dependent translation initiation machinery. Its role is to recruit mRNA to the ribosome through recognition of the 5′-terminal mRNA cap structure (m7GpppN, where G is guanosine, N is any nucleotide). eIF4E is implicated in cell transformation, tumourigenesis, and angiogenesis by facilitating translation of oncogenic mRNAs; it is thus regarded as an attractive anticancer drug target. We have used two approaches to design cap-binding inhibitors of eIF4E by modifying the N7-substituent of m7GMP and replacing the phosphate group with isosteres such as squaramides, sulfonamides, and tetrazoles, as well as by structure-based virtual screening aimed at identifying non-nucleotide cap-binding antagonists. Phosphomimetic nucleotide derivatives and highly ranking virtual hits were evaluated in a series of in vitro and cell-based assays to identify the first non-nucleotide eIF4E cap-binding inhibitor with activities in cell-based assays, N-[(5,6-dihydro-6-oxo-1,3-dioxolo[4,5-g]quinolin-7-yl)methyl]-N′-(2-methyl-propyl)-N-(phenyl-methyl)thiourea (14), including down-regulation of oncogenic proteins and suppression of RNA incorporation into polysomes. Although we did not observe cellular activity with any of our modified m7GMP phosphate isostere compounds, we obtained X-ray crystallography structures of three such compounds in complex with eIF4E, 5′-deoxy-5′-(1,2-dioxo-3-hydroxycyclobut-3-en-4-yl)amino-N7-methyl-guanosine (4a), N7-3-chlorobenzyl-5′-deoxy-5′-(1,2-dioxo-3-hydroxy-cyclobut-3-en-4-yl)amino-guanosine (4f), and N7-benzyl-5′-deoxy-5′-(trifluoromethyl-sulfamoyl)guanosine (7a). Collectively, the data we present on structure-based design of eIF4E cap-binding inhibitors should facilitate the optimisation of such compounds as potential anticancer agents.
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Filbin ME, Kieft JS. Linking Α to Ω: diverse and dynamic RNA-based mechanisms to regulate gene expression by 5'-to-3' communication. F1000Res 2016; 5. [PMID: 27610229 PMCID: PMC4995689 DOI: 10.12688/f1000research.7913.1] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 08/16/2016] [Indexed: 12/18/2022] Open
Abstract
Communication between the 5′ and 3′ ends of a eukaryotic messenger RNA (mRNA) or viral genomic RNA is a ubiquitous and important strategy used to regulate gene expression. Although the canonical interaction between initiation factor proteins at the 5′ end of an mRNA and proteins bound to the polyadenylate tail at the 3′ end is well known, in fact there are many other strategies used in diverse ways. These strategies can involve “non-canonical” proteins, RNA structures, and direct RNA-RNA base-pairing between distal elements to achieve 5′-to-3′ communication. Likewise, the communication induced by these interactions influences a variety of processes linked to the use and fate of the RNA that contains them. Recent studies are revealing how dynamic these interactions are, possibly changing in response to cellular conditions or to link various phases of the mRNA’s life, from translation to decay. Thus, 5′-to-3′ communication is about more than just making a closed circle; the RNA elements and associated proteins are key players in controlling gene expression at the post-transcriptional level.
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Affiliation(s)
- Megan E Filbin
- Department of Chemistry, Metropolitan State University of Denver, Denver, Colorado, 80217, USA
| | - Jeffrey S Kieft
- Department of Biochemistry and Molecular Genetics, University of Colorado Denver School of Medicine, Aurora, Colorado, 80045, USA
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15
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Rotavirus NSP3 Is a Translational Surrogate of the Poly(A) Binding Protein-Poly(A) Complex. J Virol 2015; 89:8773-82. [PMID: 26063427 DOI: 10.1128/jvi.01402-15] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2015] [Accepted: 06/04/2015] [Indexed: 12/26/2022] Open
Abstract
UNLABELLED Through its interaction with the 5' translation initiation factor eIF4G, poly(A) binding protein (PABP) facilitates the translation of 5'-capped and 3'-poly(A)-tailed mRNAs. Rotavirus mRNAs are capped but not polyadenylated, instead terminating in a 3' GACC motif that is recognized by the viral protein NSP3, which competes with PABP for eIF4G binding. Upon rotavirus infection, viral, GACC-tailed mRNAs are efficiently translated, while host poly(A)-tailed mRNA translation is, in contrast, severely impaired. To explore the roles of NSP3 in these two opposing events, the translational capabilities of three capped mRNAs, distinguished by either a GACC, a poly(A), or a non-GACC and nonpoly(A) 3' end, have been monitored after electroporation of cells expressing all rotavirus proteins (infected cells) or only NSP3 (stably or transiently transfected cells). In infected cells, we found that the magnitudes of translation induction (GACC-tailed mRNA) and translation reduction [poly(A)-tailed mRNA] both depended on the rotavirus strain used but that translation reduction not genetically linked to NSP3. In transfected cells, even a small amount of NSP3 was sufficient to dramatically enhance GACC-tailed mRNA translation and, surprisingly, to slightly favor the translation of both poly(A)- and nonpoly(A)-tailed mRNAs, likely by stabilizing the eIF4E-eIF4G interaction. These data suggest that NSP3 is a translational surrogate of the PABP-poly(A) complex; therefore, it cannot by itself be responsible for inhibiting the translation of host poly(A)-tailed mRNAs upon rotavirus infection. IMPORTANCE To control host cell physiology and to circumvent innate immunity, many viruses have evolved powerful mechanisms aimed at inhibiting host mRNA translation while stimulating translation of their own mRNAs. How rotavirus tackles this challenge is still a matter of debate. Using rotavirus-infected cells, we show that the magnitude of cellular poly(A) mRNA translation differs with respect to rotavirus strains but is not genetically linked to NSP3. Using cells expressing rotavirus NSP3, we show that NSP3 alone not only dramatically enhances rotavirus-like mRNA translation but also enhances poly(A) mRNA translation rather than inhibiting it, likely by stabilizing the eIF4E-eIF4G complex. Thus, the inhibition of cellular polyadenylated mRNA translation during rotavirus infection cannot be attributed solely to NSP3 and is more likely the result of global competition between viral and host mRNAs for the cellular translation machinery.
