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Wagner PA, Song M, Ficner R, Kuhle B, Marintchev A. Molecular basis for the interactions of eIF2β with eIF5, eIF2B, and 5MP1 and their regulation by CK2. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.04.25.591181. [PMID: 38712236 PMCID: PMC11071521 DOI: 10.1101/2024.04.25.591181] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2024]
Abstract
The heterotrimeric GTPase eukaryotic translation initiation factor 2 (eIF2) delivers the initiator Met-tRNAi to the ribosomal translation preinitiation complex. eIF2β has three lysine-rich repeats (K-boxes) in its N-terminal tail, which are important for binding to the GTPase-activating protein (GAP) eIF5, the guanine nucleotide exchange factor (GEF) eIF2B, and the regulator eIF5-mimic protein (5MP). Here, we combine X-ray crystallography with NMR to understand the molecular basis and dynamics of these interactions. The crystal structure of yeast eIF5-CTD in complex with K-box 3 of eIF2β reveals an extended binding site on eIF2β, far beyond the K-box. We show that human eIF5, eIF2Bε, and 5MP1 can all bind to each of the three K-boxes, while reducing each other's affinities. Moreover, all these affinities are increased by CK2 phosphomimetic mutations. Our results reveal how eIF5, eIF2B, and 5MP displace each other from eIF2, and elucidate the role of CK2 in remodeling the translation apparatus.
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2
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Mao S, Xie C, Liu Y, Zhao Y, Li M, Gao H, Xiao Y, Zou Y, Zheng Z, Gao Y, Xie J, Tian B, Wang L, Hua Y, Xu H. Apurinic/apyrimidinic endodeoxyribonuclease 1 (APE1) promotes stress granule formation via YBX1 phosphorylation in ovarian cancer. Cell Mol Life Sci 2024; 81:113. [PMID: 38436697 PMCID: PMC10912283 DOI: 10.1007/s00018-023-05086-y] [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: 09/08/2023] [Revised: 11/30/2023] [Accepted: 12/12/2023] [Indexed: 03/05/2024]
Abstract
APE1 is an essential gene involved in DNA damage repair, the redox regulation of transcriptional factors (TFs) and RNA processing. APE1 overexpression is common in cancers and correlates with poor patient survival. Stress granules (SGs) are phase-separated cytoplasmic assemblies that cells form in response to environmental stresses. Precise regulation of SGs is pivotal to cell survival, whereas their dysregulation is increasingly linked to diseases. Whether APE1 engages in modulating SG dynamics is worthy of investigation. In this study, we demonstrate that APE1 colocalizes with SGs and promotes their formation. Through phosphoproteome profiling, we discover that APE1 significantly alters the phosphorylation landscape of ovarian cancer cells, particularly the phosphoprofile of SG proteins. Notably, APE1 promotes the phosphorylation of Y-Box binding protein 1 (YBX1) at S174 and S176, leading to enhanced SG formation and cell survival. Moreover, expression of the phosphomutant YBX1 S174/176E mimicking hyperphosphorylation in APE1-knockdown cells recovered the impaired SG formation. These findings shed light on the functional importance of APE1 in SG regulation and highlight the importance of YBX1 phosphorylation in SG dynamics.
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Affiliation(s)
- Shuyu Mao
- MOE Key Laboratory of Biosystems Homeostasis and Protection, Institute of Biophysics, College of Life Science, Zhejiang University, Hangzhou, China
| | - Chong Xie
- Institute for Cancer Research, Shenzhen Bay Laboratory, Shenzhen, 518107, China
- Department of Cancer Center, Daping Hospital, Army Medical University, Chongqing, China
| | - Yufeng Liu
- MOE Key Laboratory of Biosystems Homeostasis and Protection, Institute of Biophysics, College of Life Science, Zhejiang University, Hangzhou, China
| | - Ye Zhao
- MOE Key Laboratory of Biosystems Homeostasis and Protection, Institute of Biophysics, College of Life Science, Zhejiang University, Hangzhou, China
| | - Mengxia Li
- The Cancer Hospital of the University of Chinese Academy of Sciences (Zhejiang Cancer Hospital), Institute of Basic Medicine and Cancer (IBMC), Chinses Academy of Sciences, Hangzhou, China
| | - Han Gao
- The Cancer Hospital of the University of Chinese Academy of Sciences (Zhejiang Cancer Hospital), Institute of Basic Medicine and Cancer (IBMC), Chinses Academy of Sciences, Hangzhou, China
| | - Yue Xiao
- MOE Key Laboratory of Biosystems Homeostasis and Protection, Institute of Biophysics, College of Life Science, Zhejiang University, Hangzhou, China
| | - Yongkang Zou
- Department of Cancer Center, Daping Hospital, Army Medical University, Chongqing, China
| | - Zhiguo Zheng
- Institute of Pathology, University Medical Center Göttingen, Göttingen, Germany
| | - Ya Gao
- MOE Key Laboratory of Biosystems Homeostasis and Protection, Institute of Biophysics, College of Life Science, Zhejiang University, Hangzhou, China
| | - Juan Xie
- Department of Cancer Center, Daping Hospital, Army Medical University, Chongqing, China
| | - Bing Tian
- MOE Key Laboratory of Biosystems Homeostasis and Protection, Institute of Biophysics, College of Life Science, Zhejiang University, Hangzhou, China
| | - Liangyan Wang
- MOE Key Laboratory of Biosystems Homeostasis and Protection, Institute of Biophysics, College of Life Science, Zhejiang University, Hangzhou, China
| | - Yuejin Hua
- MOE Key Laboratory of Biosystems Homeostasis and Protection, Institute of Biophysics, College of Life Science, Zhejiang University, Hangzhou, China.
| | - Hong Xu
- MOE Key Laboratory of Biosystems Homeostasis and Protection, Institute of Biophysics, College of Life Science, Zhejiang University, Hangzhou, China.
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3
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Homma MK, Nakato R, Niida A, Bando M, Fujiki K, Yokota N, Yamamoto S, Shibata T, Takagi M, Yamaki J, Kozuka-Hata H, Oyama M, Shirahige K, Homma Y. Cell cycle-dependent gene networks for cell proliferation activated by nuclear CK2α complexes. Life Sci Alliance 2024; 7:e202302077. [PMID: 37907238 PMCID: PMC10618106 DOI: 10.26508/lsa.202302077] [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: 04/05/2023] [Revised: 10/09/2023] [Accepted: 10/10/2023] [Indexed: 11/02/2023] Open
Abstract
Nuclear expression of protein kinase CK2α is reportedly elevated in human carcinomas, but mechanisms underlying its variable localization in cells are poorly understood. This study demonstrates a functional connection between nuclear CK2 and gene expression in relation to cell proliferation. Growth stimulation of quiescent human normal fibroblasts and phospho-proteomic analysis identified a pool of CK2α that is highly phosphorylated at serine 7. Phosphorylated CK2α translocates into the nucleus, and this phosphorylation appears essential for nuclear localization and catalytic activity. Protein signatures associated with nuclear CK2 complexes reveal enrichment of apparently unique transcription factors and chromatin remodelers during progression through the G1 phase of the cell cycle. Chromatin immunoprecipitation-sequencing profiling demonstrated recruitment of CK2α to active gene loci, more abundantly in late G1 phase than in early G1, notably at transcriptional start sites of core histone genes, growth stimulus-associated genes, and ribosomal RNAs. Our findings reveal that nuclear CK2α complexes may be essential to facilitate progression of the cell cycle, by activating histone genes and triggering ribosomal biogenesis, specified in association with nuclear and nucleolar transcriptional regulators.
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Affiliation(s)
- Miwako Kato Homma
- Department of Biomolecular Sciences, Fukushima Medical University School of Medicine, Fukushima, Japan
| | - Ryuichiro Nakato
- Laboratory of Computational Genomics, Institute for Quantitative Biosciences, University of Tokyo, Bunkyo, Japan
| | - Atsushi Niida
- Human Genome Center, The Institute of Medical Science, The University of Tokyo, Minato, Japan
| | - Masashige Bando
- Institute for Quantitative Biosciences, The University of Tokyo, Bunkyo, Japan
| | - Katsunori Fujiki
- Institute for Quantitative Biosciences, The University of Tokyo, Bunkyo, Japan
| | - Naoko Yokota
- Laboratory of Computational Genomics, Institute for Quantitative Biosciences, University of Tokyo, Bunkyo, Japan
| | - So Yamamoto
- Department of Biomolecular Sciences, Fukushima Medical University School of Medicine, Fukushima, Japan
| | | | - Motoki Takagi
- Translational Research Center, Fukushima Medical University School of Medicine, Fukushima, Japan
| | - Junko Yamaki
- Department of Biomolecular Sciences, Fukushima Medical University School of Medicine, Fukushima, Japan
| | - Hiroko Kozuka-Hata
- Medical Proteomics Laboratory, The Institute of Medical Science, The University of Tokyo, Minato, Japan
| | - Masaaki Oyama
- Medical Proteomics Laboratory, The Institute of Medical Science, The University of Tokyo, Minato, Japan
| | - Katsuhiko Shirahige
- Institute for Quantitative Biosciences, The University of Tokyo, Bunkyo, Japan
- Department of Biosciences and Nutrition, Karolinska Institutet, Biomedicum, Stockholm, Sweden
- Department of Cell and Molecular Biology, Karolinska Institutet, Biomedicum, Stockholm, Sweden
| | - Yoshimi Homma
- Department of Biomolecular Sciences, Fukushima Medical University School of Medicine, Fukushima, Japan
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4
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Thus YJ, De Rooij MFM, Swier N, Beijersbergen RL, Guikema JEJ, Kersten MJ, Eldering E, Pals ST, Kater AP, Spaargaren M. Inhibition of casein kinase 2 sensitizes mantle cell lymphoma to venetoclax through MCL-1 downregulation. Haematologica 2023; 108:797-810. [PMID: 36226498 PMCID: PMC9973496 DOI: 10.3324/haematol.2022.281668] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2022] [Indexed: 11/09/2022] Open
Abstract
BCL-2 family proteins are frequently aberrantly expressed in mantle cell lymphoma (MCL). Recently, the BCL-2-specific inhibitor venetoclax has been approved by the US Food and Drug Administration for chronic lymphocytic leukemia (CLL) and acute myeloid leukemia (AML). In MCL, venetoclax has shown promising efficacy in early clinical trials; however, a significant subset of patients is resistant. By conducting a kinome-centered CRISPR-Cas9 knockout sensitizer screen, we identified casein kinase 2 (CK2) as a major regulator of venetoclax resistance in MCL. Interestingly, CK2 is over-expressed in MCL and high CK2 expression is associated with poor patient survival. Targeting of CK2, either by inducible short hairpin RNA (shRNA)-mediated knockdown of CK2 or by the CK2-inhibitor silmitasertib, did not affect cell viability by itself, but strongly synergized with venetoclax in both MCL cell lines and primary samples, also if combined with ibrutinib. Furthermore, targeting of CK2 reduced MCL-1 levels, which involved impaired MCL-1 translation by inhibition of eIF4F complex assembly, without affecting BCL-2 and BCL-XL expression. Combined, this results in enhanced BCL-2 dependence and, consequently, venetoclax sensitization. In cocultures, targeting of CK2 overcame stroma-mediated venetoclax resistance of MCL cells. Taken together, our findings indicate that targeting of CK2 sensitizes MCL cells to venetoclax through downregulation of MCL-1. These novel insights provide a strong rationale for combining venetoclax with CK2 inhibition as therapeutic strategy for MCL patients.
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Affiliation(s)
- Yvonne J Thus
- Department of Pathology, Amsterdam UMC location University of Amsterdam, Amsterdam, The Netherlands; Lymphoma and Myeloma Center Amsterdam (LYMMCARE), Amsterdam, The Netherlands; Cancer Center Amsterdam (CCA), Cancer Biology and Immunology - Target and Therapy Discovery, Amsterdam
| | - Martin F M De Rooij
- Department of Pathology, Amsterdam UMC location University of Amsterdam, Amsterdam, The Netherlands; Lymphoma and Myeloma Center Amsterdam (LYMMCARE), Amsterdam, The Netherlands; Cancer Center Amsterdam (CCA), Cancer Biology and Immunology - Target and Therapy Discovery, Amsterdam
| | - Nathalie Swier
- Department of Pathology, Amsterdam UMC location University of Amsterdam, Amsterdam, The Netherlands; Lymphoma and Myeloma Center Amsterdam (LYMMCARE), Amsterdam, The Netherlands; Cancer Center Amsterdam (CCA), Cancer Biology and Immunology - Target and Therapy Discovery, Amsterdam
| | - Roderick L Beijersbergen
- Division of Molecular Carcinogenesis, Oncode Institute, Netherlands Cancer Institute, Amsterdam, The Netherlands; The NKI Robotics and Screening Center, Netherlands Cancer Institute, Amsterdam
| | - Jeroen E J Guikema
- Department of Pathology, Amsterdam UMC location University of Amsterdam, Amsterdam, The Netherlands; Lymphoma and Myeloma Center Amsterdam (LYMMCARE), Amsterdam, The Netherlands; Cancer Center Amsterdam (CCA), Cancer Biology and Immunology - Target and Therapy Discovery, Amsterdam
| | - Marie-José Kersten
- Lymphoma and Myeloma Center Amsterdam (LYMMCARE), Amsterdam, The Netherlands; Department of Hematology, Amsterdam UMC location University of Amsterdam, Amsterdam
| | - Eric Eldering
- Lymphoma and Myeloma Center Amsterdam (LYMMCARE), Amsterdam, The Netherlands; Cancer Center Amsterdam (CCA), Cancer Biology and Immunology - Target and Therapy Discovery, Amsterdam, The Netherlands; Department of Experimental Immunology, Amsterdam UMC location University of Amsterdam, Amsterdam
| | - Steven T Pals
- Department of Pathology, Amsterdam UMC location University of Amsterdam, Amsterdam, The Netherlands; Lymphoma and Myeloma Center Amsterdam (LYMMCARE), Amsterdam, The Netherlands; Cancer Center Amsterdam (CCA), Cancer Biology and Immunology - Target and Therapy Discovery, Amsterdam
| | - Arnon P Kater
- Lymphoma and Myeloma Center Amsterdam (LYMMCARE), Amsterdam, The Netherlands; Cancer Center Amsterdam (CCA), Cancer Biology and Immunology - Target and Therapy Discovery, Amsterdam, The Netherlands; Department of Hematology, Amsterdam UMC location University of Amsterdam, Amsterdam
| | - Marcel Spaargaren
- Department of Pathology, Amsterdam UMC location University of Amsterdam, Amsterdam, The Netherlands; Lymphoma and Myeloma Center Amsterdam (LYMMCARE), Amsterdam, The Netherlands; Cancer Center Amsterdam (CCA), Cancer Biology and Immunology - Target and Therapy Discovery, Amsterdam.
