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Henis M, Rücker T, Scharrenberg R, Richter M, Baltussen L, Hong S, Meka DP, Schwanke B, Neelagandan N, Daaboul D, Murtaza N, Krisp C, Harder S, Schlüter H, Kneussel M, Hermans-Borgmeyer I, de Wit J, Singh KK, Duncan KE, de Anda FC. The autism susceptibility kinase, TAOK2, phosphorylates eEF2 and modulates translation. SCIENCE ADVANCES 2024; 10:eadf7001. [PMID: 38608030 PMCID: PMC11014455 DOI: 10.1126/sciadv.adf7001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/08/2022] [Accepted: 03/12/2024] [Indexed: 04/14/2024]
Abstract
Genes implicated in translation control have been associated with autism spectrum disorders (ASDs). However, some important genetic causes of autism, including the 16p11.2 microdeletion, bear no obvious connection to translation. Here, we use proteomics, genetics, and translation assays in cultured cells and mouse brain to reveal altered translation mediated by loss of the kinase TAOK2 in 16p11.2 deletion models. We show that TAOK2 associates with the translational machinery and functions as a translational brake by phosphorylating eukaryotic elongation factor 2 (eEF2). Previously, all signal-mediated regulation of translation elongation via eEF2 phosphorylation was believed to be mediated by a single kinase, eEF2K. However, we show that TAOK2 can directly phosphorylate eEF2 on the same regulatory site, but functions independently of eEF2K signaling. Collectively, our results reveal an eEF2K-independent signaling pathway for control of translation elongation and suggest altered translation as a molecular component in the etiology of some forms of ASD.
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Affiliation(s)
- Melad Henis
- Center for Molecular Neurobiology, University Medical Center Hamburg-Eppendorf, 20251 Hamburg, Germany
- Department of Anatomy and Embryology, Faculty of Veterinary Medicine, New Valley University, 72511 El-Kharga, Egypt
| | - Tabitha Rücker
- Center for Molecular Neurobiology, University Medical Center Hamburg-Eppendorf, 20251 Hamburg, Germany
| | - Robin Scharrenberg
- Center for Molecular Neurobiology, University Medical Center Hamburg-Eppendorf, 20251 Hamburg, Germany
| | - Melanie Richter
- Center for Molecular Neurobiology, University Medical Center Hamburg-Eppendorf, 20251 Hamburg, Germany
| | - Lucas Baltussen
- VIB Center for Brain & Disease Research, Herestraat 49, 3000 Leuven, Belgium
- KU Leuven Department of Neurosciences, Leuven Brain Institute, Herestraat 49, 3000 Leuven, Belgium
| | - Shuai Hong
- Center for Molecular Neurobiology, University Medical Center Hamburg-Eppendorf, 20251 Hamburg, Germany
| | - Durga Praveen Meka
- Center for Molecular Neurobiology, University Medical Center Hamburg-Eppendorf, 20251 Hamburg, Germany
| | - Birgit Schwanke
- Center for Molecular Neurobiology, University Medical Center Hamburg-Eppendorf, 20251 Hamburg, Germany
| | - Nagammal Neelagandan
- Neuronal Translational Control Group, Center for Molecular Neurobiology (ZMNH), University Medical Center Hamburg-Eppendorf (UKE), Falkenried 94, 20251 Hamburg, Germany
- Institute of Bioengineering (IBI), École Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
| | - Danie Daaboul
- VIB Center for Brain & Disease Research, Herestraat 49, 3000 Leuven, Belgium
- KU Leuven Department of Neurosciences, Leuven Brain Institute, Herestraat 49, 3000 Leuven, Belgium
| | - Nadeem Murtaza
- Krembil Research Institute, Donald K. Johnson Eye Institute, University Health Network, 60 Leonard Ave, Toronto, Ontario M5T 0S8, Canada
- Department of Biochemistry and Biomedical Sciences, Faculty of Health Sciences, McMaster University, Hamilton, Ontario L8S 4A9, Canada
| | - Christoph Krisp
- Institute for Clinical Chemistry and Laboratory Medicine, Mass Spectrometric Proteomics Group, Campus Forschung, University Medical Center Hamburg-Eppendorf (UKE), 20246 Hamburg, Germany
| | - Sönke Harder
- Institute for Clinical Chemistry and Laboratory Medicine, Mass Spectrometric Proteomics Group, Campus Forschung, University Medical Center Hamburg-Eppendorf (UKE), 20246 Hamburg, Germany
| | - Hartmut Schlüter
- Institute for Clinical Chemistry and Laboratory Medicine, Mass Spectrometric Proteomics Group, Campus Forschung, University Medical Center Hamburg-Eppendorf (UKE), 20246 Hamburg, Germany
| | - Matthias Kneussel
- Institute of Neurogenetics, Center for Molecular Neurobiology, University Medical Center Hamburg-Eppendorf (UKE), 20251 Hamburg, Germany
| | - Irm Hermans-Borgmeyer
- Transgenic Service Group, Center for Molecular Neurobiology (ZMNH), University Medical Center Hamburg-Eppendorf (UKE), Falkenried 94, 20251 Hamburg, Germany
| | - Joris de Wit
- VIB Center for Brain & Disease Research, Herestraat 49, 3000 Leuven, Belgium
- KU Leuven Department of Neurosciences, Leuven Brain Institute, Herestraat 49, 3000 Leuven, Belgium
| | - Karun K. Singh
- Krembil Research Institute, Donald K. Johnson Eye Institute, University Health Network, 60 Leonard Ave, Toronto, Ontario M5T 0S8, Canada
- Faculty of Medicine, University of Toronto, Medical Sciences Building, 1 King's College Cir, Toronto, Ontario M5S 1 A8, Canada
| | - Kent E. Duncan
- Neuronal Translational Control Group, Center for Molecular Neurobiology (ZMNH), University Medical Center Hamburg-Eppendorf (UKE), Falkenried 94, 20251 Hamburg, Germany
- Evotec SE, Manfred Eigen Campus, Essener Bogen 7, 22419 Hamburg, Germany
| | - Froylan Calderón de Anda
- Center for Molecular Neurobiology, University Medical Center Hamburg-Eppendorf, 20251 Hamburg, Germany
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2
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Iyyappan R, Aleshkina D, Ming H, Dvoran M, Kakavand K, Jansova D, del Llano E, Gahurova L, Bruce AW, Masek T, Pospisek M, Horvat F, Kubelka M, Jiang Z, Susor A. The translational oscillation in oocyte and early embryo development. Nucleic Acids Res 2023; 51:12076-12091. [PMID: 37950888 PMCID: PMC10711566 DOI: 10.1093/nar/gkad996] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2023] [Revised: 10/03/2023] [Accepted: 10/17/2023] [Indexed: 11/13/2023] Open
Abstract
Translation is critical for development as transcription in the oocyte and early embryo is silenced. To illustrate the translational changes during meiosis and consecutive two mitoses of the oocyte and early embryo, we performed a genome-wide translatome analysis. Acquired data showed significant and uniform activation of key translational initiation and elongation axes specific to M-phases. Although global protein synthesis decreases in M-phases, translation initiation and elongation activity increases in a uniformly fluctuating manner, leading to qualitative changes in translation regulation via the mTOR1/4F/eEF2 axis. Overall, we have uncovered a highly dynamic and oscillatory pattern of translational reprogramming that contributes to the translational regulation of specific mRNAs with different modes of polysomal occupancy/translation that are important for oocyte and embryo developmental competence. Our results provide new insights into the regulation of gene expression during oocyte meiosis as well as the first two embryonic mitoses and show how temporal translation can be optimized. This study is the first step towards a comprehensive analysis of the molecular mechanisms that not only control translation during early development, but also regulate translation-related networks employed in the oocyte-to-embryo transition and embryonic genome activation.
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Affiliation(s)
- Rajan Iyyappan
- Laboratory of Biochemistry and Molecular Biology of Germ Cells, Institute of Animal Physiology and Genetics of the Czech Academy of Sciences, Rumburska 89, 277 21 Libechov, Czech Republic
| | - Daria Aleshkina
- Laboratory of Biochemistry and Molecular Biology of Germ Cells, Institute of Animal Physiology and Genetics of the Czech Academy of Sciences, Rumburska 89, 277 21 Libechov, Czech Republic
| | - Hao Ming
- Department of Animal Sciences, University of Florida, Gainesville, FL 32610, USA
| | - Michal Dvoran
- Laboratory of Biochemistry and Molecular Biology of Germ Cells, Institute of Animal Physiology and Genetics of the Czech Academy of Sciences, Rumburska 89, 277 21 Libechov, Czech Republic
| | - Kianoush Kakavand
- Laboratory of Biochemistry and Molecular Biology of Germ Cells, Institute of Animal Physiology and Genetics of the Czech Academy of Sciences, Rumburska 89, 277 21 Libechov, Czech Republic
| | - Denisa Jansova
- Laboratory of Biochemistry and Molecular Biology of Germ Cells, Institute of Animal Physiology and Genetics of the Czech Academy of Sciences, Rumburska 89, 277 21 Libechov, Czech Republic
| | - Edgar del Llano
- Laboratory of Biochemistry and Molecular Biology of Germ Cells, Institute of Animal Physiology and Genetics of the Czech Academy of Sciences, Rumburska 89, 277 21 Libechov, Czech Republic
| | - Lenka Gahurova
- Laboratory of Biochemistry and Molecular Biology of Germ Cells, Institute of Animal Physiology and Genetics of the Czech Academy of Sciences, Rumburska 89, 277 21 Libechov, Czech Republic
| | - Alexander W Bruce
- Laboratory of Early Mammalian Developmental Biology, Department of Molecular Biology & Genetics, Faculty of Science, University of South Bohemia in České Budějovice, Branisovšká 31a, České Budějovice, Czech Republic
| | - Tomas Masek
- Laboratory of RNA Biochemistry, Department of Genetics and Microbiology, Faculty of Science, Charles University, Viničná 5, 128 44 Prague 2, Czech Republic
| | - Martin Pospisek
- Laboratory of RNA Biochemistry, Department of Genetics and Microbiology, Faculty of Science, Charles University, Viničná 5, 128 44 Prague 2, Czech Republic
| | - Filip Horvat
- Laboratory of Epigenetic Regulations, Institute of Molecular Genetics of the Czech Academy of Sciences, Videnska 1083, 142 20 Prague 4, Czech Republic
- Bioinformatics Group, Division of Molecular Biology, Department of Biology, Faculty of Science, University of Zagreb, 10000, Zagreb, Croatia
| | - Michal Kubelka
- Laboratory of Biochemistry and Molecular Biology of Germ Cells, Institute of Animal Physiology and Genetics of the Czech Academy of Sciences, Rumburska 89, 277 21 Libechov, Czech Republic
| | - Zongliang Jiang
- Department of Animal Sciences, University of Florida, Gainesville, FL 32610, USA
| | - Andrej Susor
- Laboratory of Biochemistry and Molecular Biology of Germ Cells, Institute of Animal Physiology and Genetics of the Czech Academy of Sciences, Rumburska 89, 277 21 Libechov, Czech Republic
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3
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Ruan P, Wang M, Cheng A, Zhao X, Yang Q, Wu Y, Zhang S, Tian B, Huang J, Ou X, Gao Q, Sun D, He Y, Wu Z, Zhu D, Jia R, Chen S, Liu M. Mechanism of herpesvirus UL24 protein regulating viral immune escape and virulence. Front Microbiol 2023; 14:1268429. [PMID: 37808279 PMCID: PMC10559885 DOI: 10.3389/fmicb.2023.1268429] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2023] [Accepted: 09/08/2023] [Indexed: 10/10/2023] Open
Abstract
Herpesviruses have evolved a series of abilities involved in the process of host infection that are conducive to virus survival and adaptation to the host, such as immune escape, latent infection, and induction of programmed cell death for sustainable infection. The herpesvirus gene UL24 encodes a highly conserved core protein that plays an important role in effective viral infection. The UL24 protein can inhibit the innate immune response of the host by acting on multiple immune signaling pathways during virus infection, and it also plays a key role in the proliferation and pathogenicity of the virus in the later stage of infection. This article reviews the mechanism by which the UL24 protein mediates herpesvirus immune escape and its effects on viral proliferation and virulence by influencing syncytial formation, DNA damage and the cell cycle. Reviewing these studies will enhance our understanding of the pathogenesis of herpesvirus infection and provide evidence for new strategies to combat against viral infection.
