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Wakasugi K, Yokosawa T. The high-affinity tryptophan uptake transport system in human cells. Biochem Soc Trans 2024; 52:1149-1158. [PMID: 38813870 DOI: 10.1042/bst20230742] [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: 02/28/2024] [Revised: 05/15/2024] [Accepted: 05/20/2024] [Indexed: 05/31/2024]
Abstract
The L-tryptophan (Trp) transport system is highly selective for Trp with affinity in the nanomolar range. This transport system is augmented in human interferon (IFN)-γ-treated and indoleamine 2,3-dioxygenase 1 (IDO1)-expressing cells. Up-regulated cellular uptake of Trp causes a reduction in extracellular Trp and initiates immune suppression. Recent studies demonstrate that both IDO1 and tryptophanyl-tRNA synthetase (TrpRS), whose expression levels are up-regulated by IFN-γ, play a pivotal role in high-affinity Trp uptake into human cells. Furthermore, overexpression of tryptophan 2,3-dioxygenase (TDO2) elicits a similar effect as IDO1 on TrpRS-mediated high-affinity Trp uptake. In this review, we summarize recent findings regarding this Trp uptake system and put forward a possible molecular mechanism based on Trp deficiency induced by IDO1 or TDO2 and tryptophanyl-AMP production by TrpRS.
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Affiliation(s)
- Keisuke Wakasugi
- Komaba Organization for Educational Excellence, The University of Tokyo, 3-8-1 Komaba, Meguro-ku, Tokyo 153-8902, Japan
- Department of Life Sciences, Graduate School of Arts and Sciences, The University of Tokyo, 3-8-1 Komaba, Meguro-ku, Tokyo 153-8902, Japan
- Department of Biological Sciences, Graduate School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
| | - Takumi Yokosawa
- Komaba Organization for Educational Excellence, The University of Tokyo, 3-8-1 Komaba, Meguro-ku, Tokyo 153-8902, Japan
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2
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Yokosawa T, Wakasugi K. Tryptophan-Starved Human Cells Overexpressing Tryptophanyl-tRNA Synthetase Enhance High-Affinity Tryptophan Uptake via Enzymatic Production of Tryptophanyl-AMP. Int J Mol Sci 2023; 24:15453. [PMID: 37895133 PMCID: PMC10607379 DOI: 10.3390/ijms242015453] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2023] [Revised: 10/18/2023] [Accepted: 10/21/2023] [Indexed: 10/29/2023] Open
Abstract
Our previous study demonstrated that L-tryptophan (Trp)-depleted cells display a marked enhancement in Trp uptake facilitated by extracellular tryptophanyl-tRNA synthetase (TrpRS). Here, we show that Trp uptake into TrpRS-overexpressing cells is also markedly elevated upon Trp starvation. These findings indicate that a Trp-deficient condition is critical for Trp uptake, not only into cells to which TrpRS protein has been added but also into TrpRS-overexpressing cells. We also show that overexpression of TrpRS mutants, which cannot synthesize tryptophanyl-AMP, does not promote Trp uptake, and that inhibition of tryptophanyl-AMP synthesis suppresses this uptake. Overall, these data suggest that tryptophanyl-AMP production by TrpRS is critical for high-affinity Trp uptake.