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5
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Firnau MB, Brieger A. CK2 and the Hallmarks of Cancer. Biomedicines 2022; 10:1987. [PMID: 36009534 PMCID: PMC9405757 DOI: 10.3390/biomedicines10081987] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2022] [Revised: 08/08/2022] [Accepted: 08/10/2022] [Indexed: 11/29/2022] Open
Abstract
Cancer is a leading cause of death worldwide. Casein kinase 2 (CK2) is commonly dysregulated in cancer, impacting diverse molecular pathways. CK2 is a highly conserved serine/threonine kinase, constitutively active and ubiquitously expressed in eukaryotes. With over 500 known substrates and being estimated to be responsible for up to 10% of the human phosphoproteome, it is of significant importance. A broad spectrum of diverse types of cancer cells has been already shown to rely on disturbed CK2 levels for their survival. The hallmarks of cancer provide a rationale for understanding cancer's common traits. They constitute the maintenance of proliferative signaling, evasion of growth suppressors, resisting cell death, enabling of replicative immortality, induction of angiogenesis, the activation of invasion and metastasis, as well as avoidance of immune destruction and dysregulation of cellular energetics. In this work, we have compiled evidence from the literature suggesting that CK2 modulates all hallmarks of cancer, thereby promoting oncogenesis and operating as a cancer driver by creating a cellular environment favorable to neoplasia.
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Affiliation(s)
| | - Angela Brieger
- Department of Internal Medicine I, Biomedical Research Laboratory, University Hospital Frankfurt, Theodor-Stern-Kai 7, 60590 Frankfurt, Germany
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6
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Gyenis L, Menyhart D, Cruise ES, Jurcic K, Roffey SE, Chai DB, Trifoi F, Fess SR, Desormeaux PJ, Núñez de Villavicencio Díaz T, Rabalski AJ, Zukowski SA, Turowec JP, Pittock P, Lajoie G, Litchfield DW. Chemical Genetic Validation of CSNK2 Substrates Using an Inhibitor-Resistant Mutant in Combination with Triple SILAC Quantitative Phosphoproteomics. Front Mol Biosci 2022; 9:909711. [PMID: 35755813 PMCID: PMC9225150 DOI: 10.3389/fmolb.2022.909711] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2022] [Accepted: 05/02/2022] [Indexed: 11/16/2022] Open
Abstract
Casein Kinase 2 (CSNK2) is an extremely pleiotropic, ubiquitously expressed protein kinase involved in the regulation of numerous key biological processes. Mapping the CSNK2-dependent phosphoproteome is necessary for better characterization of its fundamental role in cellular signalling. While ATP-competitive inhibitors have enabled the identification of many putative kinase substrates, compounds targeting the highly conserved ATP-binding pocket often exhibit off-target effects limiting their utility for definitive kinase-substrate assignment. To overcome this limitation, we devised a strategy combining chemical genetics and quantitative phosphoproteomics to identify and validate CSNK2 substrates. We engineered U2OS cells expressing exogenous wild type CSNK2A1 (WT) or a triple mutant (TM, V66A/H160D/I174A) with substitutions at residues important for inhibitor binding. These cells were treated with CX-4945, a clinical-stage inhibitor of CSNK2, and analyzed using large-scale triple SILAC (Stable Isotope Labelling of Amino Acids in Cell Culture) quantitative phosphoproteomics. In contrast to wild-type CSNK2A1, CSNK2A1-TM retained activity in the presence of CX-4945 enabling identification and validation of several CSNK2 substrates on the basis of their increased phosphorylation in cells expressing CSNK2A1-TM. Based on high conservation within the kinase family, we expect that this strategy can be broadly adapted for identification of other kinase-substrate relationships.
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Affiliation(s)
- Laszlo Gyenis
- Department of Biochemistry, Schulich School of Medicine & Dentistry, Western University, London, ON, Canada
| | - Daniel Menyhart
- Department of Biochemistry, Schulich School of Medicine & Dentistry, Western University, London, ON, Canada
| | - Edward S Cruise
- Department of Biochemistry, Schulich School of Medicine & Dentistry, Western University, London, ON, Canada
| | - Kristina Jurcic
- Department of Biochemistry, Schulich School of Medicine & Dentistry, Western University, London, ON, Canada
| | - Scott E Roffey
- Department of Biochemistry, Schulich School of Medicine & Dentistry, Western University, London, ON, Canada
| | - Darren B Chai
- Department of Biochemistry, Schulich School of Medicine & Dentistry, Western University, London, ON, Canada
| | - Flaviu Trifoi
- Department of Biochemistry, Schulich School of Medicine & Dentistry, Western University, London, ON, Canada
| | - Sam R Fess
- Department of Biochemistry, Schulich School of Medicine & Dentistry, Western University, London, ON, Canada
| | - Paul J Desormeaux
- Department of Biochemistry, Schulich School of Medicine & Dentistry, Western University, London, ON, Canada
| | | | - Adam J Rabalski
- Department of Biochemistry, Schulich School of Medicine & Dentistry, Western University, London, ON, Canada
| | - Stephanie A Zukowski
- Department of Biochemistry, Schulich School of Medicine & Dentistry, Western University, London, ON, Canada
| | - Jacob P Turowec
- Department of Biochemistry, Schulich School of Medicine & Dentistry, Western University, London, ON, Canada
| | - Paula Pittock
- Department of Biochemistry, Schulich School of Medicine & Dentistry, Western University, London, ON, Canada
| | - Gilles Lajoie
- Department of Biochemistry, Schulich School of Medicine & Dentistry, Western University, London, ON, Canada
| | - David W Litchfield
- Department of Biochemistry, Schulich School of Medicine & Dentistry, Western University, London, ON, Canada.,Department of Oncology, Schulich School of Medicine & Dentistry, Western University, London, ON, Canada
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7
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Friedrich D, Marintchev A, Arthanari H. The metaphorical swiss army knife: The multitude and diverse roles of HEAT domains in eukaryotic translation initiation. Nucleic Acids Res 2022; 50:5424-5442. [PMID: 35552740 PMCID: PMC9177959 DOI: 10.1093/nar/gkac342] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2020] [Revised: 04/20/2022] [Accepted: 04/22/2022] [Indexed: 11/24/2022] Open
Abstract
Biomolecular associations forged by specific interaction among structural scaffolds are fundamental to the control and regulation of cell processes. One such structural architecture, characterized by HEAT repeats, is involved in a multitude of cellular processes, including intracellular transport, signaling, and protein synthesis. Here, we review the multitude and versatility of HEAT domains in the regulation of mRNA translation initiation. Structural and cellular biology approaches, as well as several biophysical studies, have revealed that a number of HEAT domain-mediated interactions with a host of protein factors and RNAs coordinate translation initiation. We describe the basic structural architecture of HEAT domains and briefly introduce examples of the cellular processes they dictate, including nuclear transport by importin and RNA degradation. We then focus on proteins in the translation initiation system featuring HEAT domains, specifically the HEAT domains of eIF4G, DAP5, eIF5, and eIF2Bϵ. Comparative analysis of their remarkably versatile interactions, including protein-protein and protein-RNA recognition, reveal the functional importance of flexible regions within these HEAT domains. Here we outline how HEAT domains orchestrate fundamental aspects of translation initiation and highlight open mechanistic questions in the area.
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Affiliation(s)
- Daniel Friedrich
- Department of Molecular and Cellular Biology, Harvard University, Cambridge, MA, USA
- Department of Cancer Biology, Dana-Farber Cancer Institute, Boston, MA, USA
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA, USA
| | - Assen Marintchev
- Department of Physiology & Biophysics, Boston University School of Medicine, Boston, MA, USA
| | - Haribabu Arthanari
- Department of Cancer Biology, Dana-Farber Cancer Institute, Boston, MA, USA
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA, USA
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8
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Paul EE, Lin KY, Gamble N, Tsai AWL, Swan SHK, Yang Y, Doran M, Marintchev A. Dynamic interaction network involving the conserved intrinsically disordered regions in human eIF5. Biophys Chem 2022; 281:106740. [PMID: 34923394 PMCID: PMC8741751 DOI: 10.1016/j.bpc.2021.106740] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2021] [Revised: 12/05/2021] [Accepted: 12/06/2021] [Indexed: 02/03/2023]
Abstract
Translation initiation in eukaryotes requires multiple eukaryotic translation initiation factors (eIFs) and involves continuous remodeling of the ribosomal preinitiation complex (PIC). The GTPase eIF2 brings the initiator Met-tRNAi to the PIC. Upon start codon selection and GTP hydrolysis, promoted by eIF5, eIF2-GDP is released in complex with eIF5. Here, we report that two intrinsically disordered regions (IDRs) in eIF5, the DWEAR motif and the C-terminal tail (CTT) dynamically contact the folded C-terminal domain (CTD) and compete with each other. The eIF5-CTD•CTT interaction favors eIF2β binding to eIF5-CTD, whereas the eIF5-CTD•DWEAR interaction favors eIF1A binding, which suggests how intramolecular contact rearrangement could play a role in PIC remodeling. We show that eIF5 phosphorylation by CK2, which is known to stimulate translation and cell proliferation, significantly increases the eIF5 affinity for eIF2. Our results also indicate that the eIF2β subunit has at least two, and likely three eIF5-binding sites.
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Affiliation(s)
- Eleanor Elise Paul
- Department of Physiology & Biophysics, Boston University School of Medicine, 700 Albany St. W336, Boston, MA 02118, USA
| | - Kay Ying Lin
- Department of Physiology & Biophysics, Boston University School of Medicine, 700 Albany St. W336, Boston, MA 02118, USA
| | - Nathan Gamble
- Department of Physiology & Biophysics, Boston University School of Medicine, 700 Albany St. W336, Boston, MA 02118, USA
| | - Amy Wei-Lun Tsai
- Department of Physiology & Biophysics, Boston University School of Medicine, 700 Albany St. W336, Boston, MA 02118, USA
| | - Simon H. K. Swan
- Department of Physiology & Biophysics, Boston University School of Medicine, 700 Albany St. W336, Boston, MA 02118, USA
| | - Yu Yang
- Department of Physiology & Biophysics, Boston University School of Medicine, 700 Albany St. W336, Boston, MA 02118, USA
| | - Matthew Doran
- Department of Physiology & Biophysics, Boston University School of Medicine, 700 Albany St. W336, Boston, MA 02118, USA
| | - Assen Marintchev
- Department of Physiology & Biophysics, Boston University School of Medicine, 700 Albany St. W336, Boston, MA 02118, USA
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9
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Gamble N, Paul EE, Anand B, Marintchev A. Regulation of the interactions between human eIF5 and eIF1A by the CK2 kinase. Curr Res Struct Biol 2022; 4:308-319. [PMID: 36164648 PMCID: PMC9508154 DOI: 10.1016/j.crstbi.2022.09.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2022] [Revised: 08/26/2022] [Accepted: 09/12/2022] [Indexed: 11/13/2022] Open
Abstract
Translation initiation in eukaryotes relies on a complex network of interactions that are continuously reorganized throughout the process. As more information becomes available about the structure of the ribosomal preinitiation complex (PIC) at various points in translation initiation, new questions arise about which interactions occur when, their roles, and regulation. The eukaryotic translation factor (eIF) 5 is the GTPase-activating protein (GAP) for the GTPase eIF2, which brings the initiator Met-tRNAi to the PIC. eIF5 also plays a central role in PIC assembly and remodeling through interactions with other proteins, including eIFs 1, 1A, and 3c. Phosphorylation by casein kinase 2 (CK2) significantly increases the eIF5 affinity for eIF2. The interaction between eIF5 and eIF1A was reported to be mediated by the eIF5 C-terminal domain (CTD) and the eIF1A N-terminal tail. Here, we report a new contact interface, between eIF5-CTD and the oligonucleotide/oligosaccharide-binding fold (OB) domain of eIF1A, which contributes to the overall affinity between the two proteins. We also show that the interaction is modulated by dynamic intramolecular interactions within both eIF5 and eIF1A. CK2 phosphorylation of eIF5 increases its affinity for eIF1A, offering new insights into the mechanisms by which CK2 stimulates protein synthesis and cell proliferation. eIF5-CTD interacts with both the N-terminal tail and the OB domain of eIF1A. The OB domain contacts stabilize the overall interaction. The eIF1A C-terminal tail and the eIF5 DWEAR motif interfere with OB domain binding. CK2 phosphorylation of eIF5 increases its affinity for eIF1A.
