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Lee JS, Dan T, Zhang H, Cheng Y, Rehfeld F, Brugarolas J, Mendell JT. An ultraconserved snoRNA-like element in long noncoding RNA CRNDE promotes ribosome biogenesis and cell proliferation. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.07.23.604857. [PMID: 39091767 PMCID: PMC11291168 DOI: 10.1101/2024.07.23.604857] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/04/2024]
Abstract
Cancer cells frequently upregulate ribosome production to support tumorigenesis. While small nucleolar RNAs (snoRNAs) are critical for ribosome biogenesis, the roles of other classes of noncoding RNAs in this process remain largely unknown. Here we performed CRISPRi screens to identify essential long noncoding RNAs (lncRNAs) in renal cell carcinoma (RCC) cells. This revealed that an alternatively-spliced isoform of lncRNA Colorectal Neoplasia Differentially Expressed containing an ultraconserved element (UCE), referred to as CRNDE UCE, is required for RCC cell proliferation. CRNDE UCE localizes to the nucleolus and promotes 60S ribosomal subunit biogenesis. The UCE of CRNDE functions as an unprocessed C/D box snoRNA that directly interacts with ribosomal RNA precursors. This facilitates delivery of eIF6, a key 60S biogenesis factor, which binds to CRNDE UCE through a sequence element adjacent to the UCE. These findings highlight the functional versatility of snoRNA sequences and expand the known mechanisms through which noncoding RNAs orchestrate ribosome biogenesis.
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Affiliation(s)
- Jong-Sun Lee
- Department of Molecular Biology, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Tu Dan
- Department of Radiation Oncology, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - He Zhang
- Quantitative Biomedical Research Center, Peter O’Donnell Jr. School of Public Health, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Yujing Cheng
- Department of Molecular Biology, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Frederick Rehfeld
- Department of Molecular Biology, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - James Brugarolas
- Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
- Kidney Cancer Program, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
- Harold C. Simmons Comprehensive Cancer Center, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Joshua T. Mendell
- Department of Molecular Biology, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
- Harold C. Simmons Comprehensive Cancer Center, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
- Hamon Center for Regenerative Science and Medicine, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
- Howard Hughes Medical Institute, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
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2
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Li C, Wang Y, Ge R, Zhang L, Du H, Zhang J, Li B, Chen K. Eukaryotic initiation factor 6 modulates the metamorphosis and reproduction of Tribolium castaneum. INSECT MOLECULAR BIOLOGY 2023; 32:106-117. [PMID: 36366777 DOI: 10.1111/imb.12817] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/28/2022] [Accepted: 11/08/2022] [Indexed: 06/16/2023]
Abstract
Eukaryotic initiation factor 6 (eIF6) is necessary for ribosome biogenesis and translation, but eIF6 has been poorly elucidated in insects. Phylogenetic analysis demonstrated that eIF6 originated from one ancestral gene among animals and exhibited specific duplication in Tribolium, yielding three homologues in Tribolium castaneum, eIF6, eIF6-like 1 (eIF6l1), and eIF6-like 2 (eIF6l2). It was found that eIF6 was highly expressed in the embryonic and early adult stages, eIF6l1 had peak expression at the adult stage, and eIF6l2 showed peak expression in late adults of T. castaneum. Tissue-specific analyses in late-stage larvae demonstrated that eIF6 was abundantly expressed in all tissues, while eIF6l1 and eIF6l2 had the highest expression in the gut and the lowest expression in the head of T. castaneum. Knockdown of eIF6 caused precocious pupation and eclosion, impaired ovary and testis development and completely repressed egg production. The expression levels of vitellogenin 1 (Vg1), Vg2 and Vg receptor (VgR) significantly decreased in ds-eIF6 females 5 days post-adult emergence. Silencing eIF6 activated ecdysteroid biosynthesis and juvenile hormone degradation but reduced the activity of insulin signalling in T. castaneum, which might mediate its roles in metamorphosis, reproduction and gene expression regulation. However, silence of eIF6l1 or eIF6l2 had no effects on metamorphosis and reproduction in T. castaneum. This study provides comprehensive information for eIF6 evolution and function in the insect.
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Affiliation(s)
- Chengjun Li
- School of Life Sciences, Jiangsu University, Zhenjiang, China
| | - Youwei Wang
- School of Life Sciences, Jiangsu University, Zhenjiang, China
| | - Runting Ge
- School of Life Sciences, Jiangsu University, Zhenjiang, China
| | - Ling Zhang
- School of Life Sciences, Jiangsu University, Zhenjiang, China
| | - Huanyu Du
- School of Life Sciences, Jiangsu University, Zhenjiang, China
| | - Jiangyan Zhang
- School of Life Sciences, Jiangsu University, Zhenjiang, China
| | - Bin Li
- Jiangsu Key Laboratory for Biodiversity and Biotechnology, College of Life Sciences, Nanjing Normal University, Nanjing, China
| | - Keping Chen
- School of Life Sciences, Jiangsu University, Zhenjiang, China
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3
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Keen AN, Payne LA, Mehta V, Rice A, Simpson LJ, Pang KL, del Rio Hernandez A, Reader JS, Tzima E. Eukaryotic initiation factor 6 regulates mechanical responses in endothelial cells. J Cell Biol 2022; 221:e202005213. [PMID: 35024764 PMCID: PMC8763864 DOI: 10.1083/jcb.202005213] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2020] [Revised: 10/11/2021] [Accepted: 12/08/2021] [Indexed: 12/22/2022] Open
Abstract
The repertoire of extratranslational functions of components of the protein synthesis apparatus is expanding to include control of key cell signaling networks. However, very little is known about noncanonical functions of members of the protein synthesis machinery in regulating cellular mechanics. We demonstrate that the eukaryotic initiation factor 6 (eIF6) modulates cellular mechanobiology. eIF6-depleted endothelial cells, under basal conditions, exhibit unchanged nascent protein synthesis, polysome profiles, and cytoskeleton protein expression, with minimal effects on ribosomal biogenesis. In contrast, using traction force and atomic force microscopy, we show that loss of eIF6 leads to reduced stiffness and force generation accompanied by cytoskeletal and focal adhesion defects. Mechanistically, we show that eIF6 is required for the correct spatial mechanoactivation of ERK1/2 via stabilization of an eIF6-RACK1-ERK1/2-FAK mechanocomplex, which is necessary for force-induced remodeling. These results reveal an extratranslational function for eIF6 and a novel paradigm for how mechanotransduction, the cellular cytoskeleton, and protein translation constituents are linked.
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Affiliation(s)
- Adam N. Keen
- Radcliffe Department of Medicine, University of Oxford, Oxford, UK
- Wellcome Centre for Human Genetics, University of Oxford, Oxford, UK
| | - Luke A. Payne
- Radcliffe Department of Medicine, University of Oxford, Oxford, UK
- Wellcome Centre for Human Genetics, University of Oxford, Oxford, UK
| | - Vedanta Mehta
- Radcliffe Department of Medicine, University of Oxford, Oxford, UK
- Wellcome Centre for Human Genetics, University of Oxford, Oxford, UK
| | - Alistair Rice
- Cellular and Molecular Biomechanics Laboratory, Department of Bioengineering, Imperial College London, London, UK
| | - Lisa J. Simpson
- Radcliffe Department of Medicine, University of Oxford, Oxford, UK
- Wellcome Centre for Human Genetics, University of Oxford, Oxford, UK
| | - Kar Lai Pang
- Radcliffe Department of Medicine, University of Oxford, Oxford, UK
- Wellcome Centre for Human Genetics, University of Oxford, Oxford, UK
| | - Armando del Rio Hernandez
- Cellular and Molecular Biomechanics Laboratory, Department of Bioengineering, Imperial College London, London, UK
| | - John S. Reader
- Radcliffe Department of Medicine, University of Oxford, Oxford, UK
- Wellcome Centre for Human Genetics, University of Oxford, Oxford, UK
| | - Ellie Tzima
- Radcliffe Department of Medicine, University of Oxford, Oxford, UK
- Wellcome Centre for Human Genetics, University of Oxford, Oxford, UK
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4
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Schatz C, Sprung S, Schartinger V, Codina-Martínez H, Lechner M, Hermsen M, Haybaeck J. Dysregulation of Translation Factors EIF2S1, EIF5A and EIF6 in Intestinal-Type Adenocarcinoma (ITAC). Cancers (Basel) 2021; 13:cancers13225649. [PMID: 34830804 PMCID: PMC8616251 DOI: 10.3390/cancers13225649] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2021] [Revised: 11/05/2021] [Accepted: 11/09/2021] [Indexed: 11/16/2022] Open
Abstract
Intestinal-type adenocarcinoma (ITAC) is a rare cancer of the nasal cavity and paranasal sinuses that occurs sporadically or secondary to exposure to occupational hazards, such as wood dust and leather. Eukaryotic translation initiation factors have been described as promising targets for novel cancer treatments in many cancers, but hardly anything is known about these factors in ITAC. Here we performed in silico analyses, evaluated the protein levels of EIF2S1, EIF5A and EIF6 in tumour samples and non-neoplastic tissue controls obtained from 145 patients, and correlated these results with clinical outcome data, including tumour site, stage, adjuvant radiotherapy and survival. In silico analyses revealed significant upregulation of the translation factors EIF6 (ITGB4BP), EIF5, EIF2S1 and EIF2S2 (p < 0.05) with a higher arithmetic mean expression in ITAC compared to non-neoplastic tissue (NNT). Immunohistochemical analyses using antibodies against EIF2S1 and EIF6 confirmed a significantly different expression at the protein level (p < 0.05). In conclusion, this work identifies the eukaryotic translation initiation factors EIF2S1 and EIF6 to be significantly upregulated in ITAC. As these factors have been described as promising therapeutic targets in other cancers, this work identifies candidate therapeutic targets in this rare but often deadly cancer.
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Affiliation(s)
- Christoph Schatz
- Institute of Pathology, Neuropathology and Molecular Pathology, Medical University of Innsbruck, 6020 Innsbruck, Austria; (C.S.); (S.S.)
| | - Susanne Sprung
- Institute of Pathology, Neuropathology and Molecular Pathology, Medical University of Innsbruck, 6020 Innsbruck, Austria; (C.S.); (S.S.)
| | - Volker Schartinger
- Institute of Otorhinolaryngology, Medical University of Innsbruck, Anichstrasse 35, 6020 Innsbruck, Austria;
| | - Helena Codina-Martínez
- Department Head and Neck Oncology, Instituto de Investigación Sanitaria del Principado de Asturias, 33011 Oviedo, Spain; (H.C.-M.); (M.H.)
| | - Matt Lechner
- UCL Cancer Institute, University College London, London WC1E 6AG, UK;
- Barts Health NHS Trust, London E1 1BB, UK
| | - Mario Hermsen
- Department Head and Neck Oncology, Instituto de Investigación Sanitaria del Principado de Asturias, 33011 Oviedo, Spain; (H.C.-M.); (M.H.)
| | - Johannes Haybaeck
- Institute of Pathology, Neuropathology and Molecular Pathology, Medical University of Innsbruck, 6020 Innsbruck, Austria; (C.S.); (S.S.)
- Diagnostic & Research Center for Molecular BioMedicine, Institute of Pathology, Medical University of Graz, 8036 Graz, Austria
- Correspondence:
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5
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Sun L, Liu S, Wang X, Zheng X, Chen Y, Shen H. eIF6 promotes the malignant progression of human hepatocellular carcinoma via the mTOR signaling pathway. J Transl Med 2021; 19:216. [PMID: 34016142 PMCID: PMC8139032 DOI: 10.1186/s12967-021-02877-4] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2020] [Accepted: 05/05/2021] [Indexed: 12/24/2022] Open
Abstract
BACKGROUND Eukaryotic translation initiation factor 6 (eIF6) has a crucial function in the maturation of 60S ribosomal subunits, and it controls the initiation of protein translation. Although emerging studies indicate that eIF6 is aberrantly expressed in various types of cancers, the functions and underlying molecular mechanisms of eIF6 in the pathological progression of hepatocellular carcinoma (HCC) remain unclear. This study aimed to evaluate the potential diagnostic and prognostic value of eIF6 in patients with HCC. METHODS HCC samples enrolled from The Cancer Genome Atlas (TCGA), Gene Expression Omnibus (GEO) and our cohort were used to explore the role and mechanism of eIF6 in HCC. The diagnostic power of eIF6 was verified by receiver operating characteristic curve (ROC) analysis and its prognostic value was assessed by Kaplan-Meier analysis, and then related biological functions of eIF6 were determined in vitro and in vivo cancer models. In addition, potential molecular mechanism of eIF6 in HCC was unveiled by the gene set enrichment analysis and western blot assay. RESULTS We demonstrated that eIF6 expression was markedly increased in HCC, and elevated eIF6 expression correlated with pathological progression of HCC. Besides, eIF6 served as not only a new diagnostic biomarker but also an independent risk factor for OS in HCC patients. Functional studies indicated that the deletion of eIF6 displayed tumor-suppressor activity in HCC cells. Furthermore, we found that eIF6 could activate the mTOR-related signaling pathway and regulate the expression level of its target genes, such as CCND1, CDK4, CDK6, MYC, CASP3 and CTNNBL1, and these activities promoted proliferation and invasion of HCC cells. CONCLUSIONS The findings of this study provided a novel basis for understanding the potential role of eIF6 in promoting tumor growth and invasion, and exploited a promising strategy for improving diagnosis and prognosis of HCC.