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Pelletier J, Graff J, Ruggero D, Sonenberg N. Targeting the eIF4F translation initiation complex: a critical nexus for cancer development. Cancer Res 2015; 75:250-63. [PMID: 25593033 DOI: 10.1158/0008-5472.can-14-2789] [Citation(s) in RCA: 265] [Impact Index Per Article: 29.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Elevated protein synthesis is an important feature of many cancer cells and often arises as a consequence of increased signaling flux channeled to eukaryotic initiation factor 4F (eIF4F), the key regulator of the mRNA-ribosome recruitment phase of translation initiation. In many cellular and preclinical models of cancer, eIF4F deregulation results in changes in translational efficiency of specific mRNA classes. Importantly, many of these mRNAs code for proteins that potently regulate critical cellular processes, such as cell growth and proliferation, enhanced cell survival and cell migration that ultimately impinge on several hallmarks of cancer, including increased angiogenesis, deregulated growth control, enhanced cellular survival, epithelial-to-mesenchymal transition, invasion, and metastasis. By being positioned as the molecular nexus downstream of key oncogenic signaling pathways (e.g., Ras, PI3K/AKT/TOR, and MYC), eIF4F serves as a direct link between important steps in cancer development and translation initiation. Identification of mRNAs particularly responsive to elevated eIF4F activity that typifies tumorigenesis underscores the critical role of eIF4F in cancer and raises the exciting possibility of developing new-in-class small molecules targeting translation initiation as antineoplastic agents.
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Affiliation(s)
- Jerry Pelletier
- Department of Biochemistry, McGill University, Montreal, Québec, Canada. The Rosalind and Morris Goodman Cancer Research Center, McGill University, Montreal, Québec, Canada. Department of Oncology, McGill University, Montreal, Québec, Canada.
| | - Jeremy Graff
- Lilly Research Laboratories, Eli Lilly and Company, Indianapolis, Indiana
| | - Davide Ruggero
- School of Medicine and Department of Urology, Helen Diller Family Comprehensive Cancer Center, University of California, San Francisco, California
| | - Nahum Sonenberg
- Department of Biochemistry, McGill University, Montreal, Québec, Canada. The Rosalind and Morris Goodman Cancer Research Center, McGill University, Montreal, Québec, Canada
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Eliseeva IA, Lyabin DN, Ovchinnikov LP. Poly(A)-binding proteins: structure, domain organization, and activity regulation. BIOCHEMISTRY (MOSCOW) 2014; 78:1377-91. [PMID: 24490729 DOI: 10.1134/s0006297913130014] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
RNA-binding proteins are of vital importance for mRNA functioning. Among these, poly(A)-binding proteins (PABPs) are of special interest due to their participation in virtually all mRNA-dependent events that is caused by their high affinity for A-rich mRNA sequences. Apart from mRNAs, PABPs interact with many proteins, thus promoting their involvement in cellular events. In the nucleus, PABPs play a role in polyadenylation, determine the length of the poly(A) tail, and may be involved in mRNA export. In the cytoplasm, they participate in regulation of translation initiation and either protect mRNAs from decay through binding to their poly(A) tails or stimulate this decay by promoting mRNA interactions with deadenylase complex proteins. This review presents modern notions of the role of PABPs in mRNA-dependent events; peculiarities of regulation of PABP amount in the cell and activities are also discussed.
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Affiliation(s)
- I A Eliseeva
- Institute of Protein Research, Russian Academy of Sciences, Pushchino, Moscow Region, 142290, Russia.