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10
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Homma MK, Kiko Y, Hashimoto Y, Nagatsuka M, Katagata N, Masui S, Homma Y, Nomizu T. Intracellular localization of CK2α as a prognostic factor in invasive breast carcinomas. Cancer Sci 2021; 112:619-628. [PMID: 33164285 PMCID: PMC7894005 DOI: 10.1111/cas.14728] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2020] [Revised: 10/04/2020] [Accepted: 11/04/2020] [Indexed: 01/15/2023] Open
Abstract
Overexpression of the ubiquitous protein kinase, CK2α, has been reported in various human cancers. Here, we demonstrate that nuclear and nucleolar CK2α localization in invasive ductal carcinomas of the breast is a reliable predictor of poor prognosis. Cellular localization of CK2α in nuclei and nucleoli was analyzed immunohistochemically using surgical tissue blocks from 112 patients, who had undergone surgery without neoadjuvant chemotherapy. Clinical data collection and median follow-up period were for more than 5 y. In total, 93.8% of patients demonstrated elevated CK2α expression in nuclei and 36.6% of them displayed elevated expression predominantly in nucleoli. Clinicopathological malignancy was strongly correlated with elevated nuclear and nucleolar CK2α expression. Recurrence-free survival was significantly worse (P = .0002) in patients with positive nucleolar CK2α staining. The 5-y survival rate decreased to a roughly 50% in nucleolar CK2α-positive patients of triple-negative (P = .0069) and p Stage 3 (P = .0073) groups. In contrast, no patients relapsed or died in the triple-negative group who exhibited a lack of nucleolar CK2α staining. Evaluation of nucleolar CK2α staining showed a high secondary index with a hazard ratio of 6.629 (P = .001), following lymph node metastasis with a hazard ratio of 14.30 (P = .0008). Multivariate analysis demonstrated that nucleolar CK2α is an independent factor for recurrence-free survival. Therefore, we propose that histochemical evaluation of nucleolar CK2α-positive staining may be a new and robust prognostic indicator for patients who need further treatment. Functional consequences of nucleolar CK2 dysfunction may be a starting point to facilitate development of novel treatments for invasive breast carcinoma.
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Affiliation(s)
- Miwako Kato Homma
- Department of Biomolecular SciencesFukushima Medical University School of MedicineFukushimaJapan
| | - Yuichiro Kiko
- Department of Diagnostic PathologyFukushima Medical University School of MedicineFukushimaJapan
| | - Yuko Hashimoto
- Department of Diagnostic PathologyFukushima Medical University School of MedicineFukushimaJapan
| | - Miki Nagatsuka
- Department of SurgeryHoshi General HospitalFukushimaJapan
| | - Naoto Katagata
- Department of SurgeryHoshi General HospitalFukushimaJapan
| | - Seiichiro Masui
- Medical Research CenterFukushima Medical University School of MedicineFukushimaJapan
| | - Yoshimi Homma
- Department of Biomolecular SciencesFukushima Medical University School of MedicineFukushimaJapan
| | - Tadashi Nomizu
- Department of SurgeryHoshi General HospitalFukushimaJapan
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11
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Feng H, Lu J, Song X, Thongkum A, Zhang F, Lou L, Reizes O, Almasan A, Gong Z. CK2 kinase-mediated PHF8 phosphorylation controls TopBP1 stability to regulate DNA replication. Nucleic Acids Res 2020; 48:10940-10952. [PMID: 33010150 PMCID: PMC7641741 DOI: 10.1093/nar/gkaa756] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2020] [Revised: 08/31/2020] [Accepted: 09/03/2020] [Indexed: 11/12/2022] Open
Abstract
ATR functions as a master regulator of the DNA-damage response. ATR activation requires the ATR activator, topoisomerase IIβ-binding protein 1 (TopBP1). However, the underlying mechanism of TopBP1 regulation and how its regulation affects DNA replication remain unknown. Here, we report a specific interaction between TopBP1 and the histone demethylase PHF8. The TopBP1/PHF8 interaction is mediated by the BRCT 7+8 domain of TopBP1 and phosphorylation of PHF8 at Ser854. This interaction is cell-cycle regulated and phosphorylation-dependent. PHF8 is phosphorylated by CK2, which regulates binding of PHF8 to TopBP1. Importantly, PHF8 regulates TopBP1 protein level by preventing its ubiquitination and degradation mediated by the E3 ligase UBR5. Interestingly, PHF8pS854 is likely to contribute to regulation of TopBP1 stability and DNA replication checkpoint. Further, both TopBP1 and PHF8 are required for efficient replication fork restart. Together, these data identify PHF8 as a TopBP1-binding protein and provide mechanistic insight into how PHF8 regulates TopBP1 stability to maintain DNA replication.
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Affiliation(s)
- Haihua Feng
- Department of Cancer Biology, Cleveland Clinic Lerner Research Institute, Cleveland, OH 44195, USA
| | - Jingchen Lu
- Department of Cancer Biology, Cleveland Clinic Lerner Research Institute, Cleveland, OH 44195, USA.,Department of Medical Oncology, Xiangya Hospital, Central South University, Changsha, China
| | - Xiaotian Song
- Department of Cancer Biology, Cleveland Clinic Lerner Research Institute, Cleveland, OH 44195, USA
| | - Angkana Thongkum
- Department of Cancer Biology, Cleveland Clinic Lerner Research Institute, Cleveland, OH 44195, USA
| | - Fan Zhang
- Department of Cancer Biology, Cleveland Clinic Lerner Research Institute, Cleveland, OH 44195, USA
| | - Lihong Lou
- Department of Cancer Biology, Cleveland Clinic Lerner Research Institute, Cleveland, OH 44195, USA
| | - Ofer Reizes
- Department of Cardiovascular & Metabolic Sciences, Cleveland Clinic Lerner Research Institute, Cleveland, OH 44195, USA
| | - Alexandru Almasan
- Department of Cancer Biology, Cleveland Clinic Lerner Research Institute, Cleveland, OH 44195, USA
| | - Zihua Gong
- Department of Cancer Biology, Cleveland Clinic Lerner Research Institute, Cleveland, OH 44195, USA.,Case Comprehensive Cancer Center, Case Western Reserve University School of Medicine, Cleveland, OH 44106, USA
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12
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Silva-Pavez E, Tapia JC. Protein Kinase CK2 in Cancer Energetics. Front Oncol 2020; 10:893. [PMID: 32626654 PMCID: PMC7315807 DOI: 10.3389/fonc.2020.00893] [Citation(s) in RCA: 40] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2020] [Accepted: 05/06/2020] [Indexed: 12/15/2022] Open
Abstract
Protein kinase CK2 (formerly known as casein kinase 2) is abnormally elevated in many cancers. This may increase tumor aggressiveness through CK2-dependent phosphorylation of key proteins in several signaling pathways. In this work, we have compiled evidence from the literature to suggest that CK2 also modulates a metabolic switch characteristic of cancer cells that enhances resistance to death, due to either drugs or to a microenvironment deficient in oxygen or nutrients. Concurrently, CK2 may help to preserve mitochondrial activity in a PTEN-dependent manner. PTEN, widely recognized as a tumor suppressor, is another CK2 substrate in the PI3K/Akt signaling pathway that promotes cancer viability and aerobic glycolysis. Given that CK2 can regulate Akt as well as two of its main effectors, namely mTORC1 and β-catenin, we comprehensively describe how CK2 may modulate cancer energetics by regulating expression of key targets and downstream processes, such as HIF-1 and autophagy, respectively. Thus, the specific inhibition of CK2 may lead to a catastrophic death of cancer cells, which could become a feasible therapeutic strategy to beat this devastating disease. In fact, ATP-competitive inhibitors, synthetic peptides and antisense oligonucleotides have been designed as CK2 inhibitors, some of them used in preclinical models of cancer, of which TBB and silmitasertib are widely known. We will finish by discussing a hypothetical scenario in which cancer cells are "addicted" to CK2; i.e., in which many proteins that regulate signaling pathways and metabolism-linked processes are highly dependent on this kinase.
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Affiliation(s)
- Eduardo Silva-Pavez
- Programa de Biología Celular y Molecular, Instituto de Ciencias Biomédicas, Facultad de Medicina, Universidad de Chile, Santiago, Chile
| | - Julio C Tapia
- Programa de Biología Celular y Molecular, Instituto de Ciencias Biomédicas, Facultad de Medicina, Universidad de Chile, Santiago, Chile
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13
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Kuang C, Li J, Liu H, Liu J, Sun X, Zhu X, Hua W. Genome-Wide Identification and Evolutionary Analysis of the Fruit-Weight 2.2-Like Gene Family in Polyploid Oilseed Rape (Brassica napus L.). DNA Cell Biol 2020; 39:766-782. [DOI: 10.1089/dna.2019.5036] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Affiliation(s)
- Chen Kuang
- Oil Crops Research Institute, Chinese Academy of Agricultural Sciences, Key Laboratory of Biology and Genetic Improvement of Oil Crops, Ministry of Agriculture and Rural Affairs, Wuhan, China
- Graduate School of Chinese Academy of Agricultural Sciences, Beijing, China
| | - Jun Li
- Oil Crops Research Institute, Chinese Academy of Agricultural Sciences, Key Laboratory of Biology and Genetic Improvement of Oil Crops, Ministry of Agriculture and Rural Affairs, Wuhan, China
| | - Hongfang Liu
- Oil Crops Research Institute, Chinese Academy of Agricultural Sciences, Key Laboratory of Biology and Genetic Improvement of Oil Crops, Ministry of Agriculture and Rural Affairs, Wuhan, China
| | - Jun Liu
- Oil Crops Research Institute, Chinese Academy of Agricultural Sciences, Key Laboratory of Biology and Genetic Improvement of Oil Crops, Ministry of Agriculture and Rural Affairs, Wuhan, China
| | - Xingchao Sun
- Oil Crops Research Institute, Chinese Academy of Agricultural Sciences, Key Laboratory of Biology and Genetic Improvement of Oil Crops, Ministry of Agriculture and Rural Affairs, Wuhan, China
| | - Xiaoyi Zhu
- Oil Crops Research Institute, Chinese Academy of Agricultural Sciences, Key Laboratory of Biology and Genetic Improvement of Oil Crops, Ministry of Agriculture and Rural Affairs, Wuhan, China
| | - Wei Hua
- Oil Crops Research Institute, Chinese Academy of Agricultural Sciences, Key Laboratory of Biology and Genetic Improvement of Oil Crops, Ministry of Agriculture and Rural Affairs, Wuhan, China
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14
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ShiYang X, Miao Y, Cui Z, Lu Y, Zhou C, Zhang Y, Xiong B. Casein kinase 2 modulates the spindle assembly checkpoint to orchestrate porcine oocyte meiotic progression. J Anim Sci Biotechnol 2020; 11:31. [PMID: 32292585 PMCID: PMC7140493 DOI: 10.1186/s40104-020-00438-1] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2019] [Accepted: 02/17/2020] [Indexed: 11/10/2022] Open
Abstract
Background CK2 (casein kinase 2) is a serine/threonine-selective protein kinase that has been involved in a variety of cellular processes such as DNA repair, cell cycle control and circadian rhythm regulation. However, its functional roles in oocyte meiosis have not been fully determined. Results We report that CK2 is essential for porcine oocyte meiotic maturation by regulating spindle assembly checkpoint (SAC). Immunostaining and immunoblotting analysis showed that CK2 was constantly expressed and located on the chromosomes during the entire oocyte meiotic maturation. Inhibition of CK2 activity by its selective inhibitor CX-4945 impaired the first polar body extrusion and arrested oocytes at M I stage, accompanied by the presence of BubR1 at kinetochores, indicative of activated SAC. In addition, we found that spindle/chromosome structure was disrupted in CK2-inhibited oocytes due to the weakened microtubule stability, which is a major cause resulting in the activation of SAC. Last, we found that the level DNA damage as assessed by γH2A.X staining was considerably elevated when CK2 was inhibited, suggesting that DNA damage might be another critical factor leading to the SAC activation and meiotic failure of oocytes. Conclusions Our findings demonstrate that CK2 promotes the porcine oocyte maturation by ensuring normal spindle assembly and DNA damage repair.
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Affiliation(s)
- Xiayan ShiYang
- College of Animal Science and Technology, Nanjing Agricultural University, Nanjing, 210095 China
| | - Yilong Miao
- College of Animal Science and Technology, Nanjing Agricultural University, Nanjing, 210095 China
| | - Zhaokang Cui
- College of Animal Science and Technology, Nanjing Agricultural University, Nanjing, 210095 China
| | - Yajuan Lu
- College of Animal Science and Technology, Nanjing Agricultural University, Nanjing, 210095 China
| | - Changyin Zhou
- College of Animal Science and Technology, Nanjing Agricultural University, Nanjing, 210095 China
| | - Yu Zhang
- College of Animal Science and Technology, Nanjing Agricultural University, Nanjing, 210095 China
| | - Bo Xiong
- College of Animal Science and Technology, Nanjing Agricultural University, Nanjing, 210095 China
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15
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Anda S, Grallert B. Cell-Cycle-Dependent Regulation of Translation: New Interpretations of Old Observations in Light of New Approaches. Bioessays 2019; 41:e1900022. [PMID: 31210378 DOI: 10.1002/bies.201900022] [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: 01/30/2019] [Revised: 04/29/2019] [Indexed: 12/22/2022]
Abstract
It is a long-standing view that global translation varies during the cell cycle and is much lower in mitosis than in other cell-cycle phases. However, the central papers in the literature are not in agreement about the extent of downregulation in mitosis, ranging from a dramatic decrease to only a marginal reduction. Herein, it is argued that the discrepancy derives from technical challenges. Cell-cycle-dependent variations are most conveniently studied in synchronized cells, but the synchronization methods by themselves often evoke stress responses that, in turn, affect translation rates. Further, it is argued that previously reported cell-cycle-dependent changes in the global translation rate to a large extent reflect responses to the synchronization methods. Recent findings strongly suggest that the global translation rate is not regulated in a cell-cycle-dependent manner. Novel techniques allowing a genome-wide analysis of translational profiles suggest that the extent and importance of selective translational regulation associated with cell-cycle transitions have been underestimated. Therefore, the main question is which messenger RNAs (mRNAs) are translated, rather than whether the global translation rate is decreased.
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Affiliation(s)
- Silje Anda
- Department of Radiation Biology, Institute for Cancer Research, Oslo University Hospital, 0379, Oslo, Norway
| | - Beáta Grallert
- Department of Radiation Biology, Institute for Cancer Research, Oslo University Hospital, 0379, Oslo, Norway
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16
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Rodríguez-Ulloa A, Ramos Y, Sánchez-Puente A, Perera Y, Musacchio-Lasa A, Fernández-de-Cossio J, Padrón G, López LJ, Besada V, Perea SE. The Combination of the CIGB-300 Anticancer Peptide and Cisplatin Modulates Proteins Related to Cell Survival, DNA Repair and Metastasis in a Lung Cancer Cell Line Model. CURR PROTEOMICS 2019. [DOI: 10.2174/1570164616666190126104325] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Background:
CIGB-300 is a pro-apoptotic peptide that abrogates CK2-mediated phosphorylation,
and can elicit synergistic interaction in vitro and in vivo when combined with certain anticancer
drugs.
