1
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Hirayama H, Tachida Y, Fujinawa R, Matsuda Y, Murase T, Nishiuchi Y, Suzuki T. Development of a fluorescence and quencher-based FRET assay for detection of endogenous peptide:N-glycanase/NGLY1 activity. J Biol Chem 2024; 300:107121. [PMID: 38417795 PMCID: PMC11065741 DOI: 10.1016/j.jbc.2024.107121] [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: 12/19/2023] [Revised: 02/17/2024] [Accepted: 02/20/2024] [Indexed: 03/01/2024] Open
Abstract
Cytosolic peptide:N-glycanase (PNGase/NGLY1 in mammals) catalyzes deglycosylation of N-glycans on glycoproteins. A genetic disorder caused by mutations in the NGLY1 gene leads to NGLY1 deficiency with symptoms including motor deficits and neurological problems. Effective therapies have not been established, though, a recent study used the administration of an adeno-associated viral vector expressing human NGLY1 to dramatically rescue motor functions in young Ngly1-/- rats. Thus, early therapeutic intervention may improve symptoms arising from central nervous system dysfunction, and assay methods for measuring NGLY1 activity in biological samples are critical for early diagnostics. In this study, we established an assay system for plate-based detection of endogenous NGLY1 activity using a FRET-based probe. Using this method, we revealed significant changes in NGLY1 activity in rat brains during aging. This novel assay offers reliable disease diagnostics and provides valuable insights into the regulation of PNGase/NGLY1 activity in diverse organisms under different stress conditions.
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Affiliation(s)
- Hiroto Hirayama
- Glycometabolic Biochemistry Laboratory, RIKEN Cluster for Pioneering Research (CPR), Riken, Wako Saitama, Japan; Takeda-CiRA Joint Program (T-CiRA), Fujisawa, Kanagawa, Japan
| | - Yuriko Tachida
- Glycometabolic Biochemistry Laboratory, RIKEN Cluster for Pioneering Research (CPR), Riken, Wako Saitama, Japan; Takeda-CiRA Joint Program (T-CiRA), Fujisawa, Kanagawa, Japan
| | - Reiko Fujinawa
- Glycometabolic Biochemistry Laboratory, RIKEN Cluster for Pioneering Research (CPR), Riken, Wako Saitama, Japan; Takeda-CiRA Joint Program (T-CiRA), Fujisawa, Kanagawa, Japan
| | | | | | | | - Tadashi Suzuki
- Glycometabolic Biochemistry Laboratory, RIKEN Cluster for Pioneering Research (CPR), Riken, Wako Saitama, Japan; Takeda-CiRA Joint Program (T-CiRA), Fujisawa, Kanagawa, Japan.
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2
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Huang C, Seino J, Honda A, Fujihira H, Wu D, Okahara K, Kitazume S, Nakaya S, Kitajima K, Sato C, Suzuki T. Rat hepatocytes secrete free oligosaccharides. J Biol Chem 2024; 300:105712. [PMID: 38309509 PMCID: PMC10912633 DOI: 10.1016/j.jbc.2024.105712] [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: 08/09/2023] [Revised: 01/24/2024] [Accepted: 01/25/2024] [Indexed: 02/05/2024] Open
Abstract
We recently established a method for the isolation of serum-free oligosaccharides, and characterized various features of their structures. However, the precise mechanism for how these glycans are formed still remains unclarified. To further investigate the mechanism responsible for these serum glycans, here, we utilized rat primary hepatocytes to examine whether they are able to secrete free glycans. Our findings indicated that a diverse array of free oligosaccharides such as sialyl/neutral free N-glycans (FNGs), as well as sialyl lactose/LacNAc-type glycans, were secreted into the culture medium by primary hepatocytes. The structural features of these free glycans in the medium were similar to those isolated from the sera of the same rat. Further evidence suggested that an oligosaccharyltransferase is involved in the release of the serum-free N-glycans. Our results indicate that the liver is indeed secreting various types of free glycans directly into the serum.