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Affiliation(s)
- Peilin Ruan
- Engineering Research Center of Southwest Animal Disease Prevention and Control Technology, Ministry of Education of the People's Republic of China, Chengdu, China
- Key Laboratory of Animal Disease and Human Health of Sichuan Province, Chengdu, China
- International Joint Research Center for Animal Disease Prevention and Control of Sichuan Province, Chengdu, China
- Institute of Veterinary Medicine and Immunology, Sichuan Agricultural University, Chengdu, China
- Research Center of Avian Disease, College of Veterinary Medicine, Sichuan Agricultural University, Chengdu, China
| | - Mingshu Wang
- Engineering Research Center of Southwest Animal Disease Prevention and Control Technology, Ministry of Education of the People's Republic of China, Chengdu, China
- Key Laboratory of Animal Disease and Human Health of Sichuan Province, Chengdu, China
- International Joint Research Center for Animal Disease Prevention and Control of Sichuan Province, Chengdu, China
- Institute of Veterinary Medicine and Immunology, Sichuan Agricultural University, Chengdu, China
- Research Center of Avian Disease, College of Veterinary Medicine, Sichuan Agricultural University, Chengdu, China
| | - Anchun Cheng
- Engineering Research Center of Southwest Animal Disease Prevention and Control Technology, Ministry of Education of the People's Republic of China, Chengdu, China
- Key Laboratory of Animal Disease and Human Health of Sichuan Province, Chengdu, China
- International Joint Research Center for Animal Disease Prevention and Control of Sichuan Province, Chengdu, China
- Institute of Veterinary Medicine and Immunology, Sichuan Agricultural University, Chengdu, China
- Research Center of Avian Disease, College of Veterinary Medicine, Sichuan Agricultural University, Chengdu, China
| | - Xinxin Zhao
- Engineering Research Center of Southwest Animal Disease Prevention and Control Technology, Ministry of Education of the People's Republic of China, Chengdu, China
- Key Laboratory of Animal Disease and Human Health of Sichuan Province, Chengdu, China
- International Joint Research Center for Animal Disease Prevention and Control of Sichuan Province, Chengdu, China
- Institute of Veterinary Medicine and Immunology, Sichuan Agricultural University, Chengdu, China
- Research Center of Avian Disease, College of Veterinary Medicine, Sichuan Agricultural University, Chengdu, China
| | - Qiao Yang
- Engineering Research Center of Southwest Animal Disease Prevention and Control Technology, Ministry of Education of the People's Republic of China, Chengdu, China
- Key Laboratory of Animal Disease and Human Health of Sichuan Province, Chengdu, China
- International Joint Research Center for Animal Disease Prevention and Control of Sichuan Province, Chengdu, China
- Institute of Veterinary Medicine and Immunology, Sichuan Agricultural University, Chengdu, China
- Research Center of Avian Disease, College of Veterinary Medicine, Sichuan Agricultural University, Chengdu, China
| | - Ying Wu
- Engineering Research Center of Southwest Animal Disease Prevention and Control Technology, Ministry of Education of the People's Republic of China, Chengdu, China
- Key Laboratory of Animal Disease and Human Health of Sichuan Province, Chengdu, China
- International Joint Research Center for Animal Disease Prevention and Control of Sichuan Province, Chengdu, China
- Institute of Veterinary Medicine and Immunology, Sichuan Agricultural University, Chengdu, China
- Research Center of Avian Disease, College of Veterinary Medicine, Sichuan Agricultural University, Chengdu, China
| | - Shaqiu Zhang
- Engineering Research Center of Southwest Animal Disease Prevention and Control Technology, Ministry of Education of the People's Republic of China, Chengdu, China
- Key Laboratory of Animal Disease and Human Health of Sichuan Province, Chengdu, China
- International Joint Research Center for Animal Disease Prevention and Control of Sichuan Province, Chengdu, China
- Institute of Veterinary Medicine and Immunology, Sichuan Agricultural University, Chengdu, China
- Research Center of Avian Disease, College of Veterinary Medicine, Sichuan Agricultural University, Chengdu, China
| | - Bin Tian
- Engineering Research Center of Southwest Animal Disease Prevention and Control Technology, Ministry of Education of the People's Republic of China, Chengdu, China
- Key Laboratory of Animal Disease and Human Health of Sichuan Province, Chengdu, China
- International Joint Research Center for Animal Disease Prevention and Control of Sichuan Province, Chengdu, China
- Institute of Veterinary Medicine and Immunology, Sichuan Agricultural University, Chengdu, China
- Research Center of Avian Disease, College of Veterinary Medicine, Sichuan Agricultural University, Chengdu, China
| | - Juan Huang
- Engineering Research Center of Southwest Animal Disease Prevention and Control Technology, Ministry of Education of the People's Republic of China, Chengdu, China
- Key Laboratory of Animal Disease and Human Health of Sichuan Province, Chengdu, China
- International Joint Research Center for Animal Disease Prevention and Control of Sichuan Province, Chengdu, China
- Institute of Veterinary Medicine and Immunology, Sichuan Agricultural University, Chengdu, China
- Research Center of Avian Disease, College of Veterinary Medicine, Sichuan Agricultural University, Chengdu, China
| | - Xumin Ou
- Engineering Research Center of Southwest Animal Disease Prevention and Control Technology, Ministry of Education of the People's Republic of China, Chengdu, China
- Key Laboratory of Animal Disease and Human Health of Sichuan Province, Chengdu, China
- International Joint Research Center for Animal Disease Prevention and Control of Sichuan Province, Chengdu, China
- Institute of Veterinary Medicine and Immunology, Sichuan Agricultural University, Chengdu, China
- Research Center of Avian Disease, College of Veterinary Medicine, Sichuan Agricultural University, Chengdu, China
| | - Qun Gao
- Engineering Research Center of Southwest Animal Disease Prevention and Control Technology, Ministry of Education of the People's Republic of China, Chengdu, China
- Key Laboratory of Animal Disease and Human Health of Sichuan Province, Chengdu, China
- International Joint Research Center for Animal Disease Prevention and Control of Sichuan Province, Chengdu, China
- Institute of Veterinary Medicine and Immunology, Sichuan Agricultural University, Chengdu, China
- Research Center of Avian Disease, College of Veterinary Medicine, Sichuan Agricultural University, Chengdu, China
| | - Di Sun
- Engineering Research Center of Southwest Animal Disease Prevention and Control Technology, Ministry of Education of the People's Republic of China, Chengdu, China
- Key Laboratory of Animal Disease and Human Health of Sichuan Province, Chengdu, China
- International Joint Research Center for Animal Disease Prevention and Control of Sichuan Province, Chengdu, China
- Institute of Veterinary Medicine and Immunology, Sichuan Agricultural University, Chengdu, China
- Research Center of Avian Disease, College of Veterinary Medicine, Sichuan Agricultural University, Chengdu, China
| | - Yu He
- Engineering Research Center of Southwest Animal Disease Prevention and Control Technology, Ministry of Education of the People's Republic of China, Chengdu, China
- Key Laboratory of Animal Disease and Human Health of Sichuan Province, Chengdu, China
- International Joint Research Center for Animal Disease Prevention and Control of Sichuan Province, Chengdu, China
- Institute of Veterinary Medicine and Immunology, Sichuan Agricultural University, Chengdu, China
- Research Center of Avian Disease, College of Veterinary Medicine, Sichuan Agricultural University, Chengdu, China
| | - Zhen Wu
- Engineering Research Center of Southwest Animal Disease Prevention and Control Technology, Ministry of Education of the People's Republic of China, Chengdu, China
- Key Laboratory of Animal Disease and Human Health of Sichuan Province, Chengdu, China
- International Joint Research Center for Animal Disease Prevention and Control of Sichuan Province, Chengdu, China
- Institute of Veterinary Medicine and Immunology, Sichuan Agricultural University, Chengdu, China
- Research Center of Avian Disease, College of Veterinary Medicine, Sichuan Agricultural University, Chengdu, China
| | - Dekang Zhu
- Engineering Research Center of Southwest Animal Disease Prevention and Control Technology, Ministry of Education of the People's Republic of China, Chengdu, China
- Key Laboratory of Animal Disease and Human Health of Sichuan Province, Chengdu, China
- International Joint Research Center for Animal Disease Prevention and Control of Sichuan Province, Chengdu, China
- Research Center of Avian Disease, College of Veterinary Medicine, Sichuan Agricultural University, Chengdu, China
| | - Renyong Jia
- Engineering Research Center of Southwest Animal Disease Prevention and Control Technology, Ministry of Education of the People's Republic of China, Chengdu, China
- Key Laboratory of Animal Disease and Human Health of Sichuan Province, Chengdu, China
- International Joint Research Center for Animal Disease Prevention and Control of Sichuan Province, Chengdu, China
- Institute of Veterinary Medicine and Immunology, Sichuan Agricultural University, Chengdu, China
- Research Center of Avian Disease, College of Veterinary Medicine, Sichuan Agricultural University, Chengdu, China
| | - Shun Chen
- Engineering Research Center of Southwest Animal Disease Prevention and Control Technology, Ministry of Education of the People's Republic of China, Chengdu, China
- Key Laboratory of Animal Disease and Human Health of Sichuan Province, Chengdu, China
- International Joint Research Center for Animal Disease Prevention and Control of Sichuan Province, Chengdu, China
- Institute of Veterinary Medicine and Immunology, Sichuan Agricultural University, Chengdu, China
- Research Center of Avian Disease, College of Veterinary Medicine, Sichuan Agricultural University, Chengdu, China
| | - Mafeng Liu
- Engineering Research Center of Southwest Animal Disease Prevention and Control Technology, Ministry of Education of the People's Republic of China, Chengdu, China
- Key Laboratory of Animal Disease and Human Health of Sichuan Province, Chengdu, China
- International Joint Research Center for Animal Disease Prevention and Control of Sichuan Province, Chengdu, China
- Institute of Veterinary Medicine and Immunology, Sichuan Agricultural University, Chengdu, China
- Research Center of Avian Disease, College of Veterinary Medicine, Sichuan Agricultural University, Chengdu, China
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Kim J, Chun Y, Ramirez CB, Hoffner LA, Jung S, Jang KH, Rubtsova VI, Jang C, Lee G. MAPK13 stabilization via m 6A mRNA modification limits anticancer efficacy of rapamycin. J Biol Chem 2023; 299:105175. [PMID: 37599001 PMCID: PMC10511813 DOI: 10.1016/j.jbc.2023.105175] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2023] [Revised: 08/10/2023] [Accepted: 08/12/2023] [Indexed: 08/22/2023] Open
Abstract
N6-adenosine methylation (m6A) is the most abundant mRNA modification that controls gene expression through diverse mechanisms. Accordingly, m6A-dependent regulation of oncogenes and tumor suppressors contributes to tumor development. However, the role of m6A-mediated gene regulation upon drug treatment or resistance is poorly understood. Here, we report that m6A modification of mitogen-activated protein kinase 13 (MAPK13) mRNA determines the sensitivity of cancer cells to the mechanistic target of rapamycin complex 1 (mTORC1)-targeting agent rapamycin. mTORC1 induces m6A modification of MAPK13 mRNA at its 3' untranslated region through the methyltransferase-like 3 (METTL3)-METTL14-Wilms' tumor 1-associating protein(WTAP) methyltransferase complex, facilitating its mRNA degradation via an m6A reader protein YTH domain family protein 2. Rapamycin blunts this process and stabilizes MAPK13. On the other hand, genetic or pharmacological inhibition of MAPK13 enhances rapamycin's anticancer effects, which suggests that MAPK13 confers a progrowth signal upon rapamycin treatment, thereby limiting rapamycin efficacy. Together, our data indicate that rapamycin-mediated MAPK13 mRNA stabilization underlies drug resistance, and it should be considered as a promising therapeutic target to sensitize cancer cells to rapamycin.
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Affiliation(s)
- Joohwan Kim
- Department of Microbiology and Molecular Genetics, Chao Family Comprehensive Cancer Center, School of Medicine, University of California Irvine, Irvine, California, USA
| | - Yujin Chun
- Department of Microbiology and Molecular Genetics, Chao Family Comprehensive Cancer Center, School of Medicine, University of California Irvine, Irvine, California, USA
| | - Cuauhtemoc B Ramirez
- Department of Microbiology and Molecular Genetics, Chao Family Comprehensive Cancer Center, School of Medicine, University of California Irvine, Irvine, California, USA; Department of Biological Chemistry, Chao Family Comprehensive Cancer Center, School of Medicine, University of California Irvine, Irvine, California, USA
| | - Lauren A Hoffner
- Department of Microbiology and Molecular Genetics, Chao Family Comprehensive Cancer Center, School of Medicine, University of California Irvine, Irvine, California, USA
| | - Sunhee Jung
- Department of Biological Chemistry, Chao Family Comprehensive Cancer Center, School of Medicine, University of California Irvine, Irvine, California, USA
| | - Ki-Hong Jang
- Department of Microbiology and Molecular Genetics, Chao Family Comprehensive Cancer Center, School of Medicine, University of California Irvine, Irvine, California, USA
| | - Varvara I Rubtsova
- Department of Biological Chemistry, Chao Family Comprehensive Cancer Center, School of Medicine, University of California Irvine, Irvine, California, USA; School of Biological Sciences, University of California Irvine, Irvine, California, USA
| | - Cholsoon Jang
- Department of Biological Chemistry, Chao Family Comprehensive Cancer Center, School of Medicine, University of California Irvine, Irvine, California, USA
| | - Gina Lee
- Department of Microbiology and Molecular Genetics, Chao Family Comprehensive Cancer Center, School of Medicine, University of California Irvine, Irvine, California, USA.
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5
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Salimi K, Alvandi M, Saberi Pirouz M, Rakhshan K, Howatson G. Regulating eEF2 and eEF2K in skeletal muscle by exercise. Arch Physiol Biochem 2023:1-12. [PMID: 36633938 DOI: 10.1080/13813455.2023.2164898] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/16/2022] [Revised: 12/15/2022] [Accepted: 12/29/2022] [Indexed: 01/13/2023]
Abstract
Skeletal muscle is a flexible and adaptable tissue that strongly responds to exercise training. The skeletal muscle responds to exercise by increasing muscle protein synthesis (MPS) when energy is available. One of protein synthesis's major rate-limiting and critical regulatory steps is the translation elongation pathway. The process of translation elongation in skeletal muscle is highly regulated. It requires elongation factors that are intensely affected by various physiological stimuli such as exercise and the total available energy of cells. Studies have shown that exercise involves the elongation pathway by numerous signalling pathways. Since the elongation pathway, has been far less studied than the other translation steps, its comprehensive prospect and quantitative understanding remain in the dark. This study highlights the current understanding of the effect of exercise training on the translation elongation pathway focussing on the molecular factors affecting the pathway, including Ca2+, AMPK, PKA, mTORC1/P70S6K, MAPKs, and myostatin. We further discussed the mode and volume of exercise training intervention on the translation elongation pathway.What is the topic of this review? This review summarises the impacts of exercise training on the translation elongation pathway in skeletal muscle focussing on eEF2 and eEF2K.What advances does it highlight? This review highlights mechanisms and factors that profoundly influence the translation elongation pathway and argues that exercise might modulate the response. This review also combines the experimental observations focussing on the regulation of translation elongation during and after exercise. The findings widen our horizon to the notion of mechanisms involved in muscle protein synthesis (MPS) through translation elongation response to exercise training.
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Affiliation(s)
- Kia Salimi
- Department of Exercise Physiology, Faculty of Sport and Exercise Sciences, University of Tehran, Tehran, Iran
| | - Masoomeh Alvandi
- Department of Biological Science in Sport and Health, University of Shahid Beheshti, Tehran, Iran
| | - Mahdi Saberi Pirouz
- Student Research Committee, Iran University of Medical Sciences, Tehran, Iran
| | - Kamran Rakhshan
- Department of Medical Physiology, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran
- Electrophysiology Research Center, Tehran University of Medical Sciences, Tehran, Iran
| | - Glyn Howatson
- Faculty of Health and Life Sciences, Northumbria University, Newcastle upon Tyne, UK
- Water Research Group, North West University, Potchefstroom, South Africa
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Curtiss BM, VanCampen J, Macaraeg J, Kong GL, Taherinasab A, Tsuchiya M, Yashar WM, Tsang YH, Horton W, Coleman DJ, Estabrook J, Lusardi TA, Mills GB, Druker BJ, Maxson JE, Braun TP. PU.1 and MYC transcriptional network defines synergistic drug responses to KIT and LSD1 inhibition in acute myeloid leukemia. Leukemia 2022; 36:1781-1793. [PMID: 35590033 PMCID: PMC9256806 DOI: 10.1038/s41375-022-01594-1] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2021] [Revised: 05/03/2022] [Accepted: 05/05/2022] [Indexed: 01/03/2023]
Abstract
Responses to kinase-inhibitor therapy in AML are frequently short-lived due to the rapid development of resistance, limiting the clinical efficacy. Combination therapy may improve initial therapeutic responses by targeting pathways used by leukemia cells to escape monotherapy. Here we report that combined inhibition of KIT and lysine-specific demethylase 1 (LSD1) produces synergistic cell death in KIT-mutant AML cell lines and primary patient samples. This drug combination evicts both MYC and PU.1 from chromatin driving cell cycle exit. Using a live cell biosensor for AKT activity, we identify early adaptive changes in kinase signaling following KIT inhibition that are reversed with the addition of LSD1 inhibitor via modulation of the GSK3a/b axis. Multi-omic analyses, including scRNA-seq, ATAC-seq and CUT&Tag, confirm these mechanisms in primary KIT-mutant AML. Collectively, this work provides rational for a clinical trial to assess the efficacy of KIT and LSD1 inhibition in patients with KIT-mutant AML.
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Affiliation(s)
- Brittany M. Curtiss
- Knight Cancer Institute, Oregon Health & Science University, Portland, Oregon, 97239, USA,Division of Oncological Sciences, Oregon Health & Science University, Portland, Oregon, 97239, USA
| | - Jake VanCampen
- Knight Cardiovascular Institute, Oregon Health & Science University, Portland, Oregon, 97239, USA
| | - Jommel Macaraeg
- Knight Cancer Institute, Oregon Health & Science University, Portland, Oregon, 97239, USA,Division of Oncological Sciences, Oregon Health & Science University, Portland, Oregon, 97239, USA
| | - Garth L. Kong
- Knight Cancer Institute, Oregon Health & Science University, Portland, Oregon, 97239, USA,Division of Oncological Sciences, Oregon Health & Science University, Portland, Oregon, 97239, USA
| | - Akram Taherinasab
- Knight Cancer Institute, Oregon Health & Science University, Portland, Oregon, 97239, USA,Division of Oncological Sciences, Oregon Health & Science University, Portland, Oregon, 97239, USA
| | - Mitsuhiro Tsuchiya
- Knight Cancer Institute, Oregon Health & Science University, Portland, Oregon, 97239, USA,Division of Oncological Sciences, Oregon Health & Science University, Portland, Oregon, 97239, USA
| | - William M. Yashar
- Knight Cancer Institute, Oregon Health & Science University, Portland, Oregon, 97239, USA,Division of Oncological Sciences, Oregon Health & Science University, Portland, Oregon, 97239, USA
| | - Yiu H. Tsang
- Knight Cancer Institute, Oregon Health & Science University, Portland, Oregon, 97239, USA,Division of Oncological Sciences, Oregon Health & Science University, Portland, Oregon, 97239, USA
| | - Wesley Horton
- Knight Cancer Institute, Oregon Health & Science University, Portland, Oregon, 97239, USA,Department of Cell, Developmental & Cancer Biology, Oregon Health & Science University, Portland, Oregon, 97239, USA
| | - Daniel J. Coleman
- Knight Cancer Institute, Oregon Health & Science University, Portland, Oregon, 97239, USA
| | - Joseph Estabrook
- Knight Cancer Institute, Oregon Health & Science University, Portland, Oregon, 97239, USA,Cancer Early Detection Advanced Research Center, Oregon Health & Science University, Portland, Oregon, 97239, USA
| | - Theresa A. Lusardi
- Knight Cancer Institute, Oregon Health & Science University, Portland, Oregon, 97239, USA,Cancer Early Detection Advanced Research Center, Oregon Health & Science University, Portland, Oregon, 97239, USA
| | - Gordon B. Mills
- Knight Cancer Institute, Oregon Health & Science University, Portland, Oregon, 97239, USA,Division of Oncological Sciences, Oregon Health & Science University, Portland, Oregon, 97239, USA
| | - Brian J. Druker
- Knight Cancer Institute, Oregon Health & Science University, Portland, Oregon, 97239, USA,Division of Oncological Sciences, Oregon Health & Science University, Portland, Oregon, 97239, USA,Division of Hematology & Medical Oncology, Oregon Health & Science University, Portland, Oregon, 97239, USA
| | - Julia E. Maxson
- Knight Cancer Institute, Oregon Health & Science University, Portland, Oregon, 97239, USA,Division of Oncological Sciences, Oregon Health & Science University, Portland, Oregon, 97239, USA,Department of Cell, Developmental & Cancer Biology, Oregon Health & Science University, Portland, Oregon, 97239, USA,Division of Hematology & Medical Oncology, Oregon Health & Science University, Portland, Oregon, 97239, USA
| | - Theodore P. Braun
- Knight Cancer Institute, Oregon Health & Science University, Portland, Oregon, 97239, USA,Division of Oncological Sciences, Oregon Health & Science University, Portland, Oregon, 97239, USA,Division of Hematology & Medical Oncology, Oregon Health & Science University, Portland, Oregon, 97239, USA
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7
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Lewis V, Rodrigue B, Arsenault E, Zhang M, Taghavi-Abkuh FF, Silva WCC, Myers M, Matta-Camacho E, Aguilar-Valles A. Translational control by ketamine and its implications for comorbid cognitive deficits in depressive disorders. J Neurochem 2022. [PMID: 35680556 DOI: 10.1111/jnc.15652] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2022] [Revised: 05/19/2022] [Accepted: 05/26/2022] [Indexed: 11/29/2022]
Abstract
Ketamine has shown antidepressant effects in patients with major depressive disorder (MDD) resistant to first-line treatments and approved for use in this patient population. Ketamine induces several forms of synaptic plasticity, which are proposed to underlie its antidepressant effects. However, the molecular mechanism of action directly responsible for ketamine's antidepressant effects remains under active investigation. It was recently demonstrated that the effectors of the mammalian target of rapamycin complex 1 (mTORC1) signalling pathway, namely, eukaryotic initiation factor 4E (eIF4E) binding proteins 1 and 2 (4E-BP1 and 4E-BP2), are central in mediating ketamine-induced synaptic plasticity and behavioural antidepressant-like effect. 4E-BPs are a family of messenger ribonucleic acid (mRNA) translation repressors inactivated by mTORC1. We observed that their expression in inhibitory interneurons mediates ketamine's effects in the forced swim and novelty suppressed feeding tests and the long-lasting inhibition of GABAergic neurotransmission in the hippocampus. In addition, another effector pathway that regulates translation elongation downstream of mTORC1, the eukaryotic elongation factor 2 kinase (eEF2K), has been implicated in ketamine's behavioural effects. We will discuss how ketamine's rapid antidepressant effect depends on the activation of neuronal mRNA translation through 4E-BP1/2 and eEF2K. Furthermore, given that these pathways also regulate cognitive functions, we will discuss the evidence of ketamine's effect on cognitive function in MDD. Overall, the data accrued from pre-clinical research have implicated the mRNA translation pathways in treating mood symptoms of MDD. However, it is yet unclear whether the pro-cognitive potential of subanesthetic ketamine in rodents also engages these pathways and whether such an effect is consistently observed in the treatment-resistant MDD population.
