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Piserchio A, Dalby KN, Ghose R. Revealing eEF-2 kinase: recent structural insights into function. Trends Biochem Sci 2024; 49:169-182. [PMID: 38103971 PMCID: PMC10950556 DOI: 10.1016/j.tibs.2023.11.004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2023] [Revised: 11/14/2023] [Accepted: 11/17/2023] [Indexed: 12/19/2023]
Abstract
The α-kinase eukaryotic elongation factor 2 kinase (eEF-2K) regulates translational elongation by phosphorylating its ribosome-associated substrate, the GTPase eEF-2. eEF-2K is activated by calmodulin (CaM) through a distinctive mechanism unlike that in other CaM-dependent kinases (CAMK). We describe recent structural insights into this unique activation process and examine the effects of specific regulatory signals on this mechanism. We also highlight key unanswered questions to guide future structure-function studies. These include structural mechanisms which enable eEF-2K to interact with upstream/downstream partners and facilitate its integration of diverse inputs, including Ca2+ transients, phosphorylation mediated by energy/nutrient-sensing pathways, pH changes, and metabolites. Answering these questions is key to establishing how eEF-2K harmonizes translation with cellular requirements within the boundaries of its molecular landscape.
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Affiliation(s)
- Andrea Piserchio
- Department of Chemistry and Biochemistry, The City College of New York, New York, NY 10031, USA
| | - Kevin N Dalby
- Division of Chemical Biology and Medicinal Chemistry, The 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; The Graduate Center of The City University of New York (CUNY), New York, NY 10016, USA.
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2
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Vilchinskaya N, Lim WF, Belova S, Roberts TC, Wood MJA, Lomonosova Y. Investigating Eukaryotic Elongation Factor 2 Kinase/Eukaryotic Translation Elongation Factor 2 Pathway Regulation and Its Role in Protein Synthesis Impairment during Disuse-Induced Skeletal Muscle Atrophy. THE AMERICAN JOURNAL OF PATHOLOGY 2023:S0002-9440(23)00060-3. [PMID: 36871751 DOI: 10.1016/j.ajpath.2023.02.009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/23/2022] [Revised: 01/16/2023] [Accepted: 02/10/2023] [Indexed: 03/07/2023]
Abstract
The principal mechanism underlying the reduced rate of protein synthesis in atrophied skeletal muscle is largely unknown. Eukaryotic elongation factor 2 kinase (eEF2k) impairs the ability of eukaryotic translation elongation factor 2 (eEF2) to bind to the ribosome via T56 phosphorylation. Perturbations in the eEF2k/eEF2 pathway during various stages of disuse muscle atrophy have been investigated utilizing a rat hind limb suspension (HS) model. Two distinct components of eEF2k/eEF2 pathway misregulation were demonstrated, observing a significant (P < 0.01) increase in eEF2k mRNA expression as early as 1-day HS and in eEF2k protein level after 3-day HS. We set out to determine whether eEF2k activation is a Ca2+-dependent process with involvement of Cav1.1. The ratio of T56-phosphorylated/total eEF2 was robustly elevated after 3-day HS, which was completely reversed by BAPTA-AM and decreased by 1.7-fold (P < 0.05) by nifedipine. Transfection of C2C12 with pCMV-eEF2k and administration with small molecules were used to modulate eEF2k and eEF2 activity. More important, pharmacologic enhancement of eEF2 phosphorylation induced phosphorylated ribosomal protein S6 kinase (T389) up-regulation and restoration of global protein synthesis in the HS rats. Taken together, the eEF2k/eEF2 pathway is up-regulated during disuse muscle atrophy involving calcium-dependent activation of eEF2k partly via Cav1.1. The study provides evidence, in vitro and in vivo, of the eEF2k/eEF2 pathway impact on ribosomal protein S6 kinase activity as well as protein expression of key atrophy biomarkers, muscle atrophy F-box/atrogin-1 and muscle RING finger-1.
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Affiliation(s)
| | - Wooi Fang Lim
- Department of Paediatrics, University of Oxford Children's Hospital, John Radcliffe Hospital, Oxford, United Kingdom; Institute of Developmental and Regenerative Medicine, Oxford, United Kingdom; MDUK Oxford Neuromuscular Centre, University of Oxford, Oxford, United Kingdom
| | | | - Thomas C Roberts
- Department of Paediatrics, University of Oxford Children's Hospital, John Radcliffe Hospital, Oxford, United Kingdom; Institute of Developmental and Regenerative Medicine, Oxford, United Kingdom; MDUK Oxford Neuromuscular Centre, University of Oxford, Oxford, United Kingdom
| | - Matthew J A Wood
- Department of Paediatrics, University of Oxford Children's Hospital, John Radcliffe Hospital, Oxford, United Kingdom; Institute of Developmental and Regenerative Medicine, Oxford, United Kingdom; MDUK Oxford Neuromuscular Centre, University of Oxford, Oxford, United Kingdom
| | - Yulia Lomonosova
- Department of Paediatrics, University of Oxford Children's Hospital, John Radcliffe Hospital, Oxford, United Kingdom; Institute of Developmental and Regenerative Medicine, Oxford, United Kingdom; MDUK Oxford Neuromuscular Centre, University of Oxford, Oxford, United Kingdom.
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3
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Piserchio A, Isiorho EA, Long K, Bohanon AL, Kumar EA, Will N, Jeruzalmi D, Dalby KN, Ghose R. Structural basis for the calmodulin-mediated activation of eukaryotic elongation factor 2 kinase. SCIENCE ADVANCES 2022; 8:eabo2039. [PMID: 35857468 PMCID: PMC9258954 DOI: 10.1126/sciadv.abo2039] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/02/2022] [Accepted: 05/20/2022] [Indexed: 05/27/2023]
Abstract
Translation is a tightly regulated process that ensures optimal protein quality and enables adaptation to energy/nutrient availability. The α-kinase eukaryotic elongation factor 2 kinase (eEF-2K), a key regulator of translation, specifically phosphorylates the guanosine triphosphatase eEF-2, thereby reducing its affinity for the ribosome and suppressing the elongation phase of protein synthesis. eEF-2K activation requires calmodulin binding and autophosphorylation at the primary stimulatory site, T348. Biochemical studies predict a calmodulin-mediated activation mechanism for eEF-2K distinct from other calmodulin-dependent kinases. Here, we resolve the atomic details of this mechanism through a 2.3-Å crystal structure of the heterodimeric complex of calmodulin and the functional core of eEF-2K (eEF-2KTR). This structure, which represents the activated T348-phosphorylated state of eEF-2KTR, highlights an intimate association of the kinase with the calmodulin C-lobe, creating an "activation spine" that connects its amino-terminal calmodulin-targeting motif to its active site through a conserved regulatory element.