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Affiliation(s)
- Chengcheng Huang
- Glycometabolic Biochemistry Laboratory, RIKEN-Cluster for Pioneering Research, Wako, Saitama, Japan
| | - Junichi Seino
- Glycometabolic Biochemistry Laboratory, RIKEN-Cluster for Pioneering Research, Wako, Saitama, Japan
| | - Akinobu Honda
- Glycometabolic Biochemistry Laboratory, RIKEN-Cluster for Pioneering Research, Wako, Saitama, Japan
| | - Haruhiko Fujihira
- Glycometabolic Biochemistry Laboratory, RIKEN-Cluster for Pioneering Research, Wako, Saitama, Japan
| | - Di Wu
- Bioscience and Biotechnology Center, Nagoya University, Chikusa, Nagoya, Japan; Institute for Glyco-core Research (iGCORE), Nagoya University, Chikusa, Nagoya, Japan
| | - Kyohei Okahara
- Discovery Concept Validation Function, KAN Research Institute, Inc, Kobe, Japan
| | - Shinobu Kitazume
- Department of Clinical Laboratory Sciences, School of Health Sciences, Fukushima Medical University, Fukushima, Japan
| | - Shuichi Nakaya
- Analytical & Measuring Instruments Division, Shimadzu Corporation, Kyoto, Japan
| | - Ken Kitajima
- Bioscience and Biotechnology Center, Nagoya University, Chikusa, Nagoya, Japan; Institute for Glyco-core Research (iGCORE), Nagoya University, Chikusa, Nagoya, Japan
| | - Chihiro Sato
- Bioscience and Biotechnology Center, Nagoya University, Chikusa, Nagoya, Japan; Institute for Glyco-core Research (iGCORE), Nagoya University, Chikusa, Nagoya, Japan
| | - Tadashi Suzuki
- Glycometabolic Biochemistry Laboratory, RIKEN-Cluster for Pioneering Research, Wako, Saitama, Japan.
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3
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Li ST, Hirayama H, Huang C, Matsuda T, Oka R, Yamasaki T, Kohda D, Suzuki T. Hydrolytic activity of yeast oligosaccharyltransferase is enhanced when misfolded proteins accumulate in the endoplasmic reticulum. FEBS J 2024; 291:884-896. [PMID: 37997624 DOI: 10.1111/febs.17011] [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: 06/14/2023] [Revised: 10/06/2023] [Accepted: 11/21/2023] [Indexed: 11/25/2023]
Abstract
It is known that oligosaccharyltransferase (OST) has hydrolytic activity toward dolichol-linked oligosaccharides (DLO), which results in the formation of free N-glycans (FNGs), i.e. unconjugated oligosaccharides with structural features similar to N-glycans. The functional importance of this hydrolytic reaction, however, remains unknown. In this study, the hydrolytic activity of OST was characterized in yeast. It was shown that the hydrolytic activity of OST is enhanced in ubiquitin ligase mutants that are involved in endoplasmic reticulum-associated degradation. Interestingly, this enhanced hydrolysis activity is completely suppressed in asparagine-linked glycosylation (alg) mutants, bearing mutations related to the biosynthesis of DLO, indicating that the effect of ubiquitin ligase on OST-mediated hydrolysis is context-dependent. The enhanced hydrolysis activity in ubiquitin ligase mutants was also found to be canceled upon treatment of the cells with dithiothreitol, a reagent that potently induces protein unfolding in the endoplasmic reticulum (ER). Our results clearly suggest that the hydrolytic activity of OST is enhanced under conditions in which the formation of unfolded proteins is promoted in the ER in yeast. The possible role of FNGs on protein folding is discussed.