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Affiliation(s)
- Vern Lewis
- Department of Neuroscience, Carleton University, Ottawa, Ontario, Canada
| | - Brandon Rodrigue
- Department of Neuroscience, Carleton University, Ottawa, Ontario, Canada
| | - Emily Arsenault
- Department of Neuroscience, Carleton University, Ottawa, Ontario, Canada
| | - Molly Zhang
- Department of Neuroscience, Carleton University, Ottawa, Ontario, Canada
| | | | | | - Mysa Myers
- Department of Neuroscience, Carleton University, Ottawa, Ontario, Canada
| | - Edna Matta-Camacho
- Department of Neuroscience, Carleton University, Ottawa, Ontario, Canada
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8
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Hijazi M, Casado P, Akhtar N, Alvarez-Teijeiro S, Rajeeve V, Cutillas PR. eEF2K Activity Determines Synergy to Cotreatment of Cancer Cells With PI3K and MEK Inhibitors. Mol Cell Proteomics 2022; 21:100240. [PMID: 35513296 PMCID: PMC9184568 DOI: 10.1016/j.mcpro.2022.100240] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2021] [Revised: 03/17/2022] [Accepted: 04/25/2022] [Indexed: 10/31/2022] Open
Abstract
PI3K-mammalian target of rapamycin and MAPK/ERK kinase (MEK)/mitogen-activated protein kinase (MAPK) are the most frequently dysregulated signaling pathways in cancer. A problem that limits the success of therapies that target individual PI3K-MAPK members is that these pathways converge to regulate downstream functions and often compensate each other, leading to drug resistance and transient responses to therapy. In order to overcome resistance, therapies based on cotreatments with PI3K/AKT and MEK/MAPK inhibitors are now being investigated in clinical trials, but the mechanisms of sensitivity to cotreatment are not fully understood. Using LC-MS/MS-based phosphoproteomics, we found that eukaryotic elongation factor 2 kinase (eEF2K), a key convergence point downstream of MAPK and PI3K pathways, mediates synergism to cotreatment with trametinib plus pictilisib (which target MEK1/2 and PI3Kα/δ, respectively). Inhibition of eEF2K by siRNA or with a small molecule inhibitor reversed the antiproliferative effects of the cotreatment with PI3K plus MEK inhibitors in a cell model-specific manner. Systematic analysis in 12 acute myeloid leukemia cell lines revealed that eEF2K activity was increased in cells for which PI3K plus MEKi cotreatment is synergistic, while PKC potentially mediated resistance to such cotreatment. Together, our study uncovers eEF2K activity as a key mediator of responses to PI3Ki plus MEKi and as a potential biomarker to predict synergy to cotreatment in cancer cells.
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Affiliation(s)
- Maruan Hijazi
- Signalling & Proteomics Group, Centre for Genomics and Computational Biology, Barts Cancer Institute, Queen Mary University of London, London, United Kingdom.
| | - Pedro Casado
- Signalling & Proteomics Group, Centre for Genomics and Computational Biology, Barts Cancer Institute, Queen Mary University of London, London, United Kingdom
| | - Nosheen Akhtar
- Signalling & Proteomics Group, Centre for Genomics and Computational Biology, Barts Cancer Institute, Queen Mary University of London, London, United Kingdom
| | - Saul Alvarez-Teijeiro
- Signalling & Proteomics Group, Centre for Genomics and Computational Biology, Barts Cancer Institute, Queen Mary University of London, London, United Kingdom
| | - Vinothini Rajeeve
- Signalling & Proteomics Group, Centre for Genomics and Computational Biology, Barts Cancer Institute, Queen Mary University of London, London, United Kingdom
| | - Pedro R Cutillas
- Signalling & Proteomics Group, Centre for Genomics and Computational Biology, Barts Cancer Institute, Queen Mary University of London, London, United Kingdom; The Alan Turing Institute, British Library, London, United Kingdom.
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9
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Deng G, Zeng F, He Y, Meng Y, Sun H, Su J, Zhao S, Cheng Y, Chen X, Yin M. EEF2K silencing inhibits tumour progression through repressing SPP1 and synergises with BET inhibitors in melanoma. Clin Transl Med 2022; 12:e722. [PMID: 35184394 PMCID: PMC8858631 DOI: 10.1002/ctm2.722] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2021] [Revised: 01/11/2022] [Accepted: 01/17/2022] [Indexed: 01/05/2023] Open
Affiliation(s)
- Guangtong Deng
- Department of Dermatology Hunan Engineering Research Center of Skin Health and Disease Hunan Key Laboratory of Skin Cancer and Psoriasis Xiangya Hospital Central South University Changsha Hunan China
- National Clinical Research Center for Geriatric Disorders Xiangya Hospital Central South University Changsha Hunan China
| | - Furong Zeng
- Department of Dermatology Hunan Engineering Research Center of Skin Health and Disease Hunan Key Laboratory of Skin Cancer and Psoriasis Xiangya Hospital Central South University Changsha Hunan China
- National Clinical Research Center for Geriatric Disorders Xiangya Hospital Central South University Changsha Hunan China
- Department of Oncology Xiangya Hospital Central South University Changsha Hunan China
| | - Yi He
- Department of Dermatology Hunan Engineering Research Center of Skin Health and Disease Hunan Key Laboratory of Skin Cancer and Psoriasis Xiangya Hospital Central South University Changsha Hunan China
- National Clinical Research Center for Geriatric Disorders Xiangya Hospital Central South University Changsha Hunan China
| | - Yu Meng
- Department of Dermatology Hunan Engineering Research Center of Skin Health and Disease Hunan Key Laboratory of Skin Cancer and Psoriasis Xiangya Hospital Central South University Changsha Hunan China
- National Clinical Research Center for Geriatric Disorders Xiangya Hospital Central South University Changsha Hunan China
| | - Huiyan Sun
- Department of Dermatology Hunan Engineering Research Center of Skin Health and Disease Hunan Key Laboratory of Skin Cancer and Psoriasis Xiangya Hospital Central South University Changsha Hunan China
- National Clinical Research Center for Geriatric Disorders Xiangya Hospital Central South University Changsha Hunan China
| | - Juan Su
- Department of Dermatology Hunan Engineering Research Center of Skin Health and Disease Hunan Key Laboratory of Skin Cancer and Psoriasis Xiangya Hospital Central South University Changsha Hunan China
- National Clinical Research Center for Geriatric Disorders Xiangya Hospital Central South University Changsha Hunan China
| | - Shuang Zhao
- Department of Dermatology Hunan Engineering Research Center of Skin Health and Disease Hunan Key Laboratory of Skin Cancer and Psoriasis Xiangya Hospital Central South University Changsha Hunan China
- National Clinical Research Center for Geriatric Disorders Xiangya Hospital Central South University Changsha Hunan China
| | - Yan Cheng
- Department of Pharmacy The Second Xiangya Hospital Central South University Changsha Hunan China
| | - Xiang Chen
- Department of Dermatology Hunan Engineering Research Center of Skin Health and Disease Hunan Key Laboratory of Skin Cancer and Psoriasis Xiangya Hospital Central South University Changsha Hunan China
- National Clinical Research Center for Geriatric Disorders Xiangya Hospital Central South University Changsha Hunan China
| | - Mingzhu Yin
- Department of Dermatology Hunan Engineering Research Center of Skin Health and Disease Hunan Key Laboratory of Skin Cancer and Psoriasis Xiangya Hospital Central South University Changsha Hunan China
- National Clinical Research Center for Geriatric Disorders Xiangya Hospital Central South University Changsha Hunan China
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10
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Ballard DJ, Peng HY, Das JK, Kumar A, Wang L, Ren Y, Xiong X, Ren X, Yang JM, Song J. Insights Into the Pathologic Roles and Regulation of Eukaryotic Elongation Factor-2 Kinase. Front Mol Biosci 2021; 8:727863. [PMID: 34532346 PMCID: PMC8438118 DOI: 10.3389/fmolb.2021.727863] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2021] [Accepted: 08/16/2021] [Indexed: 12/14/2022] Open
Abstract
Eukaryotic Elongation Factor-2 Kinase (eEF2K) acts as a negative regulator of protein synthesis, translation, and cell growth. As a structurally unique member of the alpha-kinase family, eEF2K is essential to cell survival under stressful conditions, as it contributes to both cell viability and proliferation. Known as the modulator of the global rate of protein translation, eEF2K inhibits eEF2 (eukaryotic Elongation Factor 2) and decreases translation elongation when active. eEF2K is regulated by various mechanisms, including phosphorylation through residues and autophosphorylation. Specifically, this protein kinase is downregulated through the phosphorylation of multiple sites via mTOR signaling and upregulated via the AMPK pathway. eEF2K plays important roles in numerous biological systems, including neurology, cardiology, myology, and immunology. This review provides further insights into the current roles of eEF2K and its potential to be explored as a therapeutic target for drug development.
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Affiliation(s)
- Darby J. Ballard
- Department of Microbial Pathogenesis and Immunology, Texas A&M University Health Science Center, Bryan, TX, United States
| | - Hao-Yun Peng
- Department of Microbial Pathogenesis and Immunology, Texas A&M University Health Science Center, Bryan, TX, United States
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, TX, United States
| | - Jugal Kishore Das
- Department of Microbial Pathogenesis and Immunology, Texas A&M University Health Science Center, Bryan, TX, United States
| | - Anil Kumar
- Department of Microbial Pathogenesis and Immunology, Texas A&M University Health Science Center, Bryan, TX, United States
| | - Liqing Wang
- Department of Microbial Pathogenesis and Immunology, Texas A&M University Health Science Center, Bryan, TX, United States
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, TX, United States
| | - Yijie Ren
- Department of Microbial Pathogenesis and Immunology, Texas A&M University Health Science Center, Bryan, TX, United States
| | - Xiaofang Xiong
- Department of Microbial Pathogenesis and Immunology, Texas A&M University Health Science Center, Bryan, TX, United States
| | - Xingcong Ren
- Department of Toxicology and Cancer Biology, University of Kentucky College of Medicine, Lexington, KY, United States
| | - Jin-Ming Yang
- Department of Toxicology and Cancer Biology, University of Kentucky College of Medicine, Lexington, KY, United States
| | - Jianxun Song
- Department of Microbial Pathogenesis and Immunology, Texas A&M University Health Science Center, Bryan, TX, United States
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11
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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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12
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Elongation factor eEF2 kinase and autophagy jointly promote survival of cancer cells. Biochem J 2021; 478:1547-1569. [PMID: 33779695 DOI: 10.1042/bcj20210126] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2021] [Revised: 03/22/2021] [Accepted: 03/29/2021] [Indexed: 01/07/2023]
Abstract
Cells within solid tumours can become deprived of nutrients; in order to survive, they need to invoke mechanisms to conserve these resources. Using cancer cells in culture in the absence of key nutrients, we have explored the roles of two potential survival mechanisms, autophagy and elongation factor 2 kinase (eEF2K), which, when activated, inhibits the resource-intensive elongation stage of protein synthesis. Both processes are regulated through the nutrient-sensitive AMP-activated protein kinase and mechanistic target of rapamycin complex 1 signalling pathways. We find that disabling both autophagy and eEF2K strongly compromises the survival of nutrient-deprived lung and breast cancer cells, whereas, for example, knocking out eEF2K alone has little effect. Contrary to some earlier reports, we find no evidence that eEF2K regulates autophagy. Unexpectedly, eEF2K does not facilitate survival of prostate cancer PC3 cells. Thus, eEF2K and autophagy enable survival of certain cell-types in a mutually complementary manner. To explore this further, we generated, by selection, cells which were able to survive nutrient starvation even when autophagy and eEF2K were disabled. Proteome profiling using mass spectrometry revealed that these 'resistant' cells showed lower levels of diverse proteins which are required for energy-consuming processes such as protein and fatty acid synthesis, although different clones of 'resistant cells' appear to adapt in dissimilar ways. Our data provide further information of the ways that human cells cope with nutrient limitation and to understanding of the utility of eEF2K as a potential target in oncology.
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13
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Shen Y, Zhang ZC, Cheng S, Liu A, Zuo J, Xia S, Liu X, Liu W, Jia Z, Xie W, Han J. PQBP1 promotes translational elongation and regulates hippocampal mGluR-LTD by suppressing eEF2 phosphorylation. Mol Cell 2021; 81:1425-1438.e10. [PMID: 33662272 DOI: 10.1016/j.molcel.2021.01.032] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2020] [Revised: 12/07/2020] [Accepted: 01/21/2021] [Indexed: 10/22/2022]
Abstract
Eukaryotic elongation factor 2 (eEF2) mediates translocation of peptidyl-tRNA from the ribosomal A site to the P site to promote translational elongation. Its phosphorylation on Thr56 by its single known kinase eEF2K inactivates it and inhibits translational elongation. Extensive studies have revealed that different signal cascades modulate eEF2K activity, but whether additional factors regulate phosphorylation of eEF2 remains unclear. Here, we find that the X chromosome-linked intellectual disability protein polyglutamine-binding protein 1 (PQBP1) specifically binds to non-phosphorylated eEF2 and suppresses eEF2K-mediated phosphorylation at Thr56. Loss of PQBP1 significantly reduces general protein synthesis by suppressing translational elongation. Moreover, we show that PQBP1 regulates hippocampal metabotropic glutamate receptor-dependent long-term depression (mGluR-LTD) and mGluR-LTD-associated behaviors by suppressing eEF2K-mediated phosphorylation. Our results identify PQBP1 as a novel regulator in translational elongation and mGluR-LTD, and this newly revealed regulator in the eEF2K/eEF2 pathway is also an excellent therapeutic target for various disease conditions, such as neural diseases, virus infection, and cancer.
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Affiliation(s)
- Yuqian Shen
- School of Life Science and Technology, Key Laboratory of Developmental Genes and Human Disease, Southeast University, Nanjing 210096, China
| | - Zi Chao Zhang
- School of Life Science and Technology, Key Laboratory of Developmental Genes and Human Disease, Southeast University, Nanjing 210096, China; Co-innovation Center of Neuroregeneration, Nantong University, Nantong, Jiangsu 226001, China.
| | - Shanshan Cheng
- School of Life Science and Technology, Key Laboratory of Developmental Genes and Human Disease, Southeast University, Nanjing 210096, China
| | - An Liu
- School of Life Science and Technology, Key Laboratory of Developmental Genes and Human Disease, Southeast University, Nanjing 210096, China
| | - Jian Zuo
- School of Life Science and Technology, Key Laboratory of Developmental Genes and Human Disease, Southeast University, Nanjing 210096, China
| | - Shuting Xia
- Institute of Neuroscience, Soochow University, Suzhou 215000, China
| | - Xian Liu
- School of Life Science and Technology, Key Laboratory of Developmental Genes and Human Disease, Southeast University, Nanjing 210096, China
| | - Wenhua Liu
- School of Life Science and Technology, Key Laboratory of Developmental Genes and Human Disease, Southeast University, Nanjing 210096, China
| | - Zhengping Jia
- Neurosciences and Mental Health Program, Hospital for Sick Children, University of Toronto, Toronto, ON M5S 1A1, Canada
| | - Wei Xie
- School of Life Science and Technology, Key Laboratory of Developmental Genes and Human Disease, Southeast University, Nanjing 210096, China; Co-innovation Center of Neuroregeneration, Nantong University, Nantong, Jiangsu 226001, China
| | - Junhai Han
- School of Life Science and Technology, Key Laboratory of Developmental Genes and Human Disease, Southeast University, Nanjing 210096, China; Co-innovation Center of Neuroregeneration, Nantong University, Nantong, Jiangsu 226001, China; Department of Neurology, Affiliated ZhongDa Hospital, Institute of Neuropsychiatry, Southeast University, Nanjing, Jiangsu 210009, China.