Objective:
The combination of CIGB-300 with cisplatin is studied through data mining and expressionbased
proteomics to reveal the molecular basis of this interaction. Cisplatin resistance-associated proteins,
which have also been reported as CK2 substrates, were first identified by bioinformatic analyses.
Methods:
Data from these analyses suggested that the cisplatin resistance phenotype could be directly
improved by inhibiting CK2 phosphorylation on specific substrates. Furthermore, 157 proteins were
differentially modulated on the NCI-H125 lung cancer cell line in response to CIGB-300, cisplatin or
both drugs as determined by LC-MS/MS.
Results:
The expression of 28 cisplatin resistance-associated proteins was changed when cisplatin was
combined with CIGB-300. Overall, the proteins identified are also related to cell survival, cell proliferation
and metastasis. Furthermore, the CIGB-300 regulated proteome revealed proteins that were initially
involved in the mechanism of action of CIGB-300 and cisplatin as single agents.
Conclusion:
This is the first report describing the protein array modulated by combining CIGB-300
and cisplatin that will support the rationale for future clinical settings based on a multi-target cancer
therapy.
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Affiliation(s)
| | - Yassel Ramos
- Department of Proteomics, Center for Genetic Engineering and Biotechnology, Havana, Cuba
| | - Aniel Sánchez-Puente
- Department of Proteomics, Center for Genetic Engineering and Biotechnology, Havana, Cuba
| | - Yasser Perera
- Laboratory of Molecular Oncology, Center for Genetic Engineering and Biotechnology, Havana, Cuba
| | - Alexis Musacchio-Lasa
- Department of Bioinformatics, Center for Genetic Engineering and Biotechnology, Havana, Cuba
| | | | - Gabriel Padrón
- Department of Proteomics, Center for Genetic Engineering and Biotechnology, Havana, Cuba
| | - Luis J.G. López
- Department of Proteomics, Center for Genetic Engineering and Biotechnology, Havana, Cuba
| | - Vladimir Besada
- Department of Proteomics, Center for Genetic Engineering and Biotechnology, Havana, Cuba
| | - Silvio E. Perea
- Laboratory of Molecular Oncology, Center for Genetic Engineering and Biotechnology, Havana, Cuba
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17
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Lindenblatt D, Horn M, Götz C, Niefind K, Neundorf I, Pietsch M. Design of CK2β-Mimicking Peptides as Tools To Study the CK2α/CK2β Interaction in Cancer Cells. ChemMedChem 2019; 14:833-841. [PMID: 30786177 DOI: 10.1002/cmdc.201800786] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2018] [Indexed: 11/07/2022]
Abstract
The ubiquitously expressed Ser/Thr kinase CK2 is a key regulator in a variety of key processes in normal and malignant cells. Due to its distinctive anti-apoptotic and tumor-driving properties, elevated levels of CK2 have frequently been found in tumors of different origin. In recent years, development of CK2 inhibitors has largely been focused on ATP-competitive compounds; however, targeting the CK2α/CK2β interface has emerged as a further concept that might avoid selectivity issues. To address the CK2 subunit interaction site, we have synthesized halogenated CK2β-mimicking cyclic peptides modified with the cell-penetrating peptide sC18 to mediate cellular uptake. We investigated the binding of the resulting chimeric peptides to recombinant human CK2α using a recently developed fluorescence anisotropy assay. The iodinated peptide sC18-I-Pc was identified as a potent CK2α ligand (Ki =0.622 μm). It was internalized in cells to a high extent and exhibited significant cytotoxicity toward cancerous HeLa cells (IC50 =37 μm) in contrast to non-cancerous HEK-293 cells. The attractive features and functionalities of sC18-I-Pc offer the opportunity for further improvement.
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Affiliation(s)
- Dirk Lindenblatt
- Department of Chemistry, Institute of Biochemistry, University of Cologne, Zülpicher Straße 47, 50674, Cologne, Germany
| | - Mareike Horn
- Department of Chemistry, Institute of Biochemistry, University of Cologne, Zülpicher Straße 47, 50674, Cologne, Germany
| | - Claudia Götz
- Medical Biochemistry and Molecular Biology, Saarland University, Kirrberger Str., Building 44, 66421, Homburg, Germany
| | - Karsten Niefind
- Department of Chemistry, Institute of Biochemistry, University of Cologne, Zülpicher Straße 47, 50674, Cologne, Germany
| | - Ines Neundorf
- Department of Chemistry, Institute of Biochemistry, University of Cologne, Zülpicher Straße 47, 50674, Cologne, Germany
| | - Markus Pietsch
- Institute II of Pharmacology, Center of Pharmacology, Medical Faculty, University of Cologne, Gleueler Str. 24, 50931, Cologne, Germany
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18
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Hoque A, Williamson NA, Ameen SS, Ciccotosto GD, Hossain MI, Oakhill JS, Ng DCH, Ang CS, Cheng HC. Quantitative proteomic analyses of dynamic signalling events in cortical neurons undergoing excitotoxic cell death. Cell Death Dis 2019; 10:213. [PMID: 30824683 PMCID: PMC6397184 DOI: 10.1038/s41419-019-1445-0] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2018] [Revised: 01/20/2019] [Accepted: 02/01/2019] [Indexed: 12/23/2022]
Abstract
Excitotoxicity, caused by overstimulation or dysregulation of ionotropic glutamate receptors (iGluRs), is a pathological process directing neuronal death in many neurological disorders. The aberrantly stimulated iGluRs direct massive influx of calcium ions into the affected neurons, leading to changes in expression and phosphorylation of specific proteins to modulate their functions and direct their participation in the signalling pathways that induce excitotoxic neuronal death. To define these pathways, we used quantitative proteomic approaches to identify these neuronal proteins (referred to as the changed proteins) and determine how their expression and/or phosphorylation dynamically changed in association with excitotoxic cell death. Our data, available in ProteomeXchange with identifier PXD008353, identified over 100 changed proteins exhibiting significant alterations in abundance and/or phosphorylation levels at different time points (5–240 min) in neurons after glutamate overstimulation. Bioinformatic analyses predicted that many of them are components of signalling networks directing defective neuronal morphology and functions. Among them, the well-known neuronal survival regulators including mitogen-activated protein kinases Erk1/2, glycogen synthase kinase 3 (GSK3) and microtubule-associated protein (Tau), were selected for validation by biochemical approaches, which confirmed the findings of the proteomic analysis. Bioinformatic analysis predicted Protein Kinase B (Akt), c-Jun kinase (JNK), cyclin-dependent protein kinase 5 (Cdk5), MAP kinase kinase (MEK), Casein kinase 2 (CK2), Rho-activated protein kinase (Rock) and Serum/glucocorticoid-regulated kinase 1 (SGK1) as the potential upstream kinases phosphorylating some of the changed proteins. Further biochemical investigation confirmed the predictions of sustained changes of the activation states of neuronal Akt and CK2 in excitotoxicity. Thus, future investigation to define the signalling pathways directing the dynamic alterations in abundance and phosphorylation of the identified changed neuronal proteins will help elucidate the molecular mechanism of neuronal death in excitotoxicity.
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Affiliation(s)
- Ashfaqul Hoque
- Department of Biochemistry and Molecular Biology, University of Melbourne, Parkville, VIC, 3010, Australia.,Cell Signalling Research Laboratories, University of Melbourne, Parkville, VIC, 3010, Australia.,Bio21 Molecular Science and Biotechnology Institute, University of Melbourne, Parkville, VIC, 3010, Australia.,Metabolic Signalling Laboratory, St. Vincent's Institute for Medical Research, University of Melbourne, Fitzroy, VIC, 3065, Australia
| | - Nicholas A Williamson
- Bio21 Molecular Science and Biotechnology Institute, University of Melbourne, Parkville, VIC, 3010, Australia
| | - S Sadia Ameen
- Department of Biochemistry and Molecular Biology, University of Melbourne, Parkville, VIC, 3010, Australia.,Cell Signalling Research Laboratories, University of Melbourne, Parkville, VIC, 3010, Australia
| | - Giuseppe D Ciccotosto
- Department of Pharmacology and Therapeutics, University of Melbourne, Parkville, VIC, 3010, Australia
| | - M Iqbal Hossain
- Department of Biochemistry and Molecular Biology, University of Melbourne, Parkville, VIC, 3010, Australia.,Bio21 Molecular Science and Biotechnology Institute, University of Melbourne, Parkville, VIC, 3010, Australia
| | - Jonathan S Oakhill
- Metabolic Signalling Laboratory, St. Vincent's Institute for Medical Research, University of Melbourne, Fitzroy, VIC, 3065, Australia.,Mary MacKillop Institute for Health Research, Australian Catholic University, Melbourne, Victoria, 3000, Australia
| | - Dominic C H Ng
- School of Biomedical Sciences, University of Queensland, St. Lucia, QLD, Australia
| | - Ching-Seng Ang
- Bio21 Molecular Science and Biotechnology Institute, University of Melbourne, Parkville, VIC, 3010, Australia.
| | - Heung-Chin Cheng
- Department of Biochemistry and Molecular Biology, University of Melbourne, Parkville, VIC, 3010, Australia. .,Cell Signalling Research Laboratories, University of Melbourne, Parkville, VIC, 3010, Australia. .,Bio21 Molecular Science and Biotechnology Institute, University of Melbourne, Parkville, VIC, 3010, Australia.
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19
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Myers KS, Riley NM, MacGilvray ME, Sato TK, McGee M, Heilberger J, Coon JJ, Gasch AP. Rewired cellular signaling coordinates sugar and hypoxic responses for anaerobic xylose fermentation in yeast. PLoS Genet 2019; 15:e1008037. [PMID: 30856163 PMCID: PMC6428351 DOI: 10.1371/journal.pgen.1008037] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2018] [Revised: 03/21/2019] [Accepted: 02/20/2019] [Indexed: 01/08/2023] Open
Abstract
Microbes can be metabolically engineered to produce biofuels and biochemicals, but rerouting metabolic flux toward products is a major hurdle without a systems-level understanding of how cellular flux is controlled. To understand flux rerouting, we investigated a panel of Saccharomyces cerevisiae strains with progressive improvements in anaerobic fermentation of xylose, a sugar abundant in sustainable plant biomass used for biofuel production. We combined comparative transcriptomics, proteomics, and phosphoproteomics with network analysis to understand the physiology of improved anaerobic xylose fermentation. Our results show that upstream regulatory changes produce a suite of physiological effects that collectively impact the phenotype. Evolved strains show an unusual co-activation of Protein Kinase A (PKA) and Snf1, thus combining responses seen during feast on glucose and famine on non-preferred sugars. Surprisingly, these regulatory changes were required to mount the hypoxic response when cells were grown on xylose, revealing a previously unknown connection between sugar source and anaerobic response. Network analysis identified several downstream transcription factors that play a significant, but on their own minor, role in anaerobic xylose fermentation, consistent with the combinatorial effects of small-impact changes. We also discovered that different routes of PKA activation produce distinct phenotypes: deletion of the RAS/PKA inhibitor IRA2 promotes xylose growth and metabolism, whereas deletion of PKA inhibitor BCY1 decouples growth from metabolism to enable robust fermentation without division. Comparing phosphoproteomic changes across ira2Δ and bcy1Δ strains implicated regulatory changes linked to xylose-dependent growth versus metabolism. Together, our results present a picture of the metabolic logic behind anaerobic xylose flux and suggest that widespread cellular remodeling, rather than individual metabolic changes, is an important goal for metabolic engineering.
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Affiliation(s)
- Kevin S. Myers
- Great Lakes Bioenergy Research Center, University of Wisconsin-Madison, Madison, WI, United States of America
| | - Nicholas M. Riley
- Department of Chemistry, University of Wisconsin-Madison, Madison, WI, United States of America
| | - Matthew E. MacGilvray
- Laboratory of Genetics, University of Wisconsin-Madison, Madison, WI, United States of America
| | - Trey K. Sato
- Great Lakes Bioenergy Research Center, University of Wisconsin-Madison, Madison, WI, United States of America
| | - Mick McGee
- Great Lakes Bioenergy Research Center, University of Wisconsin-Madison, Madison, WI, United States of America
| | - Justin Heilberger
- Great Lakes Bioenergy Research Center, University of Wisconsin-Madison, Madison, WI, United States of America
| | - Joshua J. Coon
- Department of Chemistry, University of Wisconsin-Madison, Madison, WI, United States of America
- Genome Center of Wisconsin, University of Wisconsin-Madison, Madison, WI, United States of America
- Department of Biomolecular Chemistry, University of Wisconsin-Madison, Madison, WI, United States of America
- Morgridge Institute for Research, Madison, WI, United States of America
| | - Audrey P. Gasch
- Great Lakes Bioenergy Research Center, University of Wisconsin-Madison, Madison, WI, United States of America
- Laboratory of Genetics, University of Wisconsin-Madison, Madison, WI, United States of America
- Genome Center of Wisconsin, University of Wisconsin-Madison, Madison, WI, United States of America
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20
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Abstract
The eukaryotic translation pathway has been studied for more than four decades, but the molecular mechanisms that regulate each stage of the pathway are not completely defined. This is in part because we have very little understanding of the kinetic framework for the assembly and disassembly of pathway intermediates. Steps of the pathway are thought to occur in the subsecond to second time frame, but most assays to monitor these events require minutes to hours to complete. Understanding translational control in sufficient detail will therefore require the development of assays that can precisely monitor the kinetics of the translation pathway in real time. Here, we describe the translation pathway from the perspective of its kinetic parameters, discuss advances that are helping us move toward the goal of a rigorous kinetic understanding, and highlight some of the challenges that remain.
