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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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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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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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Xu X, Zhou H, Zhou Q, Hong F, Vo MN, Niu W, Wang Z, Xiong X, Nakamura K, Wakasugi K, Schimmel P, Yang XL. An alternative conformation of human TrpRS suggests a role of zinc in activating non-enzymatic function. RNA Biol 2017; 15:649-658. [PMID: 28910573 PMCID: PMC6103731 DOI: 10.1080/15476286.2017.1377868] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Tryptophanyl-tRNA synthetase (TrpRS) in vertebrates contains a N-terminal extension in front of the catalytic core. Proteolytic removal of the N-terminal 93 amino acids gives rise to T2-TrpRS, which has potent anti-angiogenic activity mediated through its extracellular interaction with VE-cadherin. Zinc has been shown to have anti-angiogenic effects and can bind to human TrpRS. However, the connection between zinc and the anti-angiogenic function of TrpRS has not been explored. Here we report that zinc binding can induce structural relaxation in human TrpRS to facilitate the proteolytic generation of a T2-TrpRS-like fragment. The zinc-binding site is likely to be contained within T2-TrpRS, and the zinc-bound conformation of T2-TrpRS is mimicked by mutation H130R. We determined the crystal structure of H130R T2-TrpRS at 2.8 Å resolution, which reveals drastically different conformation from that of wild-type (WT) T2-TrpRS. The conformational change creates larger binding surfaces for VE-cadherin as suggested by molecular dynamic simulations. Surface plasmon resonance analysis indicates more than 50-fold increase in binding affinity of H130R T2-TrpRS for VE-cadherin, compared to WT T2-TrpRS. The enhanced interaction is also confirmed by a cell-based binding analysis. These results suggest that zinc plays an important role in activating TrpRS for angiogenesis regulation.
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Affiliation(s)
- Xiaoling Xu
- Department of Molecular Medicine, The Scripps Research Institute, La Jolla, CA, USA,Institute of Aging Research, School of Medicine, Hangzhou Normal University, Zhejiang Province, Hangzhou, China,Contact Xiaoling Xu Institute of Aging Research, School of Medicine, Hangzhou Normal University, Room D-615, No.1378 Wenyi West Road, Zhejiang Province, 311121, Hangzhou, China
| | - Huihao Zhou
- Department of Molecular Medicine, The Scripps Research Institute, La Jolla, CA, USA
| | - Quansheng Zhou
- Department of Molecular Medicine, The Scripps Research Institute, La Jolla, CA, USA
| | - Fei Hong
- aTyr Pharma, 3545 John Hopkins Court, San Diego, CA, USA
| | - My-Nuong Vo
- Department of Molecular Medicine, The Scripps Research Institute, La Jolla, CA, USA
| | - Wanqiang Niu
- Institute of Aging Research, School of Medicine, Hangzhou Normal University, Zhejiang Province, Hangzhou, China
| | - Zhiguo Wang
- Institute of Aging Research, School of Medicine, Hangzhou Normal University, Zhejiang Province, Hangzhou, China
| | - Xiaolin Xiong
- Department of Molecular Medicine, The Scripps Research Institute, La Jolla, CA, USA
| | - Kanaha Nakamura
- Department of Life Sciences, Graduate School of Arts and Sciences, The University of Tokyo, Meguro-ku, Tokyo, Japan
| | - Keisuke Wakasugi
- Department of Life Sciences, Graduate School of Arts and Sciences, The University of Tokyo, Meguro-ku, Tokyo, Japan
| | - Paul Schimmel
- Department of Molecular Medicine, The Scripps Research Institute, La Jolla, CA, USA
| | - Xiang-Lei Yang
- Department of Molecular Medicine, The Scripps Research Institute, La Jolla, CA, USA,Xiang-Lei Yang Department of Molecular Medicine, The Scripps Research Institute, BCC 110 10550 North Torrey Pines Road, La Jolla, CA 92037
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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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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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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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