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Affiliation(s)
- Takumi Yokosawa
- Komaba Organization for Educational Excellence, The University of Tokyo, 3-8-1 Komaba, Meguro-ku, Tokyo 153-8902, Japan
| | - Keisuke Wakasugi
- Komaba Organization for Educational Excellence, The University of Tokyo, 3-8-1 Komaba, Meguro-ku, Tokyo 153-8902, Japan
- Department of Life Sciences, Graduate School of Arts and Sciences, The University of Tokyo, 3-8-1 Komaba, Meguro-ku, Tokyo 153-8902, Japan
- Department of Biological Sciences, Graduate School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
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Rubio A, Ghosh S, Mülleder M, Ralser M, Mata J. Ribosome profiling reveals ribosome stalling on tryptophan codons and ribosome queuing upon oxidative stress in fission yeast. Nucleic Acids Res 2021; 49:383-399. [PMID: 33313903 PMCID: PMC7797079 DOI: 10.1093/nar/gkaa1180] [Citation(s) in RCA: 34] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2020] [Revised: 11/13/2020] [Accepted: 11/19/2020] [Indexed: 12/11/2022] Open
Abstract
Translational control is essential in response to stress. We investigated the translational programmes launched by the fission yeast Schizosaccharomyces pombe upon five environmental stresses. We also explored the contribution of defence pathways to these programmes: The Integrated Stress Response (ISR), which regulates translation initiation, and the stress-response MAPK pathway. We performed ribosome profiling of cells subjected to each stress, in wild type cells and in cells with the defence pathways inactivated. The transcription factor Fil1, a functional homologue of the yeast Gcn4 and the mammalian Atf4 proteins, was translationally upregulated and required for the response to most stresses. Moreover, many mRNAs encoding proteins required for ribosome biogenesis were translationally downregulated. Thus, several stresses trigger a universal translational response, including reduced ribosome production and a Fil1-mediated transcriptional programme. Surprisingly, ribosomes stalled on tryptophan codons upon oxidative stress, likely due to a decrease in charged tRNA-Tryptophan. Stalling caused ribosome accumulation upstream of tryptophan codons (ribosome queuing/collisions), demonstrating that stalled ribosomes affect translation elongation by other ribosomes. Consistently, tryptophan codon stalling led to reduced translation elongation and contributed to the ISR-mediated inhibition of initiation. We show that different stresses elicit common and specific translational responses, revealing a novel role in Tryptophan-tRNA availability.
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Affiliation(s)
- Angela Rubio
- Department of Biochemistry, University of Cambridge, UK
| | - Sanjay Ghosh
- Department of Biochemistry, University of Cambridge, UK
| | - Michael Mülleder
- The Molecular Biology of Metabolism Laboratory, The Francis Crick Institute, London, UK
| | - Markus Ralser
- The Molecular Biology of Metabolism Laboratory, The Francis Crick Institute, London, UK.,Department of Biochemistry, Charité University Medicine, Berlin, Germany
| | - Juan Mata
- Department of Biochemistry, University of Cambridge, UK
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4
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Yokosawa T, Sato A, Wakasugi K. Tryptophan Depletion Modulates Tryptophanyl-tRNA Synthetase-Mediated High-Affinity Tryptophan Uptake into Human Cells. Genes (Basel) 2020; 11:genes11121423. [PMID: 33261077 PMCID: PMC7760169 DOI: 10.3390/genes11121423] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2020] [Revised: 11/07/2020] [Accepted: 11/25/2020] [Indexed: 12/14/2022] Open
Abstract
The novel high-affinity tryptophan (Trp)-selective transport system is present at elevated levels in human interferon-γ (IFN-γ)-treated and indoleamine 2,3-dioxygenase 1 (IDO1)-expressing cells. High-affinity Trp uptake into cells results in extracellular Trp depletion and immune suppression. We have previously shown that both IDO1 and tryptophanyl-tRNA synthetase (TrpRS), whose expression levels are increased by IFN-γ, have a crucial function in high-affinity Trp uptake into human cells. Here, we aimed to elucidate the relationship between TrpRS and IDO1 in high-affinity Trp uptake. We demonstrated that overexpression of IDO1 in HeLa cells drastically enhances high-affinity Trp uptake upon addition of purified TrpRS protein to uptake assay buffer. We also clarified that high-affinity Trp uptake by Trp-starved cells is significantly enhanced by the addition of TrpRS protein to the assay buffer. Moreover, we showed that high-affinity Trp uptake is also markedly elevated by the addition of TrpRS protein to the assay buffer of cells overexpressing another Trp-metabolizing enzyme, tryptophan 2,3-dioxygenase (TDO2). Taken together, we conclude that Trp deficiency is crucial for high-affinity Trp uptake mediated by extracellular TrpRS.