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18
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O'Leary SE, Petrov A, Chen J, Puglisi JD. Dynamic recognition of the mRNA cap by Saccharomyces cerevisiae eIF4E. Structure 2013; 21:2197-207. [PMID: 24183571 DOI: 10.1016/j.str.2013.09.016] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2013] [Revised: 08/22/2013] [Accepted: 09/18/2013] [Indexed: 01/06/2023]
Abstract
Recognition of the mRNA 5' m⁷G(5')ppp(5')N cap is key to translation initiation for most eukaryotic mRNAs. The cap is bound by the eIF4F complex, consisting of a cap-binding protein (eIF4E), a "scaffold" protein (eIF4G), and an RNA helicase (eIF4A). As a central early step in initiation, regulation of eIF4F is crucial for cellular viability. Although the structure and function of eIF4E have been defined, a dynamic mechanistic picture of its activity at the molecular level in the eIF4F·mRNA complex is still unavailable. Here, using single-molecule fluorescence, we measured the effects of Saccharomyces cerevisiae eIF4F factors, mRNA secondary structure, and the poly(A)-binding protein Pab1p on eIF4E-mRNA binding dynamics. Our data provide an integrated picture of how eIF4G and mRNA structure modulate eIF4E-mRNA interaction, and uncover an eIF4G- and poly(A)-independent activity of poly(A)-binding protein that prolongs the eIF4E·mRNA complex lifetime.
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Affiliation(s)
- Seán E O'Leary
- Department of Structural Biology, Stanford University School of Medicine, Stanford, CA 94305, USA
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Afonina ZA, Myasnikov AG, Khabibullina NF, Belorusova AY, Menetret JF, Vasiliev VD, Klaholz BP, Shirokov VA, Spirin AS. Topology of mRNA chain in isolated eukaryotic double-row polyribosomes. BIOCHEMISTRY (MOSCOW) 2013; 78:445-54. [PMID: 23848146 DOI: 10.1134/s0006297913050027] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
In the process of protein synthesis, the translating ribosomes of eukaryotic cells form polyribosomes that are found to be multiplex functional complexes possessing elements of ordered spatial organization. As revealed by a number of electron microscopy studies, the predominant visible configurations of the eukaryotic polyribosomes are circles (circular polyribosomes) and two-stranded formations (so-called double-row polyribosomes). The "long" (i.e. heavy loaded) polyribosomes are usually represented by double-row structures, which can be interpreted as either topologically circular ("collapsed rings"), or topologically linear (zigzags or helices). In the present work we have analyzed the mRNA path within the eukaryotic polyribosomes, isolated from a wheat germ cell-free translation system, by integrating two approaches: the visualization of mRNA ends in polyribosomes by marking them with gold nanoparticles (3'-end) and initiating 40S subunits (5'-end), as well as by the cryoelectron tomography. Examination of the location of the mRNA markers in polyribosomes and mutual orientation of ribosomes in them has shown that the double-row polyribosomes of the same sample can have both circular and linear arrangements of their mRNA.
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Affiliation(s)
- Zh A Afonina
- Institute of Protein Research, Russian Academy of Sciences, 142290 Pushchino, Moscow Region, Russia
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20
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Safaee N, Kozlov G, Noronha AM, Xie J, Wilds CJ, Gehring K. Interdomain allostery promotes assembly of the poly(A) mRNA complex with PABP and eIF4G. Mol Cell 2012; 48:375-86. [PMID: 23041282 DOI: 10.1016/j.molcel.2012.09.001] [Citation(s) in RCA: 92] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2012] [Revised: 07/17/2012] [Accepted: 08/17/2012] [Indexed: 11/25/2022]
Abstract
Many RNA-binding proteins contain multiple single-strand nucleic acid-binding domains and assemble into large multiprotein messenger ribonucleic acid protein (mRNP) complexes. The mechanisms underlying the self-assembly of these complexes are largely unknown. In eukaryotes, the association of the translation factors polyadenylate-binding protein-1 (PABP) and eIF4G is essential for high-level expression of polyadenylated mRNAs. Here, we report the crystal structure of the ternary complex poly(A)(11)·PABP(1-190)·eIF4G(178-203) at 2.0 Å resolution. Our NMR and crystallographic data show that eIF4G interacts with the RRM2 domain of PABP. Analysis of the interaction by small-angle X-ray scattering, isothermal titration calorimetry, and electromobility shift assays reveals that this interaction is allosterically regulated by poly(A) binding to PABP. Furthermore, we have confirmed the importance of poly(A) for the endogenous PABP and eIF4G interaction in immunoprecipitation experiments using HeLa cell extracts. Our findings reveal interdomain allostery as a mechanism for cooperative assembly of RNP complexes.
