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Henis M, Rücker T, Scharrenberg R, Richter M, Baltussen L, Hong S, Meka DP, Schwanke B, Neelagandan N, Daaboul D, Murtaza N, Krisp C, Harder S, Schlüter H, Kneussel M, Hermans-Borgmeyer I, de Wit J, Singh KK, Duncan KE, de Anda FC. The autism susceptibility kinase, TAOK2, phosphorylates eEF2 and modulates translation. SCIENCE ADVANCES 2024; 10:eadf7001. [PMID: 38608030 PMCID: PMC11014455 DOI: 10.1126/sciadv.adf7001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/08/2022] [Accepted: 03/12/2024] [Indexed: 04/14/2024]
Abstract
Genes implicated in translation control have been associated with autism spectrum disorders (ASDs). However, some important genetic causes of autism, including the 16p11.2 microdeletion, bear no obvious connection to translation. Here, we use proteomics, genetics, and translation assays in cultured cells and mouse brain to reveal altered translation mediated by loss of the kinase TAOK2 in 16p11.2 deletion models. We show that TAOK2 associates with the translational machinery and functions as a translational brake by phosphorylating eukaryotic elongation factor 2 (eEF2). Previously, all signal-mediated regulation of translation elongation via eEF2 phosphorylation was believed to be mediated by a single kinase, eEF2K. However, we show that TAOK2 can directly phosphorylate eEF2 on the same regulatory site, but functions independently of eEF2K signaling. Collectively, our results reveal an eEF2K-independent signaling pathway for control of translation elongation and suggest altered translation as a molecular component in the etiology of some forms of ASD.
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Affiliation(s)
- Melad Henis
- Center for Molecular Neurobiology, University Medical Center Hamburg-Eppendorf, 20251 Hamburg, Germany
- Department of Anatomy and Embryology, Faculty of Veterinary Medicine, New Valley University, 72511 El-Kharga, Egypt
| | - Tabitha Rücker
- Center for Molecular Neurobiology, University Medical Center Hamburg-Eppendorf, 20251 Hamburg, Germany
| | - Robin Scharrenberg
- Center for Molecular Neurobiology, University Medical Center Hamburg-Eppendorf, 20251 Hamburg, Germany
| | - Melanie Richter
- Center for Molecular Neurobiology, University Medical Center Hamburg-Eppendorf, 20251 Hamburg, Germany
| | - Lucas Baltussen
- VIB Center for Brain & Disease Research, Herestraat 49, 3000 Leuven, Belgium
- KU Leuven Department of Neurosciences, Leuven Brain Institute, Herestraat 49, 3000 Leuven, Belgium
| | - Shuai Hong
- Center for Molecular Neurobiology, University Medical Center Hamburg-Eppendorf, 20251 Hamburg, Germany
| | - Durga Praveen Meka
- Center for Molecular Neurobiology, University Medical Center Hamburg-Eppendorf, 20251 Hamburg, Germany
| | - Birgit Schwanke
- Center for Molecular Neurobiology, University Medical Center Hamburg-Eppendorf, 20251 Hamburg, Germany
| | - Nagammal Neelagandan
- Neuronal Translational Control Group, Center for Molecular Neurobiology (ZMNH), University Medical Center Hamburg-Eppendorf (UKE), Falkenried 94, 20251 Hamburg, Germany
- Institute of Bioengineering (IBI), École Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
| | - Danie Daaboul
- VIB Center for Brain & Disease Research, Herestraat 49, 3000 Leuven, Belgium
- KU Leuven Department of Neurosciences, Leuven Brain Institute, Herestraat 49, 3000 Leuven, Belgium
| | - Nadeem Murtaza
- Krembil Research Institute, Donald K. Johnson Eye Institute, University Health Network, 60 Leonard Ave, Toronto, Ontario M5T 0S8, Canada
- Department of Biochemistry and Biomedical Sciences, Faculty of Health Sciences, McMaster University, Hamilton, Ontario L8S 4A9, Canada
| | - Christoph Krisp
- Institute for Clinical Chemistry and Laboratory Medicine, Mass Spectrometric Proteomics Group, Campus Forschung, University Medical Center Hamburg-Eppendorf (UKE), 20246 Hamburg, Germany
| | - Sönke Harder
- Institute for Clinical Chemistry and Laboratory Medicine, Mass Spectrometric Proteomics Group, Campus Forschung, University Medical Center Hamburg-Eppendorf (UKE), 20246 Hamburg, Germany
| | - Hartmut Schlüter
- Institute for Clinical Chemistry and Laboratory Medicine, Mass Spectrometric Proteomics Group, Campus Forschung, University Medical Center Hamburg-Eppendorf (UKE), 20246 Hamburg, Germany
| | - Matthias Kneussel
- Institute of Neurogenetics, Center for Molecular Neurobiology, University Medical Center Hamburg-Eppendorf (UKE), 20251 Hamburg, Germany
| | - Irm Hermans-Borgmeyer
- Transgenic Service Group, Center for Molecular Neurobiology (ZMNH), University Medical Center Hamburg-Eppendorf (UKE), Falkenried 94, 20251 Hamburg, Germany
| | - Joris de Wit
- VIB Center for Brain & Disease Research, Herestraat 49, 3000 Leuven, Belgium
- KU Leuven Department of Neurosciences, Leuven Brain Institute, Herestraat 49, 3000 Leuven, Belgium
| | - Karun K. Singh
- Krembil Research Institute, Donald K. Johnson Eye Institute, University Health Network, 60 Leonard Ave, Toronto, Ontario M5T 0S8, Canada
- Faculty of Medicine, University of Toronto, Medical Sciences Building, 1 King's College Cir, Toronto, Ontario M5S 1 A8, Canada
| | - Kent E. Duncan
- Neuronal Translational Control Group, Center for Molecular Neurobiology (ZMNH), University Medical Center Hamburg-Eppendorf (UKE), Falkenried 94, 20251 Hamburg, Germany
- Evotec SE, Manfred Eigen Campus, Essener Bogen 7, 22419 Hamburg, Germany
| | - Froylan Calderón de Anda
- Center for Molecular Neurobiology, University Medical Center Hamburg-Eppendorf, 20251 Hamburg, Germany
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Tempone MH, Borges-Martins VP, César F, Alexandrino-Mattos DP, de Figueiredo CS, Raony Í, dos Santos AA, Duarte-Silva AT, Dias MS, Freitas HR, de Araújo EG, Ribeiro-Resende VT, Cossenza M, P. Silva H, P. de Carvalho R, Ventura ALM, Calaza KC, Silveira MS, Kubrusly RCC, de Melo Reis RA. The Healthy and Diseased Retina Seen through Neuron-Glia Interactions. Int J Mol Sci 2024; 25:1120. [PMID: 38256192 PMCID: PMC10817105 DOI: 10.3390/ijms25021120] [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: 12/21/2023] [Revised: 01/10/2024] [Accepted: 01/12/2024] [Indexed: 01/24/2024] Open
Abstract
The retina is the sensory tissue responsible for the first stages of visual processing, with a conserved anatomy and functional architecture among vertebrates. To date, retinal eye diseases, such as diabetic retinopathy, age-related macular degeneration, retinitis pigmentosa, glaucoma, and others, affect nearly 170 million people worldwide, resulting in vision loss and blindness. To tackle retinal disorders, the developing retina has been explored as a versatile model to study intercellular signaling, as it presents a broad neurochemical repertoire that has been approached in the last decades in terms of signaling and diseases. Retina, dissociated and arranged as typical cultures, as mixed or neuron- and glia-enriched, and/or organized as neurospheres and/or as organoids, are valuable to understand both neuronal and glial compartments, which have contributed to revealing roles and mechanisms between transmitter systems as well as antioxidants, trophic factors, and extracellular matrix proteins. Overall, contributions in understanding neurogenesis, tissue development, differentiation, connectivity, plasticity, and cell death are widely described. A complete access to the genome of several vertebrates, as well as the recent transcriptome at the single cell level at different stages of development, also anticipates future advances in providing cues to target blinding diseases or retinal dysfunctions.
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Affiliation(s)
- Matheus H. Tempone
- Laboratory of Neurochemistry, Institute of Biophysics Carlos Chagas Filho, Federal University of Rio de Janeiro, Rio de Janeiro 21949-000, Brazil; (M.H.T.); (F.C.); (D.P.A.-M.); (V.T.R.-R.)
| | - Vladimir P. Borges-Martins
- Department of Physiology and Pharmacology, Biomedical Institute and Program of Neurosciences, Federal Fluminense University, Niterói 24020-150, Brazil; (V.P.B.-M.); (A.A.d.S.); (M.C.); (R.C.C.K.)
| | - Felipe César
- Laboratory of Neurochemistry, Institute of Biophysics Carlos Chagas Filho, Federal University of Rio de Janeiro, Rio de Janeiro 21949-000, Brazil; (M.H.T.); (F.C.); (D.P.A.-M.); (V.T.R.-R.)
| | - Dio Pablo Alexandrino-Mattos
- Laboratory of Neurochemistry, Institute of Biophysics Carlos Chagas Filho, Federal University of Rio de Janeiro, Rio de Janeiro 21949-000, Brazil; (M.H.T.); (F.C.); (D.P.A.-M.); (V.T.R.-R.)
| | - Camila S. de Figueiredo
- Department of Neurobiology and Program of Neurosciences, Institute of Biology, Federal Fluminense University, Niterói 24020-141, Brazil; (C.S.d.F.); (A.T.D.-S.); (E.G.d.A.); (R.P.d.C.); (A.L.M.V.); (K.C.C.)
| | - Ícaro Raony
- Institute of Medical Biochemistry Leopoldo de Meis, Federal University of Rio de Janeiro, Rio de Janeiro 21941-902, Brazil; (Í.R.); (H.R.F.)
| | - Aline Araujo dos Santos
- Department of Physiology and Pharmacology, Biomedical Institute and Program of Neurosciences, Federal Fluminense University, Niterói 24020-150, Brazil; (V.P.B.-M.); (A.A.d.S.); (M.C.); (R.C.C.K.)
| | - Aline Teixeira Duarte-Silva
- Department of Neurobiology and Program of Neurosciences, Institute of Biology, Federal Fluminense University, Niterói 24020-141, Brazil; (C.S.d.F.); (A.T.D.-S.); (E.G.d.A.); (R.P.d.C.); (A.L.M.V.); (K.C.C.)
| | - Mariana Santana Dias
- Laboratory of Gene Therapy and Viral Vectors, Institute of Biophysics Carlos Chagas Filho, Federal University of Rio de Janeiro, Rio de Janeiro 21949-000, Brazil; (M.S.D.); (H.P.S.)
| | - Hércules Rezende Freitas
- Institute of Medical Biochemistry Leopoldo de Meis, Federal University of Rio de Janeiro, Rio de Janeiro 21941-902, Brazil; (Í.R.); (H.R.F.)
| | - Elisabeth G. de Araújo
- Department of Neurobiology and Program of Neurosciences, Institute of Biology, Federal Fluminense University, Niterói 24020-141, Brazil; (C.S.d.F.); (A.T.D.-S.); (E.G.d.A.); (R.P.d.C.); (A.L.M.V.); (K.C.C.)
- National Institute of Science and Technology on Neuroimmunomodulation—INCT-NIM, Oswaldo Cruz Institute, Oswaldo Cruz Foundation, Rio de Janeiro 21040-360, Brazil
| | - Victor Tulio Ribeiro-Resende
- Laboratory of Neurochemistry, Institute of Biophysics Carlos Chagas Filho, Federal University of Rio de Janeiro, Rio de Janeiro 21949-000, Brazil; (M.H.T.); (F.C.); (D.P.A.-M.); (V.T.R.-R.)
| | - Marcelo Cossenza
- Department of Physiology and Pharmacology, Biomedical Institute and Program of Neurosciences, Federal Fluminense University, Niterói 24020-150, Brazil; (V.P.B.-M.); (A.A.d.S.); (M.C.); (R.C.C.K.)
| | - Hilda P. Silva
- Laboratory of Gene Therapy and Viral Vectors, Institute of Biophysics Carlos Chagas Filho, Federal University of Rio de Janeiro, Rio de Janeiro 21949-000, Brazil; (M.S.D.); (H.P.S.)
| | - Roberto P. de Carvalho
- Department of Neurobiology and Program of Neurosciences, Institute of Biology, Federal Fluminense University, Niterói 24020-141, Brazil; (C.S.d.F.); (A.T.D.-S.); (E.G.d.A.); (R.P.d.C.); (A.L.M.V.); (K.C.C.)
| | - Ana L. M. Ventura
- Department of Neurobiology and Program of Neurosciences, Institute of Biology, Federal Fluminense University, Niterói 24020-141, Brazil; (C.S.d.F.); (A.T.D.-S.); (E.G.d.A.); (R.P.d.C.); (A.L.M.V.); (K.C.C.)
| | - Karin C. Calaza
- Department of Neurobiology and Program of Neurosciences, Institute of Biology, Federal Fluminense University, Niterói 24020-141, Brazil; (C.S.d.F.); (A.T.D.-S.); (E.G.d.A.); (R.P.d.C.); (A.L.M.V.); (K.C.C.)
| | - Mariana S. Silveira
- Laboratory for Investigation in Neuroregeneration and Development, Institute of Biophysics Carlos Chagas Filho, Federal University of Rio de Janeiro, Rio de Janeiro 21949-000, Brazil;
| | - Regina C. C. Kubrusly
- Department of Physiology and Pharmacology, Biomedical Institute and Program of Neurosciences, Federal Fluminense University, Niterói 24020-150, Brazil; (V.P.B.-M.); (A.A.d.S.); (M.C.); (R.C.C.K.)
| | - Ricardo A. de Melo Reis
- Laboratory of Neurochemistry, Institute of Biophysics Carlos Chagas Filho, Federal University of Rio de Janeiro, Rio de Janeiro 21949-000, Brazil; (M.H.T.); (F.C.); (D.P.A.-M.); (V.T.R.-R.)