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Affiliation(s)
- Takumi Yokosawa
- Department of Biological Sciences, Graduate School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan;
| | - Aomi Sato
- Department of Life Sciences, Graduate School of Arts and Sciences, The University of Tokyo, 3-8-1 Komaba, Meguro-ku, Tokyo 153-8902, Japan;
| | - Keisuke Wakasugi
- Department of Biological Sciences, Graduate School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan;
- Department of Life Sciences, Graduate School of Arts and Sciences, The University of Tokyo, 3-8-1 Komaba, Meguro-ku, Tokyo 153-8902, Japan;
- Correspondence: ; Tel.: +81-3-5454-4392
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5
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Wakasugi K, Yokosawa T. Non-canonical functions of human cytoplasmic tyrosyl-, tryptophanyl- and other aminoacyl-tRNA synthetases. Enzymes 2020; 48:207-242. [PMID: 33837705 DOI: 10.1016/bs.enz.2020.04.001] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Aminoacyl-tRNA synthetases catalyze the aminoacylation of their cognate tRNAs. Here we review the accumulated knowledge of non-canonical functions of human cytoplasmic aminoacyl-tRNA synthetases, especially tyrosyl- (TyrRS) and tryptophanyl-tRNA synthetase (TrpRS). Human TyrRS and TrpRS have an extra domain. Two distinct cytokines, i.e., the core catalytic "mini TyrRS" and the extra C-domain, are generated from human TyrRS by proteolytic cleavage. Moreover, the core catalytic domains of human TyrRS and TrpRS function as angiogenic and angiostatic factors, respectively, whereas the full-length forms are inactive for this function. It is also known that many synthetases change their localization in response to a specific signal and subsequently exhibit alternative functions. Furthermore, some synthetases function as sensors for amino acids by changing their protein interactions in an amino acid-dependent manner. Further studies will be necessary to elucidate regulatory mechanisms of non-canonical functions of aminoacyl-tRNA synthetases in particular, by analyzing the effect of their post-translational modifications.
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Affiliation(s)
- Keisuke Wakasugi
- Department of Life Sciences, Graduate School of Arts and Sciences, The University of Tokyo, Tokyo, Japan; Department of Biological Sciences, Graduate School of Science, The University of Tokyo, Tokyo, Japan.
| | - Takumi Yokosawa
- Department of Biological Sciences, Graduate School of Science, The University of Tokyo, Tokyo, Japan
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Miyanokoshi M, Yokosawa T, Wakasugi K. Tryptophanyl-tRNA synthetase mediates high-affinity tryptophan uptake into human cells. J Biol Chem 2018; 293:8428-8438. [PMID: 29666190 DOI: 10.1074/jbc.ra117.001247] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2017] [Revised: 04/03/2018] [Indexed: 01/08/2023] Open
Abstract
The tryptophan (Trp) transport system has a high affinity and selectivity toward Trp, and has been reported to exist in both human and mouse macrophages. Although this system is highly expressed in interferon-γ (IFN-γ)-treated cells and indoleamine 2,3-dioxygenase 1 (IDO1)-expressing cells, its identity remains incompletely understood. Tryptophanyl-tRNA synthetase (TrpRS) is also highly expressed in IFN-γ-treated cells and also has high affinity and selectivity for Trp. Here, we investigated the effects of human TrpRS expression on Trp uptake into IFN-γ-treated human THP-1 monocytes or HeLa cells. Inhibition of human TrpRS expression by TrpRS-specific siRNAs decreased and overexpression of TrpRS increased Trp uptake into the cells. Of note, the TrpRS-mediated uptake system had more than hundred-fold higher affinity for Trp than the known System L amino acid transporter, promoted uptake of low Trp concentrations, and had very high Trp selectivity. Moreover, site-directed mutagenesis experiments indicated that Trp- and ATP-binding sites, but not tRNA-binding sites, in TrpRS are essential for TrpRS-mediated Trp uptake into the human cells. We further demonstrate that the addition of purified TrpRS to cell culture medium increases Trp uptake into cells. Taken together, our results reveal that TrpRS plays an important role in high-affinity Trp uptake into human cells.