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Affiliation(s)
- Liping Sun
- Department of Pathology, School of Basic Medical Sciences, Southern Medical University, Guangzhou, China
| | - Shuguang Liu
- Department of Pathology, The Eighth Affiliated Hospital, Sun Yat-Sen University, Shenzhen, China
| | - Xiaopai Wang
- Department of Pathology, School of Medicine, Guangzhou First People's Hospital, South China University of Technology, Guangzhou, China
| | - Xuefeng Zheng
- Department of Anatomy, Neuroscience Laboratory for Cognitive and Developmental Disorders, Medical College of Jinan University, Guangzhou, China
| | - Ya Chen
- Department of Pathology, School of Basic Medical Sciences, Southern Medical University, Guangzhou, China
| | - Hong Shen
- Department of Pathology, School of Basic Medical Sciences, Southern Medical University, Guangzhou, China. .,Department of Pathology, Nanfang Hospital, Southern Medical University, Guangzhou, China.
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6
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Alboushi L, Hackett AP, Naeli P, Bakhti M, Jafarnejad SM. Multifaceted control of mRNA translation machinery in cancer. Cell Signal 2021; 84:110037. [PMID: 33975011 DOI: 10.1016/j.cellsig.2021.110037] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2020] [Accepted: 05/06/2021] [Indexed: 12/15/2022]
Abstract
The mRNA translation machinery is tightly regulated through several, at times overlapping, mechanisms that modulate its efficiency and accuracy. Due to their fast rate of growth and metabolism, cancer cells require an excessive amount of mRNA translation and protein synthesis. However, unfavorable conditions, such as hypoxia, amino acid starvation, and oxidative stress, which are abundant in cancer, as well as many anti-cancer treatments inhibit mRNA translation. Cancer cells adapt to the various internal and environmental stresses by employing specialised transcript-specific translation to survive and gain a proliferative advantage. We will highlight the major signaling pathways and mechanisms of translation that regulate the global or mRNA-specific translation in response to the intra- or extra-cellular signals and stresses that are key components in the process of tumourigenesis.
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Affiliation(s)
- Lilas Alboushi
- Patrick G. Johnston Centre for Cancer Research, Queen's University Belfast, Belfast, UK
| | - Angela P Hackett
- Patrick G. Johnston Centre for Cancer Research, Queen's University Belfast, Belfast, UK
| | - Parisa Naeli
- Patrick G. Johnston Centre for Cancer Research, Queen's University Belfast, Belfast, UK
| | - Mostafa Bakhti
- Institute of Diabetes and Regeneration Research, Helmholtz Zentrum München, 85764 Neuherberg, Germany
| | - Seyed Mehdi Jafarnejad
- Patrick G. Johnston Centre for Cancer Research, Queen's University Belfast, Belfast, UK.
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7
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Lo Gullo G, De Santis ML, Paiardini A, Rosignoli S, Romagnoli A, La Teana A, Londei P, Benelli D. The Archaeal Elongation Factor EF-2 Induces the Release of aIF6 From 50S Ribosomal Subunit. Front Microbiol 2021; 12:631297. [PMID: 33841359 PMCID: PMC8024482 DOI: 10.3389/fmicb.2021.631297] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2020] [Accepted: 02/11/2021] [Indexed: 11/13/2022] Open
Abstract
The translation factor IF6 is a protein of about 25 kDa shared by the Archaea and the Eukarya but absent in Bacteria. It acts as a ribosome anti-association factor that binds to the large subunit preventing the joining to the small subunit. It must be released from the large ribosomal subunit to permit its entry to the translation cycle. In Eukarya, this process occurs by the coordinated action of the GTPase Efl1 and the docking protein SBDS. Archaea do not possess a homolog of the former factor while they have a homolog of SBDS. In the past, we have determined the function and ribosomal localization of the archaeal (Sulfolobus solfataricus) IF6 homolog (aIF6) highlighting its similarity to the eukaryotic counterpart. Here, we analyzed the mechanism of aIF6 release from the large ribosomal subunit. We found that, similarly to the Eukarya, the detachment of aIF6 from the 50S subunit requires a GTPase activity which involves the archaeal elongation factor 2 (aEF-2). However, the release of aIF6 from the 50S subunits does not require the archaeal homolog of SBDS, being on the contrary inhibited by its presence. Molecular modeling, using published structural data of closely related homologous proteins, elucidated the mechanistic interplay between the aIF6, aSBDS, and aEF2 on the ribosome surface. The results suggest that a conformational rearrangement of aEF2, upon GTP hydrolysis, promotes aIF6 ejection. On the other hand, aSBDS and aEF2 share the same binding site, whose occupation by SBDS prevents aEF2 binding, thereby inhibiting aIF6 release.
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Affiliation(s)
- Giada Lo Gullo
- Department of Cellular Biotechnologies and Haematology, Sapienza University of Rome, Rome, Italy
| | | | | | - Serena Rosignoli
- Department of Biochemical Sciences, Sapienza University of Rome, Rome, Italy
| | - Alice Romagnoli
- Department of Life and Environmental Science, New York-Marche Structural Biology Center (NY-MaSBiC), Polytechnic University of Marche, Ancona, Italy
| | - Anna La Teana
- Department of Life and Environmental Science, New York-Marche Structural Biology Center (NY-MaSBiC), Polytechnic University of Marche, Ancona, Italy
| | - Paola Londei
- Department of Molecular Medicine, Sapienza University of Rome, Rome, Italy
| | - Dario Benelli
- Department of Molecular Medicine, Sapienza University of Rome, Rome, Italy
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8
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Mechanism of ribosome shutdown by RsfS in Staphylococcus aureus revealed by integrative structural biology approach. Nat Commun 2020; 11:1656. [PMID: 32245971 PMCID: PMC7125091 DOI: 10.1038/s41467-020-15517-0] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2019] [Accepted: 03/05/2020] [Indexed: 11/08/2022] Open
Abstract
For the sake of energy preservation, bacteria, upon transition to stationary phase, tone down their protein synthesis. This process is favored by the reversible binding of small stress-induced proteins to the ribosome to prevent unnecessary translation. One example is the conserved bacterial ribosome silencing factor (RsfS) that binds to uL14 protein onto the large ribosomal subunit and prevents its association with the small subunit. Here we describe the binding mode of Staphylococcus aureus RsfS to the large ribosomal subunit and present a 3.2 Å resolution cryo-EM reconstruction of the 50S-RsfS complex together with the crystal structure of uL14-RsfS complex solved at 2.3 Å resolution. The understanding of the detailed landscape of RsfS-uL14 interactions within the ribosome shed light on the mechanism of ribosome shutdown in the human pathogen S. aureus and might deliver a novel target for pharmacological drug development and treatment of bacterial infections.
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Abstract
On January 21, 2017, I received an E-mail from Herb Tabor that I had been simultaneously hoping for and dreading for several years: an invitation to write a "Reflections" article for the Journal of Biological Chemistry On the one hand, I was honored to receive an invitation from Herb, a man I have admired for over 40 years, known for 24 years, and worked with as a member of the Editorial Board and Associate Editor of the Journal of Biological Chemistry for 17 years. On the other hand, the invitation marked the waning of my career as an academic scientist. With these conflicting emotions, I wrote this article with the goals of recording my career history and recognizing the many mentors, trainees, and colleagues who have contributed to it and, perhaps with pretension, with the desire that students who are beginning a career in research will find inspiration in the path I have taken and appreciate the importance of luck.
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Affiliation(s)
- David W Russell
- From the Department of Molecular Genetics, University of Texas Southwestern Medical Center, Dallas, Texas 75390-9046
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10
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Zhou Y, Musalgaonkar S, Johnson AW, Taylor DW. Tightly-orchestrated rearrangements govern catalytic center assembly of the ribosome. Nat Commun 2019; 10:958. [PMID: 30814529 PMCID: PMC6393466 DOI: 10.1038/s41467-019-08880-0] [Citation(s) in RCA: 41] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2018] [Accepted: 02/01/2019] [Indexed: 11/24/2022] Open
Abstract
The catalytic activity of the ribosome is mediated by RNA, yet proteins are essential for the function of the peptidyl transferase center (PTC). In eukaryotes, final assembly of the PTC occurs in the cytoplasm by insertion of the ribosomal protein Rpl10 (uL16). We determine structures of six intermediates in late nuclear and cytoplasmic maturation of the large subunit that reveal a tightly-choreographed sequence of protein and RNA rearrangements controlling the insertion of Rpl10. We also determine the structure of the biogenesis factor Yvh1 and show how it promotes assembly of the P stalk, a critical element for recruitment of GTPases that drive translation. Together, our structures provide a blueprint for final assembly of a functional ribosome. In eukaryotes, ribosome biogenesis culminates in the cytoplasm with the maturation of the peptidyl transfer center (PTC). Here the authors describe several structures of intermediates in late nuclear and cytoplasmic maturation of the large ribosomal subunit that reveal the tightly-choreographed sequence of protein and RNA rearrangements that lead to the completion of the PTC.
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Affiliation(s)
- Yi Zhou
- Department of Molecular Biosciences, University of Texas at Austin, Austin, TX, 78712, USA
| | | | - Arlen W Johnson
- Department of Molecular Biosciences, University of Texas at Austin, Austin, TX, 78712, USA. .,Institute for Cellular and Molecular Biology, University of Texas at Austin, Austin, TX, 78712, USA.
| | - David W Taylor
- Department of Molecular Biosciences, University of Texas at Austin, Austin, TX, 78712, USA.,Institute for Cellular and Molecular Biology, University of Texas at Austin, Austin, TX, 78712, USA.,Center for Systems and Synthetic Biology, University of Texas at Austin, Austin, TX, 78712, USA.,LIVESTRONG Cancer Institutes, Dell Medical School, Austin, TX, 78712, USA
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11
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Wang K, Wang C, Zhu CJ, Li G, Li Y, Feng YB, Ruan JJ, Zhu F, Meng Y, Zhou RP, Chen FH. 4-Amino-2-Trifluoromethyl-Phenyl Retinate induced leukemia cell differentiation by decreasing eIF6. Biochem Biophys Res Commun 2018; 503:2033-2039. [PMID: 30078681 DOI: 10.1016/j.bbrc.2018.07.153] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2018] [Accepted: 07/30/2018] [Indexed: 11/30/2022]
Abstract
4-Amino-2-Trifluoromethyl-Phenyl Retinate (ATPR), an all-trans retinoic acid (ATRA) derivative, possesses the ability to relief several carcinoma. Here, we explored the potential molecular mechanism of eukaryotic translation initiation factor 6 (eIF6) in ATPR-induced leukemia cell differentiation. Our research showed that ATPR could inhibit cell proliferation and promote cell differentiation in several leukemia cell lines. Besides, ATPR remarkably reduced the expression of eIF6 in vitro. Interestingly, the reduction of eIF6 contributed to restraining proliferation of K562 cells by inhibiting CyclinD1, C-myc and blocking cell cycle, as well as promoting differentiation of K562 cells by increasing the expression of C/EBPε, cell surface antigen CD11b and inducing renal-shrinkage of nuclear. Furthermore, the over-expression of eIF6 restrained the effects of ATPR on cell proliferation and maturation in K562 cells. In Addition, Notch1/CBF-1 signal activated by Chrysin could increase expression of eIF6 and restrain the differentiation in ATPR-induced K562 cells. Taken together, all above results indicated that ATPR induced differentiation of leukemia cells by decreasing eIF6 through Notch1/CBF-1 signal, which might exert an innovative treatment for leukemia.