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Affiliation(s)
- Sheng-Tao Li
- Glycometabolic Biochemistry Laboratory, RIKEN Cluster for Pioneering Research (CPR), RIKEN, Saitama, Japan
| | - Hiroto Hirayama
- Glycometabolic Biochemistry Laboratory, RIKEN Cluster for Pioneering Research (CPR), RIKEN, Saitama, Japan
| | - Chengcheng Huang
- Glycometabolic Biochemistry Laboratory, RIKEN Cluster for Pioneering Research (CPR), RIKEN, Saitama, Japan
| | - Tsugiyo Matsuda
- Glycometabolic Biochemistry Laboratory, RIKEN Cluster for Pioneering Research (CPR), RIKEN, Saitama, Japan
| | - Ritsuko Oka
- Glycometabolic Biochemistry Laboratory, RIKEN Cluster for Pioneering Research (CPR), RIKEN, Saitama, Japan
| | - Takahiro Yamasaki
- Division of Structural Biology, Medical Institute of Bioregulation, Kyushu University, Fukuoka, Japan
| | - Daisuke Kohda
- Division of Structural Biology, Medical Institute of Bioregulation, Kyushu University, Fukuoka, Japan
| | - Tadashi Suzuki
- Glycometabolic Biochemistry Laboratory, RIKEN Cluster for Pioneering Research (CPR), RIKEN, Saitama, Japan
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4
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Convergent synthesis of oligomannose-type glycans via step-economical construction of branch structures. Carbohydr Res 2023; 525:108764. [PMID: 36812846 DOI: 10.1016/j.carres.2023.108764] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2022] [Revised: 01/27/2023] [Accepted: 02/13/2023] [Indexed: 02/17/2023]
Abstract
Oligomannose-type glycans on glycoproteins are important signaling molecules in the glycoprotein quality control system in the endoplasmic reticulum. Recently, free oligomannose-type glycans generated by the hydrolysis of glycoproteins or dolichol pyrophosphate-linked oligosaccharides were recognized as important signals for immunogenicity. Hence, there is a high demand for pure oligomannose-type glycans for biochemical experiments; however, the chemical synthesis of glycans to achieve high-concentration products is laborious. In this study, we demonstrate a simple and efficient synthetic strategy for oligomannose-type glycans. Sequential regioselective α-mannosylation at the C-3 and C-6 positions of 2,3,4,6-unprotected galactose residues in galactosylchitobiose derivatives was demonstrated. Subsequently, the inversion of the configuration of the two hydroxy groups at the C-2 and C-4 positions of the galactose moiety was successfully carried out. This synthetic route reduces the number of the protection-deprotection reactions and is suitable for constructing different branching patterns of oligomannose-type glycans, such as M9, M5A, and M5B.
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5
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Okamoto N, Maeda M, Yamamoto C, Kodama R, Sugimoto K, Shinozaki Y, Ezura H, Kimura Y. Construction of tomato plants with suppressed endo-β-N-acetylglucosaminidase activity using CRISPR-Cas9 mediated genome editing. PLANT PHYSIOLOGY AND BIOCHEMISTRY : PPB 2022; 190:203-211. [PMID: 36130423 DOI: 10.1016/j.plaphy.2022.08.009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/30/2022] [Revised: 07/27/2022] [Accepted: 08/14/2022] [Indexed: 06/15/2023]
Abstract
High mannose-type free N-glycans with a single N-acetyl-D-glucosamine (GlcNAc) residue at the reducing end (GN1-HMT-FNGs) are produced by cytosolic endo-β-N-acetylglucosaminidase (EC:3.2.1.96) (ENGase) and are ubiquitous in differentiating and growing plant cells. To elucidate the physiological functions of HMT-FNGs in plants, we identified the ENGase gene in tomato (Solyc06g050930) and detected ENGase activity and increased production of GN1-HMT-FNGs during tomato fruit maturation. However, the precise role of GN1-HMT-FNGs in fruit maturation remains unclear. In this study, we established tomato ENGase mutants with suppressed ENGase activity via CRISPR/Cas9 genome editing technology. DNA sequencing of the Δeng mutants (T0 and T1 generations) revealed that they had the same mutations in the genomic DNA around the target sequences. Three null CRISPR/Cas9 segregant plants of the T1 generation (Δeng1-2, -22, and -26) were used to measure ENGase activity and analyze the structural features of HMT-FNGs in the leaves. The Δeng mutants did not exhibit ENGase activity and produced GN2-HMT-FNGs bearing tow GlcNAc residues at the reducing end side instead of GN1-HMT-FNGs. The Δeng mutants lack the N-terminal region of ENGase, indicating that the N-terminal region is important for full ENGase activity. The fruits of Δeng mutants (T2 generation) also showed loss of ENGase activity and similar structural features of HMT-FNGs of the T1 generation. However, there was no significant difference in fruit maturation between the T2 generation of the Δeng mutants and the wild type. The Δeng mutants rich in GN2-HMT-FNGs could be offered as a new tomato that is different from wild type containing GN1-HMT-FNGs.