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Affiliation(s)
- Miki Miyanokoshi
- From the Department of Life Sciences, Graduate School of Arts and Sciences, University of Tokyo, 3-8-1 Komaba, Meguro-ku, Tokyo 153-8902, Japan and
| | - Takumi Yokosawa
- Department of Biological Sciences, Graduate School of Science, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
| | - Keisuke Wakasugi
- From the Department of Life Sciences, Graduate School of Arts and Sciences, University of Tokyo, 3-8-1 Komaba, Meguro-ku, Tokyo 153-8902, Japan and .,Department of Biological Sciences, Graduate School of Science, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
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7
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Identification of a residue crucial for the angiostatic activity of human mini tryptophanyl-tRNA synthetase by focusing on its molecular evolution. Sci Rep 2016; 6:24750. [PMID: 27094087 PMCID: PMC4837363 DOI: 10.1038/srep24750] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2015] [Accepted: 04/04/2016] [Indexed: 11/28/2022] Open
Abstract
Human tryptophanyl-tRNA synthetase (TrpRS) exists in two forms: a full-length TrpRS and a mini TrpRS. We previously found that human mini, but not full-length, TrpRS is an angiostatic factor. Moreover, it was shown that the interaction between mini TrpRS and the extracellular domain of vascular endothelial (VE)-cadherin is crucial for its angiostatic activity. However, the molecular mechanism of the angiostatic activity of human mini TrpRS is only partly understood. In the present study, we investigated the effects of truncated (mini) form of TrpRS proteins from human, bovine, or zebrafish on vascular endothelial growth factor (VEGF)-stimulated chemotaxis of human umbilical vein endothelial cells (HUVECs). We show that both human and bovine mini TrpRSs inhibited VEGF-induced endothelial migration, whereas zebrafish mini TrpRS did not. Next, to identify residues crucial for the angiostatic activity of human mini TrpRS, we prepared several site-directed mutants based on amino acid sequence alignments among TrpRSs from various species and demonstrated that a human mini K153Q TrpRS mutant cannot inhibit VEGF-stimulated HUVEC migration and cannot bind to the extracellular domain of VE-cadherin. Taken together, we conclude that the Lys153 residue of human mini TrpRS is a VE-cadherin binding site and is therefore crucial for its angiostatic activity.
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Xie J, Bai X, Lavoie M, Lu H, Fan X, Pan X, Fu Z, Qian H. Analysis of the Proteome of the Marine Diatom Phaeodactylum tricornutum Exposed to Aluminum Providing Insights into Aluminum Toxicity Mechanisms. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2015; 49:11182-11190. [PMID: 26308585 DOI: 10.1021/acs.est.5b03272] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Trace aluminum (Al) concentrations can be toxic to marine phytoplankton, the basis of the marine food web, but the fundamental Al toxicity and detoxification mechanisms at the molecular levels are poorly understood. Using an array of proteomic, transcriptomic, and biochemical techniques, we describe in detail the cellular response of the model marine diatom Phaeodactylum tricornutum to a short-term sublethal Al stress (4 h of exposure to 200 μM total initial Al). A total of 2204 proteins were identified and quantified by isobaric tags for relative and absolute quantification (iTRAQ) in response to the Al stress. Among them, 87 and 78 proteins performing various cell functions were up- and down-regulated after Al treatment, respectively. We found that photosynthesis was a key Al toxicity target. The Al-induced decrease in electron transport rates in thylakoid membranes lead to an increase in reactive oxygen species (ROS) production, which cause increased lipid peroxidation. Several ROS-detoxifying proteins were induced to help decrease Al-induced oxidative stress. In parallel, glycolysis and pentose phosphate pathway were up-regulated in order to produce cell energy (NADPH, ATP) and carbon skeleton for cell growth, partially circumventing the Al-induced toxicity effects on photosynthesis. These cellular responses to Al stress were coordinated by the activation of various signal transduction pathways. The identification of Al-responsive proteins in the model marine phytoplankton P. tricornutum provides new insights on Al stress responses as well as a good start for further exploring Al detoxification mechanisms.