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Affiliation(s)
- Nozhat Safaee
- Department of Biochemistry, McGill University, Montréal, QC H3G 0B1, Canada
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21
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Le Nouën C, Toquin D, Müller H, Raue R, Kean KM, Langlois P, Cherbonnel M, Eterradossi N. Different domains of the RNA polymerase of infectious bursal disease virus contribute to virulence. PLoS One 2012; 7:e28064. [PMID: 22253687 PMCID: PMC3258228 DOI: 10.1371/journal.pone.0028064] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2011] [Accepted: 10/31/2011] [Indexed: 01/13/2023] Open
Abstract
BACKGROUND Infectious bursal disease virus (IBDV) is a pathogen of worldwide significance to the poultry industry. IBDV has a bi-segmented double-stranded RNA genome. Segments A and B encode the capsid, ribonucleoprotein and non-structural proteins, or the virus polymerase (RdRp), respectively. Since the late eighties, very virulent (vv) IBDV strains have emerged in Europe inducing up to 60% mortality. Although some progress has been made in understanding the molecular biology of IBDV, the molecular basis for the pathogenicity of vvIBDV is still not fully understood. METHODOLOGY, PRINCIPAL FINDINGS Strain 88180 belongs to a lineage of pathogenic IBDV phylogenetically related to vvIBDV. By reverse genetics, we rescued a molecular clone (mc88180), as pathogenic as its parent strain. To study the molecular basis for 88180 pathogenicity, we constructed and characterized in vivo reassortant or mosaic recombinant viruses derived from the 88180 and the attenuated Cu-1 IBDV strains. The reassortant virus rescued from segments A of 88180 (A88) and B of Cu-1 (BCU1) was milder than mc88180 showing that segment B is involved in 88180 pathogenicity. Next, the exchange of different regions of BCU1 with their counterparts in B88 in association with A88 did not fully restore a virulence equivalent to mc88180. This demonstrated that several regions if not the whole B88 are essential for the in vivo pathogenicity of 88180. CONCLUSION, SIGNIFICANCE The present results show that different domains of the RdRp, are essential for the in vivo pathogenicity of IBDV, independently of the replication efficiency of the mosaic viruses.
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Affiliation(s)
- Cyril Le Nouën
- Avian and Rabbit Virology, Immunology and Parasitology Unit, OIE Reference Laboratory for Infectious Bursal Disease, French Agency for Food, Environmental and Occupational Health Safety (Anses), Ploufragan, France
| | - Didier Toquin
- Avian and Rabbit Virology, Immunology and Parasitology Unit, OIE Reference Laboratory for Infectious Bursal Disease, French Agency for Food, Environmental and Occupational Health Safety (Anses), Ploufragan, France
| | - Hermann Müller
- Institute for Virology, Faculty of Veterinary Medicine, University of Leipzig, Leipzig, Germany
| | - Rüdiger Raue
- Institute for Virology, Faculty of Veterinary Medicine, University of Leipzig, Leipzig, Germany
| | | | - Patrick Langlois
- Virus Genetics and Biosecurity Unit, French Agency for Food, Environmental and Occupational Health Safety (ANSES), Ploufragan, France
| | - Martine Cherbonnel
- Avian and Rabbit Virology, Immunology and Parasitology Unit, OIE Reference Laboratory for Infectious Bursal Disease, French Agency for Food, Environmental and Occupational Health Safety (Anses), Ploufragan, France
| | - Nicolas Eterradossi
- Avian and Rabbit Virology, Immunology and Parasitology Unit, OIE Reference Laboratory for Infectious Bursal Disease, French Agency for Food, Environmental and Occupational Health Safety (Anses), Ploufragan, France
- * E-mail:
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22
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Ricci EP, Limousin T, Soto-Rifo R, Allison R, Pöyry T, Decimo D, Jackson RJ, Ohlmann T. Activation of a microRNA response in trans reveals a new role for poly(A) in translational repression. Nucleic Acids Res 2011; 39:5215-31. [PMID: 21385827 PMCID: PMC3130266 DOI: 10.1093/nar/gkr086] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Here, we report that the untreated rabbit reticulocyte lysate contains over 300 different endogenous microRNAs together with the major components of the RNA-induced silencing complex and thus can be used as a model in vitro system to study the effects of microRNAs on gene expression. By using this system, we were able to show that microRNA hybridization to its target resulted in a very rapid and strong inhibition of expression that was exerted exclusively at the level of translation initiation with no involvement of transcript degradation or deadenylation. Moreover, we demonstrate that the magnitude of microRNA-induced repression can only be recapitulated in the context of a competitive translating environment. By using a wide spectrum of competitor cellular and viral RNAs, we could further show that competition was not exerted at the level of general components of the translational machinery, but relied exclusively on the presence of the poly(A) tail with virtually no involvement of the cap structure.
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Affiliation(s)
- Emiliano P Ricci
- Ecole Normale Supérieure de Lyon, Unité de Virologie Humaine, IFR 128, Lyon, F-69364 France
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23
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Tavernier G, Andries O, Demeester J, Sanders NN, De Smedt SC, Rejman J. mRNA as gene therapeutic: How to control protein expression. J Control Release 2011; 150:238-47. [DOI: 10.1016/j.jconrel.2010.10.020] [Citation(s) in RCA: 150] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2010] [Accepted: 10/13/2010] [Indexed: 10/18/2022]
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25
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Cellular proteins mediate 5'-3' end contacts of Norwalk virus genomic RNA. Virology 2009; 387:322-30. [PMID: 19324388 DOI: 10.1016/j.virol.2009.02.041] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2008] [Revised: 12/30/2008] [Accepted: 02/23/2009] [Indexed: 11/24/2022]
Abstract
Long-range RNA-RNA interactions between the 5' and 3' ends are a common feature involved in the regulation of both the initiation of translation and the synthesis of the viral genomic RNAs. These interactions either take place by direct RNA-RNA contacts or can be mediated by proteins. By in silico analysis, we found three possible complementary sequences (CS) between the 5' and the 3' ends of the Norwalk virus genomic RNA. Co-precipitation assays demonstrated that physical contacts between the 5' and the 3' ends of the NV genomic RNA were stabilized by cellular proteins. Mutations and deletions within these regions, that altered the formation of the CS-1 motif disrupted the 5'-3' end contacts, while mutations that restore complementarity of the CS-1 motif, recover the ability to form these contacts. These results suggest that the NV genomic 5'-3' end contacts initially occur by RNA-RNA interactions but are further stabilized by cellular proteins.