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Affiliation(s)
- Ke Wang
- Anhui Province Key Laboratory of Major Autoimmune Diseases, Anhui Institute of Innovative Drugs, School of Pharmacy, Anhui Medical University, China; The Key laboratory of Anti-inflammatory and Immune medicines, Ministry of Education, China
| | - Cong Wang
- Anhui Province Key Laboratory of Major Autoimmune Diseases, Anhui Institute of Innovative Drugs, School of Pharmacy, Anhui Medical University, China; The Key laboratory of Anti-inflammatory and Immune medicines, Ministry of Education, China
| | - Chuan-Jun Zhu
- Anhui Province Key Laboratory of Major Autoimmune Diseases, Anhui Institute of Innovative Drugs, School of Pharmacy, Anhui Medical University, China; The Key laboratory of Anti-inflammatory and Immune medicines, Ministry of Education, China
| | - Ge Li
- Anhui Province Key Laboratory of Major Autoimmune Diseases, Anhui Institute of Innovative Drugs, School of Pharmacy, Anhui Medical University, China; The Key laboratory of Anti-inflammatory and Immune medicines, Ministry of Education, China
| | - Yue Li
- Anhui Province Key Laboratory of Major Autoimmune Diseases, Anhui Institute of Innovative Drugs, School of Pharmacy, Anhui Medical University, China; The Key laboratory of Anti-inflammatory and Immune medicines, Ministry of Education, China
| | - Yu-Bin Feng
- Anhui Province Key Laboratory of Major Autoimmune Diseases, Anhui Institute of Innovative Drugs, School of Pharmacy, Anhui Medical University, China; The Key laboratory of Anti-inflammatory and Immune medicines, Ministry of Education, China
| | - Jing-Jing Ruan
- Anhui Province Key Laboratory of Major Autoimmune Diseases, Anhui Institute of Innovative Drugs, School of Pharmacy, Anhui Medical University, China; The Key laboratory of Anti-inflammatory and Immune medicines, Ministry of Education, China
| | - Fei Zhu
- Anhui Province Key Laboratory of Major Autoimmune Diseases, Anhui Institute of Innovative Drugs, School of Pharmacy, Anhui Medical University, China; The Key laboratory of Anti-inflammatory and Immune medicines, Ministry of Education, China
| | - Yao Meng
- Anhui Province Key Laboratory of Major Autoimmune Diseases, Anhui Institute of Innovative Drugs, School of Pharmacy, Anhui Medical University, China; The Key laboratory of Anti-inflammatory and Immune medicines, Ministry of Education, China
| | - Ren-Peng Zhou
- Anhui Province Key Laboratory of Major Autoimmune Diseases, Anhui Institute of Innovative Drugs, School of Pharmacy, Anhui Medical University, China; The Key laboratory of Anti-inflammatory and Immune medicines, Ministry of Education, China
| | - Fei-Hu Chen
- Anhui Province Key Laboratory of Major Autoimmune Diseases, Anhui Institute of Innovative Drugs, School of Pharmacy, Anhui Medical University, China; The Key laboratory of Anti-inflammatory and Immune medicines, Ministry of Education, China.
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12
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Gantenbein N, Bernhart E, Anders I, Golob-Schwarzl N, Krassnig S, Wodlej C, Brcic L, Lindenmann J, Fink-Neuboeck N, Gollowitsch F, Stacher-Priehse E, Asslaber M, Gogg-Kamerer M, Rolff J, Hoffmann J, Silvestri A, Regenbrecht C, Reinhard C, Pehserl AM, Pichler M, Sokolova O, Naumann M, Mitterer V, Pertschy B, Bergler H, Popper H, Sattler W, Haybaeck J. Influence of eukaryotic translation initiation factor 6 on non-small cell lung cancer development and progression. Eur J Cancer 2018; 101:165-180. [PMID: 30077122 DOI: 10.1016/j.ejca.2018.07.001] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2018] [Revised: 06/22/2018] [Accepted: 07/02/2018] [Indexed: 12/12/2022]
Abstract
Non-small cell lung cancer (NSCLC) is the leading cause of cancer-related death worldwide. Dysregulation of protein synthesis plays a major role in carcinogenesis, a process regulated at multiple levels, including translation of mRNA into proteins. Ribosome assembly requires correct association of ribosome subunits, which is ensured by eukaryotic translation initiation factors (eIFs). eIFs have become targets in cancer therapy studies, and promising data on eIF6 in various cancer entities have been reported. Therefore, we hypothesised that eIF6 represents a crossroad for pulmonary carcinogenesis. High levels of eIF6 are associated with shorter patient overall survival in adenocarcinoma (ADC), but not in squamous cell carcinoma (SQC) of the lung. We demonstrate significantly higher protein expression of eIF6 in ADC and SQC than in healthy lung tissue based on immunohistochemical data from tissue microarrays (TMAs) and on fresh frozen lung tissue. Depletion of eIF6 in ADC and SQC lung cancer cell lines inhibited cell proliferation and induced apoptosis. Knockdown of eIF6 led to pre-rRNA processing and ribosomal 60S maturation defects. Our data indicate that eIF6 is upregulated in NSCLC, suggesting an important contribution of eIF6 to the development and progression of NSCLC and a potential for new treatment strategies against NSCLC.
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Affiliation(s)
- Nadine Gantenbein
- Diagnostic and Research Institute of Pathology, Medical University of Graz, Neue Stiftingtalstrasse 6, 8010 Graz, Austria; Center for Biomarker Research in Medicine, Stiftingtalstrasse 5, 8010 Graz, Austria
| | - Eva Bernhart
- Gottfried Schatz Research Center for Cell Signaling, Metabolism and Aging, Molecular Biology and Biochemistry, Medical University of Graz, Neue Stiftingtalstrasse 6, 8010 Graz, Austria
| | - Ines Anders
- Diagnostic and Research Institute of Pathology, Medical University of Graz, Neue Stiftingtalstrasse 6, 8010 Graz, Austria
| | - Nicole Golob-Schwarzl
- Diagnostic and Research Institute of Pathology, Medical University of Graz, Neue Stiftingtalstrasse 6, 8010 Graz, Austria; Center for Biomarker Research in Medicine, Stiftingtalstrasse 5, 8010 Graz, Austria
| | - Stefanie Krassnig
- Diagnostic and Research Institute of Pathology, Medical University of Graz, Neue Stiftingtalstrasse 6, 8010 Graz, Austria
| | - Christina Wodlej
- Diagnostic and Research Institute of Pathology, Medical University of Graz, Neue Stiftingtalstrasse 6, 8010 Graz, Austria; Center for Biomarker Research in Medicine, Stiftingtalstrasse 5, 8010 Graz, Austria
| | - Luka Brcic
- Diagnostic and Research Institute of Pathology, Medical University of Graz, Neue Stiftingtalstrasse 6, 8010 Graz, Austria
| | - Joerg Lindenmann
- Division of Thoracic and Hyperbaric Surgery, Medical University of Graz, Auenbruggerplatz 29, 8036 Graz, Austria
| | - Nicole Fink-Neuboeck
- Division of Thoracic and Hyperbaric Surgery, Medical University of Graz, Auenbruggerplatz 29, 8036 Graz, Austria
| | - Franz Gollowitsch
- Diagnostic and Research Institute of Pathology, Medical University of Graz, Neue Stiftingtalstrasse 6, 8010 Graz, Austria
| | - Elvira Stacher-Priehse
- Diagnostic and Research Institute of Pathology, Medical University of Graz, Neue Stiftingtalstrasse 6, 8010 Graz, Austria
| | - Martin Asslaber
- Diagnostic and Research Institute of Pathology, Medical University of Graz, Neue Stiftingtalstrasse 6, 8010 Graz, Austria
| | - Margit Gogg-Kamerer
- Diagnostic and Research Institute of Pathology, Medical University of Graz, Neue Stiftingtalstrasse 6, 8010 Graz, Austria
| | - Jana Rolff
- Experimental Pharmacology & Oncology Berlin GmbH-Berlin-Buch, Robert-Rössle-Str. 10, 13125 Berlin-Buch, Germany
| | - Jens Hoffmann
- Experimental Pharmacology & Oncology Berlin GmbH-Berlin-Buch, Robert-Rössle-Str. 10, 13125 Berlin-Buch, Germany
| | - Alessandra Silvestri
- Cpo - Cellular Phenomics & Oncology Berlin-Buch GmbH, Robert-Rössle-Str. 10, 13125 Berlin-Buch, Germany
| | - Christian Regenbrecht
- Cpo - Cellular Phenomics & Oncology Berlin-Buch GmbH, Robert-Rössle-Str. 10, 13125 Berlin-Buch, Germany
| | - Christoph Reinhard
- Eli Lilly & Company, Lilly Corporate Center, 46285 Indiana, Indianapolis, USA
| | - Anna-Maria Pehserl
- Division of Oncology, Medical University of Graz, Auenbruggerplatz 15, 8036 Graz, Austria
| | - Martin Pichler
- Division of Oncology, Medical University of Graz, Auenbruggerplatz 15, 8036 Graz, Austria
| | - Olga Sokolova
- Institute of Experimental Internal Medicine, Otto-von-Guericke-University Magdeburg, Leipziger Str. 44, 39120 Magdeburg, Germany
| | - Michael Naumann
- Institute of Experimental Internal Medicine, Otto-von-Guericke-University Magdeburg, Leipziger Str. 44, 39120 Magdeburg, Germany
| | - Valentin Mitterer
- Institute of Molecular Biosciences, Karl-Franzens-University of Graz, Humboldtstraße 50, 8010 Graz, Austria
| | - Brigitte Pertschy
- Institute of Molecular Biosciences, Karl-Franzens-University of Graz, Humboldtstraße 50, 8010 Graz, Austria
| | - Helmut Bergler
- Institute of Molecular Biosciences, Karl-Franzens-University of Graz, Humboldtstraße 50, 8010 Graz, Austria
| | - Helmut Popper
- Diagnostic and Research Institute of Pathology, Medical University of Graz, Neue Stiftingtalstrasse 6, 8010 Graz, Austria
| | - Wolfgang Sattler
- Gottfried Schatz Research Center for Cell Signaling, Metabolism and Aging, Molecular Biology and Biochemistry, Medical University of Graz, Neue Stiftingtalstrasse 6, 8010 Graz, Austria
| | - Johannes Haybaeck
- Diagnostic and Research Institute of Pathology, Medical University of Graz, Neue Stiftingtalstrasse 6, 8010 Graz, Austria; Center for Biomarker Research in Medicine, Stiftingtalstrasse 5, 8010 Graz, Austria; Department of Pathology, Medical Faculty, Otto-von-Guericke-University Magdeburg, Leipziger Str. 44, 39120 Magdeburg, Germany.
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13
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Gaba A, Ayalew LE, Patel A, Kumar P, Tikoo SK. Bovine adenovirus‐3 protein VIII associates with eukaryotic initiation factor‐6 during infection. Cell Microbiol 2018. [DOI: 10.1111/cmi.12842] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Affiliation(s)
- Amit Gaba
- VIDO‐InterVacUniversity of Saskatchewan Saskatoon Saskatchewan Canada
- Veterinary MicrobiologyUniversity of Saskatchewan Saskatoon Saskatchewan Canada
| | - Lisanework E. Ayalew
- VIDO‐InterVacUniversity of Saskatchewan Saskatoon Saskatchewan Canada
- Veterinary MicrobiologyUniversity of Saskatchewan Saskatoon Saskatchewan Canada
| | - Amrutlal Patel
- VIDO‐InterVacUniversity of Saskatchewan Saskatoon Saskatchewan Canada
- Veterinary MicrobiologyUniversity of Saskatchewan Saskatoon Saskatchewan Canada
| | - Pankaj Kumar
- VIDO‐InterVacUniversity of Saskatchewan Saskatoon Saskatchewan Canada
| | - Suresh K. Tikoo
- VIDO‐InterVacUniversity of Saskatchewan Saskatoon Saskatchewan Canada
- Veterinary MicrobiologyUniversity of Saskatchewan Saskatoon Saskatchewan Canada
- Vaccinology & Immunotherapeutics Program, School of Public HealthUniversity of Saskatchewan Saskatoon Saskatchewan Canada
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14
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Warren AJ. Molecular basis of the human ribosomopathy Shwachman-Diamond syndrome. Adv Biol Regul 2018; 67:109-127. [PMID: 28942353 PMCID: PMC6710477 DOI: 10.1016/j.jbior.2017.09.002] [Citation(s) in RCA: 99] [Impact Index Per Article: 16.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2017] [Accepted: 09/05/2017] [Indexed: 01/05/2023]
Abstract
Mutations that target the ubiquitous process of ribosome assembly paradoxically cause diverse tissue-specific disorders (ribosomopathies) that are often associated with an increased risk of cancer. Ribosomes are the essential macromolecular machines that read the genetic code in all cells in all kingdoms of life. Following pre-assembly in the nucleus, precursors of the large 60S and small 40S ribosomal subunits are exported to the cytoplasm where the final steps in maturation are completed. Here, I review the recent insights into the conserved mechanisms of ribosome assembly that have come from functional characterisation of the genes mutated in human ribosomopathies. In particular, recent advances in cryo-electron microscopy, coupled with genetic, biochemical and prior structural data, have revealed that the SBDS protein that is deficient in the inherited leukaemia predisposition disorder Shwachman-Diamond syndrome couples the final step in cytoplasmic 60S ribosomal subunit maturation to a quality control assessment of the structural and functional integrity of the nascent particle. Thus, study of this fascinating disorder is providing remarkable insights into how the large ribosomal subunit is functionally activated in the cytoplasm to enter the actively translating pool of ribosomes.
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MESH Headings
- Bone Marrow Diseases/metabolism
- Bone Marrow Diseases/pathology
- Cryoelectron Microscopy
- Exocrine Pancreatic Insufficiency/metabolism
- Exocrine Pancreatic Insufficiency/pathology
- Humans
- Lipomatosis/metabolism
- Lipomatosis/pathology
- Mutation
- Proteins/genetics
- Proteins/metabolism
- Ribosome Subunits, Large, Eukaryotic/genetics
- Ribosome Subunits, Large, Eukaryotic/metabolism
- Ribosome Subunits, Large, Eukaryotic/ultrastructure
- Ribosome Subunits, Small, Eukaryotic/genetics
- Ribosome Subunits, Small, Eukaryotic/metabolism
- Ribosome Subunits, Small, Eukaryotic/ultrastructure
- Shwachman-Diamond Syndrome
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Affiliation(s)
- Alan J Warren
- Cambridge Institute for Medical Research, Cambridge, UK; The Department of Haematology, University of Cambridge, Cambridge, UK; Wellcome Trust-Medical Research Council Stem Cell Institute, University of Cambridge, Cambridge, UK.