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Affiliation(s)
- Jun Xie
- College of Biological and Environmental Engineering, Zhejiang University of Technology , Hangzhou, Zhejiang 310032, P. R. of China
| | - Xiaocui Bai
- Department of Food Science and Technology, Zhejiang University of Technology , Hangzhou, Zhejiang 310032, P. R. of China
| | - Michel Lavoie
- Quebec-Ocean and Takuvik Joint International Research Unit, Université Laval , Québec City, Québec G1V 0A6 Canada
| | - Haiping Lu
- College of Agriculture and Biotechnology, Zhejiang University , Hangzhou, Zhejiang 310058, P. R. of China
| | - Xiaoji Fan
- College of Biological and Environmental Engineering, Zhejiang University of Technology , Hangzhou, Zhejiang 310032, P. R. of China
| | - Xiangliang Pan
- Xinjiang Key Laboratory of Environmental Pollution and Bioremediation, Chinese Academy of Sciences , Urumqi, Xinjiang 830011, P. R. of China
| | - Zhengwei Fu
- College of Biological and Environmental Engineering, Zhejiang University of Technology , Hangzhou, Zhejiang 310032, P. R. of China
| | - Haifeng Qian
- College of Biological and Environmental Engineering, Zhejiang University of Technology , Hangzhou, Zhejiang 310032, P. R. of China
- Department of Food Science and Technology, Zhejiang University of Technology , Hangzhou, Zhejiang 310032, P. R. of China
- Xinjiang Key Laboratory of Environmental Pollution and Bioremediation, Chinese Academy of Sciences , Urumqi, Xinjiang 830011, P. R. of China
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9
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Zhou X, Xu N, Li R, Xiao Y, Gao G, Lu Q, Ding L, Li L, Li Y, Du Q, Liu X. A comparative proteomic study of Homoharringtonine-induced apoptosis in leukemia K562 cells. Leuk Lymphoma 2015; 56:2162-9. [PMID: 25330443 DOI: 10.3109/10428194.2014.976818] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
The objective of this study was to determine the changes in protein profiles of K562 chronic myeloid leukemia (CML) cells in response to Homoharringtonine (HHT). HHT treatment significantly increased apoptosis of K562 cells. Proteomic analyses indicated 32 differentially expressed proteins, 13 of which were identified by mass spectrometry (nine down-regulated and four up-regulated). Aside from alterations in apoptotic proteins and proteins associated with transcription and translation, our data also revealed changes in oxidative stress response and redox reaction-related proteins, such as heat shock proteins (Hsps), DJ-1 and thioredoxin. Specifically, these proteins were validated to decrease after HHT treatment in K562 cells and in primary CML cells by immunoblot analysis. Additionally, Hsps, DJ-1 and thioredoxin, which were also shown to decrease in primary cells from imatinib-resistant patients, may be promising potential targets for mechanistic research and new clinical treatments.
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10
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Miyanokoshi M, Tanaka T, Tamai M, Tagawa YI, Wakasugi K. Expression of the rodent-specific alternative splice variant of tryptophanyl-tRNA synthetase in murine tissues and cells. Sci Rep 2013; 3:3477. [PMID: 24327169 PMCID: PMC3858792 DOI: 10.1038/srep03477] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2013] [Accepted: 11/26/2013] [Indexed: 11/30/2022] Open
Abstract
Tryptophanyl-tRNA synthetase (TrpRS) catalyzes the aminoacylation of tRNATrp. mRNA of a rodent-specific alternative splice variant of TrpRS (SV-TrpRS), which results in the inclusion of an additional hexapeptide at the C-terminus of full-length TrpRS (FL-TrpRS), has been identified in murine embryonic stem (ES) cells. In the present study, we evaluated the expression of mouse TrpRS mRNA by real-time reverse transcription PCR. We show that SV-TrpRS and FL-TrpRS mRNAs are highly expressed in murine ES cells, embryo, spleen, lung, liver and uterus, and that the relative expression of SV-TrpRS compared to FL-TrpRS is significantly less in the brain. Moreover, we found that interferon-γ increases the expression of TrpRS in a mouse cell line. These results provide the first evidence for tissue-specific expression and alternative splicing of mouse TrpRS.