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14
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Progress in the Development of Eukaryotic Elongation Factor 2 Kinase (eEF2K) Natural Product and Synthetic Small Molecule Inhibitors for Cancer Chemotherapy. Int J Mol Sci 2021; 22:ijms22052408. [PMID: 33673713 PMCID: PMC7957638 DOI: 10.3390/ijms22052408] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2021] [Revised: 02/24/2021] [Accepted: 02/24/2021] [Indexed: 12/12/2022] Open
Abstract
Eukaryotic elongation factor 2 kinase (eEF2K or Ca2+/calmodulin-dependent protein kinase, CAMKIII) is a new member of an atypical α-kinase family different from conventional protein kinases that is now considered as a potential target for the treatment of cancer. This protein regulates the phosphorylation of eukaryotic elongation factor 2 (eEF2) to restrain activity and inhibit the elongation stage of protein synthesis. Mounting evidence shows that eEF2K regulates the cell cycle, autophagy, apoptosis, angiogenesis, invasion, and metastasis in several types of cancers. The expression of eEF2K promotes survival of cancer cells, and the level of this protein is increased in many cancer cells to adapt them to the microenvironment conditions including hypoxia, nutrient depletion, and acidosis. The physiological function of eEF2K and its role in the development and progression of cancer are here reviewed in detail. In addition, a summary of progress for in vitro eEF2K inhibitors from anti-cancer drug discovery research in recent years, along with their structure-activity relationships (SARs) and synthetic routes or natural sources, is also described. Special attention is given to those inhibitors that have been already validated in vivo, with the overall aim to provide reference context for the further development of new first-in-class anti-cancer drugs that target eEF2K.
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15
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Chander Y, Kumar R, Khandelwal N, Singh N, Shringi BN, Barua S, Kumar N. Role of p38 mitogen-activated protein kinase signalling in virus replication and potential for developing broad spectrum antiviral drugs. Rev Med Virol 2021; 31:1-16. [PMID: 33450133 DOI: 10.1002/rmv.2217] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2020] [Revised: 12/21/2020] [Accepted: 12/23/2020] [Indexed: 12/11/2022]
Abstract
Mitogen-activated protein kinases (MAPKs) play a key role in complex cellular processes such as proliferation, development, differentiation, transformation and apoptosis. Mammals express at least four distinctly regulated groups of MAPKs which include extracellular signal-related kinases (ERK)-1/2, p38 proteins, Jun amino-terminal kinases (JNK1/2/3) and ERK5. p38 MAPK is activated by a wide range of cellular stresses and modulates activity of several downstream kinases and transcription factors which are involved in regulating cytoskeleton remodeling, cell cycle modulation, inflammation, antiviral response and apoptosis. In viral infections, activation of cell signalling pathways is part of the cellular defense mechanism with the basic aim of inducing an antiviral state. However, viruses can exploit enhanced cell signalling activities to support various stages of their replication cycles. Kinase activity can be inhibited by small molecule chemical inhibitors, so one strategy to develop antiviral drugs is to target these cellular signalling pathways. In this review, we provide an overview on the current understanding of various cellular and viral events regulated by the p38 signalling pathway, with a special emphasis on targeting these events for antiviral drug development which might identify candidates with broad spectrum activity.
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Affiliation(s)
- Yogesh Chander
- National Centre for Veterinary Type Cultures, ICAR-National Research Centre on Equines, Hisar, Haryana, India.,Department of Bio and Nano Technology, Guru Jambeshwar University of Science and Technology, Hisar, Haryana, India
| | - Ram Kumar
- National Centre for Veterinary Type Cultures, ICAR-National Research Centre on Equines, Hisar, Haryana, India.,Department of Veterinary Microbiology and Biotechnology, Rajasthan University of Veterinary and Animal Sciences, Bikaner, India
| | - Nitin Khandelwal
- National Centre for Veterinary Type Cultures, ICAR-National Research Centre on Equines, Hisar, Haryana, India.,Department of Biotechnology, GLA University, Mathura, India
| | - Namita Singh
- Department of Bio and Nano Technology, Guru Jambeshwar University of Science and Technology, Hisar, Haryana, India
| | - Brij Nandan Shringi
- Department of Veterinary Microbiology and Biotechnology, Rajasthan University of Veterinary and Animal Sciences, Bikaner, India
| | - Sanjay Barua
- National Centre for Veterinary Type Cultures, ICAR-National Research Centre on Equines, Hisar, Haryana, India
| | - Naveen Kumar
- National Centre for Veterinary Type Cultures, ICAR-National Research Centre on Equines, Hisar, Haryana, India
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16
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Ji X, Zhang X, Li Z. ULK1 inhibitor induces spindle microtubule disorganization and inhibits phosphorylation of Ser10 of histone H3. FEBS Open Bio 2020; 10:2452-2463. [PMID: 33040463 PMCID: PMC7609780 DOI: 10.1002/2211-5463.13000] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2020] [Revised: 08/20/2020] [Accepted: 10/08/2020] [Indexed: 01/28/2023] Open
Abstract
Certain tumors are dependent on autophagy for survival; thus, the use of unc‐51‐like autophagy activating kinase (ULK) 1 inhibitors to block autophagy has the potential for tumor treatment. However, ULK1 inhibitors affect processes other than autophagy. Herein, we report that the ULK1 inhibitors SBI‐0206965/MRT68921 not only inhibit phosphorylation of histone H3 (Ser10) and delay chromatin condensation but also induce spindle microtubule disorganization to form short and fragmented microtubule polymers. Although the delay in chromatin condensation also delayed mitotic entry, the disorganized microtubule polymers resulted in unsegregated chromosomes and polyploidy. Although the effect on mitotic entry was moderate, polyploidy formation was decreased in ULK1 knockout cells with or without ULK2 knockdown. In conclusion, it will be helpful to consider the roles of ULK1 inhibitors in mitotic dysregulation, as well as autophagy, when evaluating their antitumor efficacy.
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Affiliation(s)
- Xinmiao Ji
- High Magnetic Field Laboratory, Key Laboratory of High Magnetic Field and Ion Beam Physical Biology, Hefei Institutes of Physical Science, Chinese Academy of Sciences, Hefei, China
| | - Xin Zhang
- High Magnetic Field Laboratory, Key Laboratory of High Magnetic Field and Ion Beam Physical Biology, Hefei Institutes of Physical Science, Chinese Academy of Sciences, Hefei, China.,Institute of Physical Science and Information Technology, Anhui University, Hefei, China
| | - Zhiyuan Li
- High Magnetic Field Laboratory, Key Laboratory of High Magnetic Field and Ion Beam Physical Biology, Hefei Institutes of Physical Science, Chinese Academy of Sciences, Hefei, China
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17
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Harich B, van der Voet M, Klein M, Čížek P, Fenckova M, Schenck A, Franke B. From Rare Copy Number Variants to Biological Processes in ADHD. Am J Psychiatry 2020; 177:855-866. [PMID: 32600152 DOI: 10.1176/appi.ajp.2020.19090923] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
OBJECTIVE Attention deficit hyperactivity disorder (ADHD) is a highly heritable psychiatric disorder. The objective of this study was to define ADHD-associated candidate genes and their associated molecular modules and biological themes, based on the analysis of rare genetic variants. METHODS The authors combined data from 11 published copy number variation studies in 6,176 individuals with ADHD and 25,026 control subjects and prioritized genes by applying an integrative strategy based on criteria including recurrence in individuals with ADHD, absence in control subjects, complete coverage in copy number gains, and presence in the minimal region common to overlapping copy number variants (CNVs), as well as on protein-protein interactions and information from cross-species genotype-phenotype annotation. RESULTS The authors localized 2,241 eligible genes in the 1,532 reported CNVs, of which they classified 432 as high-priority ADHD candidate genes. The high-priority ADHD candidate genes were significantly coexpressed in the brain. A network of 66 genes was supported by ADHD-relevant phenotypes in the cross-species database. Four significantly interconnected protein modules were found among the high-priority ADHD genes. A total of 26 genes were observed across all applied bioinformatic methods. Lookup in the latest genome-wide association study for ADHD showed that among those 26 genes, POLR3C and RBFOX1 were also supported by common genetic variants. CONCLUSIONS Integration of a stringent filtering procedure in CNV studies with suitable bioinformatics approaches can identify ADHD candidate genes at increased levels of credibility. The authors' analytic pipeline provides additional insight into the molecular mechanisms underlying ADHD and allows prioritization of genes for functional validation in validated model organisms.
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Affiliation(s)
- Benjamin Harich
- Department of Human Genetics (Harich, van der Voet, Klein, Fenckova, Schenck, Franke) and Department of Psychiatry (Franke), Donders Institute for Brain, Cognition, and Behavior, Radboud University Medical Center, Nijmegen, the Netherlands; and Center for Molecular and Biomolecular Informatics, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, the Netherlands (Čížek)
| | - Monique van der Voet
- Department of Human Genetics (Harich, van der Voet, Klein, Fenckova, Schenck, Franke) and Department of Psychiatry (Franke), Donders Institute for Brain, Cognition, and Behavior, Radboud University Medical Center, Nijmegen, the Netherlands; and Center for Molecular and Biomolecular Informatics, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, the Netherlands (Čížek)
| | - Marieke Klein
- Department of Human Genetics (Harich, van der Voet, Klein, Fenckova, Schenck, Franke) and Department of Psychiatry (Franke), Donders Institute for Brain, Cognition, and Behavior, Radboud University Medical Center, Nijmegen, the Netherlands; and Center for Molecular and Biomolecular Informatics, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, the Netherlands (Čížek)
| | - Pavel Čížek
- Department of Human Genetics (Harich, van der Voet, Klein, Fenckova, Schenck, Franke) and Department of Psychiatry (Franke), Donders Institute for Brain, Cognition, and Behavior, Radboud University Medical Center, Nijmegen, the Netherlands; and Center for Molecular and Biomolecular Informatics, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, the Netherlands (Čížek)
| | - Michaela Fenckova
- Department of Human Genetics (Harich, van der Voet, Klein, Fenckova, Schenck, Franke) and Department of Psychiatry (Franke), Donders Institute for Brain, Cognition, and Behavior, Radboud University Medical Center, Nijmegen, the Netherlands; and Center for Molecular and Biomolecular Informatics, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, the Netherlands (Čížek)
| | - Annette Schenck
- Department of Human Genetics (Harich, van der Voet, Klein, Fenckova, Schenck, Franke) and Department of Psychiatry (Franke), Donders Institute for Brain, Cognition, and Behavior, Radboud University Medical Center, Nijmegen, the Netherlands; and Center for Molecular and Biomolecular Informatics, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, the Netherlands (Čížek)
| | - Barbara Franke
- Department of Human Genetics (Harich, van der Voet, Klein, Fenckova, Schenck, Franke) and Department of Psychiatry (Franke), Donders Institute for Brain, Cognition, and Behavior, Radboud University Medical Center, Nijmegen, the Netherlands; and Center for Molecular and Biomolecular Informatics, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, the Netherlands (Čížek)
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18
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Lee K, Kumar EA, Dalby KN, Ghose R. The role of calcium in the interaction between calmodulin and a minimal functional construct of eukaryotic elongation factor 2 kinase. Protein Sci 2020; 28:2089-2098. [PMID: 31626716 DOI: 10.1002/pro.3753] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2019] [Revised: 10/13/2019] [Accepted: 10/15/2019] [Indexed: 12/13/2022]
Abstract
Eukaryotic elongation factor 2 kinase (eEF-2K) regulates protein synthesis by phosphorylating eukaryotic elongation factor 2 (eEF-2), thereby reducing its affinity for the ribosome and suppressing global translational elongation rates. eEF-2K is regulated by calmodulin (CaM) through a mechanism that is distinct from that of other CaM-regulated kinases. We had previously identified a minimal construct of eEF-2K (TR) that is activated similarly to the wild-type enzyme by CaM in vitro and retains its ability to phosphorylate eEF-2 efficiently in cells. Here, we employ solution nuclear magnetic resonance techniques relying on Ile δ1-methyls of TR and Ile δ1- and Met ε-methyls of CaM, as probes of their mutual interaction and the influence of Ca2+ thereon. We find that in the absence of Ca2+ , CaM exclusively utilizes its C-terminal lobe (CaMC ) to engage the N-terminal CaM-binding domain (CBD) of TR in a high-affinity interaction. Avidity resulting from additional weak interactions of TR with the Ca2+ -loaded N-terminal lobe of CaM (CaMN ) at increased Ca2+ levels serves to enhance the affinity further. These latter interactions under Ca2+ saturation result in minimal perturbations in the spectra of TR in the context of its complex with CaM, suggesting that the latter is capable of driving TR to its final, presumably active conformation, in the Ca2+ -free state. Our data are consistent with a scenario in which Ca2+ enhances the affinity of the TR/CaM interactions, resulting in the increased effective concentration of the CaM-bound species without significantly modifying the conformation of TR within the final, active complex.
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Affiliation(s)
- Kwangwoon Lee
- Department of Chemistry and Biochemistry, The City College of New York, New York, New York.,Graduate Program in Biochemistry, The Graduate Center of CUNY, New York, New York
| | - Eric A Kumar
- Division of Chemical Biology and Medicinal Chemistry, University of Texas, Austin, Texas
| | - Kevin N Dalby
- Division of Chemical Biology and Medicinal Chemistry, University of Texas, Austin, Texas.,Graduate Program in Cell and Molecular Biology, University of Texas, Austin, Texas
| | - Ranajeet Ghose
- Department of Chemistry and Biochemistry, The City College of New York, New York, New York.,Graduate Program in Biochemistry, The Graduate Center of CUNY, New York, New York.,Graduate Program in Chemistry, The Graduate Center of CUNY, New York, New York.,Graduate Program in Physics, The Graduate Center of CUNY, New York, New York
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19
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Kalous J, Jansová D, Šušor A. Role of Cyclin-Dependent Kinase 1 in Translational Regulation in the M-Phase. Cells 2020; 9:cells9071568. [PMID: 32605021 PMCID: PMC7408968 DOI: 10.3390/cells9071568] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2020] [Revised: 06/15/2020] [Accepted: 06/24/2020] [Indexed: 12/20/2022] Open
Abstract
Cyclin dependent kinase 1 (CDK1) has been primarily identified as a key cell cycle regulator in both mitosis and meiosis. Recently, an extramitotic function of CDK1 emerged when evidence was found that CDK1 is involved in many cellular events that are essential for cell proliferation and survival. In this review we summarize the involvement of CDK1 in the initiation and elongation steps of protein synthesis in the cell. During its activation, CDK1 influences the initiation of protein synthesis, promotes the activity of specific translational initiation factors and affects the functioning of a subset of elongation factors. Our review provides insights into gene expression regulation during the transcriptionally silent M-phase and describes quantitative and qualitative translational changes based on the extramitotic role of the cell cycle master regulator CDK1 to optimize temporal synthesis of proteins to sustain the division-related processes: mitosis and cytokinesis.
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20
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Haneke K, Schott J, Lindner D, Hollensen AK, Damgaard CK, Mongis C, Knop M, Palm W, Ruggieri A, Stoecklin G. CDK1 couples proliferation with protein synthesis. J Cell Biol 2020; 219:e201906147. [PMID: 32040547 PMCID: PMC7054999 DOI: 10.1083/jcb.201906147] [Citation(s) in RCA: 52] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2019] [Revised: 11/20/2019] [Accepted: 01/08/2020] [Indexed: 12/26/2022] Open
Abstract
Cell proliferation exerts a high demand on protein synthesis, yet the mechanisms coupling the two processes are not fully understood. A kinase and phosphatase screen for activators of translation, based on the formation of stress granules in human cells, revealed cell cycle-associated kinases as major candidates. CDK1 was identified as a positive regulator of global translation, and cell synchronization experiments showed that this is an extramitotic function of CDK1. Different pathways including eIF2α, 4EBP, and S6K1 signaling contribute to controlling global translation downstream of CDK1. Moreover, Ribo-Seq analysis uncovered that CDK1 exerts a particularly strong effect on the translation of 5'TOP mRNAs, which includes mRNAs encoding ribosomal proteins and several translation factors. This effect requires the 5'TOP mRNA-binding protein LARP1, concurrent to our finding that LARP1 phosphorylation is strongly dependent on CDK1. Thus, CDK1 provides a direct means to couple cell proliferation with biosynthesis of the translation machinery and the rate of protein synthesis.