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Kodama T, Otani K, Okada M, Yamawaki H. Eukaryotic elongation factor 2 kinase inhibitor, A484954 induced diuresis via nitric oxide production in spontaneously hypertensive rats. J Vet Med Sci 2023; 85:1314-1318. [PMID: 37853639 PMCID: PMC10788169 DOI: 10.1292/jvms.23-0306] [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: 07/13/2023] [Accepted: 10/03/2023] [Indexed: 10/20/2023] Open
Abstract
Eukaryotic elongation factor 2 (eEF2) kinase (eEF2K) is a protein kinase that inactivates eEF2, a protein that mediates a peptidyl-tRNA translocation during an elongation step of protein synthesis. We have previously shown that eEF2K was involved in pathogenesis of essential and pulmonary hypertension. A484954 (7-amino-1-cyclopropyl-3-ethyl-2,4-dioxo-1,2,3,4-tetrahydropyrido[2,3-d] pyrimidine-6-carboxamide), a selective eEF2K inhibitor, is a membrane permeable small molecule. We have previously shown that A484954 lowered blood pressure and induced diuretic effects in spontaneously hypertensive rats (SHR) due to an increase in renal blood flow. Here we aimed to reveal mechanisms underlying the diuretic effects of A484954 in SHR. A484954-induced diuresis and increase in urinary Na+ excretion were inhibited by N (G)-nitro-L-arginine methyl ester (L-NAME), a nitric oxide (NO) synthase inhibitor. A484954 increased mRNA expression of angiotensin type 2 receptor (AT2R) and nuclear factor-erythroid 2-related factor 2 (Nrf2). In summary, we for the first time revealed that A484954 induces diuresis in SHR at least partly via the activation of NO/Nrf2/AT2R pathway.
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Affiliation(s)
- Tomoko Kodama
- Laboratory of Veterinary Pharmacology, School of Veterinary Medicine, Kitasato University, Aomori, Japan
| | - Kosuke Otani
- Laboratory of Veterinary Pharmacology, School of Veterinary Medicine, Kitasato University, Aomori, Japan
| | - Muneyoshi Okada
- Laboratory of Veterinary Pharmacology, School of Veterinary Medicine, Kitasato University, Aomori, Japan
| | - Hideyuki Yamawaki
- Laboratory of Veterinary Pharmacology, School of Veterinary Medicine, Kitasato University, Aomori, Japan
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4
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Lkhagva-Yondon E, Seo MS, Oh Y, Jung J, Jeon E, Na K, Yoo HS, Kim WC, Esser C, Song SU, Jeon MS. The aryl hydrocarbon receptor controls mesenchymal stromal cell-mediated immunomodulation via ubiquitination of eukaryotic elongation factor-2 kinase. Cell Death Dis 2023; 14:812. [PMID: 38071243 PMCID: PMC10710493 DOI: 10.1038/s41419-023-06341-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2023] [Revised: 11/07/2023] [Accepted: 11/27/2023] [Indexed: 12/18/2023]
Abstract
Mesenchymal stem cells (MSCs) have great therapeutic advantages due to their immunosuppressive properties. The aryl hydrocarbon receptor (AHR) is a ligand-activated transcription factor whose signaling plays an important role in the immune system. AHR may be involved in the regulation of MSC-associated immunomodulatory functions. However, the mechanisms by which AHR controls the immunosuppressive functions of MSCs are not well understood. Here, we report that Ahr-deficient MSCs show decreased therapeutic efficacy against graft-versus-host disease (GVHD) compared to wild-type (WT)-MSCs. This was probably due to decreased iNOS protein expression, which is a key regulatory enzyme in MSC immunomodulation. The expression of eukaryotic elongation factor 2 kinase (eEF2K), which inhibits the elongation stage of protein synthesis, is significantly increased in the Ahr-deficient MSCs. Inhibition of eEF2K restored iNOS protein expression. AHR is known to act as an E3 ligase together with CUL4B. We observed constitutive binding of AHR to eEF2K. Consequently, ubiquitination and degradation of eEF2K were inhibited in Ahr-deficient MSCs and by the AHR antagonist CH223191 in WT-MSCs. In summary, AHR regulates the immunomodulatory functions of MSCs through ubiquitination of eEF2K, thereby controlling iNOS protein synthesis and its product, nitric oxide levels.
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Affiliation(s)
- Enkhmaa Lkhagva-Yondon
- Translational Research Center, Inha University Hospital, Incheon, 22332, Republic of Korea
- Program in Biomedical Science & Engineering Inha University, Incheon, 22212, Republic of Korea
| | - Myeong Seong Seo
- Translational Research Center, Inha University Hospital, Incheon, 22332, Republic of Korea
- Program in Biomedical Science & Engineering Inha University, Incheon, 22212, Republic of Korea
| | - Yena Oh
- Translational Research Center, Inha University Hospital, Incheon, 22332, Republic of Korea
- Department of Molecular Biomedicine, College of Medicine Inha University, Incheon, 22212, Republic of Korea
| | - Jonghun Jung
- Translational Research Center, Inha University Hospital, Incheon, 22332, Republic of Korea
- Program in Biomedical Science & Engineering Inha University, Incheon, 22212, Republic of Korea
| | - Eunhae Jeon
- Translational Research Center, Inha University Hospital, Incheon, 22332, Republic of Korea
- Department of Molecular Biomedicine, College of Medicine Inha University, Incheon, 22212, Republic of Korea
| | - Kwangmin Na
- Translational Research Center, Inha University Hospital, Incheon, 22332, Republic of Korea
| | - Hyun Seung Yoo
- Translational Research Center, Inha University Hospital, Incheon, 22332, Republic of Korea
- Department of Molecular Biomedicine, College of Medicine Inha University, Incheon, 22212, Republic of Korea
| | - Woo Chul Kim
- Department of Radiation Oncology, Inha University Hospital, Incheon, 22332, Republic of Korea
| | - Charlotte Esser
- IUF-Leibniz Research Institute for Environmental Medicine, Düsseldorf, 40021, Germany
| | - Sun U Song
- Translational Research Center, Inha University Hospital, Incheon, 22332, Republic of Korea
- Department of Molecular Biomedicine, College of Medicine Inha University, Incheon, 22212, Republic of Korea
- SCM Lifescience, Incheon, 21999, Republic of Korea
| | - Myung-Shin Jeon
- Translational Research Center, Inha University Hospital, Incheon, 22332, Republic of Korea.
- Program in Biomedical Science & Engineering Inha University, Incheon, 22212, Republic of Korea.
- Department of Molecular Biomedicine, College of Medicine Inha University, Incheon, 22212, Republic of Korea.
- SCM Lifescience, Incheon, 21999, Republic of Korea.
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Aleksashin NA, Chang STL, Cate JHD. A highly efficient human cell-free translation system. RNA (NEW YORK, N.Y.) 2023; 29:1960-1972. [PMID: 37793791 PMCID: PMC10653386 DOI: 10.1261/rna.079825.123] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/05/2023] [Accepted: 09/21/2023] [Indexed: 10/06/2023]
Abstract
Cell-free protein synthesis (CFPS) systems enable easy in vitro expression of proteins with many scientific, industrial, and therapeutic applications. Here we present an optimized, highly efficient human cell-free translation system that bypasses many limitations of currently used in vitro systems. This CFPS system is based on extracts from human HEK293T cells engineered to endogenously express GADD34 and K3L proteins, which suppress phosphorylation of translation initiation factor eIF2α. Overexpression of GADD34 and K3L proteins in human cells before cell lysate preparation significantly simplifies lysate preparation. We find that expression of the GADD34 and K3L accessory proteins before cell lysis maintains low levels of phosphorylation of eIF2α in the extracts. During in vitro translation reactions, eIF2α phosphorylation increases moderately in a GCN2-dependent fashion that can be inhibited by GCN2 kinase inhibitors. This new CFPS system should be useful for exploring human translation mechanisms in more physiological conditions outside the cell.
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Affiliation(s)
- Nikolay A Aleksashin
- Innovative Genomics Institute, University of California-Berkeley, Berkeley, California 94720, USA
- Department of Molecular and Cell Biology, University of California-Berkeley, Berkeley, California 94720, USA
| | - Stacey Tsai-Lan Chang
- Innovative Genomics Institute, University of California-Berkeley, Berkeley, California 94720, USA
- Department of Molecular and Cell Biology, University of California-Berkeley, Berkeley, California 94720, USA
| | - Jamie H D Cate
- Innovative Genomics Institute, University of California-Berkeley, Berkeley, California 94720, USA
- Department of Molecular and Cell Biology, University of California-Berkeley, Berkeley, California 94720, USA
- Department of Chemistry, University of California-Berkeley, Berkeley, California 94720, USA
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Aleksashin NA, Chang STL, Cate JHD. A highly efficient human cell-free translation system. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.02.09.527910. [PMID: 36798401 PMCID: PMC9934684 DOI: 10.1101/2023.02.09.527910] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Indexed: 02/12/2023]
Abstract
Cell-free protein synthesis (CFPS) systems enable easy in vitro expression of proteins with many scientific, industrial, and therapeutic applications. Here we present an optimized, highly efficient human cell-free translation system that bypasses many limitations of currently used in vitro systems. This CFPS system is based on extracts from human HEK293T cells engineered to endogenously express GADD34 and K3L proteins, which suppress phosphorylation of translation initiation factor eIF2α. Overexpression of GADD34 and K3L proteins in human cells significantly simplifies cell lysate preparation. The new CFPS system improves the translation of 5' cap-dependent mRNAs as well as those that use internal ribosome entry site (IRES) mediated translation initiation. We find that expression of the GADD34 and K3L accessory proteins before cell lysis maintains low levels of phosphorylation of eIF2α in the extracts. During in vitro translation reactions, eIF2α phosphorylation increases moderately in a GCN2-dependent fashion that can be inhibited by GCN2 kinase inhibitors. We also find evidence for activation of regulatory pathways related to eukaryotic elongation factor 2 (eEF2) phosphorylation and ribosome quality control in the extracts. This new CFPS system should be useful for exploring human translation mechanisms in more physiological conditions outside the cell.
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Affiliation(s)
- Nikolay A. Aleksashin
- Innovative Genomics Institute, University of California-Berkeley, Berkeley, CA, USA
- Department of Molecular & Cell Biology, University of California-Berkeley, Berkeley, CA, USA
| | - Stacey Tsai-Lan Chang
- Innovative Genomics Institute, University of California-Berkeley, Berkeley, CA, USA
- Department of Molecular & Cell Biology, University of California-Berkeley, Berkeley, CA, USA
| | - Jamie H. D. Cate
- Innovative Genomics Institute, University of California-Berkeley, Berkeley, CA, USA
- Department of Molecular & Cell Biology, University of California-Berkeley, Berkeley, CA, USA
- Department of Chemistry, University of California-Berkeley, Berkeley, CA, USA
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7
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Treffers EE, Tas A, Scholte FEM, de Ru AH, Snijder EJ, van Veelen PA, van Hemert MJ. The alphavirus nonstructural protein 2 NTPase induces a host translational shut-off through phosphorylation of eEF2 via cAMP-PKA-eEF2K signaling. PLoS Pathog 2023; 19:e1011179. [PMID: 36848386 PMCID: PMC9997916 DOI: 10.1371/journal.ppat.1011179] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2022] [Revised: 03/09/2023] [Accepted: 02/03/2023] [Indexed: 03/01/2023] Open
Abstract
Chikungunya virus (CHIKV) is a reemerging alphavirus. Since 2005, it has infected millions of people during outbreaks in Africa, Asia, and South/Central America. CHIKV replication depends on host cell factors at many levels and is expected to have a profound effect on cellular physiology. To obtain more insight into host responses to infection, stable isotope labeling with amino acids in cell culture and liquid chromatography-tandem mass spectrometry were used to assess temporal changes in the cellular phosphoproteome during CHIKV infection. Among the ~3,000 unique phosphorylation sites analyzed, the largest change in phosphorylation status was measured on residue T56 of eukaryotic elongation factor 2 (eEF2), which showed a >50-fold increase at 8 and 12 h p.i. Infection with other alphaviruses (Semliki Forest, Sindbis and Venezuelan equine encephalitis virus (VEEV)) triggered a similarly strong eEF2 phosphorylation. Expression of a truncated form of CHIKV or VEEV nsP2, containing only the N-terminal and NTPase/helicase domains (nsP2-NTD-Hel), sufficed to induce eEF2 phosphorylation, which could be prevented by mutating key residues in the Walker A and B motifs of the NTPase domain. Alphavirus infection or expression of nsP2-NTD-Hel resulted in decreased cellular ATP levels and increased cAMP levels. This did not occur when catalytically inactive NTPase mutants were expressed. The wild-type nsP2-NTD-Hel inhibited cellular translation independent of the C-terminal nsP2 domain, which was previously implicated in directing the virus-induced host shut-off for Old World alphaviruses. We hypothesize that the alphavirus NTPase activates a cellular adenylyl cyclase resulting in increased cAMP levels, thus activating PKA and subsequently eukaryotic elongation factor 2 kinase. This in turn triggers eEF2 phosphorylation and translational inhibition. We conclude that the nsP2-driven increase of cAMP levels contributes to the alphavirus-induced shut-off of cellular protein synthesis that is shared between Old and New World alphaviruses. MS Data are available via ProteomeXchange with identifier PXD009381.