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21
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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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22
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Abstract
This review by Kearse and Wilusz discusses the profound impact of non-AUG start codons in eukaryotic translation. It describes how misregulation of non-AUG initiation events contributes to multiple human diseases, including cancer and neurodegeneration, and how modulation of non-AUG usage may represent a novel therapeutic strategy. Although it was long thought that eukaryotic translation almost always initiates at an AUG start codon, recent advancements in ribosome footprint mapping have revealed that non-AUG start codons are used at an astonishing frequency. These non-AUG initiation events are not simply errors but instead are used to generate or regulate proteins with key cellular functions; for example, during development or stress. Misregulation of non-AUG initiation events contributes to multiple human diseases, including cancer and neurodegeneration, and modulation of non-AUG usage may represent a novel therapeutic strategy. It is thus becoming increasingly clear that start codon selection is regulated by many trans-acting initiation factors as well as sequence/structural elements within messenger RNAs and that non-AUG translation has a profound impact on cellular states.
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Affiliation(s)
- Michael G Kearse
- Department of Biochemistry and Biophysics, University of Pennsylvania Perelman School of Medicine, Philadelphia, Pennsylvania, 19104 USA
| | - Jeremy E Wilusz
- Department of Biochemistry and Biophysics, University of Pennsylvania Perelman School of Medicine, Philadelphia, Pennsylvania, 19104 USA
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23
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Lin F, Cao SB, Ma XS, Sun HX. Inhibition of casein kinase 2 blocks G 2/M transition in early embryo mitosis but not in oocyte meiosis in mouse. J Reprod Dev 2017; 63:319-324. [PMID: 28367932 PMCID: PMC5481635 DOI: 10.1262/jrd.2016-064] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Casein kinase 2 (CK2) is a highly conserved, ubiquitously expressed serine/threonine protein kinase with hundreds of substrates. The role of CK2 in the G2/M transition of oocytes, zygotes, and 2-cell embryos was studied in mouse by enzyme activity inhibition using the specific inhibitor 4, 5, 6, 7-tetrabromobenzotriazole (TBB). Zygotes and 2-cell embryos were arrested at G2 phase by TBB treatment, and DNA damage was increased in the female pronucleus of arrested zygotes. Further developmental ability of arrested zygotes was reduced, but that of arrested 2-cell embryos was not affected after releasing from inhibition. By contrast, the G2/M transition in oocytes was not affected by TBB. These results indicate that CK2 activity is essential for mitotic G2/M transition in early embryos but not for meiotic G2/M transition in oocytes.
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Affiliation(s)
- Fei Lin
- Center for Reproductive Medicine, Nanjing Drum Tower Hospital, The Affiliated Hospital of Nanjing University Medical School, Nanjing 210008, China
| | - Shi-Bing Cao
- State Key Laboratory of Reproductive Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing 100101, China
| | - Xue-Shan Ma
- State Key Laboratory of Reproductive Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing 100101, China
| | - Hai-Xiang Sun
- Center for Reproductive Medicine, Nanjing Drum Tower Hospital, The Affiliated Hospital of Nanjing University Medical School, Nanjing 210008, China
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24
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Casein Kinase 2 Is Linked to Stress Granule Dynamics through Phosphorylation of the Stress Granule Nucleating Protein G3BP1. Mol Cell Biol 2017; 37:MCB.00596-16. [PMID: 27920254 DOI: 10.1128/mcb.00596-16] [Citation(s) in RCA: 67] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2016] [Accepted: 11/29/2016] [Indexed: 12/27/2022] Open
Abstract
Stress granules (SGs) are large macromolecular aggregates that contain translation initiation complexes and mRNAs. Stress granule formation coincides with translational repression, and stress granules actively signal to mediate cell fate decisions by signaling to the translation apparatus to (i) maintain translational repression, (ii) mount various transcriptional responses, including innate immunity, and (iii) repress apoptosis. Previous work showed that G3BP1 is phosphorylated at serine 149, which regulates G3BP1 oligomerization, stress granule assembly, and RNase activity intrinsic to G3BP1. However, the kinase that phosphorylates G3BP1 was not identified, leaving a key step in stress granule regulation uncharacterized. Here, using chemical inhibition, genetic depletion, and overexpression experiments, we show that casein kinase 2 (CK2) promotes stress granule dynamics. These results link CK2 activity with SG disassembly. We also show that casein kinase 2 phosphorylates G3BP1 at serine 149 in vitro and in cells. These data support a role for casein kinase 2 in regulation of protein synthesis by downregulating stress granule formation through G3BP1.
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Role of Eukaryotic Initiation Factors during Cellular Stress and Cancer Progression. J Nucleic Acids 2016; 2016:8235121. [PMID: 28083147 PMCID: PMC5204094 DOI: 10.1155/2016/8235121] [Citation(s) in RCA: 50] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2016] [Accepted: 11/14/2016] [Indexed: 12/12/2022] Open
Abstract
Protein synthesis can be segmented into distinct phases comprising mRNA translation initiation, elongation, and termination. Translation initiation is a highly regulated and rate-limiting step of protein synthesis that requires more than 12 eukaryotic initiation factors (eIFs). Extensive evidence shows that the transcriptome and corresponding proteome do not invariably correlate with each other in a variety of contexts. In particular, translation of mRNAs specific to angiogenesis, tumor development, and apoptosis is altered during physiological and pathophysiological stress conditions. In cancer cells, the expression and functions of eIFs are hampered, resulting in the inhibition of global translation and enhancement of translation of subsets of mRNAs by alternative mechanisms. A precise understanding of mechanisms involving eukaryotic initiation factors leading to differential protein expression can help us to design better strategies to diagnose and treat cancer. The high spatial and temporal resolution of translation control can have an immediate effect on the microenvironment of the cell in comparison with changes in transcription. The dysregulation of mRNA translation mechanisms is increasingly being exploited as a target to treat cancer. In this review, we will focus on this context by describing both canonical and noncanonical roles of eIFs, which alter mRNA translation.
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Andreev DE, O'Connor PBF, Loughran G, Dmitriev SE, Baranov PV, Shatsky IN. Insights into the mechanisms of eukaryotic translation gained with ribosome profiling. Nucleic Acids Res 2016; 45:513-526. [PMID: 27923997 PMCID: PMC5314775 DOI: 10.1093/nar/gkw1190] [Citation(s) in RCA: 105] [Impact Index Per Article: 13.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2016] [Revised: 10/31/2016] [Accepted: 11/18/2016] [Indexed: 12/29/2022] Open
Abstract
The development of Ribosome Profiling (RiboSeq) has revolutionized functional genomics. RiboSeq is based on capturing and sequencing of the mRNA fragments enclosed within the translating ribosome and it thereby provides a ‘snapshot’ of ribosome positions at the transcriptome wide level. Although the method is predominantly used for analysis of differential gene expression and discovery of novel translated ORFs, the RiboSeq data can also be a rich source of information about molecular mechanisms of polypeptide synthesis and translational control. This review will focus on how recent findings made with RiboSeq have revealed important details of the molecular mechanisms of translation in eukaryotes. These include mRNA translation sensitivity to drugs affecting translation initiation and elongation, the roles of upstream ORFs in response to stress, the dynamics of elongation and termination as well as details of intrinsic ribosome behavior on the mRNA after translation termination. As the RiboSeq method is still at a relatively early stage we will also discuss the implications of RiboSeq artifacts on data interpretation.
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Affiliation(s)
- Dmitry E Andreev
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow 119234, Russia
| | | | - Gary Loughran
- School of Biochemistry and Cell Biology, University College Cork, Cork, Ireland
| | - Sergey E Dmitriev
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow 119234, Russia
| | - Pavel V Baranov
- School of Biochemistry and Cell Biology, University College Cork, Cork, Ireland
| | - Ivan N Shatsky
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow 119234, Russia
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Song J, Che J, You Z, Ye L, Li J, Zhang Y, Qian Q, Zhong B. Phosphoproteomic analysis of the posterior silk gland of Bombyx mori provides novel insight into phosphorylation regulating the silk production. J Proteomics 2016; 148:194-201. [DOI: 10.1016/j.jprot.2016.08.007] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2016] [Revised: 08/03/2016] [Accepted: 08/09/2016] [Indexed: 11/28/2022]
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Terenin IM, Akulich KA, Andreev DE, Polyanskaya SA, Shatsky IN, Dmitriev SE. Sliding of a 43S ribosomal complex from the recognized AUG codon triggered by a delay in eIF2-bound GTP hydrolysis. Nucleic Acids Res 2016; 44:1882-93. [PMID: 26717981 PMCID: PMC4770231 DOI: 10.1093/nar/gkv1514] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2015] [Revised: 12/16/2015] [Accepted: 12/17/2015] [Indexed: 02/05/2023] Open
Abstract
During eukaryotic translation initiation, 43S ribosomal complex scans mRNA leader unless an AUG codon in an appropriate context is found. Establishing the stable codon-anticodon base-pairing traps the ribosome on the initiator codon and triggers structural rearrangements, which lead to Pi release from the eIF2-bound GTP. It is generally accepted that AUG recognition by the scanning 43S complex sets the final point in the process of start codon selection, while latter stages do not contribute to this process. Here we use translation reconstitution approach and kinetic toe-printing assay to show that after the 48S complex is formed on an AUG codon, in case GTP hydrolysis is impaired, the ribosomal subunit is capable to resume scanning and slides downstream to the next AUG. In contrast to leaky scanning, this sliding is not limited to AUGs in poor nucleotide contexts and occurs after a relatively long pause at the recognized AUG. Thus, recognition of an AUG per se does not inevitably lead to this codon being selected for initiation of protein synthesis. Instead, it is eIF5-induced GTP hydrolysis and Pi release that irreversibly trap the 48S complex, and this complex is further stabilized by eIF5B and 60S joining.
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Affiliation(s)
- Ilya M Terenin
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow 119234, Russia Engelhardt Institute of Molecular Biology, Russian Academy of Sciences, Moscow 119991, Russia
| | - Kseniya A Akulich
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow 119234, Russia School of Bioengineering and Bioinformatics, Lomonosov Moscow State University, Moscow 119234, Russia
| | - Dmitry E Andreev
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow 119234, Russia
| | - Sofya A Polyanskaya
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow 119234, Russia Department of Molecular Biology, Biological Faculty, Lomonosov Moscow State University, Moscow 119234, Russia
| | - Ivan N Shatsky
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow 119234, Russia
| | - Sergey E Dmitriev
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow 119234, Russia Engelhardt Institute of Molecular Biology, Russian Academy of Sciences, Moscow 119991, Russia Department of Biochemistry, Biological Faculty, Lomonosov Moscow State University, Moscow 119234, Russia
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Kwon OK, Kim SJ, Lee YM, Lee YH, Bae YS, Kim JY, Peng X, Cheng Z, Zhao Y, Lee S. Global analysis of phosphoproteome dynamics in embryonic development of zebrafish (Danio rerio). Proteomics 2015; 16:136-49. [DOI: 10.1002/pmic.201500017] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2015] [Revised: 09/04/2015] [Accepted: 10/01/2015] [Indexed: 11/11/2022]
Affiliation(s)
- Oh Kwang Kwon
- College of Pharmacy, Research Institute of Pharmaceutical Sciences; Kyungpook National University; Daegu South Korea
| | - Sun Ju Kim
- College of Pharmacy, Research Institute of Pharmaceutical Sciences; Kyungpook National University; Daegu South Korea
| | - You-Mie Lee
- College of Pharmacy, Research Institute of Pharmaceutical Sciences; Kyungpook National University; Daegu South Korea
| | - Young-Hoon Lee
- School of Life Sciences, KNU Creative BioResearch Group (BK21 plus program); Kyungpook National University; Daegu Korea
| | - Young-Seuk Bae
- School of Life Sciences, KNU Creative BioResearch Group (BK21 plus program); Kyungpook National University; Daegu Korea
| | - Jin Young Kim
- Mass Spectrometry Research Center; Korea Basic Science Institute; Ochang Chungbuk Republic of Korea
| | - Xiaojun Peng
- Jingjie PTM Biolabs (Hangzhou) Co. Ltd; Hangzhou P. R. China
| | - Zhongyi Cheng
- Advanced Institute of Translational Medicine; Tongji University; Shanghai P. R. China
| | - Yingming Zhao
- Ben May Department for Cancer Research; University of Chicago; Chicago IL USA
| | - Sangkyu Lee
- College of Pharmacy, Research Institute of Pharmaceutical Sciences; Kyungpook National University; Daegu South Korea
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Rasheedi S, Suragani M, Raviprasad P, Ghosh S, Suragani RNVS, Ramaiah KVA, Ehtesham NZ. Functional characterization of PeIF5B as eIF5B homologue from Pisum sativum. Biochimie 2015; 118:36-43. [PMID: 26215376 DOI: 10.1016/j.biochi.2015.07.017] [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: 01/20/2015] [Accepted: 07/21/2015] [Indexed: 10/23/2022]
Abstract
We earlier reported 'PeIF5B' as a novel factor from Pisum sativum that has sequence similarity to eIF5B (S. Rasheedi, S. Ghosh, M. Suragani et al., P. sativum contains a factor with strong homology to eIF5B, Gene 399 (2007) 144-151). The main aim of the present study was to perform functional characterization of PeIF5B as an eIF5B homologue from plant system. PeIF5B shows binding to Met - tRNA(f)(Met), hydrolyses GTP and interacts with ribosomes. In vivo growth complementation analysis shows that PeIF5B partially complements its yeast homologue. Interestingly, PeIF5B mainly localizes in the nucleus as confirmed by nuclear localization signal (NLS) prediction, confocal imaging and immunoblots of cellular fractions. Similar to the yeast eIF5B but unlike the human orthologue, PeIF5B is an intron-less gene. This study highlights PeIF5B's role as a functional eIF5B homologue possibly participating in nuclear translation in plant system.
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Affiliation(s)
- Sheeba Rasheedi
- Laboratory of Molecular and Cellular Biology, Centre for DNA Fingerprinting and Diagnostics, Hyderabad 500 001, India
| | - Madhuri Suragani
- Molecular Biology Unit, National Institute of Nutrition, Hyderabad 500 007, India
| | - Podili Raviprasad
- Molecular Biology Unit, National Institute of Nutrition, Hyderabad 500 007, India
| | - Sudip Ghosh
- Molecular Biology Unit, National Institute of Nutrition, Hyderabad 500 007, India
| | | | - Kolluru V A Ramaiah
- Department of Biochemistry, University of Hyderabad, Prof. C. R. Rao Road, Hyderabad 500 046, India
| | - Nasreen Z Ehtesham
- Inflammation Biology and Cell Signaling Laboratory, National Institute of Pathology, Safdarjung Hospital, New Delhi 110029, India.