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Affiliation(s)
- Andrea Piserchio
- Department of Chemistry and Biochemistry, The City College of New York, New York, NY 10031, USA
| | - Eta A. Isiorho
- Macromolecular Crystallization Facility, CUNY ASRC, New York, NY 10031, USA
| | - Kimberly Long
- Division of Chemical Biology and Medicinal Chemistry, University of Texas, Austin, TX 78712, USA
| | - Amanda L. Bohanon
- Division of Chemical Biology and Medicinal Chemistry, University of Texas, Austin, TX 78712, USA
- Department of Molecular Biosciences, University of Texas at Austin, Austin, TX 78712, USA
| | - Eric A. Kumar
- Division of Chemical Biology and Medicinal Chemistry, University of Texas, Austin, TX 78712, USA
| | - Nathan Will
- Department of Chemistry and Biochemistry, The City College of New York, New York, NY 10031, USA
- PhD Program in Biochemistry, The Graduate Center of CUNY, New York, NY 10016, USA
| | - David Jeruzalmi
- Department of Chemistry and Biochemistry, The City College of New York, New York, NY 10031, USA
- PhD Program in Biochemistry, The Graduate Center of CUNY, New York, NY 10016, USA
| | - Kevin N. Dalby
- 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
- PhD Program in Biochemistry, The Graduate Center of CUNY, New York, NY 10016, USA
- PhD Program in Chemistry, The Graduate Center of CUNY, New York, NY 10016, USA
- PhD Program in Physics, The Graduate Center of CUNY, New York, NY 10016, USA
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4
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Chen X, Wang K, Jiang S, Sun H, Che X, Zhang M, He J, Wen Y, Liao M, Li X, Zhou X, Song J, Ren X, Yi W, Yang J, Chen X, Yin M, Cheng Y. eEF2K promotes PD-L1 stabilization through inactivating GSK3β in melanoma. J Immunother Cancer 2022; 10:jitc-2021-004026. [PMID: 35347072 PMCID: PMC8961175 DOI: 10.1136/jitc-2021-004026] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/03/2022] [Indexed: 12/21/2022] Open
Abstract
Background Immune checkpoint blockade (ICB) targeting programmed death ligand-1 (PD-L1)/programmed cell death protein-1 (PD-1) pathway has become an attractive strategy for cancer treatment; however, unsatisfactory efficacy has limited its clinical benefits. Therefore, a more comprehensive understanding of the regulation of PD-L1 expression is essential for developing more effective cancer immunotherapy. Recent studies have revealed the important roles of eukaryotic elongation factor 2 kinase (eEF2K) in promoting epithelial-mesenchymal transition (EMT), angiogenesis, tumor cell migration and invasion; nevertheless, the exact role of eEF2K in the regulation of tumor immune microenvironment (TIME) remains largely unknown. Methods In this study, we used a cohort of 38 patients with melanoma who received anti-PD-1 treatment to explore the association between eEF2K expression and immunotherapy efficacy against melanoma. Immunoprecipitation-mass spectrometry analysis and in vitro assays were used to examine the role and molecular mechanism of eEF2K in regulating PD-L1 expression. We also determined the effects of eEF2K on tumor growth and cytotoxicity of CD8+ T cells in TIME in a mouse melanoma model. We further investigated the efficacy of the eEF2K inhibition in combination with anti-PD-1 treatment in vivo. Results High eEF2K expression is correlated with better therapeutic response and longer survival in patients with melanoma treated with PD-1 monoclonal antibody (mAb). Moreover, eEF2K protein expression is positively correlated with PD-L1 protein expression. Mechanistically, eEF2K directly bound to and inactivated glycogen synthase kinase 3 beta (GSK3β) by phosphorylating it at serine 9 (S9), leading to PD-L1 protein stabilization and upregulation, and subsequently tumor immune evasion. Knockdown of eEF2K decreased PD-L1 expression and enhanced CD8+ T cell activity, thus dramatically attenuating murine B16F10 melanoma growth in vivo. Clinically, p-GSK3β/S9 expression is positively correlated with the expressions of eEF2K and PD-L1, and the response to anti-PD-1 immunotherapy. Furthermore, eEF2K inhibitor, NH125 treatment or eEF2K knockdown enhanced the efficacy of PD-1 mAb therapy in a melanoma mouse model. Conclusions Our results suggest that eEF2K may serve as a biomarker for predicting therapeutic response and prognosis in patients receiving anti-PD-1 therapy, reveal a vital role of eEF2K in regulating TIME by controlling PD-L1 expression and provide a potential combination therapeutic strategy of eEF2K inhibition with ICB therapy.
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Affiliation(s)
- Xisha Chen
- Department of Pharmacy, The Second Xiangya Hospital, Central South University, Changsha, China
- Hunan Provincial Engineering Research Centre of Translational Medicine and Innovative Drug, Changsha, China
| | - Kuansong Wang
- Department of Pathology, Xiangya hospital and Department of Pathology, School of Basic Medicine, Central South University, Changsha, China
| | - Shilong Jiang
- Department of Pharmacy, The Second Xiangya Hospital, Central South University, Changsha, China
| | - Hongyin 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, China
| | - Xuanling Che
- 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, China
| | - Minghui Zhang
- Department of Medical Oncology, Harbin Medical University Cancer Hospital, Harbin, China
| | - Jiaying He
- Department of Pharmacy, The Second Xiangya Hospital, Central South University, Changsha, China
| | - Ying Wen
- Department of General Surgery, The Second Xiangya Hospital, Central South University, Changsha, China
| | - Mengting Liao
- 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, China
| | - Xiangling Li
- Department of Pharmacy, The Second Xiangya Hospital, Central South University, Changsha, China
- Hunan Provincial Engineering Research Centre of Translational Medicine and Innovative Drug, Changsha, China
| | - Xiaoming Zhou
- Department of Pharmacy, School of Medicine, Hunan Normal University, Changsha, China
| | - Jianxun Song
- Department of Microbial Pathogenesis and Immunology, Texas A&M University Health Science Center, Bryan, Texas, USA
| | - Xingcong Ren
- Department of Cancer Biology and Toxicology, Department of Pharmacology, College of Medicine, Markey Cancer Center, University of Kentucky, Lexington, Kentucky, USA
| | - Wenjun Yi
- Department of General Surgery, The Second Xiangya Hospital, Central South University, Changsha, China
| | - Jinming Yang
- Department of Cancer Biology and Toxicology, Department of Pharmacology, College of Medicine, Markey Cancer Center, University of Kentucky, Lexington, Kentucky, USA
| | - 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, 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, China
| | - Yan Cheng
- Department of Pharmacy, The Second Xiangya Hospital, Central South University, Changsha, China
- Hunan Provincial Engineering Research Centre of Translational Medicine and Innovative Drug, Changsha, China
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Zhao Y, Castro LFC, Monroig Ó, Cao X, Sun Y, Gao J. A zebrafish pparγ gene deletion reveals a protein kinase network associated with defective lipid metabolism. Funct Integr Genomics 2022; 22:435-450. [PMID: 35290539 DOI: 10.1007/s10142-022-00839-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2021] [Revised: 02/26/2022] [Accepted: 02/28/2022] [Indexed: 11/25/2022]
Abstract
Peroxisome proliferator-activated receptor γ (Pparγ) is a master regulator of adipogenesis. Chronic pathologies such as obesity, cardiovascular diseases, and diabetes involve the dysfunction of this transcription factor. Here, we generated a zebrafish mutant in pparγ (KO) with CRISPR/Cas9 technology and revealed its regulatory network. We uncovered the hepatic phenotypes of these male and female KO, and then the male wild-type zebrafish (WT) and KO were fed with a high-fat (HF) or standard diet (SD). We next conducted an integrated analyze of the proteomics and phosphoproteomics profiles. Compared with WT, the KO showed remarkable hyalinization and congestion lesions in the liver of males. Strikingly, pparγ deletion protected against the influence of high-fat diet feeding on lipid deposition in zebrafish. Some protein kinases critical for lipid metabolism, including serine/threonine-protein kinase TOR (mTOR), ribosomal protein S6 kinase (Rps6kb1b), and mitogen-activated protein kinase 14A (Mapk14a), were identified to be highly phosphorylated in KO based on differential proteome and phosphoproteome analysis. Our study supplies a pparγ deletion animal model and provides a comprehensive description of pparγ-induced expression level alterations of proteins and their phosphorylation, which are vital to understand the defective lipid metabolism risks posed to human health.