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Affiliation(s)
- Miki Miyanokoshi
- Department of Life Sciences, Graduate School of Arts and Sciences, The University of Tokyo, 3-8-1 Komaba, Meguro-ku, Tokyo 153-8902, Japan
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11
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Abstract
GAPDH interacts with a plethora of diverse cellular proteins. The network of interacting partners, or interactome, is presented for GAPDH with the interacting molecules grouped into specific functional and structural categories. By organizing the binding partners in this way, certain common structural features are beginning to surface, such as acidic dipeptide sequences that are found in several of these binding proteins. Additionally, the consensus sequences for target polynucleotides are being brought to light. The categories, which are presented according to function, offer an opportunity for research into the corresponding structural correlates to these interactions. Recent discoveries of interacting proteins have revealed novel relationships that are generating emerging mechanisms. Proteins that are associated with age-related neurodegenerative diseases appear to be particularly prone to binding GAPDH, suggesting that GAPDH may be playing a role in these diseases. Neurodegenerative diseases that are discussed are the conformational diseases of aging, suggesting that GAPDH may be a global sensor for cellular conformational stress. In addition to GAPDH's oxidoreductase activity, several other enzymatic functions have been discovered, including peroxidase, nitrosylase, mono-ADP-ribosylase and kinase activities.
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Affiliation(s)
- Norbert W Seidler
- Department of Biochemistry, Kansas City University of Medicine and Biosciences, Kansas City, MO, USA
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12
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Watanabe S, Wakasugi K. Module M1 of zebrafish neuroglobin acts as a structural and functional protein building block for a cell-membrane-penetrating activity. PLoS One 2011; 6:e16808. [PMID: 21304818 PMCID: PMC3033418 DOI: 10.1371/journal.pone.0016808] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2010] [Accepted: 12/31/2010] [Indexed: 11/18/2022] Open
Abstract
Neuroglobin (Ngb) is a recently discovered vertebrate globin that is expressed in the brain and can reversibly bind oxygen. Mammalian Ngb is involved in neuroprotection during oxidative stress that occurs, for example, during ischemia and reperfusion. Recently, we found that zebrafish, but not human, Ngb can translocate into cells. Moreover, we demonstrated that a chimeric ZHHH Ngb protein, in which the module M1 of human Ngb is replaced by the corresponding region of zebrafish Ngb, can penetrate cell membranes and protect cells against oxidative stress-induced cell death, suggesting that module M1 of zebrafish Ngb is important for protein transduction. Furthermore, we recently showed that Lys7, Lys9, Lys21, and Lys23 in module M1 of zebrafish Ngb are crucial for protein transduction activity. In the present study, we have investigated whether module M1 of zebrafish Ngb can be used as a building block to create novel cell-membrane-penetrating folded proteins. First, we engineered a chimeric myoglobin (Mb), in which module M1 of zebrafish Ngb was fused to the N-terminus of full-length human Mb, and investigated its functional and structural properties. Our results showed that this chimeric Mb protein is stable and forms almost the same heme environment and α-helical structure as human wild-type Mb. In addition, we demonstrated that chimeric Mb has a cell-membrane-penetrating activity similar to zebrafish Ngb. Moreover, we found that glycosaminoglycan is crucial for the cell-membrane-penetrating activity of chimeric Mb as well as that of zebrafish Ngb. These results enable us to conclude that such module substitutions will facilitate the design and production of novel functional proteins.
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Affiliation(s)
- Seiji Watanabe
- Department of Life Sciences, Graduate School of Arts and Sciences, The University of Tokyo, Tokyo, Japan
| | - Keisuke Wakasugi
- Department of Life Sciences, Graduate School of Arts and Sciences, The University of Tokyo, Tokyo, Japan
- Precursory Research for Embryonic Science and Technology (PRESTO), Japan Science and Technology Agency (JST), Saitama, Japan
- * E-mail:
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13
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Wakasugi K. An Exposed Cysteine Residue of Human Angiostatic Mini Tryptophanyl-tRNA Synthetase. Biochemistry 2010; 49:3156-60. [DOI: 10.1021/bi1000239] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Keisuke Wakasugi
- Department of Life Sciences, Graduate School of Arts and Sciences, The University of Tokyo, 3-8-1 Komaba, Meguro-ku, Tokyo 153-8902, Japan, and PRESTO, Japan Science and Technology (JST), 4-1-8 Honcho, Kawaguchi, Saitama 332-0012, Japan
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14
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Wakasugi K. Species-specific differences in the regulation of the aminoacylation activity of mammalian tryptophanyl-tRNA synthetases. FEBS Lett 2010; 584:229-32. [PMID: 19941862 DOI: 10.1016/j.febslet.2009.11.073] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2009] [Accepted: 11/19/2009] [Indexed: 11/30/2022]
Abstract
Tryptophanyl-tRNA synthetases (TrpRSs) catalyze the aminoacylation of tRNA(Trp). Previously, I demonstrated that Zn(2+)-depleted human TrpRS is enzymatically inactive and that binding of Zn(2+) or heme to human TrpRS stimulates its aminoacylation activity. In the present study, bovine and mouse TrpRSs were found to be constitutively active regardless of the presence of Zn(2+) or ferriprotoporphyrin IX chloride. Mutagenesis experiments demonstrated that the human H130R mutant is constitutively active and that the bovine R135H, E438A double mutant binds with Zn(2+) or heme to enhance its aminoacylation activity as does human wild-type TrpRS. These results provide the first evidence of species-specific regulation of TrpRS activity.