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Affiliation(s)
- Katharina Haneke
- Division of Biochemistry, Mannheim Institute for Innate Immunoscience, Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany
- Center for Molecular Biology of Heidelberg University, DKFZ-ZMBH Alliance, Heidelberg, Germany
| | - Johanna Schott
- Division of Biochemistry, Mannheim Institute for Innate Immunoscience, Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany
- Center for Molecular Biology of Heidelberg University, DKFZ-ZMBH Alliance, Heidelberg, Germany
| | - Doris Lindner
- Division of Biochemistry, Mannheim Institute for Innate Immunoscience, Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany
- Center for Molecular Biology of Heidelberg University, DKFZ-ZMBH Alliance, Heidelberg, Germany
| | - Anne Kruse Hollensen
- Department of Molecular Biology and Genetics, Aarhus University, Aarhus, Denmark
| | | | - Cyril Mongis
- Center for Molecular Biology of Heidelberg University, DKFZ-ZMBH Alliance, Heidelberg, Germany
| | - Michael Knop
- Center for Molecular Biology of Heidelberg University, DKFZ-ZMBH Alliance, Heidelberg, Germany
- Cell Morphogenesis and Signal Transduction, German Cancer Research Center, DKFZ-ZMBH Alliance, Heidelberg, Germany
| | - Wilhelm Palm
- Cell Signaling and Metabolism, German Cancer Research Center, DKFZ-ZMBH Alliance, Heidelberg, Germany
| | - Alessia Ruggieri
- Department of Infectious Diseases, Molecular Virology, Center for Integrative Infectious Diseases Research, University of Heidelberg, Heidelberg, Germany
| | - Georg Stoecklin
- Division of Biochemistry, Mannheim Institute for Innate Immunoscience, Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany
- Center for Molecular Biology of Heidelberg University, DKFZ-ZMBH Alliance, Heidelberg, Germany
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21
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Miettinen TP, Kang JH, Yang LF, Manalis SR. Mammalian cell growth dynamics in mitosis. eLife 2019; 8:44700. [PMID: 31063131 PMCID: PMC6534395 DOI: 10.7554/elife.44700] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2018] [Accepted: 05/05/2019] [Indexed: 12/20/2022] Open
Abstract
The extent and dynamics of animal cell biomass accumulation during mitosis are unknown, primarily because growth has not been quantified with sufficient precision and temporal resolution. Using the suspended microchannel resonator and protein synthesis assays, we quantify mass accumulation and translation rates between mitotic stages on a single-cell level. For various animal cell types, growth rates in prophase are commensurate with or higher than interphase growth rates. Growth is only stopped as cells approach metaphase-to-anaphase transition and growth resumes in late cytokinesis. Mitotic arrests stop growth independently of arresting mechanism. For mouse lymphoblast cells, growth in prophase is promoted by CDK1 through increased phosphorylation of 4E-BP1 and cap-dependent protein synthesis. Inhibition of CDK1-driven mitotic translation reduces daughter cell growth. Overall, our measurements counter the traditional dogma that growth during mitosis is negligible and provide insight into antimitotic cancer chemotherapies.
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Affiliation(s)
- Teemu P Miettinen
- MRC Laboratory for Molecular Cell Biology, University College London, London, United Kingdom.,Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, Cambridge, United States
| | - Joon Ho Kang
- Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, Cambridge, United States.,Department of Physics, Massachusetts Institute of Technology, Cambridge, United States
| | - Lucy F Yang
- Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, Cambridge, United States
| | - Scott R Manalis
- Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, Cambridge, United States.,Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, United States.,Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, United States
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22
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Argüello RJ, Reverendo M, Mendes A, Camosseto V, Torres AG, Ribas de Pouplana L, van de Pavert SA, Gatti E, Pierre P. SunRiSE - measuring translation elongation at single-cell resolution by means of flow cytometry. J Cell Sci 2018; 131:jcs.214346. [PMID: 29700204 DOI: 10.1242/jcs.214346] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2017] [Accepted: 04/04/2018] [Indexed: 12/30/2022] Open
Abstract
The rate at which ribosomes translate mRNAs regulates protein expression by controlling co-translational protein folding and mRNA stability. Many factors regulate translation elongation, including tRNA levels, codon usage and phosphorylation of eukaryotic elongation factor 2 (eEF2). Current methods to measure translation elongation lack single-cell resolution, require expression of multiple transgenes and have never been successfully applied ex vivo Here, we show, by using a combination of puromycilation detection and flow cytometry (a method we call 'SunRiSE'), that translation elongation can be measured accurately in primary cells in pure or heterogenous populations isolated from blood or tissues. This method allows for the simultaneous monitoring of multiple parameters, such as mTOR or S6K1/2 signaling activity, the cell cycle stage and phosphorylation of translation factors in single cells, without elaborated, costly and lengthy purification procedures. We took advantage of SunRiSE to demonstrate that, in mouse embryonic fibroblasts, eEF2 phosphorylation by eEF2 kinase (eEF2K) mostly affects translation engagement, but has a surprisingly small effect on elongation, except after proteotoxic stress induction.This article has an associated First Person interview with the first author of the paper.
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Affiliation(s)
- Rafael J Argüello
- Centre d'Immunologie de Marseille-Luminy, Aix Marseille Université, Inserm, CNRS, 13288, Marseille Cedex 9, France
| | - Marisa Reverendo
- Centre d'Immunologie de Marseille-Luminy, Aix Marseille Université, Inserm, CNRS, 13288, Marseille Cedex 9, France
| | - Andreia Mendes
- Centre d'Immunologie de Marseille-Luminy, Aix Marseille Université, Inserm, CNRS, 13288, Marseille Cedex 9, France
| | - Voahirana Camosseto
- Centre d'Immunologie de Marseille-Luminy, Aix Marseille Université, Inserm, CNRS, 13288, Marseille Cedex 9, France
| | - Adrian G Torres
- Institute for Research in Biomedicine (IRB Barcelona), The Barcelona Institute of Science and Technology, Parc Científic de Barcelona, C/Baldiri Reixac 10, 08028 Barcelona, Catalonia, Spain
| | - Lluis Ribas de Pouplana
- Institute for Research in Biomedicine (IRB Barcelona), The Barcelona Institute of Science and Technology, Parc Científic de Barcelona, C/Baldiri Reixac 10, 08028 Barcelona, Catalonia, Spain.,Catalan Institute for Research and Advanced Studies (ICREA), P/Lluis Companys 23, 08010 Barcelona, Catalonia, Spain
| | - Serge A van de Pavert
- Centre d'Immunologie de Marseille-Luminy, Aix Marseille Université, Inserm, CNRS, 13288, Marseille Cedex 9, France
| | - Evelina Gatti
- Centre d'Immunologie de Marseille-Luminy, Aix Marseille Université, Inserm, CNRS, 13288, Marseille Cedex 9, France.,Institute for Research in Biomedicine (iBiMED) and Ilidio Pinho Foundation, Department of Medical Sciences, University of Aveiro, 3810-193 Aveiro, Portugal
| | - Philippe Pierre
- Centre d'Immunologie de Marseille-Luminy, Aix Marseille Université, Inserm, CNRS, 13288, Marseille Cedex 9, France .,Institute for Research in Biomedicine (iBiMED) and Ilidio Pinho Foundation, Department of Medical Sciences, University of Aveiro, 3810-193 Aveiro, Portugal
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23
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Di Francesco L, Verrico A, Asteriti IA, Rovella P, Cirigliano P, Guarguaglini G, Schininà ME, Lavia P. Visualization of human karyopherin beta-1/importin beta-1 interactions with protein partners in mitotic cells by co-immunoprecipitation and proximity ligation assays. Sci Rep 2018; 8:1850. [PMID: 29382863 PMCID: PMC5789818 DOI: 10.1038/s41598-018-19351-9] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2017] [Accepted: 12/29/2017] [Indexed: 12/29/2022] Open
Abstract
Karyopherin beta-1/Importin beta-1 is a conserved nuclear transport receptor, acting in protein nuclear import in interphase and as a global regulator of mitosis. These pleiotropic functions reflect its ability to interact with, and regulate, different pathways during the cell cycle, operating as a major effector of the GTPase RAN. Importin beta-1 is overexpressed in cancers characterized by high genetic instability, an observation that highlights the importance of identifying its partners in mitosis. Here we present the first comprehensive profile of importin beta-1 interactors from human mitotic cells. By combining co-immunoprecipitation and proteome-wide mass spectrometry analysis of synchronized cell extracts, we identified expected (e.g., RAN and SUMO pathway factors) and novel mitotic interactors of importin beta-1, many with RNA-binding ability, that had not been previously associated with importin beta-1. These data complement interactomic studies of interphase transport pathways. We further developed automated proximity ligation assay (PLA) protocols to validate selected interactors. We succeeded in obtaining spatial and temporal resolution of genuine importin beta-1 interactions, which were visualized and localized in situ in intact mitotic cells. Further developments of PLA protocols will be helpful to dissect importin beta-1-orchestrated pathways during mitosis.
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Affiliation(s)
- Laura Di Francesco
- Dipartimento di Scienze Biochimiche, Sapienza University of Rome, Piazzale Aldo Moro 5, 00185, Rome, Italy.,Unit of Human Microbiome, Bambino Gesù Children's Hospital-IRCCS, Rome, Italy
| | - Annalisa Verrico
- Institute of Molecular Biology and Pathology (IBPM), CNR National Research Council of Italy, Via degli Apuli 4, 00185, Rome, Italy
| | - Italia Anna Asteriti
- Institute of Molecular Biology and Pathology (IBPM), CNR National Research Council of Italy, Via degli Apuli 4, 00185, Rome, Italy
| | - Paola Rovella
- Institute of Molecular Biology and Pathology (IBPM), CNR National Research Council of Italy, Via degli Apuli 4, 00185, Rome, Italy
| | | | - Giulia Guarguaglini
- Institute of Molecular Biology and Pathology (IBPM), CNR National Research Council of Italy, Via degli Apuli 4, 00185, Rome, Italy
| | - Maria Eugenia Schininà
- Dipartimento di Scienze Biochimiche, Sapienza University of Rome, Piazzale Aldo Moro 5, 00185, Rome, Italy.
| | - Patrizia Lavia
- Institute of Molecular Biology and Pathology (IBPM), CNR National Research Council of Italy, Via degli Apuli 4, 00185, Rome, Italy.
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24
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Leibovitch M, Topisirovic I. Dysregulation of mRNA translation and energy metabolism in cancer. Adv Biol Regul 2017; 67:30-39. [PMID: 29150352 DOI: 10.1016/j.jbior.2017.11.001] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2017] [Revised: 10/26/2017] [Accepted: 11/01/2017] [Indexed: 12/20/2022]
Abstract
Dysregulated mRNA translation and aberrant energy metabolism are frequent in cancer. Considering that mRNA translation is an energy demanding process, cancer cells must produce sufficient ATP to meet energy demand of hyperactive translational machinery. In recent years, the mammalian/mechanistic target of rapamycin (mTOR) emerged as a central regulatory node which coordinates energy consumption by the translation apparatus and ATP production in mitochondria. Aberrant mTOR signaling underpins the vast majority of cancers whereby increased mTOR activity is thought to be a major determinant of both malignant translatomes and metabolomes. Nonetheless, the role of mTOR and other related signaling nodes (e.g. AMPK) in orchestrating protein synthesis and cancer energetics is only recently being unraveled. In this review, we discuss recent findings that provide insights into the molecular underpinnings of coordination of translational and metabolic programs of cancer cells, and potential strategies to translate these findings into clinical treatments.
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Affiliation(s)
- Matthew Leibovitch
- Lady Davis Institute, SMBD JGH, McGill University, Montréal, QC, H3T 1E2, Canada.
| | - Ivan Topisirovic
- Gerald Bronfman Department of Oncology, Montréal, QC, H3A 1A3, Canada; Department of Biochemistry, Montréal, QC, H3A 1A3, Canada; Department of Experimental Medicine McGill University, Montréal, QC, H3A 1A3, Canada; Lady Davis Institute, SMBD JGH, McGill University, Montréal, QC, H3T 1E2, Canada
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25
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Johanns M, Pyr Dit Ruys S, Houddane A, Vertommen D, Herinckx G, Hue L, Proud CG, Rider MH. Direct and indirect activation of eukaryotic elongation factor 2 kinase by AMP-activated protein kinase. Cell Signal 2017; 36:212-221. [PMID: 28502587 DOI: 10.1016/j.cellsig.2017.05.010] [Citation(s) in RCA: 47] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2016] [Revised: 04/27/2017] [Accepted: 05/10/2017] [Indexed: 12/12/2022]
Abstract
BACKGROUND Eukaryotic elongation factor 2 (eEF2) kinase (eEF2K) is a key regulator of protein synthesis in mammalian cells. It phosphorylates and inhibits eEF2, the translation factor necessary for peptide translocation during the elongation phase of protein synthesis. When cellular energy demand outweighs energy supply, AMP-activated protein kinase (AMPK) and eEF2K become activated, leading to eEF2 phosphorylation, which reduces the rate of protein synthesis, a process that consumes a large proportion of cellular energy under optimal conditions. AIM The goal of the present study was to elucidate the mechanisms by which AMPK activation leads to increased eEF2 phosphorylation to decrease protein synthesis. METHODS Using genetically modified mouse embryo fibroblasts (MEFs), effects of treatments with commonly used AMPK activators to increase eEF2 phosphorylation were compared with that of the novel compound 991. Bacterially expressed recombinant eEF2K was phosphorylated in vitro by recombinant activated AMPK for phosphorylation site-identification by mass spectrometry followed by site-directed mutagenesis of the identified sites to alanine residues to study effects on the kinetic properties of eEF2K. Wild-type eEF2K and a Ser491/Ser492 mutant were retrovirally re-introduced in eEF2K-deficient MEFs and effects of 991 treatment on eEF2 phosphorylation and protein synthesis rates were studied in these cells. RESULTS & CONCLUSIONS AMPK activation leads to increased eEF2 phosphorylation in MEFs mainly by direct activation of eEF2K and partly by inhibition of mammalian target of rapamycin complex 1 (mTORC1) signaling. Treatment of MEFs with AMPK activators can also lead to eEF2K activation independently of AMPK probably via a rise in intracellular Ca2+. AMPK activates eEF2K by multi-site phosphorylation and the newly identified Ser491/Ser492 is important for activation, leading to mTOR-independent inhibition of protein synthesis. Our study provides new insights into the control of eEF2K by AMPK, with implications for linking metabolic stress to decreased protein synthesis to conserve energy reserves, a pathway that is of major importance in cancer cell survival.
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Affiliation(s)
- M Johanns
- Université catholique de Louvain (UCL), de Duve Institute, Avenue Hippocrate 75 bte 74.02, 1200-Brussels, Belgium
| | - S Pyr Dit Ruys
- Université catholique de Louvain (UCL), de Duve Institute, Avenue Hippocrate 75 bte 74.02, 1200-Brussels, Belgium
| | - A Houddane
- Université catholique de Louvain (UCL), de Duve Institute, Avenue Hippocrate 75 bte 74.02, 1200-Brussels, Belgium
| | - D Vertommen
- Université catholique de Louvain (UCL), de Duve Institute, Avenue Hippocrate 75 bte 74.02, 1200-Brussels, Belgium
| | - G Herinckx
- Université catholique de Louvain (UCL), de Duve Institute, Avenue Hippocrate 75 bte 74.02, 1200-Brussels, Belgium
| | - L Hue
- Université catholique de Louvain (UCL), de Duve Institute, Avenue Hippocrate 75 bte 74.02, 1200-Brussels, Belgium
| | - C G Proud
- South Australian Health and Medical Research Institute (SAHMRI), University of Adelaide, North Terrace, Adelaide, SA 5000, Australia
| | - M H Rider
- Université catholique de Louvain (UCL), de Duve Institute, Avenue Hippocrate 75 bte 74.02, 1200-Brussels, Belgium.