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Affiliation(s)
- Emmely E. Treffers
- Molecular Virology Laboratory, Department of Medical Microbiology, Leiden University Medical Center, Leiden, The Netherlands
- Center for Proteomics & Metabolomics, Leiden University Medical Center, Leiden, The Netherlands
| | - Ali Tas
- Molecular Virology Laboratory, Department of Medical Microbiology, Leiden University Medical Center, Leiden, The Netherlands
| | - Florine E. M. Scholte
- Molecular Virology Laboratory, Department of Medical Microbiology, Leiden University Medical Center, Leiden, The Netherlands
| | - Arnoud H. de Ru
- Center for Proteomics & Metabolomics, Leiden University Medical Center, Leiden, The Netherlands
| | - Eric J. Snijder
- Molecular Virology Laboratory, Department of Medical Microbiology, Leiden University Medical Center, Leiden, The Netherlands
| | - Peter A. van Veelen
- Center for Proteomics & Metabolomics, Leiden University Medical Center, Leiden, The Netherlands
| | - Martijn J. van Hemert
- Molecular Virology Laboratory, Department of Medical Microbiology, Leiden University Medical Center, Leiden, The Netherlands
- * E-mail:
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Kim HS, Pickering AM. Protein translation paradox: Implications in translational regulation of aging. Front Cell Dev Biol 2023; 11:1129281. [PMID: 36711035 PMCID: PMC9880214 DOI: 10.3389/fcell.2023.1129281] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2022] [Accepted: 01/02/2023] [Indexed: 01/15/2023] Open
Abstract
Protein translation is an essential cellular process playing key roles in growth and development. Protein translation declines over the course of age in multiple animal species, including nematodes, fruit flies, mice, rats, and even humans. In all these species, protein translation transiently peaks in early adulthood with a subsequent drop over the course of age. Conversely, lifelong reductions in protein translation have been found to extend lifespan and healthspan in multiple animal models. These findings raise the protein synthesis paradox: age-related declines in protein synthesis should be detrimental, but life-long reductions in protein translation paradoxically slow down aging and prolong lifespan. This article discusses the nature of this paradox and complies an extensive body of work demonstrating protein translation as a modulator of lifespan and healthspan.
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Affiliation(s)
- Harper S. Kim
- Center for Neurodegeneration and Experimental Therapeutics (CNET), Department of Neurology, Heersink School of Medicine, University of Alabama at Birmingham, Birmingham, AL, United States
- Medical Scientist Training Program, Heersink School of Medicine, University of Alabama at Birmingham, Birmingham, AL, United States
| | - Andrew M. Pickering
- Center for Neurodegeneration and Experimental Therapeutics (CNET), Department of Neurology, Heersink School of Medicine, University of Alabama at Birmingham, Birmingham, AL, United States
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9
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Salimi K, Alvandi M, Saberi Pirouz M, Rakhshan K, Howatson G. Regulating eEF2 and eEF2K in skeletal muscle by exercise. Arch Physiol Biochem 2023:1-12. [PMID: 36633938 DOI: 10.1080/13813455.2023.2164898] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/16/2022] [Revised: 12/15/2022] [Accepted: 12/29/2022] [Indexed: 01/13/2023]
Abstract
Skeletal muscle is a flexible and adaptable tissue that strongly responds to exercise training. The skeletal muscle responds to exercise by increasing muscle protein synthesis (MPS) when energy is available. One of protein synthesis's major rate-limiting and critical regulatory steps is the translation elongation pathway. The process of translation elongation in skeletal muscle is highly regulated. It requires elongation factors that are intensely affected by various physiological stimuli such as exercise and the total available energy of cells. Studies have shown that exercise involves the elongation pathway by numerous signalling pathways. Since the elongation pathway, has been far less studied than the other translation steps, its comprehensive prospect and quantitative understanding remain in the dark. This study highlights the current understanding of the effect of exercise training on the translation elongation pathway focussing on the molecular factors affecting the pathway, including Ca2+, AMPK, PKA, mTORC1/P70S6K, MAPKs, and myostatin. We further discussed the mode and volume of exercise training intervention on the translation elongation pathway.What is the topic of this review? This review summarises the impacts of exercise training on the translation elongation pathway in skeletal muscle focussing on eEF2 and eEF2K.What advances does it highlight? This review highlights mechanisms and factors that profoundly influence the translation elongation pathway and argues that exercise might modulate the response. This review also combines the experimental observations focussing on the regulation of translation elongation during and after exercise. The findings widen our horizon to the notion of mechanisms involved in muscle protein synthesis (MPS) through translation elongation response to exercise training.
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Affiliation(s)
- Kia Salimi
- Department of Exercise Physiology, Faculty of Sport and Exercise Sciences, University of Tehran, Tehran, Iran
| | - Masoomeh Alvandi
- Department of Biological Science in Sport and Health, University of Shahid Beheshti, Tehran, Iran
| | - Mahdi Saberi Pirouz
- Student Research Committee, Iran University of Medical Sciences, Tehran, Iran
| | - Kamran Rakhshan
- Department of Medical Physiology, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran
- Electrophysiology Research Center, Tehran University of Medical Sciences, Tehran, Iran
| | - Glyn Howatson
- Faculty of Health and Life Sciences, Northumbria University, Newcastle upon Tyne, UK
- Water Research Group, North West University, Potchefstroom, South Africa
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10
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Andreev DE, Loughran G, Fedorova AD, Mikhaylova MS, Shatsky IN, Baranov PV. Non-AUG translation initiation in mammals. Genome Biol 2022; 23:111. [PMID: 35534899 PMCID: PMC9082881 DOI: 10.1186/s13059-022-02674-2] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2021] [Accepted: 04/14/2022] [Indexed: 12/12/2022] Open
Abstract
Recent proteogenomic studies revealed extensive translation outside of annotated protein coding regions, such as non-coding RNAs and untranslated regions of mRNAs. This non-canonical translation is largely due to start codon plurality within the same RNA. This plurality is often due to the failure of some scanning ribosomes to recognize potential start codons leading to initiation downstream—a process termed leaky scanning. Codons other than AUG (non-AUG) are particularly leaky due to their inefficiency. Here we discuss our current understanding of non-AUG initiation. We argue for a near-ubiquitous role of non-AUG initiation in shaping the dynamic composition of mammalian proteomes.
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11
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Kodama T, Otani K, Okada M, Yamawaki H. Eukaryotic elongation factor 2 kinase inhibitor, A484954 inhibits perivascular sympathetic nerve stimulation-induced vasoconstriction in isolated renal artery. Eur J Pharmacol 2022; 926:175042. [DOI: 10.1016/j.ejphar.2022.175042] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2021] [Revised: 05/16/2022] [Accepted: 05/16/2022] [Indexed: 11/27/2022]
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12
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Kodama T, Kameshima S, Otani K, Okada M, Yamawaki H. Eukaryotic elongation factor 2 kinase inhibitor, A484954 induces diuretic effect via renal vasorelaxation in spontaneously hypertensive rats. Eur J Pharmacol 2021; 913:174637. [PMID: 34801528 DOI: 10.1016/j.ejphar.2021.174637] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2021] [Revised: 10/20/2021] [Accepted: 11/11/2021] [Indexed: 11/17/2022]
Abstract
Eukaryotic elongation factor 2 (eEF2) kinase (eEF2K), alternatively known as calmodulin-dependent protein kinase III, inhibits protein translation via phosphorylating its sole substrate, eEF2. We previously demonstrated that expression and activity of eEF2K change in mesenteric artery from spontaneously hypertensive rats (SHR) with aging and that eEF2K is involved in pathogenesis of essential hypertension. In addition, we have recently revealed that acute intravenous injection with A484954, a selective eEF2K inhibitor, lowers blood pressure specifically in SHR partly via inducing vasorelaxation. In this study, we examined whether A484954 induces diuretic effect. After male SHR and normotensive Wistar Kyoto rats (WKY) were given a single intraperitoneal injection of A484954 (2.5 mg/kg, 0.5-9 h), urine was collected using metabolic cage. Contraction of isolated renal arteries form SHR was isometrically measured. While A484954 did not induce diuretic effect in WKY, it increased urine output, water intake, and urinary sodium excretion in SHR. A484954 (10 μM) induced vasorelaxation in isolated renal arteries, which was inhibited by a β-adrenergic receptor antagonist, propranolol. It was confirmed that A484954 increased renal blood flow in SHR as measured by renal ultrasonography. In summary, it was for the first time revealed that A484954 induces diuretic effect in SHR at least partly via renal vasorelaxation through β-adrenergic receptor.
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Affiliation(s)
- Tomoko Kodama
- Laboratory of Veterinary Pharmacology, School of Veterinary Medicine, Kitasato University, Higashi 23 Bancho 35-1, Towada, Aomori, 034-8628, Japan
| | - Satoshi Kameshima
- Laboratory of Small Animal Internal Medicine, School of Veterinary Medicine, Kitasato University, Higashi 23 Bancho 35-1, Towada, Aomori, 034-8628, Japan
| | - Kosuke Otani
- Laboratory of Veterinary Pharmacology, School of Veterinary Medicine, Kitasato University, Higashi 23 Bancho 35-1, Towada, Aomori, 034-8628, Japan
| | - Muneyoshi Okada
- Laboratory of Veterinary Pharmacology, School of Veterinary Medicine, Kitasato University, Higashi 23 Bancho 35-1, Towada, Aomori, 034-8628, Japan
| | - Hideyuki Yamawaki
- Laboratory of Veterinary Pharmacology, School of Veterinary Medicine, Kitasato University, Higashi 23 Bancho 35-1, Towada, Aomori, 034-8628, Japan.
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13
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Elongation factor eEF2 kinase and autophagy jointly promote survival of cancer cells. Biochem J 2021; 478:1547-1569. [PMID: 33779695 DOI: 10.1042/bcj20210126] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2021] [Revised: 03/22/2021] [Accepted: 03/29/2021] [Indexed: 01/07/2023]
Abstract
Cells within solid tumours can become deprived of nutrients; in order to survive, they need to invoke mechanisms to conserve these resources. Using cancer cells in culture in the absence of key nutrients, we have explored the roles of two potential survival mechanisms, autophagy and elongation factor 2 kinase (eEF2K), which, when activated, inhibits the resource-intensive elongation stage of protein synthesis. Both processes are regulated through the nutrient-sensitive AMP-activated protein kinase and mechanistic target of rapamycin complex 1 signalling pathways. We find that disabling both autophagy and eEF2K strongly compromises the survival of nutrient-deprived lung and breast cancer cells, whereas, for example, knocking out eEF2K alone has little effect. Contrary to some earlier reports, we find no evidence that eEF2K regulates autophagy. Unexpectedly, eEF2K does not facilitate survival of prostate cancer PC3 cells. Thus, eEF2K and autophagy enable survival of certain cell-types in a mutually complementary manner. To explore this further, we generated, by selection, cells which were able to survive nutrient starvation even when autophagy and eEF2K were disabled. Proteome profiling using mass spectrometry revealed that these 'resistant' cells showed lower levels of diverse proteins which are required for energy-consuming processes such as protein and fatty acid synthesis, although different clones of 'resistant cells' appear to adapt in dissimilar ways. Our data provide further information of the ways that human cells cope with nutrient limitation and to understanding of the utility of eEF2K as a potential target in oncology.
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14
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Shen Y, Zhang ZC, Cheng S, Liu A, Zuo J, Xia S, Liu X, Liu W, Jia Z, Xie W, Han J. PQBP1 promotes translational elongation and regulates hippocampal mGluR-LTD by suppressing eEF2 phosphorylation. Mol Cell 2021; 81:1425-1438.e10. [PMID: 33662272 DOI: 10.1016/j.molcel.2021.01.032] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2020] [Revised: 12/07/2020] [Accepted: 01/21/2021] [Indexed: 10/22/2022]
Abstract
Eukaryotic elongation factor 2 (eEF2) mediates translocation of peptidyl-tRNA from the ribosomal A site to the P site to promote translational elongation. Its phosphorylation on Thr56 by its single known kinase eEF2K inactivates it and inhibits translational elongation. Extensive studies have revealed that different signal cascades modulate eEF2K activity, but whether additional factors regulate phosphorylation of eEF2 remains unclear. Here, we find that the X chromosome-linked intellectual disability protein polyglutamine-binding protein 1 (PQBP1) specifically binds to non-phosphorylated eEF2 and suppresses eEF2K-mediated phosphorylation at Thr56. Loss of PQBP1 significantly reduces general protein synthesis by suppressing translational elongation. Moreover, we show that PQBP1 regulates hippocampal metabotropic glutamate receptor-dependent long-term depression (mGluR-LTD) and mGluR-LTD-associated behaviors by suppressing eEF2K-mediated phosphorylation. Our results identify PQBP1 as a novel regulator in translational elongation and mGluR-LTD, and this newly revealed regulator in the eEF2K/eEF2 pathway is also an excellent therapeutic target for various disease conditions, such as neural diseases, virus infection, and cancer.
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Affiliation(s)
- Yuqian Shen
- School of Life Science and Technology, Key Laboratory of Developmental Genes and Human Disease, Southeast University, Nanjing 210096, China
| | - Zi Chao Zhang
- School of Life Science and Technology, Key Laboratory of Developmental Genes and Human Disease, Southeast University, Nanjing 210096, China; Co-innovation Center of Neuroregeneration, Nantong University, Nantong, Jiangsu 226001, China.
| | - Shanshan Cheng
- School of Life Science and Technology, Key Laboratory of Developmental Genes and Human Disease, Southeast University, Nanjing 210096, China
| | - An Liu
- School of Life Science and Technology, Key Laboratory of Developmental Genes and Human Disease, Southeast University, Nanjing 210096, China
| | - Jian Zuo
- School of Life Science and Technology, Key Laboratory of Developmental Genes and Human Disease, Southeast University, Nanjing 210096, China
| | - Shuting Xia
- Institute of Neuroscience, Soochow University, Suzhou 215000, China
| | - Xian Liu
- School of Life Science and Technology, Key Laboratory of Developmental Genes and Human Disease, Southeast University, Nanjing 210096, China
| | - Wenhua Liu
- School of Life Science and Technology, Key Laboratory of Developmental Genes and Human Disease, Southeast University, Nanjing 210096, China
| | - Zhengping Jia
- Neurosciences and Mental Health Program, Hospital for Sick Children, University of Toronto, Toronto, ON M5S 1A1, Canada
| | - Wei Xie
- School of Life Science and Technology, Key Laboratory of Developmental Genes and Human Disease, Southeast University, Nanjing 210096, China; Co-innovation Center of Neuroregeneration, Nantong University, Nantong, Jiangsu 226001, China
| | - Junhai Han
- School of Life Science and Technology, Key Laboratory of Developmental Genes and Human Disease, Southeast University, Nanjing 210096, China; Co-innovation Center of Neuroregeneration, Nantong University, Nantong, Jiangsu 226001, China; Department of Neurology, Affiliated ZhongDa Hospital, Institute of Neuropsychiatry, Southeast University, Nanjing, Jiangsu 210009, China.