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Affiliation(s)
- Naoko Okamoto
- Department of Biofunctional Chemistry, Graduate School of Environmental and Life Science, Okayama University, Okayama, Japan
| | - Megumi Maeda
- Department of Biofunctional Chemistry, Graduate School of Environmental and Life Science, Okayama University, Okayama, Japan.
| | - Chiharu Yamamoto
- Department of Biofunctional Chemistry, Graduate School of Environmental and Life Science, Okayama University, Okayama, Japan
| | - Reo Kodama
- Department of Biofunctional Chemistry, Graduate School of Environmental and Life Science, Okayama University, Okayama, Japan
| | - Koichi Sugimoto
- Faculty of Life and Environmental Sciences, University of Tsukuba, Ibaraki, Japan
| | - Yoshihito Shinozaki
- Faculty of Life and Environmental Sciences, University of Tsukuba, Ibaraki, Japan; Institute of Global Innovation Research, Tokyo University of Agriculture and Technology, Tokyo, Japan
| | - Hiroshi Ezura
- Faculty of Life and Environmental Sciences, University of Tsukuba, Ibaraki, Japan
| | - Yoshinobu Kimura
- Department of Biofunctional Chemistry, Graduate School of Environmental and Life Science, Okayama University, Okayama, Japan.
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6
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Increased levels of acidic free-N-glycans, including multi-antennary and fucosylated structures, in the urine of cancer patients. PLoS One 2022; 17:e0266927. [PMID: 35413075 PMCID: PMC9004742 DOI: 10.1371/journal.pone.0266927] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2022] [Accepted: 03/29/2022] [Indexed: 12/01/2022] Open
Abstract
We recently reported increased levels of urinary free-glycans in some cancer patients. Here, we focused on cancer related alterations in the levels of high molecular weight free-glycans. The rationale for this study was that branching, elongation, fucosylation and sialylation, which lead to increases in the molecular weight of glycans, are known to be up-regulated in cancer. Urine samples from patients with gastric cancer, pancreatic cancer, cholangiocarcinoma and colorectal cancer and normal controls were analyzed. The extracted free-glycans were fluorescently labeled with 2-aminopyridine and analyzed by multi-step liquid chromatography. Comparison of the glycan profiles revealed increased levels of glycans in some cancer patients. Structural analysis of the glycans was carried out by performing chromatography and mass spectrometry together with enzymatic or chemical treatments. To compare glycan levels between samples with high sensitivity and selectivity, simultaneous measurements by reversed-phase liquid chromatography-selected ion monitoring of mass spectrometry were also performed. As a result, three lactose-core glycans and 78 free-N-glycans (one phosphorylated oligomannose-type, four sialylated hybrid-type and 73 bi-, tri- and tetra-antennary complex-type structures) were identified. Among them, glycans with α1,3-fucosylation ((+/− sialyl) Lewis X), triply α2,6-sialylated tri-antennary structures and/or a (Man3)GlcNAc1-core displayed elevated levels in cancer patients. However, simple α2,3-sialylation and α1,6-core-fucosylation did not appear to contribute to the observed increase in the level of glycans. Interestingly, one tri-antennary free-N-glycan that showed remarkable elevation in some cancer patients contained a unique Glcβ1-4GlcNAc-core instead of the common GlcNAc2-core at the reducing end. This study provides further insights into free-glycans as potential tumor markers and their processing pathways in cancer.