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26
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Yamamoto A, Kormann M, Rosenecker J, Rudolph C. Current prospects for mRNA gene delivery. Eur J Pharm Biopharm 2009; 71:484-9. [DOI: 10.1016/j.ejpb.2008.09.016] [Citation(s) in RCA: 149] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2007] [Revised: 07/21/2008] [Accepted: 09/02/2008] [Indexed: 12/26/2022]
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Duncan RF. Rapamycin conditionally inhibits Hsp90 but not Hsp70 mRNA translation in Drosophila: implications for the mechanisms of Hsp mRNA translation. Cell Stress Chaperones 2008; 13:143-55. [PMID: 18418733 PMCID: PMC2673887 DOI: 10.1007/s12192-008-0024-6] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2007] [Revised: 09/26/2007] [Accepted: 10/02/2007] [Indexed: 01/25/2023] Open
Abstract
Rapamycin inhibits the activity of the target of rapamycin (TOR)-dependent signaling pathway, which has been characterized as one dedicated to translational regulation through modulating cap-dependent translation, involving eIF4E binding protein (eIF4E-BP) or 4E-BP. Results show that rapamycin strongly inhibits global translation in Drosophila cells. However, Hsp70 mRNA translation is virtually unaffected by rapamycin treatment, whereas Hsp90 mRNA translation is strongly inhibited, at normal growth temperature. Intriguingly, during heat shock Hsp90 mRNA becomes significantly less sensitive to rapamycin-mediated inhibition, suggesting the pathway for Hsp90 mRNA translation is altered during heat shock. Reporter mRNAs containing the Hsp90 or Hsp70 mRNAs' 5' untranslated region recapitulate these rapamycin-dependent translational characteristics, indicating this region regulates rapamycin-dependent translational sensitivity as well as heat shock preferential translation. Surprisingly, rapamycin-mediated inhibition of Hsp90 mRNA translation at normal growth temperature is not caused by 4E-BP-mediated inhibition of cap-dependent translation. Indeed, no evidence for rapamycin-mediated impaired eIF4E function is observed. These results support the proposal that preferential translation of different Hsp mRNA utilizes distinct translation mechanisms, even within a single species.
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Affiliation(s)
- Roger F Duncan
- Department of Pharmacology and Pharmaceutical Sciences, University of Southern California School of Pharmacy, 1985 Zonal Avenue, Los Angeles, CA 90033, USA.
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28
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Kopeina GS, Afonina ZA, Gromova KV, Shirokov VA, Vasiliev VD, Spirin AS. Step-wise formation of eukaryotic double-row polyribosomes and circular translation of polysomal mRNA. Nucleic Acids Res 2008; 36:2476-88. [PMID: 18310103 PMCID: PMC2377419 DOI: 10.1093/nar/gkm1177] [Citation(s) in RCA: 70] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
The time course of polysome formation was studied in a long-term wheat germ cell-free translation system using sedimentation and electron microscopy techniques. The polysomes were formed on uncapped luciferase mRNA with translation-enhancing 5' and 3' UTRs. The formation of fully loaded polysomes was found to be a long process that required many rounds of translation and proceeded via several phases. First, short linear polysomes containing no more than six ribosomes were formed. Next, folding of these polysomes into short double-row clusters occurred. Subsequent gradual elongation of the clusters gave rise to heavy-loaded double-row strings containing up to 30-40 ribosomes. The formation of the double-row polysomes was considered to be equivalent to circularization of polysomes, with antiparallel halves of the circle being laterally stuck together by ribosome interactions. A slow exchange with free ribosomes and free mRNA observed in the double-row type polysomes, as well as the resistance of translation in them to AMP-PNP, provided evidence that most polysomal ribosomes reinitiate translation within the circularized polysomes without scanning of 5' UTR, while de novo initiation including 5' UTR scanning proceeds at a much slower rate. Removal or replacements of 5' and 3' UTRs affected the initial phase of translation, but did not prevent the formation of the double-row polysomes during translation.