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15
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Manfrini N, Ricciardi S, Miluzio A, Fedeli M, Scagliola A, Gallo S, Brina D, Adler T, Busch DH, Gailus-Durner V, Fuchs H, Hrabě de Angelis M, Biffo S. High levels of eukaryotic Initiation Factor 6 (eIF6) are required for immune system homeostasis and for steering the glycolytic flux of TCR-stimulated CD4 + T cells in both mice and humans. DEVELOPMENTAL AND COMPARATIVE IMMUNOLOGY 2017; 77:69-76. [PMID: 28743432 DOI: 10.1016/j.dci.2017.07.022] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/14/2017] [Revised: 07/21/2017] [Accepted: 07/21/2017] [Indexed: 06/07/2023]
Abstract
Eukaryotic Initiation Factor 6 (eIF6) is required for 60S ribosomal subunit biogenesis and efficient initiation of translation. Intriguingly, in both mice and humans, endogenous levels of eIF6 are detrimental as they act as tumor and obesity facilitators, raising the question on the evolutionary pressure that maintains high eIF6 levels. Here we show that, in mice and humans, high levels of eIF6 are required for proper immune functions. First, eIF6 heterozygous (het) mice show an increased mortality during viral infection and a reduction of peripheral blood CD4+ Effector Memory T cells. In human CD4+ T cells, eIF6 levels rapidly increase upon T-cell receptor activation and drive the glycolytic switch and the acquisition of effector functions. Importantly, in CD4+ T cells, eIF6 levels control interferon-γ (IFN-γ) secretion without affecting proliferation. In conclusion, the immune system has a high evolutionary pressure for the maintenance of a dynamic and powerful regulation of the translational machinery.
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Affiliation(s)
- Nicola Manfrini
- National Institute of Molecular Genetics "Romeo ed Enrica Invernizzi" - INGM, Via F. Sforza 35, 20122 Milan, Italy.
| | - Sara Ricciardi
- National Institute of Molecular Genetics "Romeo ed Enrica Invernizzi" - INGM, Via F. Sforza 35, 20122 Milan, Italy
| | - Annarita Miluzio
- National Institute of Molecular Genetics "Romeo ed Enrica Invernizzi" - INGM, Via F. Sforza 35, 20122 Milan, Italy
| | - Maya Fedeli
- Experimental Immunology Unit, Division of Immunology, Transplantation and Infectious Diseases, DIBIT, H. San Raffaele Scientific Institute, Via Olgettina 58, 20132 Milan, Italy
| | - Alessandra Scagliola
- National Institute of Molecular Genetics "Romeo ed Enrica Invernizzi" - INGM, Via F. Sforza 35, 20122 Milan, Italy; Department of Biosciences, University of Milan, Via Celoria 26, 20133 Milan, Italy
| | - Simone Gallo
- National Institute of Molecular Genetics "Romeo ed Enrica Invernizzi" - INGM, Via F. Sforza 35, 20122 Milan, Italy; Department of Biosciences, University of Milan, Via Celoria 26, 20133 Milan, Italy
| | - Daniela Brina
- Molecular Oncology Group, Institute of Oncology Research (IOR), Oncology Institute of Southern Switzerland (IOSI), Via Mirasole 22A, Bellinzona, Switzerland
| | - Thure Adler
- German Mouse Clinic, Institute of Experimental Genetics, Helmholtz Zentrum München, German Research Center for Environmental Health, 85764 Neuherberg, Germany
| | - Dirk H Busch
- Institute for Medical Microbiology, Immunology and Hygiene, Technische Universität München, Trogerstrasse 30, 81675 Munich, Germany
| | - Valerie Gailus-Durner
- German Mouse Clinic, Institute of Experimental Genetics, Helmholtz Zentrum München, German Research Center for Environmental Health, 85764 Neuherberg, Germany
| | - Helmut Fuchs
- German Mouse Clinic, Institute of Experimental Genetics, Helmholtz Zentrum München, German Research Center for Environmental Health, 85764 Neuherberg, Germany
| | - Martin Hrabě de Angelis
- German Mouse Clinic, Institute of Experimental Genetics, Helmholtz Zentrum München, German Research Center for Environmental Health, 85764 Neuherberg, Germany; Center of Life and Food Sciences Weihenstephan, Technische Universität München, 85354 Freising, Germany; German Center for Diabetes Research, 85764 Neuherberg, Germany
| | - Stefano Biffo
- National Institute of Molecular Genetics "Romeo ed Enrica Invernizzi" - INGM, Via F. Sforza 35, 20122 Milan, Italy; Department of Biosciences, University of Milan, Via Celoria 26, 20133 Milan, Italy.
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16
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Translational control by mTOR-independent routes: how eIF6 organizes metabolism. Biochem Soc Trans 2017; 44:1667-1673. [PMID: 27913676 DOI: 10.1042/bst20160179] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2016] [Revised: 07/26/2016] [Accepted: 08/05/2016] [Indexed: 11/17/2022]
Abstract
Over the past few years, there has been a growing interest in the interconnection between translation and metabolism. Important oncogenic pathways, like those elicited by c-Myc transcription factor and mTOR kinase, couple the activation of the translational machinery with glycolysis and fatty acid synthesis. Eukaryotic initiation factor 6 (eIF6) is a factor necessary for 60S ribosome maturation. eIF6 acts also as a cytoplasmic translation initiation factor, downstream of growth factor stimulation. eIF6 is up-regulated in several tumor types. Data on mice models have demonstrated that eIF6 cytoplasmic activity is rate-limiting for Myc-induced lymphomagenesis. In spite of this, eIF6 is neither transcriptionally regulated by Myc, nor post-transcriptionally regulated by mTOR. eIF6 stimulates a glycolytic and fatty acid synthesis program necessary for tumor growth. eIF6 increases the translation of transcription factors necessary for lipogenesis, such as CEBP/β, ATF4 and CEBP/δ. Insulin stimulation leads to an increase in translation and fat synthesis blunted by eIF6 deficiency. Paradoxycally, long-term inhibition of eIF6 activity increases insulin sensitivity, suggesting that the translational activation observed upon insulin and growth factors stimulation acts as a feed-forward mechanism regulating lipid synthesis. The data on the role that eIF6 plays in cancer and in insulin sensitivity make it a tempting pharmacological target for cancers and metabolic diseases. We speculate that eIF6 inhibition will be particularly effective especially when mTOR sensitivity to rapamycin is abrogated by RAS mutations.
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17
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Ali MU, Ur Rahman MS, Jia Z, Jiang C. Eukaryotic translation initiation factors and cancer. Tumour Biol 2017; 39:1010428317709805. [PMID: 28653885 DOI: 10.1177/1010428317709805] [Citation(s) in RCA: 45] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Recent technological advancements have shown tremendous mechanistic accomplishments in our understanding of the mechanism of messenger RNA translation in eukaryotic cells. Eukaryotic messenger RNA translation is very complex process that includes four phases (initiation, elongation, termination, and ribosome recycling) and diverse mechanisms involving protein and non-protein molecules. Translation regulation is principally achieved during initiation step of translation, which is organized by multiple eukaryotic translation initiation factors. Eukaryotic translation initiation factor proteins help in stabilizing the formation of the functional ribosome around the start codon and provide regulatory mechanisms in translation initiation. Dysregulated messenger RNA translation is a common feature of tumorigenesis. Various oncogenic and tumor suppressive genes affect/are affected by the translation machinery, making the components of the translation apparatus promising therapeutic targets for the novel anticancer drug. This review provides details on the role of eukaryotic translation initiation factors in messenger RNA translation initiation, their contribution to onset and progression of tumor, and how dysregulated eukaryotic translation initiation factors can be used as a target to treat carcinogenesis.
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Affiliation(s)
- Muhammad Umar Ali
- 1 Clinical Research Center, The Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China
| | - Muhammad Saif Ur Rahman
- 1 Clinical Research Center, The Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China
| | - Zhenyu Jia
- 2 Institute of Occupational Diseases, Zhejiang Academy of Medical Sciences, Hangzhou, China
| | - Cao Jiang
- 1 Clinical Research Center, The Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China
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18
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Eukaryotic initiation factor eIF6 modulates the expression of Kermit 2/XGIPC in IGF- regulated eye development. Dev Biol 2017; 427:148-154. [DOI: 10.1016/j.ydbio.2017.04.017] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2016] [Revised: 12/28/2016] [Accepted: 04/26/2017] [Indexed: 10/19/2022]
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19
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Greber BJ. Mechanistic insight into eukaryotic 60S ribosomal subunit biogenesis by cryo-electron microscopy. RNA (NEW YORK, N.Y.) 2016; 22:1643-1662. [PMID: 27875256 PMCID: PMC5066618 DOI: 10.1261/rna.057927.116] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
Eukaryotic ribosomes, the protein-producing factories of the cell, are composed of four ribosomal RNA molecules and roughly 80 proteins. Their biogenesis is a complex process that involves more than 200 biogenesis factors that facilitate the production, modification, and assembly of ribosomal components and the structural transitions along the maturation pathways of the pre-ribosomal particles. Here, I review recent structural and mechanistic insights into the biogenesis of the large ribosomal subunit that were furthered by cryo-electron microscopy of natively purified pre-60S particles and in vitro reconstituted ribosome assembly factor complexes. Combined with biochemical, genetic, and previous structural data, these structures have provided detailed insights into the assembly and maturation of the central protuberance of the 60S subunit, the network of biogenesis factors near the ribosomal tunnel exit, and the functional activation of the large ribosomal subunit during cytoplasmic maturation.
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Affiliation(s)
- Basil J Greber
- California Institute for Quantitative Biosciences (QB3), University of California, Berkeley, California 94720-3220, USA
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20
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Miluzio A, Oliveto S, Pesce E, Mutti L, Murer B, Grosso S, Ricciardi S, Brina D, Biffo S. Expression and activity of eIF6 trigger malignant pleural mesothelioma growth in vivo. Oncotarget 2016; 6:37471-85. [PMID: 26462016 PMCID: PMC4741942 DOI: 10.18632/oncotarget.5462] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2015] [Accepted: 09/24/2015] [Indexed: 12/13/2022] Open
Abstract
eIF6 is an antiassociation factor that regulates the availability of active 80S. Its activation is driven by the RACK1/PKCβ axis, in a mTORc1 independent manner. We previously described that eIF6 haploinsufficiency causes a striking survival in the Eμ-Myc mouse lymphoma model, with lifespans extended up to 18 months. Here we screen for eIF6 expression in human cancers. We show that Malignant Pleural Mesothelioma tumors (MPM) and a MPM cell line (REN cells) contain high levels of hyperphosphorylated eIF6. Enzastaurin is a PKC beta inhibitor used in clinical trials. We prove that Enzastaurin treatment decreases eIF6 phosphorylation rate, but not eIF6 protein stability. The growth of REN, in vivo, and metastasis are reduced by either Enzastaurin treatment or eIF6 shRNA. Molecular analysis reveals that eIF6 manipulation affects the metabolic status of malignant mesothelioma cells. Less glycolysis and less ATP content are evident in REN cells depleted for eIF6 or treated with Enzastaurin (Anti-Warburg effect). We propose that eIF6 is necessary for malignant mesothelioma growth, in vivo, and can be targeted by kinase inhibitors.