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7
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Huang C, Seino J, Fujihira H, Sato K, Fujinawa R, Sumer-Bayraktar Z, Ishii N, Matsuo I, Nakaya S, Suzuki T. Occurrence of free N-glycans with a single GlcNAc at the reducing termini in animal sera. Glycobiology 2021; 32:314-332. [PMID: 34939097 DOI: 10.1093/glycob/cwab124] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2021] [Revised: 11/09/2021] [Accepted: 11/23/2021] [Indexed: 11/13/2022] Open
Abstract
Recent studies demonstrated the occurrence of sialyl free N-glycans (FNGs) in sera from a variety of animals. Unlike the intracellular FNGs that mainly carry a single N-acetylglucosamine at their reducing termini (Gn1-type), these extra-cellular FNGs have an N,N'-diacetylchitobiose at their reducing termini (Gn2-type). The detailed mechanism for how they are formed, however, remains unclarified. In this study, we report on an improved method for isolating FNGs from sera and found that, not only sialyl FNGs, but also neutral FNGs are present in animal sera. Most of the neutral oligomannose-type FNGs were found to be Gn1-type. We also found that a small portion of sialyl FNGs were Gn1-type. The ratio of Gn1-type sialyl FNGs varies between species, and appears to be partially correlated with the distribution of lysosomal chitobiase activity. We also identified small sialylated glycans similar to milk oligosaccharides, such as sialyl lactose or sialyl N-acetyllactosamine in sera. Our results indicate that there are variety of free oligosaccharides in sera and the mechanism responsible for their formation is more complicated than currently envisaged.
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Affiliation(s)
- Chengcheng Huang
- Glycometabolic Biochemistry Laboratory, RIKEN-Cluster for Pioneering Research, Wako, Saitama 351-0198, Japan
| | - Junichi Seino
- Glycometabolic Biochemistry Laboratory, RIKEN-Cluster for Pioneering Research, Wako, Saitama 351-0198, Japan
| | - Haruhiko Fujihira
- Glycometabolic Biochemistry Laboratory, RIKEN-Cluster for Pioneering Research, Wako, Saitama 351-0198, Japan.,Division of Glycobiologics, Intractable Disease Research Center, Juntendo University Graduate School of Medicine, 133-8421, Japan
| | - Keiko Sato
- Glycometabolic Biochemistry Laboratory, RIKEN-Cluster for Pioneering Research, Wako, Saitama 351-0198, Japan
| | - Reiko Fujinawa
- Glycometabolic Biochemistry Laboratory, RIKEN-Cluster for Pioneering Research, Wako, Saitama 351-0198, Japan
| | - Zeynep Sumer-Bayraktar
- Glycometabolic Biochemistry Laboratory, RIKEN-Cluster for Pioneering Research, Wako, Saitama 351-0198, Japan
| | - Nozomi Ishii
- Graduate School of Science and Technology, Gunma University, 1-5-1 Tenjin-cho, Kiryu, Gunma, 376-8515, Japan
| | - Ichiro Matsuo
- Graduate School of Science and Technology, Gunma University, 1-5-1 Tenjin-cho, Kiryu, Gunma, 376-8515, Japan
| | - Shuichi Nakaya
- Global Application Development Center, Shimadzu Corporation, Kyoto 604-8511, Japan
| | - Tadashi Suzuki
- Glycometabolic Biochemistry Laboratory, RIKEN-Cluster for Pioneering Research, Wako, Saitama 351-0198, Japan
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8
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Horiuchi R, Ozawa M, Tomii T, Kashiwada S, Miyanishi N. Structural analysis of N-glycans in medaka gut exposed to silver and titanium dioxide nanoparticles. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2021; 28:58799-58806. [PMID: 34120284 DOI: 10.1007/s11356-021-14773-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/23/2020] [Accepted: 06/02/2021] [Indexed: 06/12/2023]
Abstract
Nanomaterials are in general use in a broad range of industries. However, there are concerns that their intense use leads to heavy damage to the aquatic environment, and their discharge harms many aquatic organisms. N-Glycans are widely distributed in eukaryotic organisms and are intimately involved in most life phenomena. However, little is known about N-glycans in aquatic organisms exposed to nanomaterials. In this study, we investigated how nanomaterials affect N-glycans in the gut of adult female medaka. We found that silver nanoparticles exposure had little effect on gut N-glycans, whereas titanium dioxide nanoparticles (TiO2NPs) exposure increased the relative levels of several N-glycans in comparison with control. Structural analysis showed high levels of N-glycans of the high-mannose type, of which five N-glycans were free N-glycans with one β-N-acetylglucosamine residue on the reducing end. The levels of free N-glycans are closely related to protein quality control in the endoplasmic reticulum and cytosol. Our results suggest that TiO2NPs exposure increases the levels of misfolded glycoproteins, resulting in generation of considerable amounts of free N-glycans. Our findings also suggest that TiO2NPs exposure suppresses cytosolic α-mannosidase trimming. This study provides new evidence for the effect of TiO2NPs on medaka gut from the aspect of environmental glycobiology.