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15
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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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16
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Gladulich LFH, Peixoto-Rodrigues MC, Campello-Costa P, Paes-de-Carvalho R, Cossenza M. NMDA-induced nitric oxide generation and CREB activation in central nervous system is dependent on eukaryotic elongation factor 2 kinase. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2020; 1867:118783. [DOI: 10.1016/j.bbamcr.2020.118783] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/19/2020] [Revised: 06/11/2020] [Accepted: 06/17/2020] [Indexed: 01/28/2023]
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17
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Gladulich LFH, Xie J, Jensen KB, Kamei M, Paes-de-Carvalho R, Cossenza M, Proud CG. Bicuculline regulated protein synthesis is dependent on Homer1 and promotes its interaction with eEF2K through mTORC1-dependent phosphorylation. J Neurochem 2020; 157:1086-1101. [PMID: 32892352 DOI: 10.1111/jnc.15178] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2020] [Revised: 07/29/2020] [Accepted: 08/26/2020] [Indexed: 02/06/2023]
Abstract
The regulation of protein synthesis is a vital and finely tuned process in cellular physiology. In neurons, this process is very precisely regulated, as which mRNAs undergo translation is highly dependent on context. One of the most prominent regulators of protein synthesis is the enzyme eukaryotic elongation factor kinase 2 (eEF2K) that regulates the elongation stage of protein synthesis. This kinase and its substrate, eukaryotic elongation factor 2 (eEF2) are important in processes such as neuronal development and synaptic plasticity. eEF2K is regulated by multiple mechanisms including Ca2+ -ions and the mTORC1 signaling pathway, both of which play key roles in neurological processes such as learning and memory. In such settings, the localized control of protein synthesis is of crucial importance. In this work, we sought to investigate how the localization of eEF2K is controlled and the impact of this on protein synthesis in neuronal cells. In this study, we used both SH-SY5Y neuroblastoma cells and mouse cortical neurons, and pharmacologically and/or genetic approaches to modify eEF2K function. We show that eEF2K activity and localization can be regulated by its binding partner Homer1b/c, a scaffolding protein known for its participation in calcium-regulated signaling pathways. Furthermore, our results indicate that this interaction is regulated by the mTORC1 pathway, through a known phosphorylation site in eEF2K (S396), and that it affects rates of localized protein synthesis at synapses depending on the presence or absence of this scaffolding protein.
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Affiliation(s)
- Luis F H Gladulich
- Program of Neurosciences, Fluminense Federal University, Niterói, Brazil.,Lifelong Health, South Australia Health & Medical Research Institute (SAHMRI) Adelaide, SA, Australia
| | - Jianling Xie
- Lifelong Health, South Australia Health & Medical Research Institute (SAHMRI) Adelaide, SA, Australia
| | - Kirk B Jensen
- Lifelong Health, South Australia Health & Medical Research Institute (SAHMRI) Adelaide, SA, Australia
| | - Makoto Kamei
- Lifelong Health, South Australia Health & Medical Research Institute (SAHMRI) Adelaide, SA, Australia.,Center for Cancer Biology, University of South Australia, Adelaide, SA, Australia
| | - Roberto Paes-de-Carvalho
- Program of Neurosciences, Fluminense Federal University, Niterói, Brazil.,Department of Neurobiology, Institute of Biology, Fluminense Federal University, Niterói, Brazil
| | - Marcelo Cossenza
- Program of Neurosciences, Fluminense Federal University, Niterói, Brazil.,Department of Physiology and Pharmacology, Biomedical Institute, Fluminense Federal University, Niterói, Brazil
| | - Christopher G Proud
- Lifelong Health, South Australia Health & Medical Research Institute (SAHMRI) Adelaide, SA, Australia
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18
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Translation elongation factor 2 depletion by siRNA in mouse liver leads to mTOR-independent translational upregulation of ribosomal protein genes. Sci Rep 2020; 10:15473. [PMID: 32968084 PMCID: PMC7511953 DOI: 10.1038/s41598-020-72399-4] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2020] [Accepted: 07/15/2020] [Indexed: 11/08/2022] Open
Abstract
Due to breakthroughs in RNAi and genome editing methods in the past decade, it is now easier than ever to study fine details of protein synthesis in animal models. However, most of our understanding of translation comes from unicellular organisms and cultured mammalian cells. In this study, we demonstrate the feasibility of perturbing protein synthesis in a mouse liver by targeting translation elongation factor 2 (eEF2) with RNAi. We were able to achieve over 90% knockdown efficacy and maintain it for 2 weeks effectively slowing down the rate of translation elongation. As the total protein yield declined, both proteomics and ribosome profiling assays showed robust translational upregulation of ribosomal proteins relative to other proteins. Although all these genes bear the TOP regulatory motif, the branch of the mTOR pathway responsible for translation regulation was not activated. Paradoxically, coordinated translational upregulation of ribosomal proteins only occurred in the liver but not in murine cell culture. Thus, the upregulation of ribosomal transcripts likely occurred via passive mTOR-independent mechanisms. Impaired elongation sequesters ribosomes on mRNA and creates a shortage of free ribosomes. This leads to preferential translation of transcripts with high initiation rates such as ribosomal proteins. Furthermore, severe eEF2 shortage reduces the negative impact of positively charged amino acids frequent in ribosomal proteins on ribosome progression.
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19
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Deshpande P, Flinkman D, Hong Y, Goltseva E, Siino V, Sun L, Peltonen S, Elo LL, Kaasinen V, James P, Coffey ET. Protein synthesis is suppressed in sporadic and familial Parkinson's disease by LRRK2. FASEB J 2020; 34:14217-14233. [PMID: 32926469 DOI: 10.1096/fj.202001046r] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2020] [Revised: 07/12/2020] [Accepted: 07/29/2020] [Indexed: 12/21/2022]
Abstract
Gain of function LRRK2-G2019S is the most frequent mutation found in familial and sporadic Parkinson's disease. It is expected therefore that understanding the cellular function of LRRK2 will provide insight on the pathological mechanism not only of inherited Parkinson's, but also of sporadic Parkinson's, the more common form. Here, we show that constitutive LRRK2 activity controls nascent protein synthesis in rodent neurons. Specifically, pharmacological inhibition of LRRK2, Lrrk2 knockdown or Lrrk2 knockout, all lead to increased translation. In the rotenone model for sporadic Parkinson's, LRRK2 activity increases, dopaminergic neuron translation decreases, and the neurites atrophy. All are prevented by LRRK2 inhibitors. Moreover, in striatum and substantia nigra of rotenone treated rats, phosphorylation changes are observed on eIF2α-S52(↑), eIF2s2-S2(↓), and eEF2-T57(↑) in directions that signify protein synthesis arrest. Significantly, translation is reduced by 40% in fibroblasts from Parkinson's patients (G2019S and sporadic cases alike) and this is reversed upon LRRK2 inhibitor treatment. In cells from multiple system atrophy patients, translation is unchanged suggesting that repression of translation is specific to Parkinson's disease. These findings indicate that repression of translation is a proximal function of LRRK2 in Parkinson's pathology.
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Affiliation(s)
| | - Dani Flinkman
- Turku Bioscience, University of Turku and Åbo Akademi University, Turku, Finland.,Department of Immunotechnology, Lund University, Lund, Sweden
| | - Ye Hong
- Turku Bioscience, University of Turku and Åbo Akademi University, Turku, Finland
| | - Elena Goltseva
- Department of Immunotechnology, Lund University, Lund, Sweden
| | - Valentina Siino
- Department of Immunotechnology, Lund University, Lund, Sweden
| | - Lihua Sun
- Turku Bioscience, University of Turku and Åbo Akademi University, Turku, Finland
| | - Sirkku Peltonen
- Department of Dermatology, University of Turku and Turku University Hospital, Turku, Finland
| | - Laura L Elo
- Turku Bioscience, University of Turku and Åbo Akademi University, Turku, Finland
| | - Valtteri Kaasinen
- Division of Clinical Neurosciences, Turku University Hospital and University of Turku, Turku, Finland
| | - Peter James
- Turku Bioscience, University of Turku and Åbo Akademi University, Turku, Finland.,Department of Immunotechnology, Lund University, Lund, Sweden
| | - Eleanor T Coffey
- Turku Bioscience, University of Turku and Åbo Akademi University, Turku, Finland
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20
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Kodama T, Okada M, Yamawaki H. Eukaryotic elongation factor 2 kinase inhibitor, A484954 lowered blood pressure in spontaneously hypertensive rats via inducing vasorelaxation. J Pharmacol Sci 2020; 144:165-171. [PMID: 32811745 DOI: 10.1016/j.jphs.2020.07.007] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2020] [Revised: 07/08/2020] [Accepted: 07/09/2020] [Indexed: 10/23/2022] Open
Abstract
Eukaryotic elongation factor 2 (eEF2) kinase (eEF2K) suppresses protein translation. We previously reported eEF2K expression was upregulated in mesenteric arteries (MA) from spontaneously hypertensive rats (SHR). We have recently revealed A484954, an eEF2K inhibitor, acutely suppressed vasopressor agonists-induced increase of blood pressure (BP) in normal Wistar rats. In this study, we examined the acute effects of A484954 on BP in SHR and explored underlying mechanisms. BP was measured by a carotid cannulation method in SHR. Isometric contraction in MA from SHR was measured. Endothelial nitric oxide synthase (eNOS) dimerization was measured by low-temperature sodium dodecyl sulfate-polyacrylamide gel electrophoresis and Western blotting. A484954 lowered BP in 15-week-old SHR. A484954 induced relaxation in MA from both 4- and 7-9-week-old SHR. In MA from 4-week-old SHR, A484954-induced relaxation was inhibited almost completely by a NOS inhibitor, NG-nitro-l-arginine methyl ester (l-NAME) and significantly by a β blocker, propranolol. In MA from 7-9-week-old SHR, on the other hand, A484954-induced relaxation was inhibited partly either by l-NAME, indomethacin, a cyclooxygenase inhibitor, or l-NAME + indomethacin. A484954 promoted the dimerization of eNOS in human endothelial cells. In summary, we have revealed A484954 lowers BP in SHR perhaps through the vasorelaxation via the production of endothelium-derived relaxing factors.
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Affiliation(s)
- Tomoko Kodama
- Laboratory of Veterinary Pharmacology, School of Veterinary Medicine, Kitasato University, Higashi 23 Bancho 35-1, Towada, Aomori, 034-8628, Japan
| | - Muneyoshi Okada
- Laboratory of Veterinary Pharmacology, School of Veterinary Medicine, Kitasato University, Higashi 23 Bancho 35-1, Towada, Aomori, 034-8628, Japan
| | - Hideyuki Yamawaki
- Laboratory of Veterinary Pharmacology, School of Veterinary Medicine, Kitasato University, Higashi 23 Bancho 35-1, Towada, Aomori, 034-8628, Japan.
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21
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Xiao M, Xie J, Wu Y, Wang G, Qi X, Liu Z, Wang Y, Wang X, Hoque A, Oakhill J, Proud CG, Li J. The eEF2 kinase-induced STAT3 inactivation inhibits lung cancer cell proliferation by phosphorylation of PKM2. Cell Commun Signal 2020; 18:25. [PMID: 32054489 PMCID: PMC7020344 DOI: 10.1186/s12964-020-0528-y] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2019] [Accepted: 02/05/2020] [Indexed: 02/04/2023] Open
Abstract
BACKGROUND Eukaryotic elongation factor-2 kinase (eEF2K) is a Ca 2+ /calmodulin (CaM)-dependent protein kinase that inhibits protein synthesis. However, the role of eEF2K in cancer development was reported paradoxically and remains to be elucidated. METHODS Herein, A549 cells with eEF2K depletion or overexpression by stably transfected lentivirus plasmids were used in vitro and in vivo study. MTT and colony assays were used to detect cell proliferation and growth. Extracellular glucose and lactate concentration were measured using test kit. Immunoblot and co-immunoprecipitation assays were used to examine the molecular biology changes and molecular interaction in these cells. LC-MS/MS analysis and [γ- 32 P] ATP kinase assay were used to identify combining protein and phosphorylation site. Nude mice was utilized to study the correlation of eEF2K and tumor growth in vivo. RESULTS We demonstrated that eEF2K inhibited lung cancer cells proliferation and affected the inhibitory effects of EGFR inhibitor gefitinib. Mechanistically, we showed that eEF2K formed a complex with PKM2 and STAT3, thereby phosphorylated PKM2 at T129, leading to reduced dimerization of PKM2. Subsequently, PKM2 impeded STAT3 phosphorylation and STAT3-dependent c-Myc expression. eEF2K depletion promoted the nuclear translocation of PKM2 and increased aerobic glycolysis reflected by increased lactate secretion and glucose. CONCLUSIONS Our findings define a novel mechanism underlying the regulation of cancer cell proliferation by eEF2K independent of its role in protein synthesis, disclosing the diverse roles of eEF2K in cell biology, which lays foundation for the development of new anticancer therapeutic strategies.