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Affiliation(s)
- Yan Zhao
- College of Fisheries, Engineering Research Center of Green Development for Conventional Aquatic Biological Industry in the Yangtze River Economic Belt, Ministry of Education, Huazhong Agricultural University, Wuhan, 430070, China
- Key Lab of Freshwater Animal Breeding, Ministry of Agriculture, Wuhan, 430070, China
- School of Basic Medical Sciences, Wuhan University, Wuhan, 430070, China
| | - L Filipe C Castro
- CIIMAR/CIMAR - Interdisciplinary Centre of Marine and Environmental Research, University of Porto, Porto, Portugal
- FCUP - Faculty of Sciences, Department of Biology, University of Porto, Porto, Portugal
| | - Óscar Monroig
- Instituto de Acuicultura Torre de La Sal (IATS-CSIC), Ribera de Cabanes, 12595, Castellón, Spain
| | - Xiaojuan Cao
- College of Fisheries, Engineering Research Center of Green Development for Conventional Aquatic Biological Industry in the Yangtze River Economic Belt, Ministry of Education, Huazhong Agricultural University, Wuhan, 430070, China
- Key Lab of Freshwater Animal Breeding, Ministry of Agriculture, Wuhan, 430070, China
| | - Yonghua Sun
- State Key Laboratory of Freshwater Ecology and Biotechnology, China Zebrafish Resource Center, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, 430070, China
| | - Jian Gao
- College of Fisheries, Engineering Research Center of Green Development for Conventional Aquatic Biological Industry in the Yangtze River Economic Belt, Ministry of Education, Huazhong Agricultural University, Wuhan, 430070, China.
- Key Lab of Freshwater Animal Breeding, Ministry of Agriculture, Wuhan, 430070, China.
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6
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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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7
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Xie J, Shen K, Jones AT, Yang J, Tee AR, Shen MH, Yu M, Irani S, Wong D, Merrett JE, Lenchine RV, De Poi S, Jensen KB, Trim PJ, Snel MF, Kamei M, Martin SK, Fitter S, Tian S, Wang X, Butler LM, Zannettino ACW, Proud CG. Reciprocal signaling between mTORC1 and MNK2 controls cell growth and oncogenesis. Cell Mol Life Sci 2021; 78:249-270. [PMID: 32170339 PMCID: PMC11068017 DOI: 10.1007/s00018-020-03491-1] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2019] [Revised: 01/23/2020] [Accepted: 02/17/2020] [Indexed: 12/21/2022]
Abstract
eIF4E plays key roles in protein synthesis and tumorigenesis. It is phosphorylated by the kinases MNK1 and MNK2. Binding of MNKs to eIF4G enhances their ability to phosphorylate eIF4E. Here, we show that mTORC1, a key regulator of mRNA translation and oncogenesis, directly phosphorylates MNK2 on Ser74. This suppresses MNK2 activity and impairs binding of MNK2 to eIF4G. These effects provide a novel mechanism by which mTORC1 signaling impairs the function of MNK2 and thereby decreases eIF4E phosphorylation. MNK2[S74A] knock-in cells show enhanced phosphorylation of eIF4E and S6K1 (i.e., increased mTORC1 signaling), enlarged cell size, and increased invasive and transformative capacities. MNK2[Ser74] phosphorylation was inversely correlated with disease progression in human prostate tumors. MNK inhibition exerted anti-proliferative effects in prostate cancer cells in vitro. These findings define a novel feedback loop whereby mTORC1 represses MNK2 activity and oncogenic signaling through eIF4E phosphorylation, allowing reciprocal regulation of these two oncogenic pathways.
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Affiliation(s)
- Jianling Xie
- Lifelong Health Theme, South Australian Health and Medical Research Institute, North Terrace, Adelaide, SA, 5000, Australia
| | - Kaikai Shen
- Medical Research Council Toxicology Unit, Leicester, UK
- School of Basic Medical Sciences, Shanghai University of Traditional Chinese Medicine, Shanghai, 201203, China
| | - Ashley T Jones
- Division of Cancer and Genetics, Cardiff University, Heath Park, Cardiff, UK
| | - Jian Yang
- Division of Cancer and Genetics, Cardiff University, Heath Park, Cardiff, UK
| | - Andrew R Tee
- Division of Cancer and Genetics, Cardiff University, Heath Park, Cardiff, UK
| | - Ming Hong Shen
- Division of Cancer and Genetics, Cardiff University, Heath Park, Cardiff, UK
| | - Mengyuan Yu
- School of Basic Medical Sciences, Shanghai University of Traditional Chinese Medicine, Shanghai, 201203, China
| | - Swati Irani
- Adelaide Medical School and Freemasons Foundation Centre for Men's Health, University of Adelaide, Adelaide, Australia
- Precision Medicine Theme, South Australian Health and Medical Research Institute, Adelaide, Australia
| | - Derick Wong
- Lifelong Health Theme, South Australian Health and Medical Research Institute, North Terrace, Adelaide, SA, 5000, Australia
| | - James E Merrett
- Lifelong Health Theme, South Australian Health and Medical Research Institute, North Terrace, Adelaide, SA, 5000, Australia
- Department of Molecular and Cellular Biology, University of Adelaide, Adelaide, Australia
| | - Roman V Lenchine
- Lifelong Health Theme, South Australian Health and Medical Research Institute, North Terrace, Adelaide, SA, 5000, Australia
- Department of Molecular and Cellular Biology, University of Adelaide, Adelaide, Australia
| | - Stuart De Poi
- Lifelong Health Theme, South Australian Health and Medical Research Institute, North Terrace, Adelaide, SA, 5000, Australia
- Department of Molecular and Cellular Biology, University of Adelaide, Adelaide, Australia
| | - Kirk B Jensen
- Lifelong Health Theme, South Australian Health and Medical Research Institute, North Terrace, Adelaide, SA, 5000, Australia
- Department of Molecular and Cellular Biology, University of Adelaide, Adelaide, Australia
| | - Paul J Trim
- Hopwood Centre for Neurobiology, South Australian Health and Medical Research Institute, Adelaide, Australia
| | - Marten F Snel
- Hopwood Centre for Neurobiology, South Australian Health and Medical Research Institute, Adelaide, Australia
| | - Makoto Kamei
- Hopwood Centre for Neurobiology, South Australian Health and Medical Research Institute, Adelaide, Australia
| | - Sally Kim Martin
- Precision Medicine Theme, South Australian Health and Medical Research Institute, Adelaide, Australia
- Myeloma Research Laboratory, Adelaide Medical School, Faculty of Health and Medical Science, University of Adelaide, Adelaide, Australia
| | - Stephen Fitter
- Precision Medicine Theme, South Australian Health and Medical Research Institute, Adelaide, Australia
- Myeloma Research Laboratory, Adelaide Medical School, Faculty of Health and Medical Science, University of Adelaide, Adelaide, Australia
| | - Shuye Tian
- Lifelong Health Theme, South Australian Health and Medical Research Institute, North Terrace, Adelaide, SA, 5000, Australia
- Department of Biology, Southern University of Science and Technology, Shenzhen, China
| | - Xuemin Wang
- Lifelong Health Theme, South Australian Health and Medical Research Institute, North Terrace, Adelaide, SA, 5000, Australia
- Hopwood Centre for Neurobiology, South Australian Health and Medical Research Institute, Adelaide, Australia
| | - Lisa M Butler
- Adelaide Medical School and Freemasons Foundation Centre for Men's Health, University of Adelaide, Adelaide, Australia
- Precision Medicine Theme, South Australian Health and Medical Research Institute, Adelaide, Australia
| | - Andrew C W Zannettino
- Precision Medicine Theme, South Australian Health and Medical Research Institute, Adelaide, Australia
- Myeloma Research Laboratory, Adelaide Medical School, Faculty of Health and Medical Science, University of Adelaide, Adelaide, Australia
| | - Christopher G Proud
- Lifelong Health Theme, South Australian Health and Medical Research Institute, North Terrace, Adelaide, SA, 5000, Australia.