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Affiliation(s)
- Annarita Miluzio
- Molecular Histology and Cell Growth Unit, Istituto Nazionale Genetica Molecolare, "Romeo ed Enrica Invernizzi", Milano, Italy
| | - Stefania Oliveto
- Molecular Histology and Cell Growth Unit, Istituto Nazionale Genetica Molecolare, "Romeo ed Enrica Invernizzi", Milano, Italy.,Dipartimento di Scienze e Innovazione Tecnologica, University of Eastern Piedmont, Alessandria, Italy
| | - Elisa Pesce
- Molecular Histology and Cell Growth Unit, Istituto Nazionale Genetica Molecolare, "Romeo ed Enrica Invernizzi", Milano, Italy
| | - Luciano Mutti
- Biomedicine Institute, The University of Salford, The Crescent, Salford, UK
| | - Bruno Murer
- Hospital Dall'Angelo, Pathology Unit, Venice, Italy
| | | | - Sara Ricciardi
- Molecular Histology and Cell Growth Unit, Istituto Nazionale Genetica Molecolare, "Romeo ed Enrica Invernizzi", Milano, Italy
| | - Daniela Brina
- Molecular Histology and Cell Growth Unit, Istituto Nazionale Genetica Molecolare, "Romeo ed Enrica Invernizzi", Milano, Italy
| | - Stefano Biffo
- Molecular Histology and Cell Growth Unit, Istituto Nazionale Genetica Molecolare, "Romeo ed Enrica Invernizzi", Milano, Italy.,Department of Biosciences, University of Milan, Milan, Italy
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21
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Chakraborty B, Bhakta S, Sengupta J. Disassembly of yeast 80S ribosomes into subunits is a concerted action of ribosome-assisted folding of denatured protein. Biochem Biophys Res Commun 2016; 469:923-9. [DOI: 10.1016/j.bbrc.2015.12.107] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2015] [Accepted: 12/22/2015] [Indexed: 11/27/2022]
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22
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Brina D, Miluzio A, Ricciardi S, Clarke K, Davidsen PK, Viero G, Tebaldi T, Offenhäuser N, Rozman J, Rathkolb B, Neschen S, Klingenspor M, Wolf E, Gailus-Durner V, Fuchs H, Hrabe de Angelis M, Quattrone A, Falciani F, Biffo S. eIF6 coordinates insulin sensitivity and lipid metabolism by coupling translation to transcription. Nat Commun 2015; 6:8261. [PMID: 26383020 PMCID: PMC4595657 DOI: 10.1038/ncomms9261] [Citation(s) in RCA: 64] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2014] [Accepted: 08/04/2015] [Indexed: 02/07/2023] Open
Abstract
Insulin regulates glycaemia, lipogenesis and increases mRNA translation. Cells with reduced eukaryotic initiation factor 6 (eIF6) do not increase translation in response to insulin. The role of insulin-regulated translation is unknown. Here we show that reduction of insulin-regulated translation in mice heterozygous for eIF6 results in normal glycaemia, but less blood cholesterol and triglycerides. eIF6 controls fatty acid synthesis and glycolysis in a cell autonomous fashion. eIF6 acts by exerting translational control of adipogenic transcription factors like C/EBPβ, C/EBPδ and ATF4 that have G/C rich or uORF sequences in their 5' UTR. The outcome of the translational activation by eIF6 is a reshaping of gene expression with increased levels of lipogenic and glycolytic enzymes. Finally, eIF6 levels modulate histone acetylation and amounts of rate-limiting fatty acid synthase (Fasn) mRNA. Since obesity, type 2 diabetes, and cancer require a Fasn-driven lipogenic state, we propose that eIF6 could be a therapeutic target for these diseases.
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Affiliation(s)
- Daniela Brina
- INGM, ‘Romeo ed Enrica Invernizzi', 20122 Milano, Italy
| | | | | | - Kim Clarke
- Centre for Computational Biology and Modeling, Institute of Integrative Biology, University of Liverpool, Liverpool L69 7ZB, UK
| | - Peter K. Davidsen
- Centre for Computational Biology and Modeling, Institute of Integrative Biology, University of Liverpool, Liverpool L69 7ZB, UK
| | - Gabriella Viero
- Institute of Biophysics, 38123 Trento, Italy
- Centre for Integrative Biology, University of Trento, 38123 Trento, Italy
| | - Toma Tebaldi
- Centre for Integrative Biology, University of Trento, 38123 Trento, Italy
| | | | - Jan Rozman
- German Mouse Clinic, Institute of Experimental Genetics, Helmholtz Center Munich, 85764 Neuherberg, Germany
| | - Birgit Rathkolb
- German Mouse Clinic, Institute of Experimental Genetics, Helmholtz Center Munich, 85764 Neuherberg, Germany
- Institute of Molecular Animal Breeding and Biotechnology, Gene Center, Ludwig-Maximilian-University, 81377 Munich, Germany
| | - Susanne Neschen
- German Mouse Clinic, Institute of Experimental Genetics, Helmholtz Center Munich, 85764 Neuherberg, Germany
| | - Martin Klingenspor
- Else Kröner-Fresenius Center, Technische Universität München, 85354 Freising, Germany
| | - Eckhard Wolf
- Institute of Molecular Animal Breeding and Biotechnology, Gene Center, Ludwig-Maximilian-University, 81377 Munich, Germany
| | - Valerie Gailus-Durner
- German Mouse Clinic, Institute of Experimental Genetics, Helmholtz Center Munich, 85764 Neuherberg, Germany
| | - Helmut Fuchs
- German Mouse Clinic, Institute of Experimental Genetics, Helmholtz Center Munich, 85764 Neuherberg, Germany
| | - Martin Hrabe de Angelis
- German Mouse Clinic, Institute of Experimental Genetics, Helmholtz Center Munich, 85764 Neuherberg, Germany
- Center of Life and Food Sciences Weihenstephan, Technische Universität München, 85354 Freising, Germany
- German Center for Diabetes Research, 85764 Neuherberg, Germany
| | | | - Francesco Falciani
- Centre for Computational Biology and Modeling, Institute of Integrative Biology, University of Liverpool, Liverpool L69 7ZB, UK
| | - Stefano Biffo
- INGM, ‘Romeo ed Enrica Invernizzi', 20122 Milano, Italy
- Department of Biosciences, University of Milan, 20133 Milan, Italy
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23
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Brina D, Miluzio A, Ricciardi S, Biffo S. eIF6 anti-association activity is required for ribosome biogenesis, translational control and tumor progression. BIOCHIMICA ET BIOPHYSICA ACTA 2015; 1849:830-5. [PMID: 25252159 DOI: 10.1016/j.bbagrm.2014.09.010] [Citation(s) in RCA: 48] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/04/2014] [Revised: 09/12/2014] [Accepted: 09/14/2014] [Indexed: 12/13/2022]
Abstract
Here we discuss the function of eukaryotic initiation factor 6 (eIF6; Tif6 in yeast). eIF6 binds 60S ribosomal subunits and blocks their joining to 40S. In this context, we propose that eIF6 impedes unproductive 80S formation, namely, the formation of 80S subunits without mRNA. Genetic evidence shows that eIF6 has a dual function: in yeast and mammals, nucleolar eIF6 is necessary for the biogenesis of 60S subunits. In mammals, cytoplasmic eIF6 is required for insulin and growth factor-stimulated translation. In contrast to other translation factors, eIF6 activity is not under mTOR control. The physiological significance of eIF6 impacts on cancer and on inherited Shwachman-Bodian-Diamond syndrome. eIF6 is overexpressed in specific human tumors. In a murine model of lymphomagenesis, eIF6 depletion leads to a striking increase of survival, without adverse effects. Shwachman-Bodian-Diamond syndrome is caused by loss of function of SBDS protein. In yeast, point mutations of Tif6, the yeast homolog of eIF6, rescue the quasi-lethal effect due to the loss of the SBDS homolog, Sdo1. We propose that eIF6 is a node regulator of ribosomal function and predict that prioritizing its pharmacological targeting will be of benefit in cancer and Shwachman-Bodian-Diamond syndrome. This article is part of a Special Issue entitled: Translation and Cancer.
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Affiliation(s)
- Daniela Brina
- INGM, "Romeo ed Enrica Invernizzi," Milano 20122, Italy
| | | | - Sara Ricciardi
- INGM, "Romeo ed Enrica Invernizzi," Milano 20122, Italy; DISIT, Alessandria 15100, Italy
| | - Stefano Biffo
- INGM, "Romeo ed Enrica Invernizzi," Milano 20122, Italy; DISIT, Alessandria 15100, Italy.
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Calligari PA, Calandrini V, Ollivier J, Artero JB, Härtlein M, Johnson M, Kneller GR. Adaptation of Extremophilic Proteins with Temperature and Pressure: Evidence from Initiation Factor 6. J Phys Chem B 2015; 119:7860-73. [PMID: 25996652 DOI: 10.1021/acs.jpcb.5b02034] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
In this work, we study dynamical properties of an extremophilic protein, Initiation Factor 6 (IF6), produced by the archeabacterium Methanocaldococcus jannascii, which thrives close to deep-sea hydrothermal vents where temperatures reach 80 °C and the pressure is up to 750 bar. Molecular dynamics simulations (MD) and quasi-elastic neutron scattering (QENS) measurements give new insights into the dynamical properties of this protein with respect to its eukaryotic and mesophilic homologue. Results obtained by MD are supported by QENS data and are interpreted within the framework of a fractional Brownian dynamics model for the characterization of protein relaxation dynamics. IF6 from M. jannaschii at high temperature and pressure shares similar flexibility with its eukaryotic homologue from S. cerevisieae under ambient conditions. This work shows for the first time, to our knowledge, that the very common pattern of corresponding states for thermophilic protein adaptation can be extended to thermo-barophilic proteins. A detailed analysis of dynamic properties and of local structural fluctuations reveals a complex pattern for "corresponding" structural flexibilities. In particular, in the case of IF6, the latter seems to be strongly related to the entropic contribution given by an additional, C-terminal, 20 amino-acid tail which is evolutionary conserved in all mesophilic IF6s.
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Affiliation(s)
- Paolo A Calligari
- †SISSA, International School for Advanced Studies, via Bonomea 265, 34136 Trieste, Italy
| | - Vania Calandrini
- ‡Computational Biophysics, German Research School for Simulation Sciences, Jülich, Germany
| | - Jacques Ollivier
- §Institut Laue-Langevin, 6 Rue Jules Horowitz, BP 156, 38042 Grenoble Cedex, France
| | - Jean-Baptiste Artero
- §Institut Laue-Langevin, 6 Rue Jules Horowitz, BP 156, 38042 Grenoble Cedex, France
| | - Michael Härtlein
- §Institut Laue-Langevin, 6 Rue Jules Horowitz, BP 156, 38042 Grenoble Cedex, France
| | - Mark Johnson
- §Institut Laue-Langevin, 6 Rue Jules Horowitz, BP 156, 38042 Grenoble Cedex, France
| | - Gerald R Kneller
- ∥Centre de Biophysique Moléculaire, CNRS UPR 4301, Rue Charles Sadron, F-45071 Orléans Cedex 2, France.,⊥Synchrotron Soleil, L'Orme de Merisiers, BP 48, 91192 Gif-sur-Yvette, France.,#Université de Orléans, Chateau de la Source-Av. du Parc Floral, 45067 Orléans, France
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Tsukumo Y, Tsukahara S, Furuno A, Iemura SI, Natsume T, Tomida A. The endoplasmic reticulum-localized protein TBL2 interacts with the 60S ribosomal subunit. Biochem Biophys Res Commun 2015; 462:383-8. [PMID: 25976671 DOI: 10.1016/j.bbrc.2015.04.144] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2015] [Accepted: 04/30/2015] [Indexed: 12/31/2022]
Abstract
Transducin (beta)-like 2 (TBL2) is a poorly characterized protein comprising the N-terminal transmembrane region and the C-terminal WD40 domain. We previously showed that TBL2 is an endoplasmic reticulum (ER)-localized protein that interacts with PKR-like ER-resident kinase (PERK), and under ER stress, it mediates protein expression of activating transcription factor 4 (ATF4). However, further molecular characterization of TBL2 is useful to better understand the function of this molecule. Here, we show that TBL2 associates with the eukaryotic 60S ribosomal subunit but not with the 40S subunit. The association of TBL2 with the 60S subunit was ER stress independent while the TBL2-PERK interaction occurred upon ER stress. Immunoprecipitation analysis using TBL2 deletion mutants revealed that the WD40 domain was essential for the 60S subunit association. These results could provide an important clue to understanding how TBL2 is involved in the expression of specific proteins under ER stress conditions.
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Affiliation(s)
- Yoshinori Tsukumo
- Cancer Chemotherapy Center, Japanese Foundation for Cancer Research, 3-8-31 Ariake, Koto-ku, Tokyo 135-8550, Japan
| | - Satomi Tsukahara
- Cancer Chemotherapy Center, Japanese Foundation for Cancer Research, 3-8-31 Ariake, Koto-ku, Tokyo 135-8550, Japan
| | - Aki Furuno
- Cancer Chemotherapy Center, Japanese Foundation for Cancer Research, 3-8-31 Ariake, Koto-ku, Tokyo 135-8550, Japan
| | - Shun-ichiro Iemura
- Biomedicinal Information Research Center, National Institute of Advanced Industrial Science and Technology, Koto-ku, Tokyo 135-0064, Japan
| | - Tohru Natsume
- Biomedicinal Information Research Center, National Institute of Advanced Industrial Science and Technology, Koto-ku, Tokyo 135-0064, Japan
| | - Akihiro Tomida
- Cancer Chemotherapy Center, Japanese Foundation for Cancer Research, 3-8-31 Ariake, Koto-ku, Tokyo 135-8550, Japan.
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26
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Browning KS, Bailey-Serres J. Mechanism of cytoplasmic mRNA translation. THE ARABIDOPSIS BOOK 2015; 13:e0176. [PMID: 26019692 PMCID: PMC4441251 DOI: 10.1199/tab.0176] [Citation(s) in RCA: 144] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
Protein synthesis is a fundamental process in gene expression that depends upon the abundance and accessibility of the mRNA transcript as well as the activity of many protein and RNA-protein complexes. Here we focus on the intricate mechanics of mRNA translation in the cytoplasm of higher plants. This chapter includes an inventory of the plant translational apparatus and a detailed review of the translational processes of initiation, elongation, and termination. The majority of mechanistic studies of cytoplasmic translation have been carried out in yeast and mammalian systems. The factors and mechanisms of translation are for the most part conserved across eukaryotes; however, some distinctions are known to exist in plants. A comprehensive understanding of the complex translational apparatus and its regulation in plants is warranted, as the modulation of protein production is critical to development, environmental plasticity and biomass yield in diverse ecosystems and agricultural settings.