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Affiliation(s)
- Min Xiao
- Key Laboratory of Marine Drugs, Chinese Ministry of Education, School of Medicine and Pharmacy, Ocean University of China, Qingdao, 266003, People's Republic of China
| | - Jianling Xie
- South Australian Health & Medical Research Institute, North Terrace, Adelaide, SA, 5000, Australia
| | - Yu Wu
- Key Laboratory of Marine Drugs, Chinese Ministry of Education, School of Medicine and Pharmacy, Ocean University of China, Qingdao, 266003, People's Republic of China
| | - Genzhu Wang
- Key Laboratory of Marine Drugs, Chinese Ministry of Education, School of Medicine and Pharmacy, Ocean University of China, Qingdao, 266003, People's Republic of China
| | - Xin Qi
- Key Laboratory of Marine Drugs, Chinese Ministry of Education, School of Medicine and Pharmacy, Ocean University of China, Qingdao, 266003, People's Republic of China
| | - Zailiang Liu
- Key Laboratory of Marine Drugs, Chinese Ministry of Education, School of Medicine and Pharmacy, Ocean University of China, Qingdao, 266003, People's Republic of China
| | - Yuying Wang
- Key Laboratory of Marine Drugs, Chinese Ministry of Education, School of Medicine and Pharmacy, Ocean University of China, Qingdao, 266003, People's Republic of China
| | - Xuemin Wang
- South Australian Health & Medical Research Institute, North Terrace, Adelaide, SA, 5000, Australia
- School of Biological Sciences, University of Adelaide, Adelaide, SA, 5005, Australia
| | - Ashfaqul Hoque
- St Vincent's Institute of Medical Research, Fitzroy, SA, 4312, Australia
| | - Jon Oakhill
- St Vincent's Institute of Medical Research, Fitzroy, SA, 4312, Australia
| | - Christopher G Proud
- South Australian Health & Medical Research Institute, North Terrace, Adelaide, SA, 5000, Australia
- School of Biological Sciences, University of Adelaide, Adelaide, SA, 5005, Australia
| | - Jing Li
- Key Laboratory of Marine Drugs, Chinese Ministry of Education, School of Medicine and Pharmacy, Ocean University of China, Qingdao, 266003, People's Republic of China.
- Laboratory for Marine Drugs and Bioproducts of Qingdao National Laboratory for Marine Science and Technology, Qingdao, 266237, People's Republic of China.
- Open Studio for Druggability Research of Marine Natural Products, Pilot National Laboratory for Marine Science and Technology (Qingdao), Qingdao, People's Republic of China.
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22
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Kodama T, Okada M, Yamawaki H. Eukaryotic elongation factor 2 kinase inhibitor, A484954 potentiates β-adrenergic receptor agonist-induced acute decrease in diastolic blood pressure in rats. J Vet Med Sci 2019; 81:1509-1514. [PMID: 31484844 PMCID: PMC6863711 DOI: 10.1292/jvms.19-0425] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Eukaryotic elongation factor 2 (eEF2) kinase (eEF2K) acts to inhibit protein translation
through phosphorylating a specific substrate, eEF2. We previously found that the increased
eEF2K expression in mesenteric artery mediates hypertension development in spontaneously
hypertensive rats. More recently, we have revealed that a selective eEF2K inhibitor,
A484954 induced vasorelaxation via opening inward rectifier K+ channel and
activating β2-adrenergic receptor in smooth muscle of rat isolated mesenteric
artery, which contributes to prevent noradrenaline-induced acute increase in blood
pressure (BP). In this study, we further explored acute effects of A484954 on BP in rats,
especially focusing the action on β-adrenergic receptor. We also examined whether A484954
affects contraction and heart rate (HR) of isolated heart. BP and HR were measured by a
carotid cannulation method in rats. Isometric contraction and HR in rat isolated atria
were also measured pharmacologically. A484954 potentiated adrenaline-induced decrease in
diastolic BP (DBP) but not increase in systolic BP (SBP). A484954 potentiated
isoproterenol-induced decrease in DBP but not SBP. Contrastingly, A484954 prevented a
non-β-adrenergic receptor agonist, angiotensin II-induced increase in both SBP and DBP. In
isolated left atria, A484954 caused contraction, which was prevented by a β-adrenergic
receptor antagonist, propranolol. In isolated right atria, A484954 increased HR. In
conclusion, we for the first time demonstrated that A484954 potentiates β-adrenergic
receptor agonist-induced decrease in DBP possibly through vasorelaxation mediated via
activating β2-adrenergic receptor. It was also demonstrated that A484954 causes
contraction of rat isolated heart via activating β1-adrenergic receptor.
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Affiliation(s)
- Tomoko Kodama
- Laboratory of Veterinary Pharmacology, School of Veterinary Medicine, Kitasato University, Higashi 23 bancho 35-1, Towada, Aomori 034-8628, Japan
| | - Muneyoshi Okada
- Laboratory of Veterinary Pharmacology, School of Veterinary Medicine, Kitasato University, Higashi 23 bancho 35-1, Towada, Aomori 034-8628, Japan
| | - Hideyuki Yamawaki
- Laboratory of Veterinary Pharmacology, School of Veterinary Medicine, Kitasato University, Higashi 23 bancho 35-1, Towada, Aomori 034-8628, Japan
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23
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Proud CG. Phosphorylation and Signal Transduction Pathways in Translational Control. Cold Spring Harb Perspect Biol 2019; 11:cshperspect.a033050. [PMID: 29959191 DOI: 10.1101/cshperspect.a033050] [Citation(s) in RCA: 70] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Protein synthesis, including the translation of specific messenger RNAs (mRNAs), is regulated by extracellular stimuli such as hormones and by the levels of certain nutrients within cells. This control involves several well-understood signaling pathways and protein kinases, which regulate the phosphorylation of proteins that control the translational machinery. These pathways include the mechanistic target of rapamycin complex 1 (mTORC1), its downstream effectors, and the mitogen-activated protein (MAP) kinase (extracellular ligand-regulated kinase [ERK]) signaling pathway. This review describes the regulatory mechanisms that control translation initiation and elongation factors, in particular the effects of phosphorylation on their interactions or activities. It also discusses current knowledge concerning the impact of these control systems on the translation of specific mRNAs or subsets of mRNAs, both in physiological processes and in diseases such as cancer.
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Affiliation(s)
- Christopher G Proud
- Nutrition & Metabolism, South Australian Health & Medical Research Institute, North Terrace, Adelaide SA5000, Australia; and School of Biological Sciences, University of Adelaide, Adelaide SA5000, Australia
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24
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Muscarinic acetylcholine receptors regulate the dephosphorylation of eukaryotic translation elongation factor 2 in SNU-407 colon cancer cells. Biochem Biophys Res Commun 2019; 516:424-429. [PMID: 31227218 DOI: 10.1016/j.bbrc.2019.06.059] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2019] [Accepted: 06/11/2019] [Indexed: 11/21/2022]
Abstract
Previously, we showed that muscarinic acetylcholine receptors (mAChRs) promote global protein biosynthesis in SNU-407 colon cancer cells. However, the molecular mechanisms underlying this event are poorly understood. Here, we asked whether mAChRs modulate the activity of eukaryotic translation elongation factor 2 (eEF2), which controls ribosomal translocation during the peptide elongation step. When SNU-407 cells were treated with the cholinergic agonist carbachol, eEF2 phosphorylation at T56 was decreased in a dose- and time-dependent manner. The muscarinic antagonist atropine almost completely blocked this effect of carbachol, demonstrating that mAChRs specifically regulate eEF2 dephosphorylation. We also investigated the signaling pathways that connect mAChR stimulation to eEF2 dephosphorylation using chemical inhibitors. Treating cells with U0126, a potent MEK1/2 inhibitor, decreased carbachol-stimulated eEF2 dephosphorylation. In contrast, the mTORC1 inhibitor rapamycin did not have a significant effect on eEF2 dephosphorylation. We also found that the protein kinase C (PKC) inhibitor GF109203X substantially reduced eEF2 dephosphorylation. Together, our experimental data indicate that the MEK1/2-ERK1/2 pathway and the PKC pathway, but not the mTORC1-S6K1 pathway, are involved in mAChR-mediated eEF2 dephosphorylation.
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25
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Mateus-Seidl R, Stahl S, Dengl S, Birzele F, Herrmuth H, Mayer K, Niederfellner G, Liu XF, Pastan I, Brinkmann U. Interplay between reversible phosphorylation and irreversible ADP-ribosylation of eukaryotic translation elongation factor 2. Biol Chem 2019; 400:501-512. [PMID: 30218597 DOI: 10.1515/hsz-2018-0280] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2018] [Accepted: 09/11/2018] [Indexed: 11/15/2022]
Abstract
The functionality of eukaryotic translation elongation factor 2 (eEF2) is modulated by phosphorylation, eEF2 is simultaneously the molecular target of ADP-ribosylating toxins. We analyzed the interplay between phosphorylation and diphthamide-dependent ADP-ribosylation. Phosphorylation does not require diphthamide, eEF2 without it still becomes phosphorylated. ADP-ribosylation not only modifies the H715 diphthamide but also inhibits phosphorylation of S595 located in proximity to H715, and stimulates phosphorylation of T56. S595 can be phosphorylated by CDK2 and CDK1 which affects EEF2K-mediated T56-phosphorylation. Thus, ADP-ribosylation and S595-phosphorylation by kinases occur within the same vicinity and both trigger T56-phosphorylation. Diphthamide is surface-accessible permitting access to ADP-ribosylating enzymes, the adjacent S595 side chain extends into the interior. This orientation is incompatible with phosphorylation, neither allowing kinase access nor phosphate attachment. S595 phosphorylation must therefore be accompanied by structural alterations affecting the interface to ADP-ribosylating toxins. In agreement with that, replacement of S595 with Ala, Glu or Asp prevents ADP-ribosylation. Phosphorylation (starvation) as well as ADP-ribosylation (toxins) inhibit protein synthesis, both affect the S595/H715 region of eEF2, both trigger T57-phosphorylation eliciting similar transcriptional responses. Phosphorylation is short lived while ADP-ribosylation is stable. Thus, phosphorylation of the S595/H715 'modifier region' triggers transient interruption of translation while ADP-ribosylation arrests irreversibly.
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Affiliation(s)
- Rita Mateus-Seidl
- Roche Pharma Research and Early Development, Discovery Oncology, Roche Innovation Center Munich, Nonnenwald 2, D-82377 Penzberg, FRG, Germany
| | - Sebastian Stahl
- Roche Pharma Research and Early Development, Large Molecule Research, Roche Innovation Center Munich, Nonnenwald 2, D-82377 Penzberg, FRG, Germany
| | - Stefan Dengl
- Roche Pharma Research and Early Development, Large Molecule Research, Roche Innovation Center Munich, Nonnenwald 2, D-82377 Penzberg, FRG, Germany
| | - Fabian Birzele
- Roche Pharma Research and Early Development, Pharmaceutical Sciences- Bioinformatics, Roche Innovation Center Basel, Grenzacherstr. 124, CH-4070 Basel, Germany
| | - Hedda Herrmuth
- Roche Pharma Research and Early Development, Discovery Oncology, Roche Innovation Center Munich, Nonnenwald 2, D-82377 Penzberg, FRG, Germany
| | - Klaus Mayer
- Roche Pharma Research and Early Development, Large Molecule Research, Roche Innovation Center Munich, Nonnenwald 2, D-82377 Penzberg, FRG, Germany
| | - Gerhard Niederfellner
- Roche Pharma Research and Early Development, Discovery Oncology, Roche Innovation Center Munich, Nonnenwald 2, D-82377 Penzberg, FRG, Germany
| | - Xiu-Fen Liu
- Laboratory of Molecular Biology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, 37 Convent Dr, Bethesda, MD 20814, USA
| | - Ira Pastan
- Laboratory of Molecular Biology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, 37 Convent Dr, Bethesda, MD 20814, USA
| | - Ulrich Brinkmann
- Roche Pharma Research and Early Development, Large Molecule Research, Roche Innovation Center Munich, Nonnenwald 2, D-82377 Penzberg, FRG, Germany
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26
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Kodama T, Okada M, Yamawaki H. Eukaryotic elongation factor 2 kinase inhibitor, A484954 inhibits noradrenaline-induced acute increase of blood pressure in rats. J Vet Med Sci 2018; 81:35-41. [PMID: 30429409 PMCID: PMC6361655 DOI: 10.1292/jvms.18-0606] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Eukaryotic elongation factor 2 (eEF2) kinase (eEF2K) inhibits protein translation through the phosphorylation of its specific substrate, eEF2. We previously demonstrated that eEF2K expression increases in superior mesenteric artery from spontaneously hypertensive rats (SHR) and that eEF2K mediates development of hypertension in SHR. In addition, we recently revealed that A484954, a selective eEF2K inhibitor induced relaxation via opening smooth muscle inward rectifier K+ (Kir) channel in rat isolated superior mesenteric artery. Here, we further examined the effects of A484954 on contractility and blood pressure (BP) in rats. Isometric contraction of rat isolated superior mesenteric artery was measured. BP was measured by a carotid cannulation method. A484954 (10 µM) inhibited noradrenaline (NA)-induced contraction in a biphasic manner (magnitude of inhibition higher at high dose NA). A484954 also inhibited an α1-receptor agonist, phenylephrine-induced contraction, while it was not biphasic. Specifically, a β-receptor antagonist, propranolol (1 µM) prevented the A484954-mediated inhibition of NA (high-dose)-induced contraction. A484954 (10 µM) potentiated a β-receptor agonist, isoproterenol-induced relaxation, which was completely prevented by BaCl2 (1 mM), a Kir channel blocker. In vivo, A484954 (122 µg/kg) inhibited NA-induced increase of BP in rats. Another eEF2K inhibitor, NH125 (22 µg/kg) also inhibited the NA-induced BP increase in rats. In summary, it was concluded that A484954 lowers NA-induced BP rise perhaps through activation of β2-receptor-Kir channel and subsequent vasorelaxation via inhibiting eEF2K activity.