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Affiliation(s)
- Risa Horiuchi
- Department of Food and Nutritional Sciences, Toyo University, 1-1-1, Izumino, Itakura-machi, Ora-gun, Gunma, 374-0193, Japan
- Research Centre for Life and Environmental Sciences, Toyo University, 1-1-1, Izumino, Itakura-machi, Ora-gun, Gunma, 374-0193, Japan
| | - Mika Ozawa
- Department of Food and Nutritional Sciences, Toyo University, 1-1-1, Izumino, Itakura-machi, Ora-gun, Gunma, 374-0193, Japan
| | - Tatsuyoshi Tomii
- Department of Food and Nutritional Sciences, Toyo University, 1-1-1, Izumino, Itakura-machi, Ora-gun, Gunma, 374-0193, Japan
| | - Shosaku Kashiwada
- Department of Life Sciences, Toyo University, 1-1-1, Izumino, Itakura-machi, Ora-gun, Gunma, 374-0193, Japan
- Research Centre for Life and Environmental Sciences, Toyo University, 1-1-1, Izumino, Itakura-machi, Ora-gun, Gunma, 374-0193, Japan
| | - Nobumitsu Miyanishi
- Department of Food and Nutritional Sciences, Toyo University, 1-1-1, Izumino, Itakura-machi, Ora-gun, Gunma, 374-0193, Japan.
- Research Centre for Life and Environmental Sciences, Toyo University, 1-1-1, Izumino, Itakura-machi, Ora-gun, Gunma, 374-0193, Japan.
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9
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Fujihira H, Asahina M, Suzuki T. Physiological importance of NGLY1, as revealed by rodent model analyses. J Biochem 2021; 171:161-167. [PMID: 34580715 DOI: 10.1093/jb/mvab101] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2021] [Accepted: 09/01/2021] [Indexed: 12/29/2022] Open
Abstract
Cytosolic peptide:N-glycanase (NGLY1) is an enzyme that cleaves N-glycans from glycoproteins that has been retrotranslocated from the endoplasmic reticulum (ER) lumen into the cytosol. It is known that NGLY1 is involved in the degradation of cytosolic glycans (non-lysosomal glycan degradation) as well as ER-associated degradation (ERAD), a quality control system for newly synthesized glycoproteins. The discovery of NGLY1 deficiency, which is caused by mutations in the human NGLY1 gene and results in multisystemic symptoms, has attracted interest in the physiological functions of NGLY1 in mammals. Studies using various animal models led to the identification of possible factors that contribute to the pathogenesis of NGLY1 deficiency. In this review, we summarize phenotypic consequences that have been reported for various Ngly1-deficient rodent models, and discuss future perspectives to provide more insights into the physiological functions of NGLY1.