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Borgo C, Franchin C, Salizzato V, Cesaro L, Arrigoni G, Matricardi L, Pinna LA, Donella-Deana A. Protein kinase CK2 potentiates translation efficiency by phosphorylating eIF3j at Ser127. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2015; 1853:1693-701. [PMID: 25887626 DOI: 10.1016/j.bbamcr.2015.04.004] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/18/2014] [Revised: 03/17/2015] [Accepted: 04/07/2015] [Indexed: 11/18/2022]
Abstract
In eukaryotic protein synthesis the translation initiation factor 3 (eIF3) is a key player in the recruitment and assembly of the translation initiation machinery. Mammalian eIF3 consists of 13 subunits, including the loosely associated eIF3j subunit that plays a stabilizing role in the eIF3 complex formation and interaction with the 40S ribosomal subunit. By means of both co-immunoprecipitation and mass spectrometry analyses we demonstrate that the protein kinase CK2 interacts with and phosphorylates eIF3j at Ser127. Inhibition of CK2 activity by CX-4945 or down-regulation of the expression of CK2 catalytic subunit by siRNA cause the dissociation of j-subunit from the eIF3 complex as judged from glycerol gradient sedimentation. This finding proves that CK2-phosphorylation of eIF3j is a prerequisite for its association with the eIF3 complex. Expression of Ser127Ala-eIF3j mutant impairs both the interaction of mutated j-subunit with the other eIF3 subunits and the overall protein synthesis. Taken together our data demonstrate that CK2-phosphorylation of eIF3j at Ser127 promotes the assembly of the eIF3 complex, a crucial step in the activation of the translation initiation machinery.
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Affiliation(s)
- Christian Borgo
- Department of Biomedical Sciences, University of Padova, Via U. Bassi 58B, 35131 Padova, Italy; CNR Institute of NeuroSciences, University of Padova, Via U. Bassi 58B, 35131 Padova, Italy
| | - Cinzia Franchin
- Proteomic Center of Padova University, Via G. Orus B2, 35129 Padova, Italy
| | - Valentina Salizzato
- Department of Biomedical Sciences, University of Padova, Via U. Bassi 58B, 35131 Padova, Italy; CNR Institute of NeuroSciences, University of Padova, Via U. Bassi 58B, 35131 Padova, Italy
| | - Luca Cesaro
- Department of Biomedical Sciences, University of Padova, Via U. Bassi 58B, 35131 Padova, Italy; CNR Institute of NeuroSciences, University of Padova, Via U. Bassi 58B, 35131 Padova, Italy
| | - Giorgio Arrigoni
- Proteomic Center of Padova University, Via G. Orus B2, 35129 Padova, Italy
| | - Laura Matricardi
- Venitian Institute of Oncology (IOV-IRCCS), Via Gattamelata 64, 35128 Padova, Italy
| | - Lorenzo A Pinna
- Department of Biomedical Sciences, University of Padova, Via U. Bassi 58B, 35131 Padova, Italy; CNR Institute of NeuroSciences, University of Padova, Via U. Bassi 58B, 35131 Padova, Italy
| | - Arianna Donella-Deana
- Department of Biomedical Sciences, University of Padova, Via U. Bassi 58B, 35131 Padova, Italy; CNR Institute of NeuroSciences, University of Padova, Via U. Bassi 58B, 35131 Padova, Italy.
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Bavli-Kertselli I, Melamed D, Bar-Ziv L, Volf H, Arava Y. Overexpression of eukaryotic initiation factor 5 rescues the translational defect of tpk1w in a manner that necessitates a novel phosphorylation site. FEBS J 2014; 282:504-20. [PMID: 25417541 DOI: 10.1111/febs.13158] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2014] [Revised: 11/11/2014] [Accepted: 11/20/2014] [Indexed: 02/04/2023]
Abstract
Cells respond to changes in their environment through mechanisms that often necessitate reprogramming of the translation machinery. The fastest and strongest of all tested responses is the translation inhibition observed following abrupt depletion of glucose from the media of yeast cells. The speed of the response suggests a post-translational modification of a key component of the translation machinery. This translation factor is as yet unknown. A cAMP-dependent protein kinase mutant yeast strain (tpk1(w)) that does not respond properly to glucose depletion and maintains translation was described previously. We hypothesized that the inability of tpk1(w) to arrest translation results from abnormal expression of key translation mediators. Genome-wide analysis of steady-state mRNA levels in tpk1(w) revealed underexpression of several candidates. Elevating the cellular levels of eukaryotic initiation factor (eIF) 5 by overexpression rescued the translational defect of tpk1(w). Restoring ribosomal dissociation by eIF5 necessitated an active GAP domain and multiple regions throughout this protein. Phosphoproteomics analysis of wild-type cells overexpressing eIF5 revealed increased phosphorylation in a novel site (Thr191) upon glucose depletion. Mutating this residue and introducing it into tpk1(w) abolished the ability of eIF5 to rescue the translational defect. Intriguingly, introducing this mutation into the wild-type strain did not hamper its translational response. We further show that Thr191 is phosphorylated in vitro by Casein Kinase II (CKII), and yeast cells with a mutated CKII have a reduced response to glucose depletion. These results implicate phosphorylation of eIF5 at Thr191 by CKII as one of the pathways for regulating translation upon glucose depletion.
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Affiliation(s)
- Ira Bavli-Kertselli
- Faculty of Biology, Technion - Israel Institute of Technology, Haifa, Israel
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Mulekar JJ, Huq E. Expanding roles of protein kinase CK2 in regulating plant growth and development. JOURNAL OF EXPERIMENTAL BOTANY 2014; 65:2883-93. [PMID: 24307718 DOI: 10.1093/jxb/ert401] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/17/2023]
Abstract
Protein kinase CK2 (formerly known as casein kinase II) is a ubiquitious Ser/Thr kinase present in all eukaryotes. The α (catalytic) and β (regulatory) subunits of CK2 exist both as a tetrameric holoenzyme and as monomers in eukaryotic cells. CK2 has been implicated in multiple developmental and stress-responsive pathways including light signalling and circadian clock in plants. Recent studies using CK2 knockout and dominant negative mutants in Arabidopsis have uncovered new roles for this enzyme. CK2 substrates that have been identified so far are primarily transcription factors or regulatory proteins. CK2-mediated phosphorylation of these factors often results in alteration of the protein function including changes in the DNA-binding affinity, dimerization, stability, protein-protein interactions, and subcellular localization. CK2 has evolved as an essential housekeeping kinase in plants that modifies protein function in a dynamic way. This review summarizes the current knowledge of the role of CK2 in plant development.
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Affiliation(s)
- Jidnyasa Jayant Mulekar
- Department of Molecular Biosciences and Institute for Cellular and Molecular Biology, University of Texas at Austin, Austin, TX 78712, USA
| | - Enamul Huq
- Department of Molecular Biosciences and Institute for Cellular and Molecular Biology, University of Texas at Austin, Austin, TX 78712, USA
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Asano K. Why is start codon selection so precise in eukaryotes? ACTA ACUST UNITED AC 2014; 2:e28387. [PMID: 26779403 PMCID: PMC4705826 DOI: 10.4161/trla.28387] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2013] [Revised: 02/14/2014] [Accepted: 02/27/2014] [Indexed: 12/22/2022]
Abstract
Translation generally initiates with the AUG codon. While initiation at GUG and UUG is permitted in prokaryotes (Archaea and Bacteria), cases of CUG initiation were recently reported in human cells. The varying stringency in translation initiation between eukaryotic and prokaryotic domains largely stems from a fundamental problem for the ribosome in recognizing a codon at the peptidyl-tRNA binding site. Initiation factors specific to each domain of life evolved to confer stringent initiation by the ribosome. The mechanistic basis for high accuracy in eukaryotic initiation is described based on recent findings concerning the role of the multifactor complex (MFC) in this process. Also discussed are whether non-AUG initiation plays any role in translational control and whether start codon accuracy is regulated in eukaryotes.
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Affiliation(s)
- Katsura Asano
- Molecular Cellular and Developmental Biology Program; Division of Biology; Kansas State University; Manhattan, KS USA
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Cortelazzo A, Lampariello RL, Sticozzi C, Guerranti R, Mirasole C, Zolla L, Sacchetti G, Hajek J, Valacchi G. Proteomic profiling and post-translational modifications in human keratinocytes treated with Mucuna pruriens leaf extract. JOURNAL OF ETHNOPHARMACOLOGY 2014; 151:873-881. [PMID: 24315849 DOI: 10.1016/j.jep.2013.11.053] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/18/2013] [Revised: 11/05/2013] [Accepted: 11/27/2013] [Indexed: 06/02/2023]
Abstract
ETHNOPHARMACOLOGICAL RELEVANCE Mucuna pruriens (Mp) is a plant belonging to the Fabaceae family, with several medicinal properties among which its potential to treat diseases where reactive oxygen species (ROS) play an important role in the pathogeneses. The aim was to investigate the effects of Mp leaf methanolic extract (MPME) on human keratinocytes protein expression and its role in preventing proteins oxidation after oxidative stress (OS) exposure. MATERIAL AND METHODS The effects of MPME on HaCaT cells protein expression were evaluated treating cells with different concentrations of MPME, with glucose oxidase (GO, source of OS) and with MPME subsequently treated with GO. The protein patterns of treated HaCaT cells are analyzed by two-dimensional gel electrophoresis (2-DE) and compared with that of untreated HaCaT. Immunoblotting was then used to evaluate the role of MPME in preventing the 4-hydroxynonenal protein adducts (4-HNE PAs) formation (marker of OS). RESULTS Eighteen proteins, identified by mass spectrometry (LC-ESI-CID-MS/MS), were modulated distinctly by MPME in HaCaT. Overall, MPME counteract GO effect, reducing the GO-induced overexpression of several proteins involved in stress response (T-complex protein 1, Protein disulfide-isomerase A3, Protein DJ-1, and Stress-induced-phosphoprotein 1), in cell energy methabolism (Inorganic pyrophosphatase, Triosephosphate isomerase isoform 1, 2-phosphopyruvate-hydratase alpha-enolase, and Fructose-bisphosphate aldolase A isoform 1), in cytoskeletal organization (Cytokeratins 18, 9, 2, Cofilin-1, Annexin A2 and F-actin-capping protein subunit beta isoform 1) and in cell cycle progression (Eukaryotic translation initiation factor 5A-1 isoform B). In addition, MPME decreased the 4-HNE PAs levels, in particular on 2-phosphopyruvate-hydratase alpha-enolase and Cytokeratin 9. CONCLUSIONS Our findings show that MPME might be helpful in the treatment of OS-related skin diseases by preventing protein post-translational modifications (4-HNE PAs).
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Affiliation(s)
- Alessio Cortelazzo
- Department of Medical Biotechnologies, University of Siena, Siena, Italy; Child Neuropsychiatry Unit, University Hospital AOUS, Siena, Italy
| | - Raffaella L Lampariello
- Department of Biotechnology, Chemistry and Pharmaceutical Sciences, University of Siena, Siena, Italy
| | - Claudia Sticozzi
- Department of Life Sciences and Biotechnologies, University of Ferrara, Via Luigi Borsari 46, 44100 Ferrara, Italy
| | - Roberto Guerranti
- Department of Medical Biotechnologies, University of Siena, Siena, Italy
| | - Cristiana Mirasole
- Department of Ecological and Biological Sciences, University of Tuscia, Viterbo, Italy
| | - Lello Zolla
- Department of Ecological and Biological Sciences, University of Tuscia, Viterbo, Italy
| | - Gianni Sacchetti
- Department of Life Sciences and Biotechnologies, University of Ferrara, Via Luigi Borsari 46, 44100 Ferrara, Italy
| | - Joussef Hajek
- Child Neuropsychiatry Unit, University Hospital AOUS, Siena, Italy
| | - Giuseppe Valacchi
- Department of Life Sciences and Biotechnologies, University of Ferrara, Via Luigi Borsari 46, 44100 Ferrara, Italy; Department of Food and Nutrition, Kyung Hee University, Seoul, Rrepbulic of Korea.
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Mikami S, Kanaba T, Takizawa N, Kobayashi A, Maesaki R, Fujiwara T, Ito Y, Mishima M. Structural insights into the recruitment of SMRT by the corepressor SHARP under phosphorylative regulation. Structure 2013; 22:35-46. [PMID: 24268649 DOI: 10.1016/j.str.2013.10.007] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2013] [Revised: 09/06/2013] [Accepted: 10/07/2013] [Indexed: 12/16/2022]
Abstract
The transcriptional corepressors SMRT/NCoR, components of histone deacetylase complexes, interact with nuclear receptors and many other transcription factors. SMRT is a target for the ubiquitously expressed protein kinase CK2, which is known to phosphorylate a wide variety of substrates. Increasing evidence suggests that CK2 plays a regulatory role in many cellular events, particularly, in transcription. However, little is known about the precise mode of action involved. Here, we report the three-dimensional structure of a SMRT/HDAC1-associated repressor protein (SHARP) in complex with phosphorylated SMRT, as determined by solution NMR. Phosphorylation of the CK2 site on SMRT significantly increased affinity for SHARP. We also confirmed the significance of CK2 phosphorylation by reporter assay and propose a mechanism involving the process of phosphorylation acting as a molecular switch. Finally, we propose that the SPOC domain functions as a phosphorylation binding module.