- Hopwood Centre for Neurobiology, South Australian Health and Medical Research Institute, Adelaide, Australia.
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8
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Karakas D, Ozpolat B. Eukaryotic elongation factor-2 kinase (eEF2K) signaling in tumor and microenvironment as a novel molecular target. J Mol Med (Berl) 2020; 98:775-787. [PMID: 32377852 DOI: 10.1007/s00109-020-01917-8] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2019] [Revised: 04/26/2020] [Accepted: 04/28/2020] [Indexed: 12/25/2022]
Abstract
Eukaryotic elongation factor-2 kinase (eEF2K), an atypical member of alpha-kinase family, is highly overexpressed in breast, pancreatic, brain, and lung cancers, and associated with poor survival in patients. eEF2K promotes cell proliferation, survival, and aggressive tumor characteristics, leading to tumor growth and progression. While initial studies indicated that eEF2K acts as a negative regulator of protein synthesis by suppressing peptide elongation phase, later studies demonstrated that it has multiple functions and promotes cell cycle, angiogenesis, migration, and invasion as well as induction of epithelial-mesenchymal transition through induction of integrin β1, SRC/FAK, PI3K/AKT, cyclin D1, VEGF, ZEB1, Snail, and MMP-2. Under stress conditions such as hypoxia and metabolic distress, eEF2K is activated by several signaling pathways and slows down protein synthesis and helping cells to save energy and survive. In vivo therapeutic targeting of eEF2K by genetic methods inhibits tumor growth in various tumor models, validating it as a potential molecular target. Recent studies suggest that eEF2K plays a role in tumor microenvironment cells by monocyte chemoattractant protein-1 (MCP-1) and accumulation of tumor-associated macrophages. Due to its clinical significance and the pivotal role in tumorigenesis and progression, eEF2K is considered as an important therapeutic target in solid tumors. However, currently, there is no specific and potent inhibitor for translation into clinical studies. Here, we aim to systematically review current knowledge regarding eEF2K in tumor biology, microenvironment, and development of eEF2K targeted inhibitors and therapeutics.
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Affiliation(s)
- Didem Karakas
- Department of Molecular Biology and Genetics, Faculty of Arts and Sciences, Istinye University, Istanbul, Turkey
| | - Bulent Ozpolat
- Department of Experimental Therapeutics, The University of Texas MD Anderson Cancer Center, Houston, TX, 77030, USA.
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9
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Beretta S, Gritti L, Verpelli C, Sala C. Eukaryotic Elongation Factor 2 Kinase a Pharmacological Target to Regulate Protein Translation Dysfunction in Neurological Diseases. Neuroscience 2020; 445:42-49. [PMID: 32088293 DOI: 10.1016/j.neuroscience.2020.02.015] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2019] [Revised: 02/10/2020] [Accepted: 02/11/2020] [Indexed: 02/02/2023]
Abstract
Two major processes tightly regulate protein synthesis, the initiation of mRNA translation and elongation phase that mediates the movement of ribosomes along the mRNA. The elongation phase is a high energy-consuming process, and is mainly regulated by the eukaryotic elongation factor 2 kinase (eEF2K) activity that phosphorylates and inhibits eEF2, the only known substrate of the kinase. eEF2K activity is closely regulated by several signaling pathways because the translation elongation phase strongly influences the cellular energy demand and can change the expression of specific proteins in different tissues. An increasing number of recent findings link eEF2k over activation to an array of human diseases, such as atherosclerosis, pulmonary arterial hypertension, progression of solid tumors, and some major neurological disorders. Several neurological studies suggest that eEF2K is a valuable target in treating epilepsy, depression and major neurodegenerative diseases. Despite eEF2k is an ubiquitous and conserved protein, it has been proved that its deletion does not affect development in animal models and in general cell viability. Therefore, it is possible to postulate that inhibiting its function may not cause serious side effects. In addition, eEF2K is a peculiar kinase molecularly different from most of other mammalian kinases and new compounds that inhibit eEF2K should not necessarily interfere with other important protein kinases. In this review we will critically summarize the evidence supporting the role of the altered eEF2K/eEF2 pathway in defined neurological diseases and its implications in curing these diseases in animal models, and possibly in humans, by targeting eEF2K activity.
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Affiliation(s)
| | | | | | - Carlo Sala
- CNR Neuroscience Institute, Milano, Italy.
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10
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Piserchio A, Will N, Giles DH, Hajredini F, Dalby KN, Ghose R. Solution Structure of the Carboxy-Terminal Tandem Repeat Domain of Eukaryotic Elongation Factor 2 Kinase and Its Role in Substrate Recognition. J Mol Biol 2019; 431:2700-2717. [PMID: 31108082 PMCID: PMC6599559 DOI: 10.1016/j.jmb.2019.05.019] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2019] [Revised: 04/15/2019] [Accepted: 05/12/2019] [Indexed: 12/31/2022]
Abstract
Eukaryotic elongation factor 2 kinase (eEF-2K), an atypical calmodulin-activated protein kinase, regulates translational elongation by phosphorylating its substrate, eukaryotic elongation factor 2 (eEF-2), thereby reducing its affinity for the ribosome. The activation and activity of eEF-2K are critical for survival under energy-deprived conditions and is implicated in a variety of essential physiological processes. Previous biochemical experiments have indicated that the binding site for the substrate eEF-2 is located in the C-terminal domain of eEF-2K, a region predicted to harbor several α-helical repeats. Here, using NMR methodology, we have determined the solution structure of a C-terminal fragment of eEF-2K, eEF-2K562-725 that encodes two α-helical repeats. The structure of eEF-2K562-725 shows signatures characteristic of TPR domains and of their SEL1-like sub-family. Furthermore, using the analyses of NMR spectral perturbations and ITC measurements, we have localized the eEF-2 binding site on eEF-2K562-725. We find that eEF-2K562-725 engages eEF-2 with an affinity comparable to that of the full-length enzyme. Furthermore, eEF-2K562-725 is able to inhibit the phosphorylation of eEF-2 by full-length eEF-2K in trans. Our present studies establish that eEF-2K562-725 encodes the major elements necessary to enable the eEF-2K/eEF-2 interactions.