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Affiliation(s)
- Gelina S Kopeina
- Institute of Protein Research, Russian Academy of Sciences, 142290 Pushchino, Moscow Region, Russia
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29
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Rifo RS, Ricci EP, Décimo D, Moncorgé O, Ohlmann T. Back to basics: the untreated rabbit reticulocyte lysate as a competitive system to recapitulate cap/poly(A) synergy and the selective advantage of IRES-driven translation. Nucleic Acids Res 2007; 35:e121. [PMID: 17881372 PMCID: PMC2094066 DOI: 10.1093/nar/gkm682] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2007] [Revised: 08/17/2007] [Accepted: 08/18/2007] [Indexed: 12/17/2022] Open
Abstract
Translation of most eukaryotic mRNAs involves the synergistic action between the 5' cap structure and the 3' poly(A) tail at the initiation step. The poly(A) tail has also been shown to stimulate translation of picornavirus internal ribosome entry sites (IRES)-directed translation. These effects have been attributed principally to interactions between eIF4G and poly(A)-binding protein (PABP) but also to the participation of PABP in other steps during translation initiation. As the rabbit reticulocyte lysate (RRL) does not recapitulate this cap/poly(A) synergy, several systems based on cellular cell-free extracts have been developed to study the effects of poly(A) tail in vitro but they generally exhibit low translational efficiency. Here, we describe that the non-nuclease-treated RRL (untreated RRL) is able to recapitulate the effects of poly(A) tail on translation in vitro. In this system, translation of a capped/polyadenylated RNA was specifically inhibited by either Paip2 or poly(rA), whereas translation directed by HCV IRES remained unaffected. Moreover, cleavage of eIF4G by FMDV L protease strongly stimulated translation directed by the EMCV IRES, thus recapitulating the competitive advantage that the proteolytic processing of eIF4G confers to IRES-driven RNAs.
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Affiliation(s)
- Ricardo Soto Rifo
- Inserm U 758, Lyon, F-69364 and Ecole Normale Supérieure de Lyon, Unité de Virologie Humaine, IFR 128, Lyon, F-69364, France
| | - Emiliano P. Ricci
- Inserm U 758, Lyon, F-69364 and Ecole Normale Supérieure de Lyon, Unité de Virologie Humaine, IFR 128, Lyon, F-69364, France
| | - Didier Décimo
- Inserm U 758, Lyon, F-69364 and Ecole Normale Supérieure de Lyon, Unité de Virologie Humaine, IFR 128, Lyon, F-69364, France
| | - Olivier Moncorgé
- Inserm U 758, Lyon, F-69364 and Ecole Normale Supérieure de Lyon, Unité de Virologie Humaine, IFR 128, Lyon, F-69364, France
| | - Théophile Ohlmann
- Inserm U 758, Lyon, F-69364 and Ecole Normale Supérieure de Lyon, Unité de Virologie Humaine, IFR 128, Lyon, F-69364, France
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30
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Zohra FT, Chowdhury EH, Tada S, Hoshiba T, Akaike T. Effective delivery with enhanced translational activity synergistically accelerates mRNA-based transfection. Biochem Biophys Res Commun 2007; 358:373-8. [PMID: 17475211 DOI: 10.1016/j.bbrc.2007.04.059] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2007] [Accepted: 04/12/2007] [Indexed: 11/28/2022]
Abstract
mRNA instead of DNA provides a new and attractive approach for gene therapy and genetic vaccination. Current technologies for mRNA delivery are based on cationic lipids with DOTAP being the most efficient one. We previously reported on the synthesis of an inorganic-organic hybrid carrier by embedding inorganic nano-particles of carbonate apatite onto liposomal carrier DOTAP and demonstrated its high transfection potency of luciferase mRNA both in mitotic and non-mitotic cells. Here we show that in addition to the carrier design for effective endocytosis and release of mRNA to the cytoplasm, enhancement of mRNA translation efficiency is a prerequisite for maximum protein expression. We used the modified cap analog (ARCA) during in vitro transcription of luciferase DNA for proper cap orientation and demonstrated that transfection with ARCA-mRNA resulted in higher protein expression than the mRNA with usual cap structure for both DOTAP and DOTAP-apatite complex. Secondly, exogenous poly(A) was co-delivered with mRNA by the DOTAP-apatite, resulting in very significant expression compared to mRNA delivery only. Finally, when combined both of the effects of smart carrier and the modifications at mRNA translational level, a notable enhancement (100 times) was achieved as compared to the existing DOTAP-based liposome technology. Our findings, therefore, unveiled a novel approach that an effective delivery system can be developed by the improvement of the gene expression level in combination with the enhancement of the carrier potency.
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Affiliation(s)
- F T Zohra
- Department of Biomolecular Engineering, Graduate School of Bioscience and Biotechnology, Tokyo Institute of Technology, 4259 Nagatsuta-cho, Midori-ku, Yokohama 226-8501, Japan
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31
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Mockey M, Gonçalves C, Dupuy FP, Lemoine FM, Pichon C, Midoux P. mRNA transfection of dendritic cells: synergistic effect of ARCA mRNA capping with Poly(A) chains in cis and in trans for a high protein expression level. Biochem Biophys Res Commun 2005; 340:1062-8. [PMID: 16403444 DOI: 10.1016/j.bbrc.2005.12.105] [Citation(s) in RCA: 118] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2005] [Accepted: 12/16/2005] [Indexed: 11/26/2022]
Abstract
The occurrence of translation mechanism in the cytosol offers advantages to mRNA transfer over DNA-based transfection in non-dividing cells. Here, we sought to optimize mRNA constructs allowing a high level of protein upon lipofection. We found that luciferase into mouse dendritic cells (JAWSII cells) was approximately 20-fold higher when the luciferase mRNA was capped with 3'-O-methyl-m7(5')Gppp5'G (anti-reverse cap analogue; ARCA) than with m7(5')Gppp5'G (CAP). Adding a Poly(A) tail of 100 instead of 64 adenosines in cis increased by approximately 35-fold more the protein level. Finally, ARCA-Luc-mRNA-A100 construct was 700-fold better efficient than the CAP-Luc-mRNA-A64 one. Moreover, co-transfection with free Poly(A) chains in trans enhanced by 100% the luciferase level. The efficiency of ARCA-mRNA-A100 construct was validated in immature and mature human CD34-derived dendritic cells. Such mRNA construct was also successful to obtain high level of MART-1 tumor antigen.