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Affiliation(s)
- Suzuka Mikami
- Graduate School of Science and Engineering, Tokyo Metropolitan University, 1-1 Minamiosawa Hachioji 192-0397, Japan
| | - Teppei Kanaba
- Graduate School of Science and Engineering, Tokyo Metropolitan University, 1-1 Minamiosawa Hachioji 192-0397, Japan
| | - Naoki Takizawa
- Institute of Microbial Chemistry, Tokyo 3-14-23 Kamiosaki, Shinagawa-ku 141-0021, Japan
| | - Ayaho Kobayashi
- Graduate School of Science and Engineering, Tokyo Metropolitan University, 1-1 Minamiosawa Hachioji 192-0397, Japan
| | - Ryoko Maesaki
- Graduate School of Science and Engineering, Tokyo Metropolitan University, 1-1 Minamiosawa Hachioji 192-0397, Japan; Graduate School of Bioscience, Nara Institute of Science and Technology, 8916-5 Takayama, Ikoma, Nara 630-0192, Japan
| | - Toshinobu Fujiwara
- Institute of Microbial Chemistry, Tokyo 3-14-23 Kamiosaki, Shinagawa-ku 141-0021, Japan
| | - Yutaka Ito
- Graduate School of Science and Engineering, Tokyo Metropolitan University, 1-1 Minamiosawa Hachioji 192-0397, Japan
| | - Masaki Mishima
- Graduate School of Science and Engineering, Tokyo Metropolitan University, 1-1 Minamiosawa Hachioji 192-0397, Japan.
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Eukaryotic translation initiation factors in cancer development and progression. Cancer Lett 2013; 340:9-21. [PMID: 23830805 DOI: 10.1016/j.canlet.2013.06.019] [Citation(s) in RCA: 113] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2013] [Revised: 06/11/2013] [Accepted: 06/14/2013] [Indexed: 01/03/2023]
Abstract
Eukaryotic gene expression is a complicated process primarily regulated at the levels of gene transcription and mRNA translation. The latter involves four main steps: initiation, elongation, termination and recycling. Translation regulation is primarily achieved during initiation which is orchestrated by 12 currently known eukaryotic initiation factors (eIFs). Here, we review the current state of eIF research and present a concise summary of the various eIF subunits. As eIFs turned out to be critically implicated in different oncogenic processes the various eIF members and their contribution to onset and progression of cancer are featured.
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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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Ogura M, Yamaki J, Homma M, Homma Y. Mitochondrial c-Src regulates cell survival through phosphorylation of respiratory chain components. Biochem J 2012; 447:281-9. [PMID: 22823520 PMCID: PMC3459221 DOI: 10.1042/bj20120509] [Citation(s) in RCA: 70] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2012] [Revised: 07/17/2012] [Accepted: 07/24/2012] [Indexed: 12/26/2022]
Abstract
Mitochondrial protein tyrosine phosphorylation is an important mechanism for the modulation of mitochondrial functions. In the present study, we have identified novel substrates of c-Src in mitochondria and investigated their function in the regulation of oxidative phosphorylation. The Src family kinase inhibitor PP2 {amino-5-(4-chlorophenyl)-7-(t-butyl) pyrazolo [3,4d] pyrimidine} exhibits significant reduction of respiration. Similar results were obtained from cells expressing kinase-dead c-Src, which harbours a mitochondrial-targeting sequence. Phosphorylation-site analysis selects c-Src targets, including NDUFV2 (NADH dehydrogenase [ubiquinone] flavoprotein 2) at Tyr(193) of respiratory complex I and SDHA (succinate dehydrogenase A) at Tyr(215) of complex II. The phosphorylation of these sites by c-Src is supported by an in vivo assay using cells expressing their phosphorylation-defective mutants. Comparison of cells expressing wild-type proteins and their mutants reveals that NDUFV2 phosphorylation is required for NADH dehydrogenase activity, affecting respiration activity and cellular ATP content. SDHA phosphorylation shows no effect on enzyme activity, but perturbed electron transfer, which induces reactive oxygen species. Loss of viability is observed in T98G cells and the primary neurons expressing these mutants. These results suggest that mitochondrial c-Src regulates the oxidative phosphorylation system by phosphorylating respiratory components and that c-Src activity is essential for cell viability.
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Key Words
- cell death
- energy metabolism
- mitochondrion
- src
- tyrosine kinase
- reactive oxygen species (ros)
- ant, adenine nucleotide translocase
- bn, blue native
- ca, constitutive-active
- cox, cytochrome c oxidase
- csk, c-terminal src kinase
- ddm, n-dodecyl-β-d-maltoside
- 2-de, two-dimensional page
- he, hydroethidine
- hek, human embryonic kidney
- ipg, immobilized ph gradient
- kd, kinase-dead
- ldh, lactate dehydrogenase
- mab, monoclonal antibody
- map2, microtubule-associated protein 2
- mts, mitochondria-targeting sequence
- nbt, nitro blue tetrazolium
- ndufb10, nadh dehydrogenase [ubiquinone] 1β subcomplex subunit 10
- ndufv2, nadh dehydrogenase [ubiquinone] flavoprotein 2
- pi, propidium iodide
- pms, phenazine methosulfate
- pp2, amino-5-(4-chlorophenyl)-7-(t-butyl) pyrazolo [3,4d] pyrimidine
- ros, reactive oxygen species
- sdha, succinate dehydrogenase a
- sfk, src family kinase
- ucp, uncoupling protein
- vlcad, very long chain acyl-coa dehydrogenase
- wt, wild-type
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Affiliation(s)
- Masato Ogura
- Department of Biomolecular Science, Fukushima Medical University School of Medicine, Fukushima 960-1295, Japan
| | - Junko Yamaki
- Department of Biomolecular Science, Fukushima Medical University School of Medicine, Fukushima 960-1295, Japan
| | - Miwako K. Homma
- Department of Biomolecular Science, Fukushima Medical University School of Medicine, Fukushima 960-1295, Japan
| | - Yoshimi Homma
- Department of Biomolecular Science, Fukushima Medical University School of Medicine, Fukushima 960-1295, Japan
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40
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Rose CM, Venkateshwaran M, Volkening JD, Grimsrud PA, Maeda J, Bailey DJ, Park K, Howes-Podoll M, den Os D, Yeun LH, Westphall MS, Sussman MR, Ané JM, Coon JJ. Rapid phosphoproteomic and transcriptomic changes in the rhizobia-legume symbiosis. Mol Cell Proteomics 2012; 11:724-44. [PMID: 22683509 PMCID: PMC3434772 DOI: 10.1074/mcp.m112.019208] [Citation(s) in RCA: 83] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2012] [Revised: 06/07/2012] [Indexed: 11/06/2022] Open
Abstract
Symbiotic associations between legumes and rhizobia usually commence with the perception of bacterial lipochitooligosaccharides, known as Nod factors (NF), which triggers rapid cellular and molecular responses in host plants. We report here deep untargeted tandem mass spectrometry-based measurements of rapid NF-induced changes in the phosphorylation status of 13,506 phosphosites in 7739 proteins from the model legume Medicago truncatula. To place these phosphorylation changes within a biological context, quantitative phosphoproteomic and RNA measurements in wild-type plants were compared with those observed in mutants, one defective in NF perception (nfp) and one defective in downstream signal transduction events (dmi3). Our study quantified the early phosphorylation and transcription dynamics that are specifically associated with NF-signaling, confirmed a dmi3-mediated feedback loop in the pathway, and suggested "cryptic" NF-signaling pathways, some of them being also involved in the response to symbiotic arbuscular mycorrhizal fungi.
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Affiliation(s)
- Christopher M. Rose
- From the ‡Department of Chemistry, University of Wisconsin, Madison, Wisconsin 53706
- ‖Genome Center of Wisconsin, University of Wisconsin, Madison, Wisconsin 53706
| | | | - Jeremy D. Volkening
- ¶Department of Biochemistry, University of Wisconsin, Madison, Wisconsin 53706
| | - Paul A. Grimsrud
- ¶Department of Biochemistry, University of Wisconsin, Madison, Wisconsin 53706
| | - Junko Maeda
- §Department of Agronomy, University of Wisconsin, Madison, Wisconsin 53706
| | - Derek J. Bailey
- From the ‡Department of Chemistry, University of Wisconsin, Madison, Wisconsin 53706
- ‖Genome Center of Wisconsin, University of Wisconsin, Madison, Wisconsin 53706
| | - Kwanghyun Park
- ‖Genome Center of Wisconsin, University of Wisconsin, Madison, Wisconsin 53706
- **Department of Computer Sciences, University of Wisconsin, Madison, Wisconsin 53706
| | | | - Désirée den Os
- §Department of Agronomy, University of Wisconsin, Madison, Wisconsin 53706
- §§Present address: Penn State Biology Department, University Park, Pennsylvania 16802
| | - Li Huey Yeun
- §Department of Agronomy, University of Wisconsin, Madison, Wisconsin 53706
| | - Michael S. Westphall
- From the ‡Department of Chemistry, University of Wisconsin, Madison, Wisconsin 53706
- ‖Genome Center of Wisconsin, University of Wisconsin, Madison, Wisconsin 53706
| | - Michael R. Sussman
- ¶Department of Biochemistry, University of Wisconsin, Madison, Wisconsin 53706
- ‖Genome Center of Wisconsin, University of Wisconsin, Madison, Wisconsin 53706
| | - Jean-Michel Ané
- §Department of Agronomy, University of Wisconsin, Madison, Wisconsin 53706
| | - Joshua J. Coon
- From the ‡Department of Chemistry, University of Wisconsin, Madison, Wisconsin 53706
- ‖Genome Center of Wisconsin, University of Wisconsin, Madison, Wisconsin 53706
- ‡‡Department of Biomolecular Chemistry, University of Wisconsin, Madison, Wisconsin 53706
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41
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Singh CR, Watanabe R, Zhou D, Jennings MD, Fukao A, Lee B, Ikeda Y, Chiorini JA, Campbell SG, Ashe MP, Fujiwara T, Wek RC, Pavitt GD, Asano K. Mechanisms of translational regulation by a human eIF5-mimic protein. Nucleic Acids Res 2011; 39:8314-28. [PMID: 21745818 PMCID: PMC3201852 DOI: 10.1093/nar/gkr339] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2011] [Revised: 04/22/2011] [Accepted: 04/25/2011] [Indexed: 11/29/2022] Open
Abstract
The translation factor eIF5 is an important partner of eIF2, directly modulating its function in several critical steps. First, eIF5 binds eIF2/GTP/Met-tRNA(i)(Met) ternary complex (TC), promoting its recruitment to 40S ribosomal subunits. Secondly, its GTPase activating function promotes eIF2 dissociation for ribosomal subunit joining. Finally, eIF5 GDP dissociation inhibition (GDI) activity can antagonize eIF2 reactivation by competing with the eIF2 guanine exchange factor (GEF), eIF2B. The C-terminal domain (CTD) of eIF5, a W2-type HEAT domain, mediates its interaction with eIF2. Here, we characterize a related human protein containing MA3- and W2-type HEAT domains, previously termed BZW2 and renamed here as eIF5-mimic protein 1 (5MP1). Human 5MP1 interacts with eIF2 and eIF3 and inhibits general and gene-specific translation in mammalian systems. We further test whether 5MP1 is a mimic or competitor of the GEF catalytic subunit eIF2Bε or eIF5, using yeast as a model. Our results suggest that 5MP1 interacts with yeast eIF2 and promotes TC formation, but inhibits TC binding to the ribosome. Moreover, 5MP1 is not a GEF but a weak GDI for yeast eIF2. We propose that 5MP1 is a partial mimic and competitor of eIF5, interfering with the key steps by which eIF5 regulates eIF2 function.