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Affiliation(s)
- Andrea Piserchio
- Department of Chemistry and Biochemistry, The City College of New York, NewYork, NY 10031, USA
| | - Nathan Will
- Department of Chemistry and Biochemistry, The City College of New York, NewYork, NY 10031, USA; Graduate Program in Biochemistry, The Graduate Center of CUNY, New York, NY 10016, USA
| | - David H Giles
- Graduate Program in Cell and Molecular Biology, University of Texas, Austin, TX 78712, USA
| | - Fatlum Hajredini
- Department of Chemistry and Biochemistry, The City College of New York, NewYork, NY 10031, USA; Graduate Program in Biochemistry, The Graduate Center of CUNY, New York, NY 10016, 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, NewYork, 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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11
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Will N, Lee K, Hajredini F, Giles DH, Abzalimov RR, Clarkson M, Dalby KN, Ghose R. Structural Dynamics of the Activation of Elongation Factor 2 Kinase by Ca 2+-Calmodulin. J Mol Biol 2018; 430:2802-2821. [PMID: 29800565 DOI: 10.1016/j.jmb.2018.05.033] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2018] [Revised: 05/16/2018] [Accepted: 05/16/2018] [Indexed: 11/18/2022]
Abstract
Eukaryotic elongation factor 2 kinase (eEF-2K), the only known calmodulin (CaM)-activated α-kinase, phosphorylates eukaryotic elongation factor 2 (eEF-2) on a specific threonine (Thr-56) diminishing its affinity for the ribosome and reducing the rate of nascent chain elongation during translation. Despite its critical cellular role, the precise mechanisms underlying the CaM-mediated activation of eEF-2K remain poorly defined. Here, employing a minimal eEF-2K construct (TR) that exhibits activity comparable to the wild-type enzyme and is fully activated by CaM in vitro and in cells, and using a variety of complimentary biophysical techniques in combination with computational modeling, we provide a structural mechanism by which CaM activates eEF-2K. Native mass analysis reveals that CaM, with two bound Ca2+ ions, forms a stoichiometric 1:1 complex with TR. Chemical crosslinking mass spectrometry and small-angle X-ray scattering measurements localize CaM near the N-lobe of the TR kinase domain and the spatially proximal C-terminal helical repeat. Hydrogen/deuterium exchange mass spectrometry and methyl NMR indicate that the conformational changes induced on TR by the engagement of CaM are not localized but are transmitted to remote regions that include the catalytic site and the functionally important phosphate binding pocket. The structural insights obtained from the present analyses, together with our previously published kinetics data, suggest that TR, and by inference, wild-type eEF-2K, upon engaging CaM undergoes a conformational transition resulting in a state that is primed to efficiently auto-phosphorylate on the primary activating T348 en route to full activation.
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Affiliation(s)
- Nathan Will
- 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
| | - 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
| | - Fatlum Hajredini
- 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
| | - David H Giles
- Division of Chemical Biology and Medicinal Chemistry, University of Texas, Austin, TX 78712, USA
| | - Rinat R Abzalimov
- Biomolecular Mass Spectrometry Facility, CUNY ASRC, New York, NY 10031, USA
| | - Michael Clarkson
- Molecular Structures Core, University of Arizona, Tucson, AZ 85721, USA
| | - Kevin N Dalby
- Division of Chemical Biology and Medicinal Chemistry, University of Texas, Austin, TX 78712, USA; Graduate Program in Cell and Molecular Biology, 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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12
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Eukaryotic Elongation Factor 2 Kinase (eEF2K) in Cancer. Cancers (Basel) 2017; 9:cancers9120162. [PMID: 29186827 PMCID: PMC5742810 DOI: 10.3390/cancers9120162] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2017] [Revised: 11/24/2017] [Accepted: 11/25/2017] [Indexed: 12/31/2022] Open
Abstract
Eukaryotic elongation factor 2 kinase (eEF2K) is a highly unusual protein kinase that negatively regulates the elongation step of protein synthesis. This step uses the vast majority of the large amount of energy and amino acids required for protein synthesis. eEF2K activity is controlled by an array of regulatory inputs, including inhibition by signalling through mammalian target of rapamycin complex 1 (mTORC1). eEF2K is activated under conditions of stress, such as energy depletion or nutrient deprivation, which can arise in poorly-vascularised tumours. In many such stress conditions, eEF2K exerts cytoprotective effects. A growing body of data indicates eEF2K aids the growth of solid tumours in vivo. Since eEF2K is not essential (in mice) under ‘normal’ conditions, eEF2K may be a useful target in the treatment of solid tumours. However, some reports suggest that eEF2K may actually impair tumorigenesis in some situations. Such a dual role of eEF2K in cancer would be analogous to the situation for other pathways involved in cell metabolism, such as autophagy and mTORC1. Further studies are needed to define the role of eEF2K in different tumour types and at differing stages in tumorigenesis, and to assess its utility as a therapeutic target in oncology.
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13
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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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14
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McCamphill PK, Ferguson L, Sossin WS. A decrease in eukaryotic elongation factor 2 phosphorylation is required for local translation of sensorin and long-term facilitation in Aplysia. J Neurochem 2017; 142:246-259. [PMID: 28345161 DOI: 10.1111/jnc.14030] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2017] [Revised: 03/15/2017] [Accepted: 03/17/2017] [Indexed: 12/20/2022]
Abstract
Mechanistic target of rapamycin complex 1 (mTORC1)-dependent protein synthesis is required for many forms of synaptic plasticity and memory, but the downstream pathways important for synaptic plasticity are poorly understood. Long-term facilitation (LTF) in Aplysia is a form of synaptic plasticity that is closely linked to behavioral memory and an attractive model system for examining the important downstream targets for mTORC1 in regulating synaptic plasticity. Although mTORC1-regulated protein synthesis has been strongly linked to translation initiation, translation elongation is also regulated by mTORC1 and LTF leads to an mTORC1-dependent decrease in eukaryotic elongation factor 2 (eEF2) phosphorylation. The purpose of this study is to test the hypothesis that the decrease in eEF2 phosphorylation is required for mTORC1-dependent translation and plasticity. We show that the LTF-induced decrease in eEF2 phosphorylation is blocked by expression of an eEF2 kinase (eEF2K) modified to be resistant to mTORC1 regulation. We found that expression of this modified kinase blocked LTF. LTF requires local protein synthesis of the neuropeptide sensorin and importantly, local sensorin synthesis can be measured using a dendra fluorescent protein containing the 5' and 3' untranslated regions (UTRs) of sensorin. Using this construct, we show that blocking eEF2 dephosphorylation also blocks the increase in local sensorin synthesis. These results identify decreases in eEF2 phosphorylation as a critical downstream effector of mTOR required for long-term plasticity and identify an important translational target regulated by decreases in eEF2 phosphorylation.
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Affiliation(s)
- Patrick K McCamphill
- Department of Neurology and Neurosurgery, Montreal Neurological Institute, McGill University, Montreal, Quebec, Canada
| | - Larissa Ferguson
- Department of Neurology and Neurosurgery, Montreal Neurological Institute, McGill University, Montreal, Quebec, Canada
| | - Wayne S Sossin
- Department of Neurology and Neurosurgery, Montreal Neurological Institute, McGill University, Montreal, Quebec, Canada
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15
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Neurons secrete miR-132-containing exosomes to regulate brain vascular integrity. Cell Res 2017; 27:882-897. [PMID: 28429770 PMCID: PMC5518987 DOI: 10.1038/cr.2017.62] [Citation(s) in RCA: 245] [Impact Index Per Article: 35.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2016] [Revised: 02/25/2017] [Accepted: 03/26/2017] [Indexed: 12/11/2022] Open
Abstract
Vascular integrity helps maintain brain microenvironment homeostasis, which is critical for the normal development and function of the central nervous system. It is known that neural cells can regulate brain vascular integrity. However, due to the high complexity of neurovascular interactions involved, understanding of the neural regulation of brain vascular integrity is still rudimentary. Using intact zebrafish larvae and cultured rodent brain cells, we find that neurons transfer miR-132, a highly conserved and neuron-enriched microRNA, via secreting exosomes to endothelial cells (ECs) to maintain brain vascular integrity. Following translocation to ECs through exosome internalization, miR-132 regulates the expression of vascular endothelial cadherin (VE-cadherin), an important adherens junction protein, by directly targeting eukaryotic elongation factor2kinase (eef2k). Disruption of neuronal miR-132 expression or exosome secretion, or overexpression of vascular eef2k impairs VE-cadherin expression and brain vascular integrity. Our study indicates that miR-132 acts as an intercellular signal mediating neural regulation of the brain vascular integrity and suggests that the neuronal exosome is a novel avenue for neurovascular communication.