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Affiliation(s)
- Michael Mockey
- Centre de Biophysique Moléculaire, UPR4301 CNRS, affiliated to the University of Orléans and INSERM, rue Charles Sadron, 45071 Orléans cedex 2, France
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32
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Edgil D, Harris E. End-to-end communication in the modulation of translation by mammalian RNA viruses. Virus Res 2005; 119:43-51. [PMID: 16307817 PMCID: PMC7172311 DOI: 10.1016/j.virusres.2005.10.012] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2005] [Revised: 09/14/2005] [Accepted: 10/20/2005] [Indexed: 02/05/2023]
Abstract
A 5′–3′ end interaction leading to stimulation of translation has been described for many cellular and viral mRNAs. Enhancement of viral translational efficiency mediated by 5′ and 3′ untranslated regions (UTRs) has been shown to occur via RNA–RNA interactions or novel RNA–protein interactions. Mammalian RNA viruses make use of end-to-end communication in conjunction with both viral and cellular factors to regulate multiple processes including translation initiation and the switch between translation and RNA synthesis during the viral lifecycle.
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Affiliation(s)
- Dianna Edgil
- Division of Infectious Diseases, School of Public Health, University of California, Berkeley, CA 94720-7360, USA
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Peng J, Schoenberg DR. mRNA with a <20-nt poly(A) tail imparted by the poly(A)-limiting element is translated as efficiently in vivo as long poly(A) mRNA. RNA (NEW YORK, N.Y.) 2005; 11:1131-40. [PMID: 15929942 PMCID: PMC1237109 DOI: 10.1261/rna.2470905] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/02/2023]
Abstract
The poly(A)-limiting element (PLE) is a conserved sequence that restricts the length of the poly(A) tail to <20 nt. This study compared the translation of PLE-containing short poly(A) mRNA expressed in cells with translation in vitro of mRNAs with varying length poly(A) tails. In transfected cells, PLE-containing mRNA had a <20-nt poly(A) and accumulated to a level 20% higher than a matching control without a PLE. It was translated as well as the matching control mRNA with long poly(A) and showed equivalent binding to polysomes. Translation in a HeLa cell cytoplasmic extract was used to examine the impact of the PLE in the context of varying length poly(A) tails. Here the overall translation of +PLE mRNA was less than control mRNA with the same length poly(A), and the PLE did not overcome the effect of a short poly(A) tail. Because poly(A)-binding protein (PABP) is a dominant effector of poly(A)-dependent translation we reasoned excess PABP in our extract might overwhelm PLE regulation of translation. This was confirmed by experiments where PABP was inactivated with poly(rA) or Paip2, and the effect of both treatments was reversed by addition of recombinant PABP. These data indicate that the PLE functionally substitutes for bound PABP to stimulate translation of short poly(A) mRNA.
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Affiliation(s)
- Jing Peng
- Department of Molecular and Cellular Biochemistry, The Ohio State University, 1645 Neil Ave., Columbus, OH 43210-1218, USA
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Abstract
Great advances have been made in the past three decades in understanding the molecular mechanics underlying protein synthesis in bacteria, but our understanding of the corresponding events in eukaryotic organisms is only beginning to catch up. In this review we describe the current state of our knowledge and ignorance of the molecular mechanics underlying eukaryotic translation. We discuss the mechanisms conserved across the three kingdoms of life as well as the important divergences that have taken place in the pathway.
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Affiliation(s)
- Lee D Kapp
- Department of Biophysics and Biophysical Chemistry, Johns Hopkins University School of Medicine, 725 North Wolfe Street, Baltimore, Maryland 21205-2185, USA.
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35
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Preiss T, W Hentze M. Starting the protein synthesis machine: eukaryotic translation initiation. Bioessays 2004; 25:1201-11. [PMID: 14635255 DOI: 10.1002/bies.10362] [Citation(s) in RCA: 150] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The final assembly of the protein synthesis machinery occurs during translation initiation. This delicate process involves both ends of eukaryotic messenger RNAs as well as multiple sequential protein-RNA and protein-protein interactions. As is expected from its critical position in the gene expression pathway between the transcriptome and the proteome, translation initiation is a selective and highly regulated process. This synopsis summarises the current status of the field and identifies intriguing open questions.
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Affiliation(s)
- Thomas Preiss
- Victor Chang Cardiac Research Institute (VCCRI), Molecular Genetics Program, Sydney, Australia.