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Affiliation(s)
- Karen S. Browning
- Department of Molecular Biosciences and Institute for Cell and Molecular Biology, University of Texas at Austin, Austin TX 78712-0165
- Both authors contributed equally to this work
| | - Julia Bailey-Serres
- Department of Botany and Plant Sciences and Center for Plant Cell Biology, University of California, Riverside, CA, 92521 USA
- Both authors contributed equally to this work
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Nerurkar P, Altvater M, Gerhardy S, Schütz S, Fischer U, Weirich C, Panse VG. Eukaryotic Ribosome Assembly and Nuclear Export. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2015; 319:107-40. [DOI: 10.1016/bs.ircmb.2015.07.002] [Citation(s) in RCA: 78] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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Shao S, Hegde RS. Reconstitution of a minimal ribosome-associated ubiquitination pathway with purified factors. Mol Cell 2014; 55:880-890. [PMID: 25132172 PMCID: PMC4175178 DOI: 10.1016/j.molcel.2014.07.006] [Citation(s) in RCA: 86] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2014] [Revised: 06/23/2014] [Accepted: 07/10/2014] [Indexed: 12/31/2022]
Abstract
Ribosomes stalled on aberrant mRNAs engage quality control mechanisms that degrade the partially translated nascent polypeptide. Ubiquitination of the nascent protein is mediated by the E3 ligase Listerin via a mechanism involving ribosome subunit dissociation. Here, we reconstitute ribosome-associated ubiquitination with purified factors to define the minimal components and essential steps in this process. We find that the primary role of the ribosome splitting factors Hbs1, Pelota, and ABCE1 is to permit Listerin access to the nascent chain. Listerin alone can discriminate 60S- from 80S-nascent chain complexes to selectively ubiquitinate the former. Splitting factors can be bypassed by artificially removing the 40S subunit, suggesting that mere steric hindrance impedes Listerin recruitment. This was illustrated by a cryo-EM reconstruction of the 60S-Listerin complex that identifies a binding interface that clashes with the 40S ribosomal subunit. These results reveal the mechanistic logic of the core steps in a ribosome-associated quality control pathway.
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Affiliation(s)
- Sichen Shao
- MRC Laboratory of Molecular Biology, Cambridge, CB2 0QH, UK
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29
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Assembly and nuclear export of pre-ribosomal particles in budding yeast. Chromosoma 2014; 123:327-44. [PMID: 24817020 DOI: 10.1007/s00412-014-0463-z] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2013] [Revised: 03/18/2014] [Accepted: 04/07/2014] [Indexed: 11/27/2022]
Abstract
The ribosome is responsible for the final step of decoding genetic information into proteins. Therefore, correct assembly of ribosomes is a fundamental task for all living cells. In eukaryotes, the construction of the ribosome which begins in the nucleolus requires coordinated efforts of >350 specialized factors that associate with pre-ribosomal particles at distinct stages to perform specific assembly steps. On their way through the nucleus, diverse energy-consuming enzymes are thought to release assembly factors from maturing pre-ribosomal particles after accomplishing their task(s). Subsequently, recruitment of export factors prepares pre-ribosomal particles for transport through nuclear pore complexes. Pre-ribosomes are exported into the cytoplasm in a functionally inactive state, where they undergo final maturation before initiating translation. Accumulating evidence indicates a tight coupling between nuclear export, cytoplasmic maturation, and final proofreading of the ribosome. In this review, we summarize our current understanding of nuclear export of pre-ribosomal subunits and cytoplasmic maturation steps that render pre-ribosomal subunits translation-competent.
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30
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Sulima SO, Gülay SP, Anjos M, Patchett S, Meskauskas A, Johnson AW, Dinman JD. Eukaryotic rpL10 drives ribosomal rotation. Nucleic Acids Res 2013; 42:2049-63. [PMID: 24214990 PMCID: PMC3919601 DOI: 10.1093/nar/gkt1107] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
Ribosomes transit between two conformational states, non-rotated and rotated, through the elongation cycle. Here, we present evidence that an internal loop in the essential yeast ribosomal protein rpL10 is a central controller of this process. Mutations in this loop promote opposing effects on the natural equilibrium between these two extreme conformational states. rRNA chemical modification analyses reveals allosteric interactions involved in coordinating intersubunit rotation originating from rpL10 in the core of the large subunit (LSU) through both subunits, linking all the functional centers of the ribosome. Mutations promoting rotational disequilibria showed catalytic, biochemical and translational fidelity defects. An rpL3 mutation promoting opposing structural and biochemical effects, suppressed an rpL10 mutant, re-establishing rotational equilibrium. The rpL10 loop is also involved in Sdo1p recruitment, suggesting that rotational status is important for ensuring late-stage maturation of the LSU, supporting a model in which pre-60S subunits undergo a ‘test drive’ before final maturation.
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Affiliation(s)
- Sergey O Sulima
- Department of Cell Biology and Molecular Genetics, University of Maryland, College Park, MD 20742, USA, Section of Molecular Genetics and Microbiology, Institute for Cellular and Molecular Biology, University of Texas at Austin, Austin, TX 78712, USA and Department of Biotechnology and Microbiology, Vilnius University, Vilnius LT-03101, Lithuania
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31
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Woolford JL, Baserga SJ. Ribosome biogenesis in the yeast Saccharomyces cerevisiae. Genetics 2013; 195:643-81. [PMID: 24190922 PMCID: PMC3813855 DOI: 10.1534/genetics.113.153197] [Citation(s) in RCA: 558] [Impact Index Per Article: 50.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2013] [Accepted: 08/26/2013] [Indexed: 01/09/2023] Open
Abstract
Ribosomes are highly conserved ribonucleoprotein nanomachines that translate information in the genome to create the proteome in all cells. In yeast these complex particles contain four RNAs (>5400 nucleotides) and 79 different proteins. During the past 25 years, studies in yeast have led the way to understanding how these molecules are assembled into ribosomes in vivo. Assembly begins with transcription of ribosomal RNA in the nucleolus, where the RNA then undergoes complex pathways of folding, coupled with nucleotide modification, removal of spacer sequences, and binding to ribosomal proteins. More than 200 assembly factors and 76 small nucleolar RNAs transiently associate with assembling ribosomes, to enable their accurate and efficient construction. Following export of preribosomes from the nucleus to the cytoplasm, they undergo final stages of maturation before entering the pool of functioning ribosomes. Elaborate mechanisms exist to monitor the formation of correct structural and functional neighborhoods within ribosomes and to destroy preribosomes that fail to assemble properly. Studies of yeast ribosome biogenesis provide useful models for ribosomopathies, diseases in humans that result from failure to properly assemble ribosomes.
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Affiliation(s)
- John L. Woolford
- Department of Biological Sciences, Center for Nucleic Acids Science and Technology, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213
| | - Susan J. Baserga
- Molecular Biophysics and Biochemistry, Genetics and Therapeutic Radiology, Yale University, New Haven, Connecticut 06520-8024
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32
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Translation initiation in the crenarchaeon Sulfolobus solfataricus: eukaryotic features but bacterial route. Biochem Soc Trans 2013; 41:350-5. [DOI: 10.1042/bst20120300] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
The formation of the translation initiation complex represents the rate-limiting step in protein synthesis. Translation initiation in the crenarchaeon Sulfolobus solfataricus depends on several translation IFs (initiation factors), some of which have eukaryal but no bacterial counterparts. In the present paper, we review the current knowledge of the structure, function and evolution of the IFs in S. solfataricus in the context of eukaryotic and bacterial orthologues. Despite similarities between eukaryotic and S. solfataricus IFs, the sequence of events in translation initiation in S. solfataricus follows the bacterial mode.
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Abstract
Shwachman-Diamond syndrome (SDS) is an autosomal-recessive marrow failure syndrome with a predisposition to leukemia. SDS patients harbor biallelic mutations in the SBDS gene, resulting in low levels of SBDS protein. Data from nonhuman models demonstrate that the SBDS protein facilitates the release of eIF6, a factor that prevents ribosome joining. The complete abrogation of Sbds expression in these models results in severe cellular and lethal physiologic abnormalities that differ from the human disease phenotype. Because human SDS cells are characterized by partial rather than complete loss of SBDS expression, we interrogated SDS patient cells for defects in ribosomal assembly. SDS patient cells exhibit altered ribosomal profiles and impaired association of the 40S and 60S subunits. Introduction of a wild-type SBDS cDNA into SDS patient cells corrected the ribosomal association defect, while patient-derived SBDS point mutants only partially improved subunit association. Knockdown of eIF6 expression improved ribosomal subunit association but did not correct the hematopoietic defect of SBDS-deficient cells. In summary, we demonstrate an SBDS-dependent ribosome maturation defect in SDS patient cells. The role of ribosomal subunit joining in marrow failure warrants further investigation.
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Proteomic and protein interaction network analysis of human T lymphocytes during cell-cycle entry. Mol Syst Biol 2012; 8:573. [PMID: 22415777 PMCID: PMC3321526 DOI: 10.1038/msb.2012.5] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2011] [Accepted: 01/30/2012] [Indexed: 12/23/2022] Open
Abstract
Proteomic analysis of T cells emerging from quiescence identifies dynamic network-level changes in key cellular processes. Disruption of two such processes, ribosome biogenesis and RNA splicing, reveals that the programs controlling cell growth and cell-cycle entry are separable. ![]()
The authors conduct a proteomic and protein interaction network analysis of human T lymphocytes during entry into the first cell cycle. Inhibiting the induction of eIF6 (60S ribosome biogenesis) causes T cells to enter the cell cycle without growing in size. Inhibiting the induction of SF3B2/SF3B4 (U2/U12-dependent RNA splicing) allows an increase in cell size without entering the cell cycle. These results provide proof of principle that blastogenesis and proliferation programs are separable in primary human T cells.
Regulating the transition of cells such as T lymphocytes from quiescence (G0) into an activated, proliferating state involves initiation of cellular programs resulting in entry into the cell cycle (proliferation), the growth cycle (blastogenesis, cell size) and effector (functional) activation. We show the first proteomic analysis of protein interaction networks activated during entry into the first cell cycle from G0. We also provide proof of principle that blastogenesis and proliferation programs are separable in primary human T cells. We employed a proteomic profiling method to identify large-scale changes in chromatin/nuclear matrix-bound and unbound proteins in human T lymphocytes during the transition from G0 into the first cell cycle and mapped them to form functionally annotated, dynamic protein interaction networks. Inhibiting the induction of two proteins involved in two of the most significantly upregulated cellular processes, ribosome biogenesis (eIF6) and hnRNA splicing (SF3B2/SF3B4), showed, respectively, that human T cells can enter the cell cycle without growing in size, or increase in size without entering the cell cycle.
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Cryo-EM structure of the archaeal 50S ribosomal subunit in complex with initiation factor 6 and implications for ribosome evolution. J Mol Biol 2012; 418:145-60. [PMID: 22306461 DOI: 10.1016/j.jmb.2012.01.018] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2011] [Revised: 01/05/2012] [Accepted: 01/13/2012] [Indexed: 11/20/2022]
Abstract
Translation of mRNA into proteins by the ribosome is universally conserved in all cellular life. The composition and complexity of the translation machinery differ markedly between the three domains of life. Organisms from the domain Archaea show an intermediate level of complexity, sharing several additional components of the translation machinery with eukaryotes that are absent in bacteria. One of these translation factors is initiation factor 6 (IF6), which associates with the large ribosomal subunit. We have reconstructed the 50S ribosomal subunit from the archaeon Methanothermobacter thermautotrophicus in complex with archaeal IF6 at 6.6 Å resolution using cryo-electron microscopy (EM). The structure provides detailed architectural insights into the 50S ribosomal subunit from a methanogenic archaeon through identification of the rRNA expansion segments and ribosomal proteins that are shared between this archaeal ribosome and eukaryotic ribosomes but are mostly absent in bacteria and in some archaeal lineages. Furthermore, the structure reveals that, in spite of highly divergent evolutionary trajectories of the ribosomal particle and the acquisition of novel functions of IF6 in eukaryotes, the molecular binding of IF6 on the ribosome is conserved between eukaryotes and archaea. The structure also provides a snapshot of the reductive evolution of the archaeal ribosome and offers new insights into the evolution of the translation system in archaea.