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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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18
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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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19
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Ye Q, Yang Y, van Staalduinen L, Crawley SW, Liu L, Brennan S, Côté GP, Jia Z. Structure of the Dictyostelium Myosin-II Heavy Chain Kinase A (MHCK-A) α-kinase domain apoenzyme reveals a novel autoinhibited conformation. Sci Rep 2016; 6:26634. [PMID: 27211275 PMCID: PMC4876393 DOI: 10.1038/srep26634] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2015] [Accepted: 05/04/2016] [Indexed: 02/06/2023] Open
Abstract
The α-kinases are a family of a typical protein kinases present in organisms ranging from protozoa to mammals. Here we report an autoinhibited conformation for the α-kinase domain of Dictyostelium myosin-II heavy chain kinase A (MHCK-A) in which nucleotide binding to the catalytic cleft, located at the interface between an N-terminal and C-terminal lobe, is sterically blocked by the side chain of a conserved arginine residue (Arg592). Previous α-kinase structures have shown that an invariant catalytic aspartic acid residue (Asp766) is phosphorylated. Unexpectedly, in the autoinhibited conformation the phosphoryl group is transferred to the adjacent Asp663, creating an interaction network that stabilizes the autoinhibited state. The results suggest that Asp766 phosphorylation may play both catalytic and regulatory roles. The autoinhibited structure also provides the first view of a phosphothreonine residue docked into the phospho-specific allosteric binding site (Pi-pocket) in the C-lobe of the α-kinase domain.
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Affiliation(s)
- Qilu Ye
- Department of Biomedical and Molecular Sciences, Queen's University, Kingston, ON, K7L 3N6, Canada
| | - Yidai Yang
- Department of Biomedical and Molecular Sciences, Queen's University, Kingston, ON, K7L 3N6, Canada
| | - Laura van Staalduinen
- Department of Biomedical and Molecular Sciences, Queen's University, Kingston, ON, K7L 3N6, Canada
| | - Scott William Crawley
- Department of Biomedical and Molecular Sciences, Queen's University, Kingston, ON, K7L 3N6, Canada
| | - Linda Liu
- Department of Biomedical and Molecular Sciences, Queen's University, Kingston, ON, K7L 3N6, Canada
| | - Stephanie Brennan
- Department of Biomedical and Molecular Sciences, Queen's University, Kingston, ON, K7L 3N6, Canada
| | - Graham P Côté
- Department of Biomedical and Molecular Sciences, Queen's University, Kingston, ON, K7L 3N6, Canada
| | - Zongchao Jia
- Department of Biomedical and Molecular Sciences, Queen's University, Kingston, ON, K7L 3N6, Canada
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20
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Abstract
Eukaryotic elongation factor 2 kinase (eEF2K) belongs to the small family of atypical protein kinases termed α-kinases, and is the only calcium/calmodulin (Ca/CaM)-dependent member of that group. It phosphorylates and inactivates eEF2, to slow down the rate of elongation, the stage in mRNA translation that consumes almost all the energy and amino acids consumed by protein synthesis. In addition to activation by Ca/CaM, eEF2K is also regulated by an array of other regulatory inputs, which include inhibition by the nutrient- and growth-factor activated signalling pathways. Recent evidence shows that eEF2K plays an important role in learning and memory, processes that require the synthesis of new proteins and involve Ca-mediated signalling. eEF2K is activated under conditions of nutrient and energy depletion. In cancer cells, or certain tumours, eEF2K exerts cytoprotective effects, which probably reflect its ability to inhibit protein synthesis, and nutrient consumption, under starvation conditions. eEF2K is being evaluated as a potential therapeutic target in cancer.
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Fu LL, Xie T, Zhang SY, Liu B. Eukaryotic elongation factor-2 kinase (eEF2K): a potential therapeutic target in cancer. Apoptosis 2015; 19:1527-31. [PMID: 25023961 DOI: 10.1007/s10495-014-1019-7] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Eukaryotic elongation factor-2 kinase (eEF2K), encoded by the EEF2K gene, is well-known to be a Ca(2+)/calmodulin (CaM)-dependent kinase which can negatively modulate protein synthesis. It is highly conserved among eukaryotes from mammals to invertebrates, of which human and mouse may have 99 % overall amino acid identity. This kinase can phosphorylate eukaryotic elongation factor-2 (eEF2) or undergo the process of autophosphorylation at multiple sites to inhibit its function in translation elongation. Due to the fact that regulation of eEF2 by eEF2K is an evolutionarily conserved mechanism, eEF2K activity may confer tumor cell adaption to metabolic stress under acute nutrient depletion, and the high expressed level of eEF2K has been found in several types of malignancies. eEF2K may modulate the expression of some apoptotic proteins such as XIAP, c-FLIPL, Bcl-XL, PI3KCI and p70(S6K) to inhibit apoptotic process in cancer. On the other hand, it plays a regulatory role in autophagy involved in mTORC1, AMPK and Atg8, thereby promoting cancer cell survival. Additionally, eEF2K may play a crucial role in the crosstalk between apoptosis and autophagy in cancer. Collectively, these findings have led to the conclusions that eEF2K may contribute to carcinogenesis, and thus being utilized as a potential target for future cancer therapy.
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Affiliation(s)
- L L Fu
- State Key Laboratory of Biotherapy & Collaborative Innovation Center of Biotherapy, West China Hospital, Sichuan University, Chengdu, 610041, China
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22
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Regulated stability of eukaryotic elongation factor 2 kinase requires intrinsic but not ongoing activity. Biochem J 2015; 467:321-31. [DOI: 10.1042/bj20150089] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Eukaryotic elongation factor 2 kinase (eEF2K) is an atypical protein kinase which negatively regulates protein synthesis, is activated under stress conditions and plays a role in cytoprotection, e.g. in cancer cells. It is regarded as a possible target for therapeutic intervention in solid tumours. Earlier studies showed that eEF2K is degraded by a proteasome-dependent pathway in response to genotoxic stress and that this requires a phosphodegron that includes an autophosphorylation site. Thus, application of eEF2K inhibitors would stabilize eEF2K, partially negating the effects of inhibiting its activity. In the present study, we show that under a range of other stress conditions, including acidosis or treatment of cells with 2-deoxyglucose, eEF2K is also degraded. However, in these settings, the previously identified phosphodegron is not required for its degradation. Nevertheless, kinase-dead and other activity-deficient mutants of eEF2K are stabilized, as is a mutant lacking a critical autophosphorylation site (Thr348 in eEF2K), which is thought to be required for eEF2K and other α-kinases to achieve their active conformations. In contrast, application of small-molecule eEF2K inhibitors does not stabilize the protein. Our data suggest that achieving an active conformation, rather than eEF2K activity per se, is required for its susceptibility to degradation. Additional degrons and E3 ligases beyond those already identified are probably involved in regulating eEF2K levels. Our findings have significant implications for therapeutic targeting of eEF2K, e.g. in oncology.