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26
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Wang F, Qiu Y, Zhang HM, Hanson P, Ye X, Zhao G, Xie R, Tong L, Yang D. Heat shock protein 70 promotes coxsackievirus B3 translation initiation and elongation via Akt-mTORC1 pathway depending on activation of p70S6K and Cdc2. Cell Microbiol 2017; 19. [DOI: 10.1111/cmi.12725] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2016] [Revised: 12/15/2016] [Accepted: 01/01/2017] [Indexed: 12/19/2022]
Affiliation(s)
- Fengping Wang
- Department of Pathology and Laboratory Medicine; University of British Columbia, Center for Heart Lung Innovation, St. Paul's Hospital; Vancouver British Columbia Canada
| | - Ye Qiu
- Department of Pathology and Laboratory Medicine; University of British Columbia, Center for Heart Lung Innovation, St. Paul's Hospital; Vancouver British Columbia Canada
| | - Huifang M. Zhang
- Department of Pathology and Laboratory Medicine; University of British Columbia, Center for Heart Lung Innovation, St. Paul's Hospital; Vancouver British Columbia Canada
| | - Paul Hanson
- Department of Pathology and Laboratory Medicine; University of British Columbia, Center for Heart Lung Innovation, St. Paul's Hospital; Vancouver British Columbia Canada
| | - Xin Ye
- Department of Pathology and Laboratory Medicine; University of British Columbia, Center for Heart Lung Innovation, St. Paul's Hospital; Vancouver British Columbia Canada
| | - Guangze Zhao
- Department of Pathology and Laboratory Medicine; University of British Columbia, Center for Heart Lung Innovation, St. Paul's Hospital; Vancouver British Columbia Canada
| | - Ronald Xie
- Department of Pathology and Laboratory Medicine; University of British Columbia, Center for Heart Lung Innovation, St. Paul's Hospital; Vancouver British Columbia Canada
| | - Lei Tong
- Department of Pathology and Laboratory Medicine; University of British Columbia, Center for Heart Lung Innovation, St. Paul's Hospital; Vancouver British Columbia Canada
| | - Decheng Yang
- Department of Pathology and Laboratory Medicine; University of British Columbia, Center for Heart Lung Innovation, St. Paul's Hospital; Vancouver British Columbia Canada
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27
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Kameshima S, Okada M, Yamawaki H. [Mechanisms of control of cardiovascular, tumorous and neuronal diseases by eEF2K/eEF2 signaling and suggestion of eEF2K/eEF2 as pharmacotherapeutic target]. Nihon Yakurigaku Zasshi 2017; 149:194-199. [PMID: 28484099 DOI: 10.1254/fpj.149.194] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
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28
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Tavares CDJ, Giles DH, Stancu G, Chitjian CA, Ferguson SB, Wellmann RM, Kaoud TS, Ghose R, Dalby KN. Signal Integration at Elongation Factor 2 Kinase: THE ROLES OF CALCIUM, CALMODULIN, AND SER-500 PHOSPHORYLATION. J Biol Chem 2016; 292:2032-2045. [PMID: 27956550 DOI: 10.1074/jbc.m116.753277] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2016] [Revised: 11/28/2016] [Indexed: 12/22/2022] Open
Abstract
Eukaryotic elongation factor 2 kinase (eEF-2K), the only calmodulin (CaM)-dependent member of the unique α-kinase family, impedes protein synthesis by phosphorylating eEF-2. We recently identified Thr-348 and Ser-500 as two key autophosphorylation sites within eEF-2K that regulate its activity. eEF-2K is regulated by Ca2+ ions and multiple upstream signaling pathways, but how it integrates these signals into a coherent output, i.e. phosphorylation of eEF-2, is unclear. This study focuses on understanding how the post-translational phosphorylation of Ser-500 integrates with Ca2+ and CaM to regulate eEF-2K. CaM is shown to be absolutely necessary for efficient activity of eEF-2K, and Ca2+ is shown to enhance the affinity of CaM toward eEF-2K. Ser-500 is found to undergo autophosphorylation in cells treated with ionomycin and is likely also targeted by PKA. In vitro, autophosphorylation of Ser-500 is found to require Ca2+ and CaM and is inhibited by mutations that compromise binding of phosphorylated Thr-348 to an allosteric binding pocket on the kinase domain. A phosphomimetic Ser-500 to aspartic acid mutation (eEF-2K S500D) enhances the rate of activation (Thr-348 autophosphorylation) by 6-fold and lowers the EC50 for Ca2+/CaM binding to activated eEF-2K (Thr-348 phosphorylated) by 20-fold. This is predicted to result in an elevation of the cellular fraction of active eEF-2K. In support of this mechanism, eEF-2K knock-out MCF10A cells reconstituted with eEF-2K S500D display relatively high levels of phospho-eEF-2 under basal conditions. This study reports how phosphorylation of a regulatory site (Ser-500) integrates with Ca2+ and CaM to influence eEF-2K activity.
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Affiliation(s)
- Clint D J Tavares
- From the Graduate Program in Cell and Molecular Biology, University of Texas, Austin, Texas 78712; Division of Chemical Biology and Medicinal Chemistry, University of Texas, Austin, Texas 78712.
| | - David H Giles
- Division of Chemical Biology and Medicinal Chemistry, University of Texas, Austin, Texas 78712
| | - Gabriel Stancu
- Division of Chemical Biology and Medicinal Chemistry, University of Texas, Austin, Texas 78712
| | - Catrina A Chitjian
- From the Graduate Program in Cell and Molecular Biology, University of Texas, Austin, Texas 78712; Division of Chemical Biology and Medicinal Chemistry, University of Texas, Austin, Texas 78712
| | - Scarlett B Ferguson
- Division of Chemical Biology and Medicinal Chemistry, University of Texas, Austin, Texas 78712
| | - Rebecca M Wellmann
- Division of Chemical Biology and Medicinal Chemistry, University of Texas, Austin, Texas 78712
| | - Tamer S Kaoud
- Division of Chemical Biology and Medicinal Chemistry, University of Texas, Austin, Texas 78712
| | - Ranajeet Ghose
- the Department of Chemistry, City College of New York, New York, New York 10031; the Graduate Center, City University of New York, New York, New York 10016
| | - Kevin N Dalby
- From the Graduate Program in Cell and Molecular Biology, University of Texas, Austin, Texas 78712; Division of Chemical Biology and Medicinal Chemistry, University of Texas, Austin, Texas 78712.
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Will N, Piserchio A, Snyder I, Ferguson SB, Giles DH, Dalby KN, Ghose R. Structure of the C-Terminal Helical Repeat Domain of Eukaryotic Elongation Factor 2 Kinase. Biochemistry 2016; 55:5377-86. [PMID: 27571275 DOI: 10.1021/acs.biochem.6b00711] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Eukaryotic elongation factor 2 kinase (eEF-2K) phosphorylates its only known physiological substrate, elongation factor 2 (eEF-2), which reduces the affinity of eEF-2 for the ribosome and results in an overall reduction in protein translation rates. The C-terminal region of eEF-2K, which is predicted to contain several SEL-1-like helical repeats (SLRs), is required for the phosphorylation of eEF-2. Using solution nuclear magnetic resonance methodology, we have determined the structure of a 99-residue fragment from the extreme C-terminus of eEF-2K (eEF-2K627-725) that encompasses a region previously suggested to be essential for eEF-2 phosphorylation. eEF-2K627-725 contains four helices, of which the first (αI) is flexible, and does not pack stably against the ordered helical core formed by the last three helices (αII-αIV). The helical core is structurally similar to members of the tetratricopeptide repeat (TPR) family that includes SLRs. The two penultimate helices, αII and αIII, comprise the TPR, and the last helix, αIV, appears to have a capping function. The eEF-2K627-725 structure illustrates that the C-terminal deletion that was shown to abolish eEF-2 phosphorylation does so by destabilizing αIV and, therefore, the helical core. Indeed, mutation of two conserved C-terminal tyrosines (Y712A/Y713A) in eEF-2K previously shown to abolish eEF-2 phosphorylation leads to the unfolding of eEF-2K627-725. Preliminary functional analyses indicate that neither a peptide encoding a region deemed crucial for eEF-2 binding nor isolated eEF-2K627-725 inhibits eEF-2 phosphorylation by full-length eEF-2K. Taken together, our data suggest that the extreme C-terminal region of eEF-2K, in isolation, does not provide a primary docking site for eEF-2.
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Affiliation(s)
- Nathan Will
- Department of Chemistry and Biochemistry, The City College of New York , New York, New York 10031, United States
| | - Andrea Piserchio
- Department of Chemistry and Biochemistry, The City College of New York , New York, New York 10031, United States
| | - Isaac Snyder
- Department of Chemistry and Biochemistry, The City College of New York , New York, New York 10031, United States
| | - Scarlet B Ferguson
- Division of Chemical Biology and Medicinal Chemistry, University of Texas , Austin, Texas 78712, United States
| | - David H Giles
- Division of Chemical Biology and Medicinal Chemistry, University of Texas , Austin, Texas 78712, United States
| | - Kevin N Dalby
- Division of Chemical Biology and Medicinal Chemistry, University of Texas , Austin, Texas 78712, United States.,Graduate Program in Cell and Molecular Biology, University of Texas , Austin, Texas 78712, United States
| | - Ranajeet Ghose
- Department of Chemistry and Biochemistry, The City College of New York , New York, New York 10031, United States
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Lee K, Alphonse S, Piserchio A, Tavares CDJ, Giles DH, Wellmann RM, Dalby KN, Ghose R. Structural Basis for the Recognition of Eukaryotic Elongation Factor 2 Kinase by Calmodulin. Structure 2016; 24:1441-51. [PMID: 27499441 DOI: 10.1016/j.str.2016.06.015] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2016] [Revised: 06/06/2016] [Accepted: 06/10/2016] [Indexed: 12/25/2022]
Abstract
Binding of Ca(2+)-loaded calmodulin (CaM) activates eukaryotic elongation factor 2 kinase (eEF-2K) that phosphorylates eEF-2, its only known cellular target, leading to a decrease in global protein synthesis. Here, using an eEF-2K-derived peptide (eEF-2KCBD) that encodes the region necessary for its CaM-mediated activation, we provide a structural basis for their interaction. The striking feature of this association is the absence of Ca(2+) from the CaM C-lobe sites, even under high Ca(2+) conditions. eEF-2KCBD engages CaM largely through the C lobe of the latter in an anti-parallel 1-5-8 hydrophobic mode reinforced by a pair of unique electrostatic contacts. Sparse interactions of eEF-2KCBD with the CaM N lobe results in persisting inter-lobe mobility. A conserved eEF-2K residue (W85) anchors it to CaM by inserting into a deep hydrophobic cavity within the CaM C lobe. Mutation of this residue (W85S) substantially weakens interactions between full-length eEF-2K and CaM in vitro and reduces eEF-2 phosphorylation in cells.
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Affiliation(s)
- Kwangwoon Lee
- Department of Chemistry and Biochemistry, The City College of New York, New York, NY 10031, USA; Graduate Program in Biochemistry, The Graduate Center of CUNY, New York, NY 10016, USA
| | - Sébastien Alphonse
- Department of Chemistry and Biochemistry, The City College of New York, New York, NY 10031, USA
| | - Andrea Piserchio
- Department of Chemistry and Biochemistry, The City College of New York, New York, NY 10031, USA
| | - Clint D J Tavares
- Graduate Program in Cell and Molecular Biology, University of Texas, Austin, TX 78712, USA
| | - David H Giles
- Division of Chemical Biology and Medicinal Chemistry, University of Texas, Austin, TX 78712, USA
| | - Rebecca M Wellmann
- Division of Chemical Biology and Medicinal Chemistry, University of Texas, Austin, TX 78712, USA
| | - Kevin N Dalby
- Graduate Program in Cell and Molecular Biology, University of Texas, Austin, TX 78712, USA; Division of Chemical Biology and Medicinal Chemistry, University of Texas, Austin, TX 78712, USA
| | - Ranajeet Ghose
- Department of Chemistry and Biochemistry, The City College of New York, New York, NY 10031, USA; Graduate Program in Biochemistry, The Graduate Center of CUNY, New York, NY 10016, USA; Graduate Program in Chemistry, The Graduate Center of CUNY, New York, NY 10016, USA; Graduate Program in Physics, The Graduate Center of CUNY, New York, NY 10016, USA.
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31
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Liao Y, Chu HP, Hu Z, Merkin JJ, Chen J, Liu Z, Degenhardt K, White E, Ryazanov AG. Paradoxical Roles of Elongation Factor-2 Kinase in Stem Cell Survival. J Biol Chem 2016; 291:19545-57. [PMID: 27466362 DOI: 10.1074/jbc.m116.724856] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2016] [Indexed: 11/06/2022] Open
Abstract
Protein synthesis inhibition is an immediate response during stress to switch the composition of protein pool in order to adapt to the new environment. It was reported that this response could be either protective or deleterious. However, how cells choose to live or die upon protein synthesis inhibition is largely unknown. Previously, we have shown that elongation factor-2 kinase (eEF2K), a protein kinase that suppresses protein synthesis during elongation phase, is a positive regulator of apoptosis both in vivo and in vitro Consistently, here we report that knock-out of eEF2K protects mice from a lethal dose of whole-body ionizing radiation at 8 Gy by reducing apoptosis levels in both bone marrow and gastrointestinal tracts. Surprisingly, similar to the loss of p53, eEF2K deficiency results in more severe damage to the gastrointestinal tract at 20 Gy with the increased mitotic cell death in small intestinal stem cells. Furthermore, using epithelial cell lines, we showed that eEF2K is required for G2/M arrest induced by radiation to prevent mitotic catastrophe in a p53-independent manner. Specifically, we observed the elevation of Akt/ERK activity as well as the reduction of p21 expression in Eef2k(-/-) cells. Therefore, eEF2K also provides a protective strategy to maintain genomic integrity by arresting cell cycle in response to stress. Our results suggest that protective versus pro-apoptotic roles of eEF2K depend on the type of cells: eEF2K is protective in highly proliferative cells, such as small intestinal stem cells and cancer cells, which are more susceptible to mitotic catastrophe.
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Affiliation(s)
- Yi Liao
- From the Eye Institute of Xiamen University, Fujian Provincial Key Laboratory of Ophthalmology and Visual Science, Xiamen, Fujian 361102, China, the Department of Pharmacology, Robert Wood Johnson Medical School, and
| | - Hsueh-Ping Chu
- the Department of Pharmacology, Robert Wood Johnson Medical School, and the Department of Molecular Biology, Massachusetts General Hospital, Department of Genetics, Harvard Medical School, Boston, Massachusetts 02114
| | - Zhixian Hu
- the Department of Pharmacology, Robert Wood Johnson Medical School, and
| | - Jason J Merkin
- the Department of Pharmacology, Robert Wood Johnson Medical School, and
| | - Jianmin Chen
- the Department of Cell Biology and Neuroscience, Rutgers University, Piscataway, New Jersey 08854
| | - Zuguo Liu
- From the Eye Institute of Xiamen University, Fujian Provincial Key Laboratory of Ophthalmology and Visual Science, Xiamen, Fujian 361102, China, the Affiliated Xiamen Eye Center of Xiamen University, Xiamen, Fujian 361102, China
| | - Kurt Degenhardt
- the Cancer Institute of New Jersey, New Brunswick, New Jersey 08903, and
| | - Eileen White
- the Cancer Institute of New Jersey, New Brunswick, New Jersey 08903, and
| | - Alexey G Ryazanov
- the Department of Pharmacology, Robert Wood Johnson Medical School, and
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Abstract
Based on own translational research of the biochemical and hormonal effects of cow's milk consumption in humans, this review presents milk as a signaling system of mammalian evolution that activates the nutrient-sensitive kinase mechanistic target of rapamycin complex 1 (mTORC1), the pivotal regulator of translation. Milk, a mammary gland-derived secretory product, is required for species-specific gene-nutrient interactions that promote appropriate growth and development of the newborn mammal. This signaling system is highly conserved and tightly controlled by the lactation genome. Milk is sufficient to activate mTORC1, the crucial regulator of protein, lipid, and nucleotide synthesis orchestrating anabolism, cell growth and proliferation. To fulfill its mTORC1-activating function, milk delivers four key metabolic messengers: (1) essential branched-chain amino acids (BCAAs); (2) glutamine; (3) palmitic acid; and (4) bioactive exosomal microRNAs, which in a synergistical fashion promote mTORC1-dependent translation. In all mammals except Neolithic humans, postnatal activation of mTORC1 by milk intake is restricted to the postnatal lactation period. It is of critical concern that persistent hyperactivation of mTORC1 is associated with aging and the development of age-related disorders such as obesity, type 2 diabetes mellitus, cancer, and neurodegenerative diseases. Persistent mTORC1 activation promotes endoplasmic reticulum (ER) stress and drives an aimless quasi-program, which promotes aging and age-related diseases.
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Zhu H, Yang X, Liu J, Zhou L, Zhang C, Xu L, Qin Q, Zhan L, Lu J, Cheng H, Sun X. Eukaryotic elongation factor 2 kinase confers tolerance to stress conditions in cancer cells. Cell Stress Chaperones 2015; 20:217-20. [PMID: 25248493 PMCID: PMC4326389 DOI: 10.1007/s12192-014-0545-0] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2014] [Revised: 08/23/2014] [Accepted: 09/11/2014] [Indexed: 12/25/2022] Open
Abstract
Eukaryotic elongation factor 2 (eEF2) is a member of the GTP-binding translation elongation factor family that is essential for protein synthesis. eEF2 kinase (eEF2K) is a structurally and functionally unique protein kinase in the calmodulin-mediated signaling pathway. eEF2K phosphorylates eEF2, thereby inhibiting eEF2 function under stressful conditions. eEF2K regulates numerous processes, such as protein synthesis, cell cycle progression, and induction of autophagy and apoptosis in cancer cells. This review will demonstrate the mechanisms underlying eEF2K activity in cancer cells under different stresses, such as nutrient deprivation, hypoxia, and DNA damage via eEF2 regulation. In vivo, in vitro, and clinical studies indicated that eEF2K may be a novel biomarker and therapeutic target for cancer.