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36
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Grosso S, Pesce E, Brina D, Beugnet A, Loreni F, Biffo S. Sensitivity of global translation to mTOR inhibition in REN cells depends on the equilibrium between eIF4E and 4E-BP1. PLoS One 2011; 6:e29136. [PMID: 22216185 PMCID: PMC3245250 DOI: 10.1371/journal.pone.0029136] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2011] [Accepted: 11/21/2011] [Indexed: 01/08/2023] Open
Abstract
Initiation is the rate-limiting phase of protein synthesis, controlled by signaling pathways regulating the phosphorylation of translation factors. Initiation has three steps, 43S, 48S and 80S formation. 43S formation is repressed by eIF2α phosphorylation. The subsequent steps, 48S and 80S formation are enabled by growth factors. 48S relies on eIF4E-mediated assembly of eIF4F complex; 4E-BPs competitively displace eIF4E from eIF4F. Two pathways control eIF4F: 1) mTORc1 phosphorylates and inactivates 4E-BPs, leading to eIF4F formation; 2) the Ras-Mnk cascade phosphorylates eIF4E. We show that REN and NCI-H28 mesothelioma cells have constitutive activation of both pathways and maximal translation rate, in the absence of exogenous growth factors. Translation is rapidly abrogated by phosphorylation of eIF2α. Surprisingly, pharmacological inhibition of mTORc1 leads to the complete dephosphorylation of downstream targets, without changes in methionine incorporation. In addition, the combined administration of mTORc1 and MAPK/Mnk inhibitors has no additive effect. The inhibition of both mTORc1 and mTORc2 does not affect the metabolic rate. In spite of this, mTORc1 inhibition reduces eIF4F complex formation, and depresses translocation of TOP mRNAs on polysomes. Downregulation of eIF4E and overexpression of 4E-BP1 induce rapamycin sensitivity, suggesting that disruption of eIF4F complex, due to eIF4E modulation, competes with its recycling to ribosomes. These data suggest the existence of a dynamic equilibrium in which eIF4F is not essential for all mRNAs and is not displaced from translated mRNAs, before recycling to the next.
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Affiliation(s)
- Stefano Grosso
- Molecular Histology and Cell Growth, DIBIT-HSR, Milan, Italy.
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37
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Miluzio A, Beugnet A, Grosso S, Brina D, Mancino M, Campaner S, Amati B, de Marco A, Biffo S. Impairment of cytoplasmic eIF6 activity restricts lymphomagenesis and tumor progression without affecting normal growth. Cancer Cell 2011; 19:765-75. [PMID: 21665150 DOI: 10.1016/j.ccr.2011.04.018] [Citation(s) in RCA: 76] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/22/2010] [Revised: 02/14/2011] [Accepted: 04/29/2011] [Indexed: 12/13/2022]
Abstract
Eukaryotic Initiation Factor 6 (eIF6) controls translation by regulating 80S subunit formation. eIF6 is overexpressed in tumors. Here, we demonstrate that eIF6 inactivation delays tumorigenesis and reduces tumor growth in vivo. eIF6(+/-) mice resist to Myc-induced lymphomagenesis and have prolonged tumor-free survival and reduced tumor growth. eIF6(+/-) mice are also protected by p53 loss. Myc-driven lymphomas contain PKCβII and phosphorylated eIF6; eIF6 is phosphorylated by tumor-derived PKCβII, but not by the eIF4F activator mTORC1. Mutation of PKCβII phosphosite of eIF6 reduces tumor growth. Thus, eIF6 is a rate-limiting controller of initiation of translation, able to affect tumorigenesis and tumor growth. Modulation of eIF6 activity, independent from eIF4F complex, may lead to a therapeutical avenue in tumor therapy.
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Affiliation(s)
- Annarita Miluzio
- Histology and Cell Growth, San Raffaele Scientific Institute, Milan, Italy
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38
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Abstract
Initiation is a critical step in translation, during which the ribosome lands on the start codon and sets the correct reading frame for mRNA decoding. The rate and efficiency of translation are largely determined by initiation, which is therefore the preferred target of translation regulation mechanisms. Initiation has incurred an extensive evolutionary divergence among the primary domains of cell descent. The Archaea, albeit prokaryotes, have an initiation mechanism and apparatus more complex than those of the Bacteria; the molecular details of archaeal initiation are just beginning to be unravelled. The most notable aspects of archaeal initiation are the presence of two, perhaps three, distinct mechanisms for mRNA-ribosome interaction and the presence of a relatively large set of IFs (initiation factors), several of which are shared exclusively with the Eukarya. Among these, the protein termed a/eIF2 (archaeal/eukaryotic IF2) and aIF6 (archaeal IF6) are of special interest, since they appear to play key regulatory roles in the Eukarya. Studies of the function of these factors in Archaea have uncovered new features that will help to elucidate their conserved and domain-specific functions.
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Biswas A, Mukherjee S, Das S, Shields D, Chow CW, Maitra U. Opposing action of casein kinase 1 and calcineurin in nucleo-cytoplasmic shuttling of mammalian translation initiation factor eIF6. J Biol Chem 2010; 286:3129-38. [PMID: 21084295 DOI: 10.1074/jbc.m110.188565] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Eukaryotic initiation factor 6 (eIF6), a highly conserved protein from yeast to mammals, is essential for 60 S ribosome biogenesis and assembly. Both yeast and mammalian eIF6 are phosphorylated at Ser-174 and Ser-175 by the nuclear isoform of casein kinase 1 (CK1). The molecular basis of eIF6 phosphorylation, however, remains elusive. In the present work, we show that subcellular distribution of eIF6 in the nuclei and the cytoplasm of mammalian cells is mediated by dephosphorylation and phosphorylation, respectively. This nucleo-cytoplasmic shuttling is dependent on the phosphorylation status at Ser-174 and Ser-175 of eIF6. We demonstrate that Ca(2+)-activated calcineurin phosphatase binds to and promotes nuclear localization of eIF6. Increase in intracellular concentration of Ca(2+) leads to rapid translocation of eIF6 from the cytoplasm to the nucleus, an event that is blocked by specific calcineurin inhibitors cyclosporin A or FK520. Nuclear export of eIF6 is regulated by phosphorylation at Ser-174 and Ser-175 by the nuclear isoform of CK1. Mutation of eIF6 at the phosphorylatable Ser-174 and Ser-175 to alanine or treatment of cells with the CK1 inhibitor, D4476 inhibits nuclear export of eIF6 and results in nuclear accumulation of eIF6. Together, these results establish eIF6 as a substrate for calcineurin and suggest a novel paradigm for calcineurin function in 60 S ribosome biogenesis via regulating the nuclear accumulation of eIF6.
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Affiliation(s)
- Arunima Biswas
- Department of Developmental and Molecular Biology, Albert Einstein College of Medicine, Bronx, New York 10461, USA
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40
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Panse VG, Johnson AW. Maturation of eukaryotic ribosomes: acquisition of functionality. Trends Biochem Sci 2010; 35:260-6. [PMID: 20137954 DOI: 10.1016/j.tibs.2010.01.001] [Citation(s) in RCA: 163] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2009] [Revised: 01/03/2010] [Accepted: 01/04/2010] [Indexed: 11/29/2022]
Abstract
In eukaryotic cells, ribosomes are pre-assembled in the nucleus and exported to the cytoplasm where they undergo final maturation. This involves the release of trans-acting shuttling factors, transport factors, incorporation of the remaining ribosomal proteins, and final rRNA processing steps. Recent work, particularly on the large (60S) ribosomal subunit, has confirmed that the 60S subunit is exported from the nucleus in a functionally inactive state. Its arrival in the cytoplasm triggers events that render it translationally competent. Here we focus on these cytoplasmic maturation events and speculate why eukaryotic cells have evolved such an elaborate maturation pathway.
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Lo KY, Li Z, Bussiere C, Bresson S, Marcotte EM, Johnson AW. Defining the pathway of cytoplasmic maturation of the 60S ribosomal subunit. Mol Cell 2010; 39:196-208. [PMID: 20670889 PMCID: PMC2925414 DOI: 10.1016/j.molcel.2010.06.018] [Citation(s) in RCA: 150] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2010] [Revised: 04/26/2010] [Accepted: 05/05/2010] [Indexed: 11/23/2022]
Abstract
In eukaryotic cells the final maturation of ribosomes occurs in the cytoplasm, where trans-acting factors are removed and critical ribosomal proteins are added for functionality. Here, we have carried out a comprehensive analysis of cytoplasmic maturation, ordering the known steps into a coherent pathway. Maturation is initiated by the ATPase Drg1. Downstream, assembly of the ribosome stalk is essential for the release of Tif6. The stalk recruits GTPases during translation. Because the GTPase Efl1, which is required for the release of Tif6, resembles the translation elongation factor eEF2, we suggest that assembly of the stalk recruits Efl1, triggering a step in 60S biogenesis that mimics aspects of translocation. Efl1 could thereby provide a mechanism to functionally check the nascent subunit. Finally, the release of Tif6 is a prerequisite for the release of the nuclear export adaptor Nmd3. Establishing this pathway provides an important conceptual framework for understanding ribosome maturation.
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Affiliation(s)
- Kai-Yin Lo
- Section of Molecular Genetics and Microbiology, University of Texas at Austin, Austin, TX 78712, USA
- The Institute for Cellular and Molecular Biology, University of Texas at Austin, Austin, TX 78712, USA
| | - Zhihua Li
- The Institute for Cellular and Molecular Biology, University of Texas at Austin, Austin, TX 78712, USA
- Center for Systems and Synthetic Biology, Department of Chemistry and Biochemistry University of Texas at Austin, Austin, TX 78712, USA
| | - Cyril Bussiere
- Section of Molecular Genetics and Microbiology, University of Texas at Austin, Austin, TX 78712, USA
- The Institute for Cellular and Molecular Biology, University of Texas at Austin, Austin, TX 78712, USA
| | - Stefan Bresson
- Section of Molecular Genetics and Microbiology, University of Texas at Austin, Austin, TX 78712, USA
- The Institute for Cellular and Molecular Biology, University of Texas at Austin, Austin, TX 78712, USA
| | - Edward M Marcotte
- The Institute for Cellular and Molecular Biology, University of Texas at Austin, Austin, TX 78712, USA
- Center for Systems and Synthetic Biology, Department of Chemistry and Biochemistry University of Texas at Austin, Austin, TX 78712, USA
| | - Arlen W. Johnson
- Section of Molecular Genetics and Microbiology, University of Texas at Austin, Austin, TX 78712, USA
- The Institute for Cellular and Molecular Biology, University of Texas at Austin, Austin, TX 78712, USA
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Gartmann M, Blau M, Armache JP, Mielke T, Topf M, Beckmann R. Mechanism of eIF6-mediated inhibition of ribosomal subunit joining. J Biol Chem 2010; 285:14848-14851. [PMID: 20356839 PMCID: PMC2865328 DOI: 10.1074/jbc.c109.096057] [Citation(s) in RCA: 95] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2009] [Revised: 02/09/2010] [Indexed: 01/25/2023] Open
Abstract
During the process of ribosomal assembly, the essential eukaryotic translation initiation factor 6 (eIF6) is known to act as a ribosomal anti-association factor. However, a molecular understanding of the anti-association activity of eIF6 is still missing. Here we present the cryo-electron microscopy reconstruction of a complex of the large ribosomal subunit with eukaryotic eIF6 from Saccharomyces cerevisiae. The structure reveals that the eIF6 binding site involves mainly rpL23 (L14p in Escherichia coli). Based on our structural data, we propose that the mechanism of the anti-association activity of eIF6 is based on steric hindrance of intersubunit bridge formation around the dynamic bridge B6.
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Affiliation(s)
- Marco Gartmann
- Department of Biochemistry, Gene Center and Center for Integrated Protein Science (CiPSM), Ludwig-Maximilians-Universität München, Feodor-Lynen-Strasse 25, 81377 Munich, Germany
| | - Michael Blau
- Institut für Biochemie der Charité, Humboldt Universität Berlin, Monbijoustrasse 2, 10117 Berlin, Germany
| | - Jean-Paul Armache
- Department of Biochemistry, Gene Center and Center for Integrated Protein Science (CiPSM), Ludwig-Maximilians-Universität München, Feodor-Lynen-Strasse 25, 81377 Munich, Germany
| | - Thorsten Mielke
- UltraStrukturNetzwerk, Max Planck Institute for Molecular Genetics, Ihnestrasse 73, 14195 Berlin; Institut für Medizinische Physik und Biophysik, Charité, Ziegelstrasse 5-9, 10098 Berlin, Germany
| | - Maya Topf
- Institute of Structural and Molecular Biology, School of Crystallography, Birkbeck College, University of London, Malet Street, London WC1E 7HX, United Kingdom
| | - Roland Beckmann
- Department of Biochemistry, Gene Center and Center for Integrated Protein Science (CiPSM), Ludwig-Maximilians-Universität München, Feodor-Lynen-Strasse 25, 81377 Munich, Germany.
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Miluzio A, Beugnet A, Volta V, Biffo S. Eukaryotic initiation factor 6 mediates a continuum between 60S ribosome biogenesis and translation. EMBO Rep 2009; 10:459-65. [PMID: 19373251 PMCID: PMC2680881 DOI: 10.1038/embor.2009.70] [Citation(s) in RCA: 87] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2009] [Accepted: 03/24/2009] [Indexed: 12/11/2022] Open
Abstract
Eukaryotic ribosome biogenesis and translation are linked processes that limit the rate of cell growth. Although ribosome biogenesis and translation are mainly controlled by distinct factors, eukaryotic initiation factor 6 (eIF6) has been found to regulate both processes. eIF6 is a necessary protein with a unique anti-association activity, which prevents the interaction of 40S ribosomal subunits with 60S subunits through its binding to 60S ribosomes. In the nucleolus, eIF6 is a component of the pre-ribosomal particles and is required for the biogenesis of 60S subunits, whereas in the cytoplasm it mediates translation downstream from growth factors. The translational activity of eIF6 could be due to its anti-association properties, which are regulated by post-translational modifications; whether this anti-association activity is required for the biogenesis and nuclear export of ribosomes is unknown. eIF6 is necessary for tissue-specific growth and oncogene-driven transformation, and could be a new rate-limiting step for the initiation of translation.