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Rajkowitsch L, Vilela C, Berthelot K, Ramirez CV, McCarthy JEG. Reinitiation and Recycling are Distinct Processes Occurring Downstream of Translation Termination in Yeast. J Mol Biol 2004; 335:71-85. [PMID: 14659741 DOI: 10.1016/j.jmb.2003.10.049] [Citation(s) in RCA: 57] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The circularisation model of the polysome suggests that ribosome recycling is facilitated by 5'-3' interactions mediated by the cap-binding complex eIF4F and the poly(A)-binding protein, Pab1. Alternatively, downstream of a short upstream open reading frame (uORF) in the 5' untranslated region of a gene, posttermination ribosomes can maintain the competence to (re)initiate translation. Our data show that recycling and reinitiation must be distinct processes in Saccharomyces cerevisiae. The role of the 3'UTR in recycling was assessed by restricting ribosome movement along the mRNA using a poly(G) stretch or the mammalian iron regulatory protein bound to the iron responsive element. We find that although 3'UTR structure can influence translation, the main pathway of ribosome recycling does not depend on scanning-like movement through the 3'UTR. Changes in termination kinetics or disruption of the Pab1-eIF4F interaction do not affect recycling, yet the maintenance of normal in vivo mRNP structure is important to this process. Using bicistronic ACT1-LUC constructs, elongating yeast ribosomes were found to maintain the competence to (re)initiate over only short distances. Thus, as the first ORF to be translated is progressively truncated, reinitiation downstream of an uORF of 105nt is found to be just detectable, and increases markedly in efficiency as uORF length is reduced to 15nt. Experiments using a strain mutated in the Cca1 nucleotidyltransferase suggest that the uORF length-dependence of changes in reinitiation competence is affected by peptide elongation kinetics, but that ORF length per se may also be relevant.
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Affiliation(s)
- Lukas Rajkowitsch
- Posttranscriptional Control Group, Department of Biomolecular Sciences, UMIST, P.O. Box 88, M60 1QD, Manchester, UK
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37
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Choi YH, Hagedorn CH. Purifying mRNAs with a high-affinity eIF4E mutant identifies the short 3' poly(A) end phenotype. Proc Natl Acad Sci U S A 2003; 100:7033-8. [PMID: 12777618 PMCID: PMC165825 DOI: 10.1073/pnas.1232347100] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2003] [Indexed: 11/18/2022] Open
Abstract
The use of DNA microarrays has revolutionized the manner in which mRNA populations are analyzed. One limitation of the current technology is that mRNAs are often purified on the basis of their 3' poly(A) ends, which can be extremely short or absent in some mRNAs. To circumvent this limitation, we have developed a procedure for the purification of eukaryotic mRNAs using a mutant version of the mRNA 5' cap-binding protein (eIF4E) with increased affinity for the m7GTP moiety of the cap. By using this procedure, we have compared the populations of mammalian mRNAs purified by oligo(dT) and 5' cap selection with oligonucleotide microarrays. This analysis has identified a subpopulation of mRNAs that are present with short 3' poly(A) ends at steady state and are missed or underrepresented after purification by oligo(dT). These mRNAs may respond to specific posttranscriptional control mechanisms such as cytoplasmic polyadenylation.
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Affiliation(s)
- Youkyung Hwang Choi
- Department of Medicine, Genetics Program, Winship Cancer Institute, Emory University School of Medicine, Atlanta, GA 30322, USA
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38
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Nekrasov MP, Ivshina MP, Chernov KG, Kovrigina EA, Evdokimova VM, Thomas AAM, Hershey JWB, Ovchinnikov LP. The mRNA-binding protein YB-1 (p50) prevents association of the eukaryotic initiation factor eIF4G with mRNA and inhibits protein synthesis at the initiation stage. J Biol Chem 2003; 278:13936-43. [PMID: 12582179 DOI: 10.1074/jbc.m209145200] [Citation(s) in RCA: 108] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The cytoplasmic messenger ribonucleoprotein particles of mammalian somatic cells contain the protein YB-1, also called p50, as a major core component. YB-1 is multifunctional and involved in regulation of mRNA transcription and translation. Our previous studies demonstrated that YB-1 stimulates initiation of translation in vitro at a low YB-1/mRNA ratio, whereas an increase of YB-1 bound to mRNA resulted in inhibition of protein synthesis in vitro and in vivo. Here we show that YB-1-mediated translation inhibition in a rabbit reticulocyte cell-free system is followed by a decay of polysomes, which is not a result of mRNA degradation or its functional inactivation. The inhibition does not change the ribosome transit time, and therefore, it affects neither elongation nor termination of polypeptide chains and only occurs at the stage of initiation. YB-1 induces accumulation of mRNA in the form of free messenger ribonucleoprotein particles, i.e. it blocks mRNA association with the small ribosomal subunit. The accumulation is accompanied by eukaryotic initiation factor eIF4G dissociation from mRNA. The C-terminal domain of YB-1 is responsible for inhibition of translation as well as the disruption of mRNA interaction with eIF4G.
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Affiliation(s)
- Maxim P Nekrasov
- Institute of Protein Research, Russian Academy of Sciences, Pushchino, Moscow Region, 142290 Russian Federation, Russia
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