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Affiliation(s)
- Hongcheng Zhu
- />Department of Radiation Oncology, The First Affiliated Hospital of Nanjing Medical University, Nanjing, China
| | - Xi Yang
- />Department of Radiation Oncology, The First Affiliated Hospital of Nanjing Medical University, Nanjing, China
| | - Jia Liu
- />Department of Radiation Oncology, The First Affiliated Hospital of Nanjing Medical University, Nanjing, China
| | - Lu Zhou
- />Department of Neurosurgery, Nanjing Drum Tower Hospital and Clinical College of Nanjing Medical University, Nanjing, China
| | - Chi Zhang
- />Department of Radiation Oncology, The First Affiliated Hospital of Nanjing Medical University, Nanjing, China
| | - Liping Xu
- />Department of Radiation Oncology, The First Affiliated Hospital of Nanjing Medical University, Nanjing, China
| | - Qin Qin
- />Department of Radiation Oncology, The First Affiliated Hospital of Nanjing Medical University, Nanjing, China
| | - Liangliang Zhan
- />Department of Radiation Oncology, The First Affiliated Hospital of Nanjing Medical University, Nanjing, China
| | - Jing Lu
- />Department of Radiation Oncology, The First Affiliated Hospital of Nanjing Medical University, Nanjing, China
| | - Hongyan Cheng
- />Department of General Internal Medicine, The First Affiliated Hospital of Nanjing Medical University, Nanjing, China
| | - Xinchen Sun
- />Department of Radiation Oncology, The First Affiliated Hospital of Nanjing Medical University, Nanjing, China
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Usui T, Nijima R, Sakatsume T, Otani K, Kameshima S, Okada M, Yamawaki H. Eukaryotic elongation factor 2 kinase controls proliferation and migration of vascular smooth muscle cells. Acta Physiol (Oxf) 2015; 213:472-80. [PMID: 25069823 DOI: 10.1111/apha.12354] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2014] [Revised: 07/14/2014] [Accepted: 07/17/2014] [Indexed: 11/27/2022]
Abstract
AIM Eukaryotic elongation factor 2 kinase (eEF2K), also known as calmodulin (CaM)-dependent protein kinase (CaMK) III, is a unique member of CaMK family protein. We have recently found that expression of eEF2K protein increased in mesenteric artery from spontaneously hypertensive rats. As pathogenesis of hypertension is in part regulated by vascular structural remodelling via proliferation and migration of vascular smooth muscle cells (SMCs), we tested the hypothesis that eEF2K controls SMCs proliferation and migration. METHODSAND RESULTS In rat mesenteric arterial SMCs, an eEF2K inhibitor, A-484954 (10 μm), significantly inhibited platelet-derived growth factor (PDGF)-BB (10 ng mL(-1) )-induced SMCs proliferation as determined by a cell counting and bromodeoxyuridine incorporation assay. PDGF-BB (10 ng mL(-1) )-induced SMCs migration was significantly inhibited by A-484954 (10 μm) as determined by a Boyden chamber assay. A-484954 (10 μm) significantly inhibited PDGF-BB (10 ng mL(-1) )-induced phosphorylation of eEF2K, extracellular signal-regulated kinase (ERK), Akt, p38 and heat-shock protein (HSP) 27 as determined by Western blotting. It was confirmed that a CaM inhibitor, W-7 (50 μm), inhibited PDGF-BB (10 ng mL(-1) )-induced phosphorylation of eEF2K. In an ex vivo mesenteric arterial ring assay, 10% foetal bovine serum-induced SMCs outgrowth was significantly inhibited by A-484954 (10 μm). CONCLUSION We for the first time revealed that eEF2K mediates PDGF-BB-induced SMCs proliferation and migration through activating ERK, Akt, p38 and HSP27 signals in a CaM-dependent manner. Our results suggest eEF2K as a novel pharmaceutical target for the prevention of hypertensive cardiovascular diseases.
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Affiliation(s)
- T. Usui
- Laboratory of Veterinary Pharmacology; School of Veterinary Medicine; Kitasato University; Towada Aomori Japan
| | - R. Nijima
- Laboratory of Veterinary Pharmacology; School of Veterinary Medicine; Kitasato University; Towada Aomori Japan
| | - T. Sakatsume
- Laboratory of Veterinary Pharmacology; School of Veterinary Medicine; Kitasato University; Towada Aomori Japan
| | - K. Otani
- Laboratory of Veterinary Pharmacology; School of Veterinary Medicine; Kitasato University; Towada Aomori Japan
| | - S. Kameshima
- Laboratory of Veterinary Pharmacology; School of Veterinary Medicine; Kitasato University; Towada Aomori Japan
| | - M. Okada
- Laboratory of Veterinary Pharmacology; School of Veterinary Medicine; Kitasato University; Towada Aomori Japan
| | - H. Yamawaki
- Laboratory of Veterinary Pharmacology; School of Veterinary Medicine; Kitasato University; Towada Aomori Japan
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Leprivier G, Rotblat B, Khan D, Jan E, Sorensen PH. Stress-mediated translational control in cancer cells. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2014; 1849:845-60. [PMID: 25464034 DOI: 10.1016/j.bbagrm.2014.11.002] [Citation(s) in RCA: 73] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 08/22/2014] [Revised: 10/31/2014] [Accepted: 11/04/2014] [Indexed: 12/22/2022]
Abstract
Tumor cells are continually subjected to diverse stress conditions of the tumor microenvironment, including hypoxia, nutrient deprivation, and oxidative or genotoxic stress. Tumor cells must evolve adaptive mechanisms to survive these conditions to ultimately drive tumor progression. Tight control of mRNA translation is critical for this response and the adaptation of tumor cells to such stress forms. This proceeds though a translational reprogramming process which restrains overall translation activity to preserve energy and nutrients, but which also stimulates the selective synthesis of major stress adaptor proteins. Here we present the different regulatory signaling pathways which coordinate mRNA translation in the response to different stress forms, including those regulating eIF2α, mTORC1 and eEF2K, and we explain how tumor cells hijack these pathways for survival under stress. Finally, mechanisms for selective mRNA translation under stress, including the utilization of upstream open reading frames (uORFs) and internal ribosome entry sites (IRESes) are discussed in the context of cell stress. This article is part of a Special Issue entitled: Translation and Cancer.
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Affiliation(s)
- Gabriel Leprivier
- Department of Molecular Oncology, British Columbia Cancer Research Centre, Vancouver, British Columbia V5Z 1L4, Canada; Department of Pathology, University of British Columbia, Vancouver, British Columbia V6T 2B5, Canada
| | - Barak Rotblat
- Department of Life Science, Ben-Gurion University of the Negev, Beer-Sheva 84105, Israel
| | - Debjit Khan
- Department of Molecular Oncology, British Columbia Cancer Research Centre, Vancouver, British Columbia V5Z 1L4, Canada; Department of Pathology, University of British Columbia, Vancouver, British Columbia V6T 2B5, Canada
| | - Eric Jan
- Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, British Columbia V6T1Z3, Canada
| | - Poul H Sorensen
- Department of Molecular Oncology, British Columbia Cancer Research Centre, Vancouver, British Columbia V5Z 1L4, Canada; Department of Pathology, University of British Columbia, Vancouver, British Columbia V6T 2B5, Canada.
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Land SC, Scott CL, Walker D. mTOR signalling, embryogenesis and the control of lung development. Semin Cell Dev Biol 2014; 36:68-78. [PMID: 25289569 DOI: 10.1016/j.semcdb.2014.09.023] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2014] [Revised: 09/07/2014] [Accepted: 09/11/2014] [Indexed: 12/15/2022]
Abstract
The existence of a nutrient sensitive "autocatakinetic" regulator of embryonic tissue growth has been hypothesised since the early 20th century, beginning with pioneering work on the determinants of foetal size by the Australian physiologist, Thorburn Brailsford-Robertson. We now know that the mammalian target of rapamycin complexes (mTORC1 and 2) perform this essential function in all eukaryotic tissues by balancing nutrient and energy supply during the first stages of embryonic cleavage, the formation of embryonic stem cell layers and niches, the highly specified programmes of tissue growth during organogenesis and, at birth, paving the way for the first few breaths of life. This review provides a synopsis of the role of the mTOR complexes in each of these events, culminating in an analysis of lung branching morphogenesis as a way of demonstrating the central role mTOR in defining organ structural complexity. We conclude that the mTOR complexes satisfy the key requirements of a nutrient sensitive growth controller and can therefore be considered as Brailsford-Robertson's autocatakinetic centre that drives tissue growth programmes during foetal development.
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Affiliation(s)
- Stephen C Land
- Division of Cardiovascular and Diabetes Medicine, Medical Research Institute, Ninewells Hospital and Medical School, University of Dundee, Dundee DD1 9SY, UK.
| | - Claire L Scott
- Prostrakan Pharmaceuticals, Galabank Business Park, Galashiels TD1 1PR, UK
| | - David Walker
- School of Psychology & Neuroscience, Westburn Lane, St Andrews KY16 9JP, UK
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Fonseca BD, Smith EM, Yelle N, Alain T, Bushell M, Pause A. The ever-evolving role of mTOR in translation. Semin Cell Dev Biol 2014; 36:102-12. [PMID: 25263010 DOI: 10.1016/j.semcdb.2014.09.014] [Citation(s) in RCA: 71] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2014] [Revised: 09/12/2014] [Accepted: 09/15/2014] [Indexed: 02/06/2023]
Abstract
Control of translation allows for the production of stoichiometric levels of each protein in the cell. Attaining such a level of fine-tuned regulation of protein production requires the coordinated temporal and spatial control of numerous cellular signalling cascades impinging on the various components of the translational machinery. Foremost among these is the mTOR signalling pathway. The mTOR pathway regulates both the initiation and elongation steps of protein synthesis through the phosphorylation of numerous translation factors, while simultaneously ensuring adequate folding of nascent polypeptides through co-translational degradation of misfolded proteins. Perhaps most remarkably, mTOR is also a key regulator of the synthesis of ribosomal proteins and translation factors themselves. Two seminal studies have recently shown in translatome analysis that the mTOR pathway preferentially regulates the translation of mRNAs encoding ribosomal proteins and translation factors. Therefore, the role of the mTOR pathway in the control of protein synthesis extends far beyond immediate translational control. By controlling ribosome production (and ultimately ribosome availability), mTOR is a master long-term controller of protein synthesis. Herein, we review the literature spanning the early discoveries of mTOR on translation to the latest advances in our understanding of how the mTOR pathway controls the synthesis of ribosomal proteins.
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Affiliation(s)
- Bruno D Fonseca
- Children's Hospital of Eastern Ontario Research Institute, 401 Smyth Road, Ottawa, ON K1H 8L1, Canada.
| | - Ewan M Smith
- MRC Toxicology Unit, Hodgkin Building, Lancaster Road, Leicester LE1 9HN, UK
| | - Nicolas Yelle
- Children's Hospital of Eastern Ontario Research Institute, 401 Smyth Road, Ottawa, ON K1H 8L1, Canada
| | - Tommy Alain
- Children's Hospital of Eastern Ontario Research Institute, 401 Smyth Road, Ottawa, ON K1H 8L1, Canada
| | - Martin Bushell
- MRC Toxicology Unit, Hodgkin Building, Lancaster Road, Leicester LE1 9HN, UK
| | - Arnim Pause
- Goodman Cancer Research Centre, Department of Biochemistry, McGill University, Montreal, QC H3A 1A3, Canada.
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38
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Eukaryotic elongation factor 2 kinase activity is controlled by multiple inputs from oncogenic signaling. Mol Cell Biol 2014; 34:4088-103. [PMID: 25182533 DOI: 10.1128/mcb.01035-14] [Citation(s) in RCA: 72] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Eukaryotic elongation factor 2 kinase (eEF2K), an atypical calmodulin-dependent protein kinase, phosphorylates and inhibits eEF2, slowing down translation elongation. eEF2K contains an N-terminal catalytic domain, a C-terminal α-helical region and a linker containing several regulatory phosphorylation sites. eEF2K is expressed at high levels in certain cancers, where it may act to help cell survival, e.g., during nutrient starvation. However, it is a negative regulator of protein synthesis and thus cell growth, suggesting that cancer cells may possess mechanisms to inhibit eEF2K under good growth conditions, to allow protein synthesis to proceed. We show here that the mTORC1 pathway and the oncogenic Ras/Raf/MEK/extracellular signal-regulated kinase (ERK) pathway cooperate to restrict eEF2K activity. We identify multiple sites in eEF2K whose phosphorylation is regulated by mTORC1 and/or ERK, including new ones in the linker region. We demonstrate that certain sites are phosphorylated directly by mTOR or ERK. Our data reveal that glycogen synthase kinase 3 signaling also regulates eEF2 phosphorylation. In addition, we show that phosphorylation sites remote from the N-terminal calmodulin-binding motif regulate the phosphorylation of N-terminal sites that control CaM binding. Mutations in the former sites, which occur in cancer cells, cause the activation of eEF2K. eEF2K is thus regulated by a network of oncogenic signaling pathways.
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39
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Tavares CDJ, Ferguson SB, Giles DH, Wang Q, Wellmann RM, O'Brien JP, Warthaka M, Brodbelt JS, Ren P, Dalby KN. The molecular mechanism of eukaryotic elongation factor 2 kinase activation. J Biol Chem 2014; 289:23901-16. [PMID: 25012662 DOI: 10.1074/jbc.m114.577148] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Calmodulin (CaM)-dependent eukaryotic elongation factor 2 kinase (eEF-2K) impedes protein synthesis through phosphorylation of eukaryotic elongation factor 2 (eEF-2). It is subject to complex regulation by multiple upstream signaling pathways, through poorly described mechanisms. Precise integration of these signals is critical for eEF-2K to appropriately regulate protein translation rates. Here, an allosteric mechanism comprising two sequential conformations is described for eEF-2K activation. First, Ca(2+)/CaM binds eEF-2K with high affinity (Kd(CaM)(app) = 24 ± 5 nm) to enhance its ability to autophosphorylate Thr-348 in the regulatory loop (R-loop) by > 10(4)-fold (k(auto) = 2.6 ± 0.3 s(-1)). Subsequent binding of phospho-Thr-348 to a conserved basic pocket in the kinase domain potentially drives a conformational transition of the R-loop, which is essential for efficient substrate phosphorylation. Ca(2+)/CaM binding activates autophosphorylated eEF-2K by allosterically enhancing k(cat)(app) for peptide substrate phosphorylation by 10(3)-fold. Thr-348 autophosphorylation results in a 25-fold increase in the specificity constant (k(cat)(app)/K(m)(Pep-S) (app)), with equal contributions from k(cat)(app) and K(m)(Pep-S)(app), suggesting that peptide substrate binding is partly impeded in the unphosphorylated enzyme. In cells, Thr-348 autophosphorylation appears to control the catalytic output of active eEF-2K, contributing more than 5-fold to its ability to promote eEF-2 phosphorylation. Fundamentally, eEF-2K activation appears to be analogous to an amplifier, where output volume may be controlled by either toggling the power switch (switching on the kinase) or altering the volume control (modulating stability of the active R-loop conformation). Because upstream signaling events have the potential to modulate either allosteric step, this mechanism allows for exquisite control of eEF-2K output.
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Affiliation(s)
- Clint D J Tavares
- From the Graduate Program in Cell and Molecular Biology, the Division of Medicinal Chemistry, College of Pharmacy,
| | | | - David H Giles
- the Division of Medicinal Chemistry, College of Pharmacy
| | - Qiantao Wang
- the Division of Medicinal Chemistry, College of Pharmacy, the Department of Biomedical Engineering, Cockrell School of Engineering, and
| | | | - John P O'Brien
- the Department of Chemistry and Biochemistry, College of Natural Sciences, University of Texas, Austin, Texas 78712
| | | | - Jennifer S Brodbelt
- the Department of Chemistry and Biochemistry, College of Natural Sciences, University of Texas, Austin, Texas 78712
| | - Pengyu Ren
- the Department of Biomedical Engineering, Cockrell School of Engineering, and
| | - Kevin N Dalby
- From the Graduate Program in Cell and Molecular Biology, the Division of Medicinal Chemistry, College of Pharmacy,
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40
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Kenney JW, Moore CE, Wang X, Proud CG. Eukaryotic elongation factor 2 kinase, an unusual enzyme with multiple roles. Adv Biol Regul 2014; 55:15-27. [PMID: 24853390 DOI: 10.1016/j.jbior.2014.04.003] [Citation(s) in RCA: 132] [Impact Index Per Article: 13.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2014] [Accepted: 04/15/2014] [Indexed: 12/27/2022]
Abstract
Eukaryotic elongation factor 2 kinase (eEF2K) is a member of the small group of atypical 'α-kinases'. It phosphorylates and inhibits eukaryotic elongation factor 2, to slow down the elongation stage of protein synthesis, which normally consumes a great deal of energy and amino acids. The activity of eEF2K is normally dependent on calcium ions and calmodulin. eEF2K is also regulated by a plethora of other inputs, including inhibition by signalling downstream of anabolic signalling pathways such as the mammalian target of rapamycin complex 1. Recent data show that eEF2K helps to protect cancer cells against nutrient starvation and is also cytoprotective in other settings, including hypoxia. Growing evidence points to roles for eEF2K in neurological processes such as learning and memory and perhaps in depression.