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Affiliation(s)
- Tomoko Kodama
- Laboratory of Veterinary Pharmacology, School of Veterinary Medicine, Kitasato University, Higashi 23 Bancho 35-1, Towada, Aomori 034-8628, Japan
| | - Muneyoshi Okada
- Laboratory of Veterinary Pharmacology, School of Veterinary Medicine, Kitasato University, Higashi 23 Bancho 35-1, Towada, Aomori 034-8628, Japan
| | - Hideyuki Yamawaki
- Laboratory of Veterinary Pharmacology, School of Veterinary Medicine, Kitasato University, Higashi 23 Bancho 35-1, Towada, Aomori 034-8628, Japan
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27
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Abstract
Translation is a key step in the regulation of gene expression and one of the most energy-consuming processes in the cell. In response to various stimuli, multiple signaling pathways converge on the translational machinery to regulate its function. To date, the roles of phosphoinositide 3-kinase (PI3K)/AKT and the mitogen-activated protein kinase (MAPK) pathways in the regulation of translation are among the best understood. Both pathways engage the mechanistic target of rapamycin (mTOR) to regulate a variety of components of the translational machinery. While these pathways regulate protein synthesis in homeostasis, their dysregulation results in aberrant translation leading to human diseases, including diabetes, neurological disorders, and cancer. Here we review the roles of the PI3K/AKT and MAPK pathways in the regulation of mRNA translation. We also highlight additional signaling mechanisms that have recently emerged as regulators of the translational apparatus.
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28
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Kodama T, Okada M, Yamawaki H. Mechanisms underlying the relaxation by A484954, a eukaryotic elongation factor 2 kinase inhibitor, in rat isolated mesenteric artery. J Pharmacol Sci 2018; 137:86-92. [PMID: 29778449 DOI: 10.1016/j.jphs.2018.04.006] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2018] [Revised: 04/22/2018] [Accepted: 04/24/2018] [Indexed: 12/13/2022] Open
Abstract
Eukaryotic elongation factor 2 kinase (eEF2K) is a calmodulin-related protein kinase which regulates protein translation. A484954 is an inhibitor of eEF2K. In the present study, we investigated the acute effects of A484954 on contractility of isolated blood vessels. Isometric contraction of rat isolated aorta and main branch of superior mesenteric artery (MA) was measured. Expression of an inward rectifier K+ (Kir) channel subtype mRNA and protein was examined. A484954 caused relaxation in endothelium-intact [E (+)] and -denuded [E (-)] aorta or MA precontracted with noradrenaline (NA). The relaxation was higher in MA than aorta. The relaxation was partially inhibited by a nitric oxide (NO) synthase inhibitor, NG-nitro-l-arginine methyl ester (300 μM) in E (+) MA. The relaxation was significantly smaller in MA precontracted with high K+ than NA. The A484954-induced relaxation was significantly inhibited by a Kir channel blocker, BaCl2 (1 mM) compared with vehicle control in E (-) MA. Expression of Kir2.2 mRNA and protein was significantly higher in MA than aorta. We for the first time revealed that A484954 induces relaxation through opening smooth muscle Kir (Kir2.2) channel and through endothelium-derived NO in MA.
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Affiliation(s)
- Tomoko Kodama
- Laboratory of Veterinary Pharmacology, School of Veterinary Medicine, Kitasato University, Higashi 23 Bancho 35-1, Towada City, Aomori, 034-8628, Japan
| | - Muneyoshi Okada
- Laboratory of Veterinary Pharmacology, School of Veterinary Medicine, Kitasato University, Higashi 23 Bancho 35-1, Towada City, Aomori, 034-8628, Japan
| | - Hideyuki Yamawaki
- Laboratory of Veterinary Pharmacology, School of Veterinary Medicine, Kitasato University, Higashi 23 Bancho 35-1, Towada City, Aomori, 034-8628, Japan.
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29
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Xie J, Shen K, Lenchine RV, Gethings LA, Trim PJ, Snel MF, Zhou Y, Kenney JW, Kamei M, Kochetkova M, Wang X, Proud CG. Eukaryotic elongation factor 2 kinase upregulates the expression of proteins implicated in cell migration and cancer cell metastasis. Int J Cancer 2017; 142:1865-1877. [PMID: 29235102 DOI: 10.1002/ijc.31210] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2017] [Revised: 10/23/2017] [Accepted: 12/05/2017] [Indexed: 01/01/2023]
Abstract
Eukaryotic elongation factor 2 kinase (eEF2K) negatively regulates the elongation phase of mRNA translation and hence protein synthesis. Increasing evidence indicates that eEF2K plays an important role in the survival and migration of cancer cells and in tumor progression. As demonstrated by two-dimensional wound-healing and three-dimensional transwell invasion assays, knocking down or inhibiting eEF2K in cancer cells impairs migration and invasion of cancer cells. Conversely, exogenous expression of eEF2K or knocking down eEF2 (the substrate of eEF2K) accelerates wound healing and invasion. Importantly, using LC-HDMSE analysis, we identify 150 proteins whose expression is decreased and 73 proteins which are increased upon knocking down eEF2K in human lung carcinoma cells. Of interest, 34 downregulated proteins are integrins and other proteins implicated in cell migration, suggesting that inhibiting eEF2K may help prevent cancer cell mobility and metastasis. Interestingly, eEF2K promotes the association of integrin mRNAs with polysomes, providing a mechanism by which eEF2K may enhance their cellular levels. Consistent with this, genetic knock down or pharmacological inhibition of eEF2K reduces the protein expression levels of integrins. Notably, pharmacological or genetic inhibition of eEF2K almost completely blocked tumor growth and effectively prevented the spread of tumor cells in vivo. High levels of eEF2K expression were associated with invasive carcinoma and metastatic tumors. These data provide the evidence that eEF2K is a new potential therapeutic target for preventing tumor metastasis.
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Affiliation(s)
- Jianling Xie
- Nutrition & Metabolism, South Australian Health & Medical Research Institute, Adelaide, Australia.,Centre for Biological Sciences, University of Southampton, Southampton, United Kingdom
| | - Kaikai Shen
- School of Basic Medical Sciences, Shanghai University of Traditional Chinese Medicine, Shanghai, China
| | - Roman V Lenchine
- Nutrition & Metabolism, South Australian Health & Medical Research Institute, Adelaide, Australia
| | - Lee A Gethings
- Waters Corporation, Stamford Avenue, Altrincham Road, Wilmslow, United Kingdom
| | - Paul J Trim
- Hopwood Centre for Neurobiology, South Australian Health & Medical Research Institute, Adelaide, Australia
| | - Marten F Snel
- Hopwood Centre for Neurobiology, South Australian Health & Medical Research Institute, Adelaide, Australia
| | - Ying Zhou
- School of Basic Medical Sciences, Shanghai University of Traditional Chinese Medicine, Shanghai, China
| | - Justin W Kenney
- Program in Neurosciences and Mental Health, the Hospital for Sick Children, Toronto, Canada
| | - Makoto Kamei
- Hopwood Centre for Neurobiology, South Australian Health & Medical Research Institute, Adelaide, Australia
| | - Marina Kochetkova
- Centre for Cancer Biology, SA Pathology and the University of South Australia, Adelaide, Australia
| | - Xuemin Wang
- Nutrition & Metabolism, South Australian Health & Medical Research Institute, Adelaide, Australia.,Centre for Biological Sciences, University of Southampton, Southampton, United Kingdom.,School of Biological Sciences, University of Adelaide, Adelaide, Australia
| | - Christopher G Proud
- Nutrition & Metabolism, South Australian Health & Medical Research Institute, Adelaide, Australia.,Centre for Biological Sciences, University of Southampton, Southampton, United Kingdom.,Hopwood Centre for Neurobiology, South Australian Health & Medical Research Institute, Adelaide, Australia.,School of Biological Sciences, University of Adelaide, Adelaide, Australia
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30
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Biever A, Boubaker-Vitre J, Cutando L, Gracia-Rubio I, Costa-Mattioli M, Puighermanal E, Valjent E. Repeated Exposure to D-Amphetamine Decreases Global Protein Synthesis and Regulates the Translation of a Subset of mRNAs in the Striatum. Front Mol Neurosci 2017; 9:165. [PMID: 28119566 PMCID: PMC5223439 DOI: 10.3389/fnmol.2016.00165] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2016] [Accepted: 12/20/2016] [Indexed: 01/21/2023] Open
Abstract
Repeated psychostimulant exposure induces persistent gene expression modifications that contribute to enduring changes in striatal GABAergic spiny projecting neurons (SPNs). However, it remains unclear whether changes in the control of mRNA translation are required for the establishment of these durable modifications. Here we report that repeated exposure to D-amphetamine decreases global striatal mRNA translation. This effect is paralleled by an enhanced phosphorylation of the translation factors, eIF2α and eEF2, and by the concomitant increased translation of a subset of mRNAs, among which the mRNA encoding for the activity regulated cytoskeleton-associated protein, also known as activity regulated gene 3.1 (Arc/Arg3.1). The enrichment of Arc/Arg3.1 mRNA in the polysomal fraction is accompanied by a robust increase of Arc/Arg3.1 protein levels within the striatum. Immunofluorescence analysis revealed that this increase occurred preferentially in D1R-expressing SPNs localized in striosome compartments. Our results suggest that the decreased global protein synthesis following repeated exposure to D-amphetamine favors the translation of a specific subset of mRNAs in the striatum.
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Affiliation(s)
- Anne Biever
- Centre National de la Recherche Scientifique (CNRS), UMR-5203, Institut de Génomique FonctionnelleMontpellier, France; Institut National de la Santé et de la Recherche Médicale (INSERM), U1191Montpellier, France; Université de Montpellier, UMR-5203Montpellier, France
| | - Jihane Boubaker-Vitre
- Centre National de la Recherche Scientifique (CNRS), UMR-5203, Institut de Génomique FonctionnelleMontpellier, France; Institut National de la Santé et de la Recherche Médicale (INSERM), U1191Montpellier, France; Université de Montpellier, UMR-5203Montpellier, France
| | - Laura Cutando
- Centre National de la Recherche Scientifique (CNRS), UMR-5203, Institut de Génomique FonctionnelleMontpellier, France; Institut National de la Santé et de la Recherche Médicale (INSERM), U1191Montpellier, France; Université de Montpellier, UMR-5203Montpellier, France
| | - Irene Gracia-Rubio
- Centre National de la Recherche Scientifique (CNRS), UMR-5203, Institut de Génomique FonctionnelleMontpellier, France; Institut National de la Santé et de la Recherche Médicale (INSERM), U1191Montpellier, France; Université de Montpellier, UMR-5203Montpellier, France
| | - Mauro Costa-Mattioli
- Department of Neuroscience, Memory and Brain Research Center, Baylor College of Medicine, Houston TX, USA
| | - Emma Puighermanal
- Centre National de la Recherche Scientifique (CNRS), UMR-5203, Institut de Génomique FonctionnelleMontpellier, France; Institut National de la Santé et de la Recherche Médicale (INSERM), U1191Montpellier, France; Université de Montpellier, UMR-5203Montpellier, France
| | - Emmanuel Valjent
- Centre National de la Recherche Scientifique (CNRS), UMR-5203, Institut de Génomique FonctionnelleMontpellier, France; Institut National de la Santé et de la Recherche Médicale (INSERM), U1191Montpellier, France; Université de Montpellier, UMR-5203Montpellier, France
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31
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Dynamics of elongation factor 2 kinase regulation in cortical neurons in response to synaptic activity. J Neurosci 2015; 35:3034-47. [PMID: 25698741 DOI: 10.1523/jneurosci.2866-14.2015] [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] [Indexed: 12/25/2022] Open
Abstract
The rapid regulation of cell signaling in response to calcium in neurons is essential for real-time processing of large amounts of information in the brain. A vital regulatory component, and one of the most energy-intensive biochemical processes in cells, is the elongation phase of mRNA translation, which is controlled by the Ca(2+)/CaM-dependent elongation factor 2 kinase (eEF2K). However, little is known about the dynamics of eEF2K regulation in neurons despite its established role in learning and synaptic plasticity. To explore eEF2K dynamics in depth, we stimulated synaptic activity in mouse primary cortical neurons. We find that synaptic activity results in a rapid, but transient, increase in eEF2K activity that is regulated by a combination of AMPA and NMDA-type glutamate receptors and the mitogen-activated protein kinase (MEK)/extracellular signal-regulated kinase (ERK) and mammalian target of rapamycin complex 1 (mTORC1) pathways. We then used computational modeling to test the hypothesis that considering Ca(2+)-coordinated MEK/ERK, mTORC1, and eEF2k activation is sufficient to describe the observed eEF2K dynamics. Although such a model could partially fit the empirical findings, it also suggested that a crucial positive regulator of eEF2K was also necessary. Through additional modeling and empirical evidence, we demonstrate that AMP kinase (AMPK) is also an important regulator of synaptic activity-driven eEF2K dynamics in neurons. Our combined modeling and experimental findings provide the first evidence that it is necessary to consider the combined interactions of Ca(2+) with MEK/ERK, mTORC1, and AMPK to adequately explain eEF2K regulation in neurons.
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32
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Eukaryotic elongation factor 2 kinase regulates the cold stress response by slowing translation elongation. Biochem J 2015; 465:227-38. [PMID: 25353634 DOI: 10.1042/bj20141014] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Cells respond to external stress conditions by controlling gene expression, a process which occurs rapidly via post-transcriptional regulation at the level of protein synthesis. Global control of translation is mediated by modification of translation factors to allow reprogramming of the translatome and synthesis of specific proteins that are required for stress protection or initiation of apoptosis. In the present study, we have investigated how global protein synthesis rates are regulated upon mild cooling. We demonstrate that although there are changes to the factors that control initiation, including phosphorylation of eukaryotic translation initiation factor 2 (eIF2) on the α-subunit, the reduction in the global translation rate is mediated by regulation of elongation via phosphorylation of eukaryotic elongation factor 2 (eEF2) by its specific kinase, eEF2K (eukaryotic elongation factor 2 kinase). The AMP/ATP ratio increases following cooling, consistent with a reduction in metabolic rates, giving rise to activation of AMPK (5'-AMP-activated protein kinase), which is upstream of eEF2K. However, our data show that the major trigger for activation of eEF2K upon mild cooling is the release of Ca2+ ions from the endoplasmic reticulum (ER) and, importantly, that it is possible to restore protein synthesis rates in cooled cells by inhibition of this pathway at multiple points. As cooling has both therapeutic and industrial applications, our data provide important new insights into how the cellular responses to this stress are regulated, opening up new possibilities to modulate these responses for medical or industrial use at physiological or cooler temperatures.