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Affiliation(s)
- Annarita Miluzio
- Laboratory of Molecular Histology and Cell Growth, Division of Oncology, San Raffaele Scientific Institute, Via Olgettina 58, 20132 Milano, Italy
| | - Anne Beugnet
- Laboratory of Molecular Histology and Cell Growth, Division of Oncology, San Raffaele Scientific Institute, Via Olgettina 58, 20132 Milano, Italy
| | - Viviana Volta
- Laboratory of Molecular Histology and Cell Growth, Division of Oncology, San Raffaele Scientific Institute, Via Olgettina 58, 20132 Milano, Italy
- Environmental and Life Science Department (DISAV), University of Eastern Piedmont, Via Bellini 15G, 15100 Alessandria, Italy
| | - Stefano Biffo
- Laboratory of Molecular Histology and Cell Growth, Division of Oncology, San Raffaele Scientific Institute, Via Olgettina 58, 20132 Milano, Italy
- Environmental and Life Science Department (DISAV), University of Eastern Piedmont, Via Bellini 15G, 15100 Alessandria, Italy
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Benelli D, Marzi S, Mancone C, Alonzi T, la Teana A, Londei P. Function and ribosomal localization of aIF6, a translational regulator shared by archaea and eukarya. Nucleic Acids Res 2008; 37:256-67. [PMID: 19036786 PMCID: PMC2615626 DOI: 10.1093/nar/gkn959] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
The translation factor IF6 is shared by the Archaea and the Eukarya, but is not found in Bacteria. The properties of eukaryal IF6 (eIF6) have been extensively studied, but remain somewhat elusive. eIF6 behaves as a ribosome-anti-association factor and is involved in miRNA-mediated gene silencing; however, it also seems to participate in ribosome synthesis and export. Here we have determined the function and ribosomal localization of the archaeal (Sulfolobus solfataricus) IF6 homologue (aIF6). We find that aIF6 binds specifically to the 50S ribosomal subunits, hindering the formation of 70S ribosomes and strongly inhibiting translation. aIF6 is uniformly expressed along the cell cycle, but it is upregulated following both cold- and heat shock. The aIF6 ribosomal binding site lies in the middle of the 30-S interacting surface of the 50S subunit, including a number of critical RNA and protein determinants involved in subunit association. The data suggest that the IF6 protein evolved in the archaeal–eukaryal lineage to modulate translational efficiency under unfavourable environmental conditions, perhaps acquiring additional functions during eukaryotic evolution.
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Affiliation(s)
- Dario Benelli
- Dipartimento Biotecnologie Cellulari ed Ematologia, Policlinico Umberto I, Università di Roma Sapienza, Roma, Italy
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Eukaryotic initiation factor 6 is rate-limiting in translation, growth and transformation. Nature 2008; 455:684-8. [PMID: 18784653 DOI: 10.1038/nature07267] [Citation(s) in RCA: 169] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2007] [Accepted: 07/15/2008] [Indexed: 12/17/2022]
Abstract
Cell growth and proliferation require coordinated ribosomal biogenesis and translation. Eukaryotic initiation factors (eIFs) control translation at the rate-limiting step of initiation. So far, only two eIFs connect extracellular stimuli to global translation rates: eIF4E acts in the eIF4F complex and regulates binding of capped messenger RNA to 40S subunits, downstream of growth factors, and eIF2 controls loading of the ternary complex on the 40S subunit and is inhibited on stress stimuli. No eIFs have been found to link extracellular stimuli to the activity of the large 60S ribosomal subunit. eIF6 binds 60S ribosomes precluding ribosome joining in vitro. However, studies in yeasts showed that eIF6 is required for ribosome biogenesis rather than translation. Here we show that mammalian eIF6 is required for efficient initiation of translation, in vivo. eIF6 null embryos are lethal at preimplantation. Heterozygous mice have 50% reduction of eIF6 levels in all tissues, and show reduced mass of hepatic and adipose tissues due to a lower number of cells and to impaired G1/S cell cycle progression. eIF6(+/-) cells retain sufficient nucleolar eIF6 and normal ribosome biogenesis. The liver of eIF6(+/-) mice displays an increase of 80S in polysomal profiles, indicating a defect in initiation of translation. Consistently, isolated hepatocytes have impaired insulin-stimulated translation. Heterozygous mouse embryonic fibroblasts recapitulate the organism phenotype and have normal ribosome biogenesis, reduced insulin-stimulated translation, and delayed G1/S phase progression. Furthermore, eIF6(+/-) cells are resistant to oncogene-induced transformation. Thus, eIF6 is the first eIF associated with the large 60S subunit that regulates translation in response to extracellular signals.
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Altered eIF6 and Dicer expression is associated with clinicopathological features in ovarian serous carcinoma patients. Mod Pathol 2008; 21:676-84. [PMID: 18327211 DOI: 10.1038/modpathol.2008.33] [Citation(s) in RCA: 83] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
MicroRNAs are a group of small non-coding RNAs approximately 22 nucleotides in length. Recent work has shown differential expression of mature microRNAs in human cancers. Production and function of microRNAs require coordinated processing by proteins of the microRNA machinery. Dicer and Drosha (RNase III endonucleases) are essential components of the microRNA machinery. Recently, the ribosome anti-association factor eIF6 has also been found to have a role in microRNA-mediated post-transcriptional silencing. We characterized the alterations in the expression of genes encoding proteins of microRNA machinery in ovarian serous carcinoma. Protein expression of eIF6 and Dicer was quantified in a tissue microarray of 66 ovarian serous carcinomas. Dicer, Drosha and eIF6 mRNA expression was analysed using quantitative reverse transcription-PCR on an independent set of 50 formalin-fixed, paraffin-embedded ovarian serous carcinoma samples. Expression profiles of eIF6 and Dicer were correlated with clinicopathological and patient survival data. We provide definitive evidence that eIF6 and Dicer are both upregulated in a significant proportion of ovarian serous carcinomas and are associated with specific clinicopathological features, most notably low eIF6 expression being associated with reduced disease-free survival. The status of eIF6 and proteins of the microRNA machinery may help predict toxicity and susceptibility to future interfering RNA-based therapy.
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MicroRNA-repressed mRNAs contain 40S but not 60S components. Proc Natl Acad Sci U S A 2008; 105:5343-8. [PMID: 18390669 DOI: 10.1073/pnas.0801102105] [Citation(s) in RCA: 86] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
MicroRNAs (miRNAs) are small noncoding RNAs that may target more than one-third of human genes, yet the mechanisms used by miRNAs to repress translation of target mRNAs are obscure. Using a recently described cell-free assay of miRNA function, we observe that miRNA-targeted mRNAs are enriched for 40S but not 60S ribosome components. Additionally, toeprinting analysis of miRNA-targeted mRNAs demonstrates that approximately 18 nt 3' relative to the initiating AUG are protected, consistent with 40S ribosome subunits positioned at the AUG codon. Our results suggest that miRNAs repress translation initiation by preventing 60S subunit joining to miRNA-targeted mRNAs.
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Ray P, Basu U, Ray A, Majumdar R, Deng H, Maitra U. The Saccharomyces cerevisiae 60 S ribosome biogenesis factor Tif6p is regulated by Hrr25p-mediated phosphorylation. J Biol Chem 2008; 283:9681-91. [PMID: 18256024 DOI: 10.1074/jbc.m710294200] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The biosynthesis of 60 S ribosomal subunits in Saccharomyces cerevisiae requires Tif6p, the yeast homologue of mammalian eIF6. This protein is necessary for the formation of 60 S ribosomal subunits because it is essential for the processing of 35 S pre-rRNA to the mature 25 S and 5.8 S rRNAs. In the present work, using molecular genetic and biochemical analyses, we show that Hrr25p, an isoform of yeast casein kinase I, phosphorylates Tif6p both in vitro and in vivo. Tryptic phosphopeptide mapping of in vitro phosphorylated Tif6p by Hrr25p and (32)P-labeled Tif6p isolated from yeast cells followed by mass spectrometric analysis revealed that phosphorylation occurred on a single tryptic peptide at Ser-174. Sucrose gradient fractionation and coimmunoprecipitation experiments demonstrate that a small but significant fraction of Hrr25p is bound to 66 S preribosomal particles that also contain bound Tif6p. Depletion of Hrr25p from a conditional yeast mutant that fails to phosphorylate Tif6p was unable to process pre-rRNAs efficiently, resulting in significant reduction in the formation of 25 S rRNA. These results along with our previous observations that phosphorylatable Ser-174 is required for yeast cell growth and viability, suggest that Hrr25p-mediated phosphorylation of Tif6p plays a critical role in the biogenesis of 60 S ribosomal subunits in yeast cells.
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Affiliation(s)
- Partha Ray
- Department of Developmental and Molecular Biology, Albert Einstein College of Medicine of Yeshiva University, Bronx, NY 10461, USA
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Demeshkina N, Hirokawa G, Kaji A, Kaji H. Novel activity of eukaryotic translocase, eEF2: dissociation of the 80S ribosome into subunits with ATP but not with GTP. Nucleic Acids Res 2007; 35:4597-607. [PMID: 17586816 PMCID: PMC1950535 DOI: 10.1093/nar/gkm468] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
Abstract
Ribosomes must dissociate into subunits in order to begin protein biosynthesis. The enzymes that catalyze this fundamental process in eukaryotes remained unknown. Here, we demonstrate that eukaryotic translocase, eEF2, which catalyzes peptide elongation in the presence of GTP, dissociates yeast 80S ribosomes into subunits in the presence of ATP but not GTP or other nucleoside triphosphates. Dissociation was detected by light scattering or ultracentrifugation after the split subunits were stabilized. ATP was hydrolyzed during the eEF2-dependent dissociation, while a non-hydrolyzable analog of ATP was inactive in ribosome splitting by eEF2. GTP inhibited not only ATP hydrolysis but also dissociation. Sordarin, a fungal eEF2 inhibitor, averted the splitting but stimulated ATP hydrolysis. Another elongation inhibitor, cycloheximide, also prevented eEF2/ATP-dependent splitting, while the inhibitory effect of fusidic acid on the splitting was nominal. Upon dissociation of the 80S ribosome, eEF2 was found on the subunits. We propose that the dissociation activity of eEF2/ATP plays a role in mobilizing 80S ribosomes for protein synthesis during the shift up of physiological conditions.
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Affiliation(s)
- Natalia Demeshkina
- Department of Biochemistry and Molecular Biology, Thomas Jefferson University, Philadelphia, PA 19107 and Department of Microbiology, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Go Hirokawa
- Department of Biochemistry and Molecular Biology, Thomas Jefferson University, Philadelphia, PA 19107 and Department of Microbiology, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Akira Kaji
- Department of Biochemistry and Molecular Biology, Thomas Jefferson University, Philadelphia, PA 19107 and Department of Microbiology, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Hideko Kaji
- Department of Biochemistry and Molecular Biology, Thomas Jefferson University, Philadelphia, PA 19107 and Department of Microbiology, University of Pennsylvania, Philadelphia, PA 19104, USA
- *To whom correspondence should be addressed.+1 215 503 6547+1 215 923 7343
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Chendrimada TP, Finn KJ, Ji X, Baillat D, Gregory RI, Liebhaber SA, Pasquinelli AE, Shiekhattar R. MicroRNA silencing through RISC recruitment of eIF6. Nature 2007; 447:823-8. [PMID: 17507929 DOI: 10.1038/nature05841] [Citation(s) in RCA: 346] [Impact Index Per Article: 20.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2006] [Accepted: 04/13/2007] [Indexed: 12/13/2022]
Abstract
MicroRNAs (miRNAs) are a class of small RNAs that act post-transcriptionally to regulate messenger RNA stability and translation. To elucidate how miRNAs mediate their repressive effects, we performed biochemical and functional assays to identify new factors in the miRNA pathway. Here we show that human RISC (RNA-induced silencing complex) associates with a multiprotein complex containing MOV10--which is the homologue of Drosophila translational repressor Armitage--and proteins of the 60S ribosome subunit. Notably, this complex contains the anti-association factor eIF6 (also called ITGB4BP or p27BBP), a ribosome inhibitory protein known to prevent productive assembly of the 80S ribosome. Depletion of eIF6 in human cells specifically abrogates miRNA-mediated regulation of target protein and mRNA levels. Similarly, depletion of eIF6 in Caenorhabditis elegans diminishes lin-4 miRNA-mediated repression of the endogenous LIN-14 and LIN-28 target protein and mRNA levels. These results uncover an evolutionarily conserved function of the ribosome anti-association factor eIF6 in miRNA-mediated post-transcriptional silencing.
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