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Affiliation(s)
- Justin W Kenney
- Centre for Biological Sciences, Life Sciences Building, University of Southampton, Southampton, SO16 7LB, UK
| | - Claire E Moore
- Centre for Biological Sciences, Life Sciences Building, University of Southampton, Southampton, SO16 7LB, UK
| | - Xuemin Wang
- Centre for Biological Sciences, Life Sciences Building, University of Southampton, Southampton, SO16 7LB, UK
| | - Christopher G Proud
- Centre for Biological Sciences, Life Sciences Building, University of Southampton, Southampton, SO16 7LB, UK.
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41
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Liu R, Iadevaia V, Averous J, Taylor PM, Zhang Z, Proud CG. Impairing the production of ribosomal RNA activates mammalian target of rapamycin complex 1 signalling and downstream translation factors. Nucleic Acids Res 2014; 42:5083-96. [PMID: 24526220 PMCID: PMC4005692 DOI: 10.1093/nar/gku130] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Ribosome biogenesis is a key process for maintaining protein synthetic capacity in dividing or growing cells, and requires coordinated production of ribosomal proteins and ribosomal RNA (rRNA), including the processing of the latter. Signalling through mammalian target of rapamycin complex 1 (mTORC1) activates all these processes. Here, we show that, in human cells, impaired rRNA processing, caused by expressing an interfering mutant of BOP1 or by knocking down components of the PeBoW complex elicits activation of mTORC1 signalling. This leads to enhanced phosphorylation of its substrates S6K1 and 4E-BP1, and stimulation of proteins involved in translation initiation and elongation. In particular, we observe both inactivation and downregulation of the eukaryotic elongation factor 2 kinase, which normally inhibits translation elongation. The latter effect involves decreased expression of the eEF2K mRNA. The mRNAs for ribosomal proteins, whose translation is positively regulated by mTORC1 signalling, also remain associated with ribosomes. Therefore, our data demonstrate that disrupting rRNA production activates mTORC1 signalling to enhance the efficiency of the translational machinery, likely to help compensate for impaired ribosome production.
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Affiliation(s)
- Rui Liu
- Centre for Biological Sciences, University of Southampton, Highfield Campus, Southampton SO17 1BJ, UK, Centre de Recherche en Nutrition Humaine, INRA Clermont-Theix, Unité de Nutrition Humaine, 63122 Ceyrat, France and Division of Molecular Physiology, James Black Centre, College of Life Sciences, University of Dundee, Dundee, DD1 5EH, UK
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42
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Workman JJ, Chen H, Laribee RN. Environmental signaling through the mechanistic target of rapamycin complex 1: mTORC1 goes nuclear. Cell Cycle 2014; 13:714-25. [PMID: 24526113 PMCID: PMC3979908 DOI: 10.4161/cc.28112] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
Mechanistic target of rapamycin complex 1 (mTORC1) is a well-known regulator of cell growth and proliferation in response to environmental stimuli and stressors. To date, the majority of mTORC1 studies have focused on its function as a cytoplasmic effector of translation regulation. However, recent studies have identified additional, nuclear-specific roles for mTORC1 signaling related to transcription of the ribosomal DNA (rDNA) and ribosomal protein (RP) genes, mitotic cell cycle control, and the regulation of epigenetic processes. As this area of study is still in its infancy, the purpose of this review to highlight these significant findings and discuss the relevance of nuclear mTORC1 signaling dysregulation as it pertains to health and disease.
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Affiliation(s)
- Jason J Workman
- Department of Pathology and Laboratory Medicine and Center for Cancer Research; University of Tennessee Health Science Center; Memphis, TN USA
| | - Hongfeng Chen
- Department of Pathology and Laboratory Medicine and Center for Cancer Research; University of Tennessee Health Science Center; Memphis, TN USA
| | - R Nicholas Laribee
- Department of Pathology and Laboratory Medicine and Center for Cancer Research; University of Tennessee Health Science Center; Memphis, TN USA
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Coldwell MJ, Cowan JL, Vlasak M, Mead A, Willett M, Perry LS, Morley SJ. Phosphorylation of eIF4GII and 4E-BP1 in response to nocodazole treatment: a reappraisal of translation initiation during mitosis. Cell Cycle 2013; 12:3615-28. [PMID: 24091728 DOI: 10.4161/cc.26588] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Translation mechanisms at different stages of the cell cycle have been studied for many years, resulting in the dogma that translation rates are slowed during mitosis, with cap-independent translation mechanisms favored to give expression of key regulatory proteins. However, such cell culture studies involve synchronization using harsh methods, which may in themselves stress cells and affect protein synthesis rates. One such commonly used chemical is the microtubule de-polymerization agent, nocodazole, which arrests cells in mitosis and has been used to demonstrate that translation rates are strongly reduced (down to 30% of that of asynchronous cells). Using synchronized HeLa cells released from a double thymidine block (G 1/S boundary) or the Cdk1 inhibitor, RO3306 (G 2/M boundary), we have systematically re-addressed this dogma. Using FACS analysis and pulse labeling of proteins with labeled methionine, we now show that translation rates do not slow as cells enter mitosis. This study is complemented by studies employing confocal microscopy, which show enrichment of translation initiation factors at the microtubule organizing centers, mitotic spindle, and midbody structure during the final steps of cytokinesis, suggesting that translation is maintained during mitosis. Furthermore, we show that inhibition of translation in response to extended times of exposure to nocodazole reflects increased eIF2α phosphorylation, disaggregation of polysomes, and hyperphosphorylation of selected initiation factors, including novel Cdk1-dependent N-terminal phosphorylation of eIF4GII. Our work suggests that effects on translation in nocodazole-arrested cells might be related to those of the treatment used to synchronize cells rather than cell cycle status.
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Affiliation(s)
- Mark J Coldwell
- Centre for Biological Sciences; University of Southampton; Southampton, UK
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Usui T, Okada M, Hara Y, Yamawaki H. Eukaryotic elongation factor 2 kinase regulates the development of hypertension through oxidative stress-dependent vascular inflammation. Am J Physiol Heart Circ Physiol 2013; 305:H756-68. [PMID: 23812389 DOI: 10.1152/ajpheart.00373.2013] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Eukaryotic elongation factor 2 kinase (eEF2K) is a Ca2+/calmodulin-dependent protein kinase. We recently demonstrated that eEF2K protein increases in mesenteric artery from spontaneously hypertensive rats (SHR). Pathogenesis of hypertension is regulated in part by vascular inflammation. We tested the hypothesis whether eEF2K mediates vascular inflammatory responses and development of hypertension. In vascular endothelial cells, small interfering RNA (siRNA) against eEF2K inhibited induction of VCAM-1 and endothelial-selectin as well as monocyte adhesion by TNF-α (10 ng/ml). eEF2K siRNA inhibited phosphorylation of JNK and NF-κB p65 as well as reactive oxygen species (ROS) production by TNF-α. In vascular smooth muscle cells, eEF2K siRNA also inhibited VCAM-1 induction and phosphorylation of JNK and NF-κB by TNF-α. In vivo, increased blood pressure in SHR and ROS production, induction of inflammatory molecules, and hypertrophy in SHR superior mesenteric artery were reduced by an eEF2K inhibitor NH125 (500 μg·kg(-1)·day(-1)). In SHR superior mesenteric artery, impairment of ACh-induced relaxation was normalized by NH125. The present results for the first time demonstrate that eEF2K mediates TNF-α-induced vascular inflammation via ROS-dependent mechanism, which is at least partly responsible for the development of hypertension in SHR.
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Affiliation(s)
- Tatsuya Usui
- Laboratory of Veterinary Pharmacology, School of Veterinary Medicine, Kitasato University, Towada, Aomori, Japan
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45
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Matsui A, Kamada Y, Matsuura A. The role of autophagy in genome stability through suppression of abnormal mitosis under starvation. PLoS Genet 2013; 9:e1003245. [PMID: 23382696 PMCID: PMC3561091 DOI: 10.1371/journal.pgen.1003245] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2012] [Accepted: 11/30/2012] [Indexed: 01/07/2023] Open
Abstract
The coordination of subcellular processes during adaptation to environmental change is a key feature of biological systems. Starvation of essential nutrients slows cell cycling and ultimately causes G1 arrest, and nitrogen starvation delays G2/M progression. Here, we show that budding yeast cells can be efficiently returned to the G1 phase under starvation conditions in an autophagy-dependent manner. Starvation attenuates TORC1 activity, causing a G2/M delay in a Swe1-dependent checkpoint mechanism, and starvation-induced autophagy assists in the recovery from a G2/M delay by supplying amino acids required for cell growth. Persistent delay of the cell cycle by a deficiency in autophagy causes aberrant nuclear division without sufficient cell growth, leading to an increased frequency in aneuploidy after refeeding the nitrogen source. Our data establish the role of autophagy in genome stability through modulation of cell division under conditions that repress cell growth.
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Affiliation(s)
- Aiko Matsui
- Department of Nanobiology, Graduate School of Advanced Integration Science, Chiba University, Inage-ku, Chiba, Japan
| | | | - Akira Matsuura
- Department of Nanobiology, Graduate School of Advanced Integration Science, Chiba University, Inage-ku, Chiba, Japan
- * E-mail:
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Abstract
The senescence program is activated in response to diverse stress stimuli potentially compromising genetic stability and leads to an irreversible cell cycle arrest. The mTOR pathway plays a crucial role in the regulation of cell metabolism and cellular growth. The goal of this chapter is to present evidence linking these two processes, which have one common regulator-the tumor suppressor p53. While the role of mTOR in senescence is still controversial, recent papers have shed new light onto this issue. This review, far from being exhaustive given the complexity of the field, will hopefully stimulate further research in this domain, whose relevance for ageing is becoming increasingly documented.
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Phosphorylation of eukaryotic elongation factor 2 (eEF2) by cyclin A-cyclin-dependent kinase 2 regulates its inhibition by eEF2 kinase. Mol Cell Biol 2012. [PMID: 23184662 DOI: 10.1128/mcb.01270-12] [Citation(s) in RCA: 60] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Protein synthesis is highly regulated via both initiation and elongation. One mechanism that inhibits elongation is phosphorylation of eukaryotic elongation factor 2 (eEF2) on threonine 56 (T56) by eEF2 kinase (eEF2K). T56 phosphorylation inactivates eEF2 and is the only known normal eEF2 functional modification. In contrast, eEF2K undergoes extensive regulatory phosphorylations that allow diverse pathways to impact elongation. We describe a new mode of eEF2 regulation and show that its phosphorylation by cyclin A-cyclin-dependent kinase 2 (CDK2) on a novel site, serine 595 (S595), directly regulates T56 phosphorylation by eEF2K. S595 phosphorylation varies during the cell cycle and is required for efficient T56 phosphorylation in vivo. Importantly, S595 phosphorylation by cyclin A-CDK2 directly stimulates eEF2 T56 phosphorylation by eEF2K in vitro, and we suggest that S595 phosphorylation facilitates T56 phosphorylation by recruiting eEF2K to eEF2. S595 phosphorylation is thus the first known eEF2 modification that regulates its inhibition by eEF2K and provides a novel mechanism linking the cell cycle machinery to translational control. Because all known eEF2 regulation is exerted via eEF2K, S595 phosphorylation may globally couple the cell cycle machinery to regulatory pathways that impact eEF2K activity.
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Huber-Keener KJ, Evans BR, Ren X, Cheng Y, Zhang Y, Hait WN, Yang JM. Phosphorylation of elongation factor-2 kinase differentially regulates the enzyme's stability under stress conditions. Biochem Biophys Res Commun 2012; 424:308-14. [PMID: 22749997 DOI: 10.1016/j.bbrc.2012.06.112] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2012] [Accepted: 06/21/2012] [Indexed: 01/17/2023]
Abstract
Eukaryotic elongation factor-2 kinase (eEF-2K) is a Ca(2+)/calmodulin-dependent enzyme that negatively regulates protein synthesis. eEF-2K has been shown to be up-regulated in cancer, and to play an important role in cell survival through inhibition of protein synthesis. Post-translational modification of protein synthesis machinery is important for its regulation and could be critical for survival of cancer cells encountering stress. The purpose of our study was to examine the regulation of eEF-2K during stress with a focus on the roles of phosphorylation in determining the stability of eEF-2K. We found that stress conditions (nutrient deprivation and hypoxia) increase eEF-2K protein. mRNA levels are only transiently increased and shortly return to normal, while eEF-2K protein levels continue to increase after further exposure to stress. A seemingly paradoxical decrease in eEF-2K stability was found when glioma cells were subjected to stress despite increased protein expression. We further demonstrated that phosphorylation of eEF-2K differentially affects the enzyme's turnover under both normal and stress conditions, as evidenced by the different half-lives of phosphorylation-defective mutants of eEF-2K. We further found that the eEF-2K site (Ser398) phosphorylated by AMPK is pivotal to the protein's stability, as the half-life of S398A mutant increases to greater than 24h under both normal and stress conditions. These data indicate that eEF-2K is regulated at multiple levels with phosphorylation playing a critical role in the enzyme's turnover under stressful conditions. The complexity of eEF-2K phosphorylation highlights the intricacies of protein synthesis control during cellular stress.
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Affiliation(s)
- Kathryn J Huber-Keener
- Department of Pharmacology and The Penn State Hershey Cancer Institute, The Pennsylvania State University College of Medicine and Milton S. Hershey Medical Center, 500 University Drive, Hershey, PA 17033, USA
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Abstract
eEF2K [eEF2 (eukaryotic elongation factor 2) kinase] phosphorylates and inactivates the translation elongation factor eEF2. eEF2K is not a member of the main eukaryotic protein kinase superfamily, but instead belongs to a small group of so-called α-kinases. The activity of eEF2K is normally dependent upon Ca2+ and calmodulin. eEF2K has previously been shown to undergo autophosphorylation, the stoichiometry of which suggested the existence of multiple sites. In the present study we have identified several autophosphorylation sites, including Thr348, Thr353, Ser366 and Ser445, all of which are highly conserved among vertebrate eEF2Ks. We also identified a number of other sites, including Ser78, a known site of phosphorylation, and others, some of which are less well conserved. None of the sites lies in the catalytic domain, but three affect eEF2K activity. Mutation of Ser78, Thr348 and Ser366 to a non-phosphorylatable alanine residue decreased eEF2K activity. Phosphorylation of Thr348 was detected by immunoblotting after transfecting wild-type eEF2K into HEK (human embryonic kidney)-293 cells, but not after transfection with a kinase-inactive construct, confirming that this is indeed a site of autophosphorylation. Thr348 appears to be constitutively autophosphorylated in vitro. Interestingly, other recent data suggest that the corresponding residue in other α-kinases is also autophosphorylated and contributes to the activation of these enzymes [Crawley, Gharaei, Ye, Yang, Raveh, London, Schueler-Furman, Jia and Cote (2011) J. Biol. Chem. 286, 2607–2616]. Ser366 phosphorylation was also detected in intact cells, but was still observed in the kinase-inactive construct, demonstrating that this site is phosphorylated not only autocatalytically but also in trans by other kinases.
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50
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Insights into the regulation of eukaryotic elongation factor 2 kinase and the interplay between its domains. Biochem J 2012; 442:105-18. [PMID: 22115317 PMCID: PMC3268225 DOI: 10.1042/bj20111536] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
eEF2K (eukaryotic elongation factor 2 kinase) is a Ca2+/CaM (calmodulin)-dependent protein kinase which regulates the translation elongation machinery. eEF2K belongs to the small group of so-called ‘α-kinases’ which are distinct from the main eukaryotic protein kinase superfamily. In addition to the α-kinase catalytic domain, other domains have been identified in eEF2K: a CaM-binding region, N-terminal to the kinase domain; a C-terminal region containing several predicted α-helices (resembling SEL1 domains); and a probably rather unstructured ‘linker’ region connecting them. In the present paper, we demonstrate: (i) that several highly conserved residues, implicated in binding ATP or metal ions, are critical for eEF2K activity; (ii) that Ca2+/CaM enhance the ability of eEF2K to bind to ATP, providing the first insight into the allosteric control of eEF2K; (iii) that the CaM-binding/α-kinase domain of eEF2K itself possesses autokinase activity, but is unable to phosphorylate substrates in trans; (iv) that phosphorylation of these substrates requires the SEL1-like domains of eEF2K; and (v) that highly conserved residues in the C-terminal tip of eEF2K are essential for the phosphorylation of eEF2, but not a peptide substrate. On the basis of these findings, we propose a model for the functional organization and control of eEF2K.
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