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33
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Usui T, Nijima R, Sakatsume T, Otani K, Kameshima S, Okada M, Yamawaki H. Eukaryotic elongation factor 2 kinase controls proliferation and migration of vascular smooth muscle cells. Acta Physiol (Oxf) 2015; 213:472-80. [PMID: 25069823 DOI: 10.1111/apha.12354] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2014] [Revised: 07/14/2014] [Accepted: 07/17/2014] [Indexed: 11/27/2022]
Abstract
AIM Eukaryotic elongation factor 2 kinase (eEF2K), also known as calmodulin (CaM)-dependent protein kinase (CaMK) III, is a unique member of CaMK family protein. We have recently found that expression of eEF2K protein increased in mesenteric artery from spontaneously hypertensive rats. As pathogenesis of hypertension is in part regulated by vascular structural remodelling via proliferation and migration of vascular smooth muscle cells (SMCs), we tested the hypothesis that eEF2K controls SMCs proliferation and migration. METHODSAND RESULTS In rat mesenteric arterial SMCs, an eEF2K inhibitor, A-484954 (10 μm), significantly inhibited platelet-derived growth factor (PDGF)-BB (10 ng mL(-1) )-induced SMCs proliferation as determined by a cell counting and bromodeoxyuridine incorporation assay. PDGF-BB (10 ng mL(-1) )-induced SMCs migration was significantly inhibited by A-484954 (10 μm) as determined by a Boyden chamber assay. A-484954 (10 μm) significantly inhibited PDGF-BB (10 ng mL(-1) )-induced phosphorylation of eEF2K, extracellular signal-regulated kinase (ERK), Akt, p38 and heat-shock protein (HSP) 27 as determined by Western blotting. It was confirmed that a CaM inhibitor, W-7 (50 μm), inhibited PDGF-BB (10 ng mL(-1) )-induced phosphorylation of eEF2K. In an ex vivo mesenteric arterial ring assay, 10% foetal bovine serum-induced SMCs outgrowth was significantly inhibited by A-484954 (10 μm). CONCLUSION We for the first time revealed that eEF2K mediates PDGF-BB-induced SMCs proliferation and migration through activating ERK, Akt, p38 and HSP27 signals in a CaM-dependent manner. Our results suggest eEF2K as a novel pharmaceutical target for the prevention of hypertensive cardiovascular diseases.
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Affiliation(s)
- T. Usui
- Laboratory of Veterinary Pharmacology; School of Veterinary Medicine; Kitasato University; Towada Aomori Japan
| | - R. Nijima
- Laboratory of Veterinary Pharmacology; School of Veterinary Medicine; Kitasato University; Towada Aomori Japan
| | - T. Sakatsume
- Laboratory of Veterinary Pharmacology; School of Veterinary Medicine; Kitasato University; Towada Aomori Japan
| | - K. Otani
- Laboratory of Veterinary Pharmacology; School of Veterinary Medicine; Kitasato University; Towada Aomori Japan
| | - S. Kameshima
- Laboratory of Veterinary Pharmacology; School of Veterinary Medicine; Kitasato University; Towada Aomori Japan
| | - M. Okada
- Laboratory of Veterinary Pharmacology; School of Veterinary Medicine; Kitasato University; Towada Aomori Japan
| | - H. Yamawaki
- Laboratory of Veterinary Pharmacology; School of Veterinary Medicine; Kitasato University; Towada Aomori Japan
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Leprivier G, Sorensen PH. How does oncogene transformation render tumor cells hypersensitive to nutrient deprivation? Bioessays 2014; 36:1082-90. [PMID: 25244326 DOI: 10.1002/bies.201400085] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Oncogene activation leads to cellular transformation by deregulation of biological processes such as proliferation and metabolism. Paradoxically, this can also sensitize cells to nutrient deprivation, potentially representing an Achilles' heel in early stage tumors. The mechanisms underlying this phenotype include loss of energetic and redox homeostasis as a result of metabolic reprogramming, favoring synthesis of macromolecules. Moreover, an emerging mechanism involving the deregulation of mRNA translation elongation through inhibition of eukaryotic elongation factor 2 kinase (eEF2K) is presented. The potential consequences of eEF2K deregulation leading to cell death under nutrient depletion are discussed. Finally, the relevance of eEF2K as a master regulator of the response to nutrient deprivation in vivo, and its potential exploitation for therapeutic targeting of cancers, are elaborated. Overall, a better understanding of the adaptive mechanisms allowing tumors to circumvent oncogene-induced hypersensitivity to nutrient deprivation is a promising avenue for uncovering novel therapeutic targets in cancers.
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Affiliation(s)
- Gabriel Leprivier
- Department of Molecular Oncology, British Columbia Cancer Research Centre, Vancouver, British Columbia, Canada; Department of Pathology, University of British Columbia, Vancouver, British Columbia, Canada
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35
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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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36
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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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37
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Yao Q, Liu BQ, Li H, McGarrigle D, Xing BW, Zhou MT, Wang Z, Zhang JJ, Huang XY, Guo L. C-terminal Src kinase (Csk)-mediated phosphorylation of eukaryotic elongation factor 2 (eEF2) promotes proteolytic cleavage and nuclear translocation of eEF2. J Biol Chem 2014; 289:12666-78. [PMID: 24648518 DOI: 10.1074/jbc.m113.546481] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Protein-tyrosine kinase C-terminal Src kinase (Csk) was originally purified as a kinase for phosphorylating Src and other Src family kinases. The phosphorylation of a C-terminal tyrosine residue of Src family kinases suppresses their kinase activity. Therefore, most physiological studies regarding Csk function have been focused on Csk as a negative regulator of Src family tyrosine kinases and as a potential tumor suppressor. Paradoxically, the protein levels of Csk were elevated in some human carcinomas. In this report, we show that eukaryotic elongation factor 2 (eEF2) is a new protein substrate of Csk and could locate in the nucleus. We demonstrate that Csk-mediated phosphorylation of eEF2 has no effect on its cytoplasmic function in regulating protein translation. However, phosphorylation of eEF2 enhances its proteolytic cleavage and the nuclear translocation of the cleaved eEF2 through a SUMOylation-regulated process. Furthermore, we show that cleaved fragments of eEF2 can induce nuclear morphological changes and aneuploidy similar to those in cancer cells, suggesting that there is an additional mechanism for Csk in tumorigenesis through regulation of eEF2 subcellular localization.
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Affiliation(s)
- Qi Yao
- From the State Key Laboratory of Virology, College of Life Sciences, Wuhan University, Wuhan 430072, China and
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38
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Phosphorylation of eukaryotic elongation factor 2 (eEF2) by cyclin A-cyclin-dependent kinase 2 regulates its inhibition by eEF2 kinase. Mol Cell Biol 2012. [PMID: 23184662 DOI: 10.1128/mcb.01270-12] [Citation(s) in RCA: 61] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Protein synthesis is highly regulated via both initiation and elongation. One mechanism that inhibits elongation is phosphorylation of eukaryotic elongation factor 2 (eEF2) on threonine 56 (T56) by eEF2 kinase (eEF2K). T56 phosphorylation inactivates eEF2 and is the only known normal eEF2 functional modification. In contrast, eEF2K undergoes extensive regulatory phosphorylations that allow diverse pathways to impact elongation. We describe a new mode of eEF2 regulation and show that its phosphorylation by cyclin A-cyclin-dependent kinase 2 (CDK2) on a novel site, serine 595 (S595), directly regulates T56 phosphorylation by eEF2K. S595 phosphorylation varies during the cell cycle and is required for efficient T56 phosphorylation in vivo. Importantly, S595 phosphorylation by cyclin A-CDK2 directly stimulates eEF2 T56 phosphorylation by eEF2K in vitro, and we suggest that S595 phosphorylation facilitates T56 phosphorylation by recruiting eEF2K to eEF2. S595 phosphorylation is thus the first known eEF2 modification that regulates its inhibition by eEF2K and provides a novel mechanism linking the cell cycle machinery to translational control. Because all known eEF2 regulation is exerted via eEF2K, S595 phosphorylation may globally couple the cell cycle machinery to regulatory pathways that impact eEF2K activity.
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39
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Abstract
mRNA translation is the most energy consuming process in the cell. In addition, it plays a pivotal role in the control of gene expression and is therefore tightly regulated. In response to various extracellular stimuli and intracellular cues, signaling pathways induce quantitative and qualitative changes in mRNA translation by modulating the phosphorylation status and thus the activity of components of the translational machinery. In this work we focus on the phosphoinositide 3-kinase (PI3K)/AKT and the mitogen-activated protein kinase (MAPK) pathways, as they are strongly implicated in the regulation of translation in homeostasis, whereas their malfunction has been linked to aberrant translation in human diseases, including cancer.
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Affiliation(s)
- Philippe P Roux
- Institute for Research in Immunology and Cancer, Université de Montréal, Québec, Canada.
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40
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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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Kruiswijk F, Yuniati L, Magliozzi R, Low TY, Lim R, Bolder R, Mohammed S, Proud CG, Heck AJR, Pagano M, Guardavaccaro D. Coupled activation and degradation of eEF2K regulates protein synthesis in response to genotoxic stress. Sci Signal 2012; 5:ra40. [PMID: 22669845 PMCID: PMC3812825 DOI: 10.1126/scisignal.2002718] [Citation(s) in RCA: 71] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
The kinase eEF2K [eukaryotic elongation factor 2 (eEF2) kinase] controls the rate of peptide chain elongation by phosphorylating eEF2, the protein that mediates the movement of the ribosome along the mRNA by promoting translocation of the transfer RNA from the A to the P site in the ribosome. eEF2K-mediated phosphorylation of eEF2 on threonine 56 (Thr⁵⁶) decreases its affinity for the ribosome, thereby inhibiting elongation. Here, we show that in response to genotoxic stress, eEF2K was activated by AMPK (adenosine monophosphate-activated protein kinase)-mediated phosphorylation on serine 398. Activated eEF2K phosphorylated eEF2 and induced a temporary ribosomal slowdown at the stage of elongation. Subsequently, during DNA damage checkpoint silencing, a process required to allow cell cycle reentry, eEF2K was degraded by the ubiquitin-proteasome system through the ubiquitin ligase SCF(βTrCP) (Skp1-Cul1-F-box protein, β-transducin repeat-containing protein) to enable rapid resumption of translation elongation. This event required autophosphorylation of eEF2K on a canonical βTrCP-binding domain. The inability to degrade eEF2K during checkpoint silencing caused sustained phosphorylation of eEF2 on Thr⁵⁶ and delayed the resumption of translation elongation. Our study therefore establishes a link between DNA damage signaling and translation elongation.
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Affiliation(s)
- Flore Kruiswijk
- Hubrecht Institute-KNAW and University Medical Center Utrecht, Uppsalalaan 8, 3584 CT Utrecht, The Netherlands
| | - Laurensia Yuniati
- Hubrecht Institute-KNAW and University Medical Center Utrecht, Uppsalalaan 8, 3584 CT Utrecht, The Netherlands
| | - Roberto Magliozzi
- Hubrecht Institute-KNAW and University Medical Center Utrecht, Uppsalalaan 8, 3584 CT Utrecht, The Netherlands
| | - Teck Yew Low
- Biomolecular Mass Spectrometry and Proteomics Group, Bijvoet Center for Biomolecular Research and Utrecht Institute for Pharmaceutical Sciences, Utrecht University, Padualaan 8, 3584 CH Utrecht, The Netherlands
- The Netherlands Proteomics Center, Padualaan 8, 3584 CH Utrecht, The Netherlands
| | - Ratna Lim
- Hubrecht Institute-KNAW and University Medical Center Utrecht, Uppsalalaan 8, 3584 CT Utrecht, The Netherlands
| | - Renske Bolder
- Hubrecht Institute-KNAW and University Medical Center Utrecht, Uppsalalaan 8, 3584 CT Utrecht, The Netherlands
| | - Shabaz Mohammed
- Biomolecular Mass Spectrometry and Proteomics Group, Bijvoet Center for Biomolecular Research and Utrecht Institute for Pharmaceutical Sciences, Utrecht University, Padualaan 8, 3584 CH Utrecht, The Netherlands
- The Netherlands Proteomics Center, Padualaan 8, 3584 CH Utrecht, The Netherlands
| | - Christopher G. Proud
- School of Biological Sciences, School of Biological Sciences, Life Sciences Building, University of Southampton, Southampton SO17 1BJ, UK
| | - Albert J. R. Heck
- Biomolecular Mass Spectrometry and Proteomics Group, Bijvoet Center for Biomolecular Research and Utrecht Institute for Pharmaceutical Sciences, Utrecht University, Padualaan 8, 3584 CH Utrecht, The Netherlands
- The Netherlands Proteomics Center, Padualaan 8, 3584 CH Utrecht, The Netherlands
| | - Michele Pagano
- Department of Pathology, NYU Cancer Institute, New York University School of Medicine, 522 First Avenue, SRB1107, New York, NY 10016, USA
- Howard Hughes Medical Institute
| | - Daniele Guardavaccaro
- Hubrecht Institute-KNAW and University Medical Center Utrecht, Uppsalalaan 8, 3584 CT Utrecht, The Netherlands
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Middelbeek J, Clark K, Venselaar H, Huynen MA, van Leeuwen FN. The alpha-kinase family: an exceptional branch on the protein kinase tree. Cell Mol Life Sci 2010; 67:875-90. [PMID: 20012461 PMCID: PMC2827801 DOI: 10.1007/s00018-009-0215-z] [Citation(s) in RCA: 84] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2009] [Revised: 10/27/2009] [Accepted: 11/10/2009] [Indexed: 01/19/2023]
Abstract
The alpha-kinase family represents a class of atypical protein kinases that display little sequence similarity to conventional protein kinases. Early studies on myosin heavy chain kinases in Dictyostelium discoideum revealed their unusual propensity to phosphorylate serine and threonine residues in the context of an alpha-helix. Although recent studies show that some members of this family can also phosphorylate residues in non-helical regions, the name alpha-kinase has remained. During evolution, the alpha-kinase domains combined with many different functional subdomains such as von Willebrand factor-like motifs (vWKa) and even cation channels (TRPM6 and TRPM7). As a result, these kinases are implicated in a large variety of cellular processes such as protein translation, Mg(2+) homeostasis, intracellular transport, cell migration, adhesion, and proliferation. Here, we review the current state of knowledge on different members of this kinase family and discuss the potential use of alpha-kinases as drug targets in diseases such as cancer.