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Affiliation(s)
- Keisuke Wakasugi
- Department of Life Sciences, Graduate School of Arts and Sciences, The University of Tokyo, Tokyo, Japan.
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15
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Watanabe S, Wakasugi K. Zebrafish Neuroglobin Is a Cell-Membrane-Penetrating Globin. Biochemistry 2008; 47:5266-70. [DOI: 10.1021/bi800286m] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Affiliation(s)
- Seiji Watanabe
- Department of Life Sciences, Graduate School of Arts and Sciences, The University of Tokyo, 3-8-1 Komaba, Meguro-ku, Tokyo 153-8902, Japan, and Precursory Research for Embryonic Science and Technology (PRESTO), Japan Science and Technology (JST), 4-1-8 Honcho, Kawaguchi, Saitama 332-0012, Japan
| | - Keisuke Wakasugi
- Department of Life Sciences, Graduate School of Arts and Sciences, The University of Tokyo, 3-8-1 Komaba, Meguro-ku, Tokyo 153-8902, Japan, and Precursory Research for Embryonic Science and Technology (PRESTO), Japan Science and Technology (JST), 4-1-8 Honcho, Kawaguchi, Saitama 332-0012, Japan
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16
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Disher K, Skandalis A. Evidence of the modulation of mRNA splicing fidelity in humans by oxidative stress and p53. Genome 2008; 50:946-53. [PMID: 18059557 DOI: 10.1139/g07-074] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The majority of human genes generate mRNA splice variants and while there is little doubt that alternative splicing is an important biological phenomenon, it has also become apparent that some splice variants are associated with disease. To elucidate the molecular mechanisms responsible for generating aberrant splice variants, we have investigated alternative splicing of the human genes HPRT and POLB following oxidative stress in different genetic backgrounds. Our study revealed that splicing fidelity is sensitive to oxidative stress. Following treatment of cells with H2O2, the overall frequency of aberrant, unproductive splice variants increased in both loci. At least in POLB, splicing fidelity is p53 dependent. In the absence of p53, the frequency of POLB splice variants is elevated but oxidative stress does not further increase the frequency of splice variants. Our data indicate that mis-splicing following oxidative stress represents a novel and significant genotoxic outcome and that it is not simply DNA lesions induced by oxidative stress that lead to mis-splicing but changes in the alternative splicing machinery itself.
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Affiliation(s)
- Kim Disher
- Department of Biological Sciences, Brock University, 500 Glenridge Avenue, St. Catharines, ON L2S 3A1, Canada
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Abstract
We identified 1113 articles (103 reviews, 1010 primary research articles) published in 2005 that describe experiments performed using commercially available optical biosensors. While this number of publications is impressive, we find that the quality of the biosensor work in these articles is often pretty poor. It is a little disappointing that there appears to be only a small set of researchers who know how to properly perform, analyze, and present biosensor data. To help focus the field, we spotlight work published by 10 research groups that exemplify the quality of data one should expect to see from a biosensor experiment. Also, in an effort to raise awareness of the common problems in the biosensor field, we provide side-by-side examples of good and bad data sets from the 2005 literature.
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Affiliation(s)
- Rebecca L Rich
- Center for Biomolecular Interaction Analysis, University of Utah, Salt Lake City, UT 84132, USA
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