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23
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Pieper R, Martin L, Schunter N, Villodre Tudela C, Weise C, Klopfleisch R, Zentek J, Einspanier R, Bondzio A. Impact of high dietary zinc on zinc accumulation, enzyme activity and proteomic profiles in the pancreas of piglets. J Trace Elem Med Biol 2015; 30:30-6. [PMID: 25744507 DOI: 10.1016/j.jtemb.2015.01.008] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/28/2014] [Revised: 01/13/2015] [Accepted: 01/14/2015] [Indexed: 12/26/2022]
Abstract
The exocrine pancreas plays an important role in zinc homeostasis. Feeding very high (2000-3000mgzinc/kg diet) levels of zinc oxide to piglets for short periods is a common practice in the swine industry to improve performance and prevent diseases. The impact on pancreatic function and possible side effects during long-term feeding of high dietary zinc levels are still poorly understood. A total of 54 weaned piglets were either fed with low (57mg/kg, LZn), normal (164mg/kg, NZn) or high (2425mg/kg, HZn) zinc concentration in the diets. After 4 weeks of feeding, ten piglets per treatment were euthanized and pancreas samples were taken. Tissue zinc concentration and metallothionein abundance was greater with HZn compared with NZn and LZn (P<0.05). Similarly, activity of α-amylase, lipase, trypsin and chymotrypsin was higher with HZn as compared with NZn and LZn diets (P<0.05), whereas elastase activity was unchanged. Total trolox equivalent antioxidative capacity of pancreas tissue was higher with HZn diets compared with the other treatments (P<0.05). Pancreatic protein profiles of NZn and HZn fed piglets were obtained by 2D-DIGE technique and revealed 15 differentially expressed proteins out of 2100 detected spots (P<0.05). The differentially expressed proteins aldose reductase, eukaryotic elongation factor II and peroxiredoxin III were confirmed by immunoblotting. Identified proteins include zinc finger-containing transcription factors and proteins mainly associated with oxidative stress response and signal transduction in HZn compared with NZn pigs. Histologic examination however showed no morphologic changes. The results suggest that long-term supply of very high dietary zinc increases zinc and metallothionein concentration, and digestive enzyme activity, but also triggers oxidative stress reactions in the pancreas of young pigs. The data provide new insights into pancreatic function under outbalanced zinc homeostasis.
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Affiliation(s)
- R Pieper
- Institute of Animal Nutrition, Department of Veterinary Medicine, Freie Universität Berlin, Königin-Luise-Strasse 49, D-14195 Berlin, Germany.
| | - L Martin
- Institute of Animal Nutrition, Department of Veterinary Medicine, Freie Universität Berlin, Königin-Luise-Strasse 49, D-14195 Berlin, Germany
| | - N Schunter
- Institute of Animal Nutrition, Department of Veterinary Medicine, Freie Universität Berlin, Königin-Luise-Strasse 49, D-14195 Berlin, Germany
| | - C Villodre Tudela
- Institute of Animal Nutrition, Department of Veterinary Medicine, Freie Universität Berlin, Königin-Luise-Strasse 49, D-14195 Berlin, Germany
| | - C Weise
- Institute of Chemistry and Biochemistry, Department of Biology, Chemistry and Pharmacy, Freie Universität Berlin, Takustrasse 3, D-14195 Berlin, Germany
| | - R Klopfleisch
- Institute of Veterinary Pathology, Department of Veterinary Medicine, Freie Universität Berlin, Robert-von-Ostertag-Strasse 15, D-14163 Berlin, Germany
| | - J Zentek
- Institute of Animal Nutrition, Department of Veterinary Medicine, Freie Universität Berlin, Königin-Luise-Strasse 49, D-14195 Berlin, Germany
| | - R Einspanier
- Institute of Veterinary Biochemistry, Department of Veterinary Medicine, Freie Universität Berlin, Oertzenweg 19b, D-14163 Berlin, Germany
| | - A Bondzio
- Institute of Veterinary Biochemistry, Department of Veterinary Medicine, Freie Universität Berlin, Oertzenweg 19b, D-14163 Berlin, Germany
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24
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Molecular Mechanism for the Control of Eukaryotic Elongation Factor 2 Kinase by pH: Role in Cancer Cell Survival. Mol Cell Biol 2015; 35:1805-24. [PMID: 25776553 DOI: 10.1128/mcb.00012-15] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2015] [Accepted: 03/03/2015] [Indexed: 01/09/2023] Open
Abstract
Acidification of the extracellular and/or intracellular environment is involved in many aspects of cell physiology and pathology. Eukaryotic elongation factor 2 kinase (eEF2K) is a Ca(2+)/calmodulin-dependent kinase that regulates translation elongation by phosphorylating and inhibiting eEF2. Here we show that extracellular acidosis elicits activation of eEF2K in vivo, leading to enhanced phosphorylation of eEF2. We identify five histidine residues in eEF2K that are crucial for the activation of eEF2K during acidosis. Three of them (H80, H87, and H94) are in its calmodulin-binding site, and their protonation appears to enhance the ability of calmodulin to activate eEF2K. The other two histidines (H227 and H230) lie in the catalytic domain of eEF2K. We also identify His108 in calmodulin as essential for activation of eEF2K. Acidification of cancer cell microenvironments is a hallmark of malignant solid tumors. Knocking down eEF2K in cancer cells attenuated the decrease in global protein synthesis when cells were cultured at acidic pH. Importantly, activation of eEF2K is linked to cancer cell survival under acidic conditions. Inhibition of eEF2K promotes cancer cell death under acidosis.
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25
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Elongation Factor 2 Kinase Is Regulated by Proline Hydroxylation and Protects Cells during Hypoxia. Mol Cell Biol 2015; 35:1788-804. [PMID: 25755286 DOI: 10.1128/mcb.01457-14] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2014] [Accepted: 03/01/2015] [Indexed: 12/19/2022] Open
Abstract
Protein synthesis, especially translation elongation, requires large amounts of energy, which is often generated by oxidative metabolism. Elongation is controlled by phosphorylation of eukaryotic elongation factor 2 (eEF2), which inhibits its activity and is catalyzed by eEF2 kinase (eEF2K), a calcium/calmodulin-dependent α-kinase. Hypoxia causes the activation of eEF2K and induces eEF2 phosphorylation independently of previously known inputs into eEF2K. Here, we show that eEF2K is subject to hydroxylation on proline-98. Proline hydroxylation is catalyzed by proline hydroxylases, oxygen-dependent enzymes which are inactivated during hypoxia. Pharmacological inhibition of proline hydroxylases also stimulates eEF2 phosphorylation. Pro98 lies in a universally conserved linker between the calmodulin-binding and catalytic domains of eEF2K. Its hydroxylation partially impairs the binding of calmodulin to eEF2K and markedly limits the calmodulin-stimulated activity of eEF2K. Neuronal cells depend on oxygen, and eEF2K helps to protect them from hypoxia. eEF2K is the first example of a protein directly involved in a major energy-consuming process to be regulated by proline hydroxylation. Since eEF2K is cytoprotective during hypoxia and other conditions of nutrient insufficiency, it may be a valuable target for therapy of poorly vascularized solid tumors.