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Affiliation(s)
- Jeroen Middelbeek
- Laboratory of Pediatric Oncology, Nijmegen Centre for Molecular Life Sciences, Radboud University Nijmegen Medical Centre, PO Box 9101, 6500 HB Nijmegen, The Netherlands
| | - Kristopher Clark
- MRC Protein Phosphorylation Unit, Sir James Black Centre, College of Life Sciences, University of Dundee, Dundee, DD1 5EH Scotland UK
| | - Hanka Venselaar
- Centre for Molecular and Biomolecular Informatics, Nijmegen Centre for Molecular Life Sciences, Radboud University Nijmegen Medical Centre, PO Box 9101, 6500 HB Nijmegen, The Netherlands
| | - Martijn A. Huynen
- Centre for Molecular and Biomolecular Informatics, Nijmegen Centre for Molecular Life Sciences, Radboud University Nijmegen Medical Centre, PO Box 9101, 6500 HB Nijmegen, The Netherlands
| | - Frank N. van Leeuwen
- Laboratory of Pediatric Oncology, Nijmegen Centre for Molecular Life Sciences, Radboud University Nijmegen Medical Centre, PO Box 9101, 6500 HB Nijmegen, The Netherlands
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Chen JH, Riazy M, Smith EM, Proud CG, Steinbrecher UP, Duronio V. Oxidized LDL-Mediated Macrophage Survival Involves Elongation Factor-2 Kinase. Arterioscler Thromb Vasc Biol 2009; 29:92-8. [DOI: 10.1161/atvbaha.108.174599] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Affiliation(s)
- Johnny H. Chen
- From the Department of Medicine (J.H.C., M.R., U.P.S., V.D.), University of British Columbia, and Vancouver Coastal Health Research Institute, Vancouver, BC, Canada; Genome Damage and Stability Centre (E.M.S.), University of Sussex, Falmer, Brighton, UK; and the School of Biological Sciences (C.G.P.), University of Southampton, UK
| | - Maziar Riazy
- From the Department of Medicine (J.H.C., M.R., U.P.S., V.D.), University of British Columbia, and Vancouver Coastal Health Research Institute, Vancouver, BC, Canada; Genome Damage and Stability Centre (E.M.S.), University of Sussex, Falmer, Brighton, UK; and the School of Biological Sciences (C.G.P.), University of Southampton, UK
| | - Ewan M. Smith
- From the Department of Medicine (J.H.C., M.R., U.P.S., V.D.), University of British Columbia, and Vancouver Coastal Health Research Institute, Vancouver, BC, Canada; Genome Damage and Stability Centre (E.M.S.), University of Sussex, Falmer, Brighton, UK; and the School of Biological Sciences (C.G.P.), University of Southampton, UK
| | - Christopher G. Proud
- From the Department of Medicine (J.H.C., M.R., U.P.S., V.D.), University of British Columbia, and Vancouver Coastal Health Research Institute, Vancouver, BC, Canada; Genome Damage and Stability Centre (E.M.S.), University of Sussex, Falmer, Brighton, UK; and the School of Biological Sciences (C.G.P.), University of Southampton, UK
| | - Urs P. Steinbrecher
- From the Department of Medicine (J.H.C., M.R., U.P.S., V.D.), University of British Columbia, and Vancouver Coastal Health Research Institute, Vancouver, BC, Canada; Genome Damage and Stability Centre (E.M.S.), University of Sussex, Falmer, Brighton, UK; and the School of Biological Sciences (C.G.P.), University of Southampton, UK
| | - Vincent Duronio
- From the Department of Medicine (J.H.C., M.R., U.P.S., V.D.), University of British Columbia, and Vancouver Coastal Health Research Institute, Vancouver, BC, Canada; Genome Damage and Stability Centre (E.M.S.), University of Sussex, Falmer, Brighton, UK; and the School of Biological Sciences (C.G.P.), University of Southampton, UK
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Hong-Brown LQ, Brown CR, Huber DS, Lang CH. Lopinavir impairs protein synthesis and induces eEF2 phosphorylation via the activation of AMP-activated protein kinase. J Cell Biochem 2008; 105:814-23. [PMID: 18712774 DOI: 10.1002/jcb.21882] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
HIV anti-retroviral drugs decrease protein synthesis, although the underlying regulatory mechanisms of this process are not fully established. Therefore, we investigated the effects of the HIV protease inhibitor lopinavir (LPV) on protein metabolism. We also characterized the mechanisms that mediate the effects of this drug on elongation factor-2 (eEF2), a key component of the translational machinery. Treatment of C2C12 myocytes with LPV produced a dose-dependent inhibitory effect on protein synthesis. This effect was observed at 15 min and was maintained for at least 4 h. Mechanistically, LPV increased the phosphorylation of eEF2 and thereby decreased the activity of this protein. Increased phosphorylation of eEF2 was associated with increased activity of its upstream regulators AMP-activated protein kinase (AMPK) and eEF2 kinase (eEF2K). Both AMPK and eEF2K directly phosphorylated eEF2 in an in vitro kinase assay suggesting two distinct paths lead to eEF2 phosphorylation. To verify this connection, myocytes were treated with the AMPK inhibitor compound C. Compound C blocked eEF2K and eEF2 phosphorylation, demonstrating that LPV affects eEF2 activity via an AMPK-eEF2K dependent pathway. In contrast, incubation of myocytes with rottlerin suppressed eEF2K, but not eEF2 phosphorylation, suggesting that eEF2 can be regulated independent of eEF2K. Finally, LPV did not affect PP2A activity when either eEF2 or peptide was used as the substrate. Collectively, these results indicate that LPV decreases protein synthesis, at least in part, via inhibition of eEF2. This appears regulated by AMPK which can act directly on eEF2 or indirectly via the action of eEF2K.
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Affiliation(s)
- Ly Q Hong-Brown
- Department of Cellular and Molecular Physiology, Penn State University, College of Medicine, Hershey, Pennsylvania 17033, USA.
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Yung HW, Calabrese S, Hynx D, Hemmings BA, Cetin I, Charnock-Jones DS, Burton GJ. Evidence of placental translation inhibition and endoplasmic reticulum stress in the etiology of human intrauterine growth restriction. THE AMERICAN JOURNAL OF PATHOLOGY 2008; 173:451-62. [PMID: 18583310 DOI: 10.2353/ajpath.2008.071193] [Citation(s) in RCA: 283] [Impact Index Per Article: 17.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Unexplained intrauterine growth restriction of the fetus (IUGR) results from impaired placental development, frequently associated with maternal malperfusion. Some cases are complicated further by preeclampsia (PE+IUGR). Here, we provide the first evidence that placental protein synthesis inhibition and endoplasmic reticulum (ER) stress play key roles in IUGR pathophysiology. Increased phosphorylation of eukaryotic initiation factor 2alpha suggests suppression of translation initiation in IUGR placentas, with a further increase in PE+IUGR cases. Consequently, AKT levels were reduced at the protein, but not mRNA, level. Additionally, levels of other proteins in the AKT-mammalian target of rapamycin pathway were decreased, and there was associated dephosphorylation of 4E-binding protein 1 and activation of glycogen synthase kinase 3beta. Cyclin D1 and the eukaryotic initiation factor 2B epsilon subunit were also down-regulated, providing additional evidence for this placental phenotype. The central role of AKT signaling in placental growth regulation was confirmed in Akt1 null mice, which display IUGR. In addition, we demonstrated ultrastructural and molecular evidence of ER stress in human IUGR and PE+IUGR placentas, providing a potential mechanism for eukaryotic initiation factor 2alpha phosphorylation. In confirmation, induction of low-grade ER stress in trophoblast-like cell lines reduced cellular proliferation. PE+IUGR placentas showed elevated ER stress with the additional expression of the pro-apoptotic protein C/EBP-homologous protein/growth arrest and DNA damage 153. These findings may account for the increased microparticulate placental debris in the maternal circulation of these cases, leading to endothelial cell activation and impairing placental development.
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Affiliation(s)
- Hong-wa Yung
- Department of Physiology, Development and Neuroscience, University of Cambridge, Cambridge CB2 3EG, UK
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Determinants for substrate phosphorylation by Dictyostelium myosin II heavy chain kinases A and B and eukaryotic elongation factor-2 kinase. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2008; 1784:908-15. [DOI: 10.1016/j.bbapap.2008.03.001] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/16/2007] [Revised: 01/28/2008] [Accepted: 03/04/2008] [Indexed: 11/23/2022]
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Bartish G, Nygård O. Importance of individual amino acids in the Switch I region in eEF2 studied by functional complementation in S. cerevisiae. Biochimie 2008; 90:736-48. [DOI: 10.1016/j.biochi.2008.01.006] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2007] [Accepted: 01/17/2008] [Indexed: 10/22/2022]
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Sugimoto I, Li Z, Sakamoto Y, Ito S, Hashimoto E. Mass-spectrometric identification of proteins detected in forskolin-stimulated Xenopus laevis oocytes using antibody against phospho-(Ser/Thr) cAMP-dependent protein kinase substrate. ACTA ACUST UNITED AC 2008; 28:231-8. [PMID: 18000335 DOI: 10.2220/biomedres.28.231] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
In order to study the phosphorylated proteins in the resting Xenopus laevis oocytes, the proteins detected by Western blotting using phospho-(Ser/Thr) PKA substrate antibody (PKA substrate antibody) in forskolin-stimulated oocytes were purified and identified by mass spectrometry. Several proteins (ribosomal S6 protein, elongation factor-2 (EF-2), poly A binding protein, releasing factor 1) were identified, and the phosphorylation of EF-2 was further studied. Partially purified Xenopus EF-2 (xEF-2) was phosphorylated by PKA in vitro and this phosphorylation was detected by Western blotting using PKA substrate antibody. The phosphorylation of Thr-57 in xEF-2 (corresponding to Thr-56 of the mammalian enzyme) was detected in the partially purified xEF-2 from the resting oocytes, but this xEF-2 did not react with the PKA substrate antibody. These results suggest that Thr-57 in xEF-2 was phosphorylated, but xEF-2 does not seem to be phosphorylated by PKA in resting oocytes although PKA can phosphorylate xEF-2 in vitro and probably in forskolin-treated oocytes.
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Affiliation(s)
- Isamu Sugimoto
- Division of Pathological Biochemistry, Department of Biomedical Sciences, School of Life Sciences, Faculty of Medicine, Tottori University, Nishi-cho, Yonago
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A pharmacoproteomic approach implicates eukaryotic elongation factor 2 kinase in ER stress-induced cell death. Cell Death Differ 2008; 15:589-99. [PMID: 18188169 DOI: 10.1038/sj.cdd.4402296] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
Apoptosis triggered by endoplasmic reticulum (ER) stress has been implicated in many diseases but its cellular regulation remains poorly understood. Previously, we identified salubrinal (sal), a small molecule that protects cells from ER stress-induced apoptosis by selectively activating a subset of endogenous ER stress-signaling events. Here, we use sal as a probe in a proteomic approach to discover new information about the endogenous cellular response to ER stress. We show that sal induces phosphorylation of the translation elongation factor eukaryotic translation elongation factor 2 (eEF-2), an event that depends on eEF-2 kinase (eEF-2K). ER stress itself also induces eEF-2K-dependent eEF-2 phosphorylation, and this pathway promotes translational arrest and cell death in this context, identifying eEF-2K as a hitherto unknown regulator of ER stress-induced apoptosis. Finally, we use both sal and ER stress models to show that eEF-2 phosphorylation can be activated by at least two signaling mechanisms. Our work identifies eEF-2K as a new component of the ER stress response and underlines the utility of novel small molecules in discovering new cell biology.
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Bartish G, Moradi H, Nygård O. Amino acids Thr56 and Thr58 are not essential for elongation factor 2 function in yeast. FEBS J 2007; 274:5285-97. [PMID: 17892487 DOI: 10.1111/j.1742-4658.2007.06054.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
Yeast elongation factor 2 is an essential protein that contains two highly conserved threonine residues, T56 and T58, that could potentially be phosphorylated by the Rck2 kinase in response to environmental stress. The importance of residues T56 and T58 for elongation factor 2 function in yeast was studied using site directed mutagenesis and functional complementation. Mutations T56D, T56G, T56K, T56N and T56V resulted in nonfunctional elongation factor 2 whereas mutated factor carrying point mutations T56M, T56C, T56S, T58S and T58V was functional. Expression of mutants T56C, T56S and T58S was associated with reduced growth rate. The double mutants T56M/T58W and T56M/T58V were also functional but the latter mutant caused increased cell death and considerably reduced growth rate. The results suggest that the physiological role of T56 and T58 as phosphorylation targets is of little importance in yeast under standard growth conditions. Yeast cells expressing mutants T56C and T56S were less able to cope with environmental stress induced by increased growth temperatures. Similarly, cells expressing mutants T56M and T56M/T58W were less capable of adapting to increased osmolarity whereas cells expressing mutant T58V behaved normally. All mutants tested were retained their ability to bind to ribosomes in vivo. However, mutants T56D, T56G and T56K were under-represented on the ribosome, suggesting that these nonfunctional forms of elongation factor 2 were less capable of competing with wild-type elongation factor 2 in ribosome binding. The presence of nonfunctional but ribosome binding forms of elongation factor 2 did not affect the growth rate of yeast cells also expressing wild-type elongation factor 2.
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Affiliation(s)
- Galyna Bartish
- School of Life Sciences, Södertörns högskola, Huddinge, Sweden
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