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Affiliation(s)
- Chingakham Ranjit Singh
- Molecular Cellular and Developmental Biology Program, Division of Biology, Kansas State University, Manhattan, KS 66506, Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, IN 46202, USA, Faculty of Life Sciences, The University of Manchester, Manchester, M13 9PT, UK, Department of Chemical Science and Engineering, Graduate School of Engineering, Kobe University, Kobe 657-8501, Japan and NIDCR, NIH, Bethesda, MD 20892, USA
| | - Ryosuke Watanabe
- Molecular Cellular and Developmental Biology Program, Division of Biology, Kansas State University, Manhattan, KS 66506, Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, IN 46202, USA, Faculty of Life Sciences, The University of Manchester, Manchester, M13 9PT, UK, Department of Chemical Science and Engineering, Graduate School of Engineering, Kobe University, Kobe 657-8501, Japan and NIDCR, NIH, Bethesda, MD 20892, USA
| | - Donghui Zhou
- Molecular Cellular and Developmental Biology Program, Division of Biology, Kansas State University, Manhattan, KS 66506, Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, IN 46202, USA, Faculty of Life Sciences, The University of Manchester, Manchester, M13 9PT, UK, Department of Chemical Science and Engineering, Graduate School of Engineering, Kobe University, Kobe 657-8501, Japan and NIDCR, NIH, Bethesda, MD 20892, USA
| | - Martin D. Jennings
- Molecular Cellular and Developmental Biology Program, Division of Biology, Kansas State University, Manhattan, KS 66506, Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, IN 46202, USA, Faculty of Life Sciences, The University of Manchester, Manchester, M13 9PT, UK, Department of Chemical Science and Engineering, Graduate School of Engineering, Kobe University, Kobe 657-8501, Japan and NIDCR, NIH, Bethesda, MD 20892, USA
| | - Akira Fukao
- Molecular Cellular and Developmental Biology Program, Division of Biology, Kansas State University, Manhattan, KS 66506, Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, IN 46202, USA, Faculty of Life Sciences, The University of Manchester, Manchester, M13 9PT, UK, Department of Chemical Science and Engineering, Graduate School of Engineering, Kobe University, Kobe 657-8501, Japan and NIDCR, NIH, Bethesda, MD 20892, USA
| | - Bumjun Lee
- Molecular Cellular and Developmental Biology Program, Division of Biology, Kansas State University, Manhattan, KS 66506, Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, IN 46202, USA, Faculty of Life Sciences, The University of Manchester, Manchester, M13 9PT, UK, Department of Chemical Science and Engineering, Graduate School of Engineering, Kobe University, Kobe 657-8501, Japan and NIDCR, NIH, Bethesda, MD 20892, USA
| | - Yuka Ikeda
- Molecular Cellular and Developmental Biology Program, Division of Biology, Kansas State University, Manhattan, KS 66506, Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, IN 46202, USA, Faculty of Life Sciences, The University of Manchester, Manchester, M13 9PT, UK, Department of Chemical Science and Engineering, Graduate School of Engineering, Kobe University, Kobe 657-8501, Japan and NIDCR, NIH, Bethesda, MD 20892, USA
| | - John A. Chiorini
- Molecular Cellular and Developmental Biology Program, Division of Biology, Kansas State University, Manhattan, KS 66506, Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, IN 46202, USA, Faculty of Life Sciences, The University of Manchester, Manchester, M13 9PT, UK, Department of Chemical Science and Engineering, Graduate School of Engineering, Kobe University, Kobe 657-8501, Japan and NIDCR, NIH, Bethesda, MD 20892, USA
| | - Susan G. Campbell
- Molecular Cellular and Developmental Biology Program, Division of Biology, Kansas State University, Manhattan, KS 66506, Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, IN 46202, USA, Faculty of Life Sciences, The University of Manchester, Manchester, M13 9PT, UK, Department of Chemical Science and Engineering, Graduate School of Engineering, Kobe University, Kobe 657-8501, Japan and NIDCR, NIH, Bethesda, MD 20892, USA
| | - Mark P. Ashe
- Molecular Cellular and Developmental Biology Program, Division of Biology, Kansas State University, Manhattan, KS 66506, Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, IN 46202, USA, Faculty of Life Sciences, The University of Manchester, Manchester, M13 9PT, UK, Department of Chemical Science and Engineering, Graduate School of Engineering, Kobe University, Kobe 657-8501, Japan and NIDCR, NIH, Bethesda, MD 20892, USA
| | - Toshinobu Fujiwara
- Molecular Cellular and Developmental Biology Program, Division of Biology, Kansas State University, Manhattan, KS 66506, Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, IN 46202, USA, Faculty of Life Sciences, The University of Manchester, Manchester, M13 9PT, UK, Department of Chemical Science and Engineering, Graduate School of Engineering, Kobe University, Kobe 657-8501, Japan and NIDCR, NIH, Bethesda, MD 20892, USA
| | - Ronald C. Wek
- Molecular Cellular and Developmental Biology Program, Division of Biology, Kansas State University, Manhattan, KS 66506, Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, IN 46202, USA, Faculty of Life Sciences, The University of Manchester, Manchester, M13 9PT, UK, Department of Chemical Science and Engineering, Graduate School of Engineering, Kobe University, Kobe 657-8501, Japan and NIDCR, NIH, Bethesda, MD 20892, USA
| | - Graham D. Pavitt
- Molecular Cellular and Developmental Biology Program, Division of Biology, Kansas State University, Manhattan, KS 66506, Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, IN 46202, USA, Faculty of Life Sciences, The University of Manchester, Manchester, M13 9PT, UK, Department of Chemical Science and Engineering, Graduate School of Engineering, Kobe University, Kobe 657-8501, Japan and NIDCR, NIH, Bethesda, MD 20892, USA
| | - Katsura Asano
- Molecular Cellular and Developmental Biology Program, Division of Biology, Kansas State University, Manhattan, KS 66506, Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, IN 46202, USA, Faculty of Life Sciences, The University of Manchester, Manchester, M13 9PT, UK, Department of Chemical Science and Engineering, Graduate School of Engineering, Kobe University, Kobe 657-8501, Japan and NIDCR, NIH, Bethesda, MD 20892, USA
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42
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Siddiqui-Jain A, Drygin D, Streiner N, Chua P, Pierre F, O'Brien SE, Bliesath J, Omori M, Huser N, Ho C, Proffitt C, Schwaebe MK, Ryckman DM, Rice WG, Anderes K. CX-4945, an Orally Bioavailable Selective Inhibitor of Protein Kinase CK2, Inhibits Prosurvival and Angiogenic Signaling and Exhibits Antitumor Efficacy. Cancer Res 2010; 70:10288-98. [DOI: 10.1158/0008-5472.can-10-1893] [Citation(s) in RCA: 395] [Impact Index Per Article: 28.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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43
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An integrated approach to uncover drivers of cancer. Cell 2010; 143:1005-17. [PMID: 21129771 DOI: 10.1016/j.cell.2010.11.013] [Citation(s) in RCA: 354] [Impact Index Per Article: 25.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2010] [Revised: 08/31/2010] [Accepted: 10/22/2010] [Indexed: 11/23/2022]
Abstract
Systematic characterization of cancer genomes has revealed a staggering number of diverse aberrations that differ among individuals, such that the functional importance and physiological impact of most tumor genetic alterations remain poorly defined. We developed a computational framework that integrates chromosomal copy number and gene expression data for detecting aberrations that promote cancer progression. We demonstrate the utility of this framework using a melanoma data set. Our analysis correctly identified known drivers of melanoma and predicted multiple tumor dependencies. Two dependencies, TBC1D16 and RAB27A, confirmed empirically, suggest that abnormal regulation of protein trafficking contributes to proliferation in melanoma. Together, these results demonstrate the ability of integrative Bayesian approaches to identify candidate drivers with biological, and possibly therapeutic, importance in cancer.
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44
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Hershey JWB. Regulation of protein synthesis and the role of eIF3 in cancer. Braz J Med Biol Res 2010; 43:920-30. [PMID: 20922269 DOI: 10.1590/s0100-879x2010007500098] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2010] [Accepted: 09/08/2010] [Indexed: 02/06/2023] Open
Abstract
Maintenance of cell homeostasis and regulation of cell proliferation depend importantly on regulating the process of protein synthesis. Many disease states arise when disregulation of protein synthesis occurs. This review focuses on mechanisms of translational control and how disregulation results in cell malignancy. Most translational controls occur during the initiation phase of protein synthesis, with the initiation factors being the major target of regulation through their phosphorylation. In particular, the recruitment of mRNAs through the m⁷G-cap structure and the binding of the initiator methionyl-tRNA(i) are frequent targets. However, translation, especially of specific mRNAs, may also be regulated by sequestration into processing bodies or stress granules, by trans-acting proteins or by microRNAs. When the process of protein synthesis is hyper-activated, weak mRNAs are translated relatively more efficiently, leading to an imbalance of cellular proteins that promotes cell proliferation and malignant transformation. This occurs, for example, when the cap-binding protein, eIF4E, is overexpressed, or when the methionyl-tRNA(i)-binding factor, eIF2, is too active. In addition, enhanced activity of eIF3 contributes to oncogenesis. The importance of the translation initiation factors as regulators of protein synthesis and cell proliferation makes them potential therapeutic targets for the treatment of cancer.
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Affiliation(s)
- John W B Hershey
- Department of Biochemistry and Molecular Medicine, University of California, Davis, 95616, USA.
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45
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CK2 activity is modulated by growth rate in Saccharomyces cerevisiae. Biochem Biophys Res Commun 2010; 398:44-50. [DOI: 10.1016/j.bbrc.2010.06.028] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2010] [Accepted: 06/05/2010] [Indexed: 02/02/2023]
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46
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Inhibitory activity of blasticidin A, a strong aflatoxin production inhibitor, on protein synthesis of yeast: selective inhibition of aflatoxin production by protein synthesis inhibitors. J Antibiot (Tokyo) 2010; 63:309-14. [PMID: 20414321 DOI: 10.1038/ja.2010.36] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Blasticidin A (BcA), an antibiotic produced by Streptomyces, inhibits aflatoxin production without strong growth inhibition toward aflatoxin-producing fungi. During the course of our study on the mode of action of BcA by two-dimensional differential gel electrophoresis (2D-DIGE), we found a decrease in the abundances of ribosomal proteins in Saccharomyces cerevisiae after exposure to BcA. This phenomenon was also observed by treatment with blasticidin S (BcS) or cycloheximide. BcA inhibited protein synthesis in a galactose-induced expression system in S. cerevisiae similar to BcS and cycloheximide. BcS, but not cycloheximide, inhibited aflatoxin production in Aspergillus parasiticus without inhibition of fungal growth, similar to BcA. A decrease in the abundances of aflatoxin biosynthetic enzymes was observed in 2D-DIGE experiments with Aspergillus flavus after exposure to BcA or BcS. These results suggested that protein synthesis inhibitors are useful to control aflatoxin production.
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47
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Mahoney SJ, Dempsey JM, Blenis J. Cell signaling in protein synthesis ribosome biogenesis and translation initiation and elongation. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2009; 90:53-107. [PMID: 20374739 DOI: 10.1016/s1877-1173(09)90002-3] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Protein synthesis is a highly energy-consuming process that must be tightly regulated. Signal transduction cascades respond to extracellular and intracellular cues to phosphorylate proteins involved in ribosomal biogenesis and translation initiation and elongation. These phosphorylation events regulate the timing and rate of translation of both specific and total mRNAs. Alterations in this regulation can result in dysfunction and disease. While many signaling pathways intersect to control protein synthesis, the mTOR and MAPK pathways appear to be key players. This chapter briefly reviews the mTOR and MAPK pathways and then focuses on individual phosphorylation events that directly control ribosome biogenesis and translation.
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Affiliation(s)
- Sarah J Mahoney
- Department of Cell Biology, Harvard Medical School, Boston, Massachusetts 02115, USA
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48
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Dennis MD, Person MD, Browning KS. Phosphorylation of plant translation initiation factors by CK2 enhances the in vitro interaction of multifactor complex components. J Biol Chem 2009; 284:20615-28. [PMID: 19509420 DOI: 10.1074/jbc.m109.007658] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
CK2 phosphorylates a wide variety of substrates, including translation initiation factors. A mass spectrometric approach was used to identify residues phosphorylated by CK2, which may regulate the activity of initiation factors during the translation initiation process in plants. CK2 in vitro phosphorylation sites were identified in wheat and Arabidopsis thaliana eIF2alpha, eIF2beta, eIF5, and wheat eIF3c. Native wheat eIF5 and eIF2alpha were found to have phosphorylation sites that corresponded to some of the in vitro CK2 phosphorylation sites. A large number of the CK2 sites identified in this study are in conserved binding domains that have been implicated in the yeast multifactor complex (eIF1-eIF3-eIF5-eIF2-GTP-Met-tRNA(i)(Met)). This is the first study to demonstrate that plant initiation factors are capable of forming a multifactor complex in vitro. In addition, the interaction of factors within these complexes was enhanced both in vitro and in native extracts by phosphorylation of one or more initiation factors by CK2. The importance of CK2 phosphorylation of eIF5 was evaluated by site-directed mutagenesis of eIF5 to remove CK2 phosphorylation sites. Removal of CK2 phosphorylation sites from eIF5 inhibits the CK2-mediated increase in eIF5 interaction with eIF1 and eIF3c in pulldown assays and reduces the eIF5-mediated stimulation of translation initiation in vitro. These results suggest a functional role for CK2 phosphorylation in the initiation of plant translation.
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Affiliation(s)
- Michael D Dennis
- Department of Chemistry and Biochemistry, Institute for Cellular and Molecular Biology, University of Texas, Austin, Texas 78712, USA
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49
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Dennis MD, Browning KS. Differential phosphorylation of plant translation initiation factors by Arabidopsis thaliana CK2 holoenzymes. J Biol Chem 2009; 284:20602-14. [PMID: 19509278 DOI: 10.1074/jbc.m109.006692] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
A previously described wheat germ protein kinase (Yan, T. F., and Tao, M. (1982) J. Biol. Chem. 257, 7037-7043) was identified unambiguously as CK2 using mass spectrometry. CK2 is a ubiquitous eukaryotic protein kinase that phosphorylates a wide range of substrates. In previous studies, this wheat germ kinase was shown to phosphorylate eIF2alpha, eIF3c, and three large subunit (60 S) ribosomal proteins (Browning, K. S., Yan, T. F., Lauer, S. J., Aquino, L. A., Tao, M., and Ravel, J. M. (1985) Plant Physiol. 77, 370-373). To further characterize the role of CK2 in the regulation of translation initiation, Arabidopsis thaliana catalytic (alpha1 and alpha2) and regulatory (beta1, beta2, beta3, and beta4) subunits of CK2 were cloned and expressed in Escherichia coli. Recombinant A. thaliana CK2beta subunits spontaneously dimerize and assemble into holoenzymes in the presence of either CK2alpha1 or CK2alpha2 and exhibit autophosphorylation. The purified CK2 subunits were used to characterize the properties of the individual subunits and their ability to phosphorylate various plant protein substrates. CK2 was shown to phosphorylate eIF2alpha, eIF2beta, eIF3c, eIF4B, eIF5, and histone deacetylase 2B but did not phosphorylate eIF1, eIF1A, eIF4A, eIF4E, eIF4G, eIFiso4E, or eIFiso4G. Differential phosphorylation was exhibited by CK2 in the presence of various regulatory beta-subunits. Analysis of A. thaliana mutants either lacking or overexpressing CK2 subunits showed that the amount of eIF2beta protein present in extracts was affected, which suggests that CK2 phosphorylation may play a role in eIF2beta stability. These results provide evidence for a potential mechanism through which the expression and/or subcellular distribution of CK2 beta-subunits could participate in the regulation of the initiation of translation and other physiological processes in plants.
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Affiliation(s)
- Michael D Dennis
- Department of Chemistry and Biochemistry and the Institute for Cellular and Molecular Biology, University of Texas, Austin, Texas 78712, USA
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50
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Abstract
Casein kinase 2 (CK2) is a highly conserved and ubiquitous eukaryotic Ser/Thr protein kinase. Genetic, biochemical, and cell biological studies have indicated the involvement of this enzyme in the control of cell proliferation and in signal transduction. The regulation of CK2 is not well defined, and it has been considered a constitutively non-regulated protein kinase. However, we show that CK2 activation occurred during the progression of cell cycle in response to FBS stimuli of G0 arrested cells. Importantly, we show that as the downstream target for CK2, the phosphorylation of eukaryotic translation-initiation factor eIF5 by CK2 may play a critical role in cell cycle progression. We find that eIF5 is associated with CK2 when the kinase activity is at the highest level in vivo, and is phosphorylated at Ser389 and Ser390 by CK2. Expression of eIF5 mutants that lack those phosphorylation sites reveals that these mutants have a dominant-negative effect on phosphorylation of endogenous eIF5, as well as a significant reduction in the formation of the mature complex, in the growth rate, and the expression of cell cycle-regulated proteins. Also, a pool of CK2 translocates into the nuclear fraction following its activation during the progression of the cell cycle. Consistent with these findings, we report that CK2 may be involved in the regulation of cell cycle progression through the phosphorylation of a key molecule for translation initiation and of nuclear substrates upon activation of CK2 by itself.
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