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26
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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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27
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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: 77] [Impact Index Per Article: 7.7] [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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28
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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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29
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Lee MY, Faucher F, Jia Z. Growth of Diffraction-Quality Protein Crystals Using a Harvestable Microfluidic Device. CRYSTAL GROWTH & DESIGN 2014; 14:3179-3181. [PMID: 25013386 PMCID: PMC4082397 DOI: 10.1021/cg500450b] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 04/01/2014] [Revised: 05/19/2014] [Indexed: 06/03/2023]
Abstract
Protein crystallization is the major bottleneck in the entire process of protein crystallography, and obtaining diffraction-quality crystals can be unpredictable and sometimes exceptionally difficult, requiring many rounds of high-throughput screening. Recently, a more time- and cost-saving strategy to use the commercially available microfluidic devices called Crystal Formers has emerged. Herein we show the application of such a device using a protein from Legionella pneumophila called LidL that is predicted to be involved in the ability to efficiently manipulate host cell trafficking events once internalized by the host cell. After setting up just one 96-channel Crystal Former tray, we were able to obtain a diffraction-quality crystal that diffracted to 2.76 Å. These results show that Crystal Formers can be used to screen and optimize crystals to directly produce crystals for structure determination.
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30
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Hait WN, Versele M, Yang JM. Surviving Metabolic Stress: Of Mice (Squirrels) and Men. Cancer Discov 2014; 4:646-9. [DOI: 10.1158/2159-8290.cd-14-0114] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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31
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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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32
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A conserved loop in the catalytic domain of eukaryotic elongation factor 2 kinase plays a key role in its substrate specificity. Mol Cell Biol 2014; 34:2294-307. [PMID: 24732796 DOI: 10.1128/mcb.00388-14] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
Eukaryotic elongation factor 2 kinase (eEF2K) is the best-characterized member of the α-kinase family. Within this group, only eEF2K and myosin heavy chain kinases (MHCKs) have known substrates. Here we have studied the roles of specific residues, selected on the basis of structural data for MHCK A and TRPM7, in the function of eEF2K. Our data provide the first information regarding the basis of the substrate specificity of α-kinases, in particular the roles of residues in the so-called N/D loop, which appears to occupy a position in the structure of α-kinases similar to that of the activation loop in other kinases. Several mutations in the EEF2K gene occur in tumors, one of which (Arg303Cys) is at a highly conserved residue in the N/D loop. This mutation greatly enhances eEF2K activity and may be cytoprotective. Our data support the concept that the major autophosphorylation site (Thr348 in eEF2K) docks into a binding pocket to help create the kinase-competent conformation. This is similar to the situation for MHCK A and is consistent with this being a common feature of α-kinases.
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33
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Heise C, Gardoni F, Culotta L, di Luca M, Verpelli C, Sala C. Elongation factor-2 phosphorylation in dendrites and the regulation of dendritic mRNA translation in neurons. Front Cell Neurosci 2014; 8:35. [PMID: 24574971 PMCID: PMC3918593 DOI: 10.3389/fncel.2014.00035] [Citation(s) in RCA: 70] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2013] [Accepted: 01/23/2014] [Indexed: 11/13/2022] Open
Abstract
Neuronal activity results in long lasting changes in synaptic structure and function by regulating mRNA translation in dendrites. These activity dependent events yield the synthesis of proteins known to be important for synaptic modifications and diverse forms of synaptic plasticity. Worthy of note, there is accumulating evidence that the eukaryotic Elongation Factor 2 Kinase (eEF2K)/eukaryotic Elongation Factor 2 (eEF2) pathway may be strongly involved in this process. Upon activation, eEF2K phosphorylates and thereby inhibits eEF2, resulting in a dramatic reduction of mRNA translation. eEF2K is activated by elevated levels of calcium and binding of Calmodulin (CaM), hence its alternative name calcium/CaM-dependent protein kinase III (CaMKIII). In dendrites, this process depends on glutamate signaling and N-methyl-D-aspartate receptor (NMDAR) activation. Interestingly, it has been shown that eEF2K can be activated in dendrites by metabotropic glutamate receptor (mGluR) 1/5 signaling, as well. Therefore, neuronal activity can induce local proteomic changes at the postsynapse by altering eEF2K activity. Well-established targets of eEF2K in dendrites include brain-derived neurotrophic factor (BDNF), activity-regulated cytoskeletal-associated protein (Arc), the alpha subunit of calcium/CaM-dependent protein kinase II (αCaMKII), and microtubule-associated protein 1B (MAP1B), all of which have well-known functions in different forms of synaptic plasticity. In this review we will give an overview of the involvement of the eEF2K/eEF2 pathway at dendrites in regulating the translation of dendritic mRNA in the context of altered NMDAR- and neuronal activity, and diverse forms of synaptic plasticity, such as metabotropic glutamate receptor-dependent-long-term depression (mGluR-LTD). For this, we draw on studies carried out both in vitro and in vivo.
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Affiliation(s)
- Christopher Heise
- CNR Institute of Neuroscience and Department of Biotechnology and Translational Medicine, University of Milan Milan, Italy
| | - Fabrizio Gardoni
- Department of Pharmacological and Biomolecular Sciences, University of Milan Milan, Italy
| | - Lorenza Culotta
- CNR Institute of Neuroscience and Department of Biotechnology and Translational Medicine, University of Milan Milan, Italy
| | - Monica di Luca
- Department of Pharmacological and Biomolecular Sciences, University of Milan Milan, Italy
| | - Chiara Verpelli
- CNR Institute of Neuroscience and Department of Biotechnology and Translational Medicine, University of Milan Milan, Italy
| | - Carlo Sala
- CNR Institute of Neuroscience and Department of Biotechnology and Translational Medicine, University of Milan Milan, Italy ; Neuromuscular Diseases and Neuroimmunology, Foundation Carlo Besta Neurological Institute Milan, Italy
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The role of eukaryotic elongation factor 2 kinase in rapid antidepressant action of ketamine. Biol Psychiatry 2013; 73:1199-203. [PMID: 23062356 PMCID: PMC3574622 DOI: 10.1016/j.biopsych.2012.09.006] [Citation(s) in RCA: 143] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/02/2012] [Revised: 08/30/2012] [Accepted: 09/05/2012] [Indexed: 01/26/2023]
Abstract
Major depressive disorder is a devastating mental disorder. Current antidepressant medications can be effective for some patients with depression; however, these drugs exert mood-elevating effects only after prolonged administration, and a sizable fraction of the patient population fails to respond to treatment. There is an urgent need for faster-acting antidepressants with reliable treatment outcomes and sustained efficacy for individuals with depression, in particular those contemplating suicide. Recent clinical studies report that ketamine, an ionotropic glutamatergic N-methyl-D-aspartate (NMDA) receptor blocker, shows fast-acting antidepressant action, thus bringing fresh perspective into preclinical studies investigating novel antidepressant targets and treatments. Our recent studies show that the effects of ketamine are dependent on brain-derived neurotrophic factor (BDNF) and subsequent activation of the high-affinity BDNF receptor, TrkB. Our findings also suggest that the fast-acting antidepressant effects of ketamine require rapid protein translation, but not transcription, resulting in robust increases in dendritic BDNF protein levels that are important for the behavioral effect. These findings also uncover eukaryotic elongation factor 2 kinase (eEF2K), a Ca²⁺/calmodulin dependent serine/threonine kinase that phosphorylates eEF2 and regulates the elongation step of protein translation, as a major molecular substrate mediating the rapid antidepressant effect of ketamine. Our results show that ketamine-mediated suppression of resting NMDA receptor activity leads to inhibition of eEF2 kinase and subsequent dephosphorylation of eEF2 and augmentation of BDNF synthesis. This article outlines our recent studies on the synaptic mechanisms that underlie ketamine action, in particular the properties of eEF2K as a potential antidepressant target.
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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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