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Affiliation(s)
- Haruhiko Fujihira
- Glycometabolic Biochemistry Laboratory, RIKEN Cluster for Pioneering Research, RIKEN, 3510198 Saitama, Japan.,Division of Glycobiologics, Intractable Disease Research Center, Juntendo University Graduate School of Medicine, 1138421 Tokyo, Japan
| | - Makoto Asahina
- T-CiRA Discovery, Takeda Pharmaceutical Company Ltd, 2518555 Kanagawa, Japan
| | - Tadashi Suzuki
- Glycometabolic Biochemistry Laboratory, RIKEN Cluster for Pioneering Research, RIKEN, 3510198 Saitama, Japan.,T-CiRA Discovery, Takeda Pharmaceutical Company Ltd, 2518555 Kanagawa, Japan
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10
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Fujitani N, Ariki S, Hasegawa Y, Uehara Y, Saito A, Takahashi M. Integrated Structural Analysis of N-Glycans and Free Oligosaccharides Allows for a Quantitative Evaluation of ER Stress. Biochemistry 2021; 60:1708-1721. [PMID: 33983715 DOI: 10.1021/acs.biochem.0c00969] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Endoplasmic reticulum (ER) stress has been reported in a variety of diseases. Although ER stress can be detected using specific markers, it is still difficult to quantitatively evaluate the degree of stress and to identify the cause of the stress. The ER is the primary site for folding of secretory or transmembrane proteins as well as the site where glycosylation is initiated. This study therefore postulates that tracing the biosynthetic pathway of asparagine-linked glycans (N-glycans) would be a reporter for reflecting the state of the ER and serve as a quantitative descriptor of ER stress. Glycoblotting-assisted mass spectrometric analysis of the HeLa cell line enabled quantitative determination of the changes in the structures of N-glycans and degraded free oligosaccharides (fOSs) in response to tunicamycin- or thapsigargin-induced ER stress. The integrated analysis of neutral and sialylated N-glycans and fOSs showed the potential to elucidate the cause of ER stress, which cannot be readily done by protein markers alone. Changes in the total amount of glycans, increase in the ratio of high-mannose type N-glycans, increase in fOSs, and changes in the ratio of sialylated N-glycans in response to ER stress were shown to be potential descriptors of ER stress. Additionally, drastic clearance of accumulated N-glycans was observed in thapsigargin-treated cells, which may suggest the observation of ER stress-mediated autophagy or ER-phagy in terms of glycomics. Quantitative analysis of N-glycoforms composed of N-glycans and fOSs provides the dynamic indicators reflecting the ER status and the promising strategies for quantitative evaluation of ER stress.
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Affiliation(s)
- Naoki Fujitani
- Department of Biochemistry, Sapporo Medical University School of Medicine, Sapporo 060-8556, Japan
| | - Shigeru Ariki
- Department of Biochemistry, Sapporo Medical University School of Medicine, Sapporo 060-8556, Japan.,Department of Chemistry, Sapporo Medical University Center for Medical Education, Sapporo 060-8556, Japan
| | - Yoshihiro Hasegawa
- Department of Biochemistry, Sapporo Medical University School of Medicine, Sapporo 060-8556, Japan.,Department of Respiratory Medicine and Allergology, Sapporo Medical University School of Medicine, Sapporo 060-8543, Japan
| | - Yasuaki Uehara
- Department of Biochemistry, Sapporo Medical University School of Medicine, Sapporo 060-8556, Japan.,Department of Respiratory Medicine and Allergology, Sapporo Medical University School of Medicine, Sapporo 060-8543, Japan
| | - Atsushi Saito
- Department of Respiratory Medicine and Allergology, Sapporo Medical University School of Medicine, Sapporo 060-8543, Japan
| | - Motoko Takahashi
- Department of Biochemistry, Sapporo Medical University School of Medicine, Sapporo 060-8556, Japan
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11
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Katsube M, Ebara N, Maeda M, Kimura Y. Cytosolic Free N-Glycans Are Retro-Transported Into the Endoplasmic Reticulum in Plant Cells. FRONTIERS IN PLANT SCIENCE 2021; 11:610124. [PMID: 33537045 PMCID: PMC7847903 DOI: 10.3389/fpls.2020.610124] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/25/2020] [Accepted: 12/17/2020] [Indexed: 06/12/2023]
Abstract
During endoplasmic reticulum (ER)-associated degradation, free N-glycans (FNGs) are produced from misfolded nascent glycoproteins via the combination of the cytosolic peptide N-glycanase (cPNGase) and endo-β-N-acetylglucosaminidase (ENGase) in the plant cytosol. The resulting high-mannose type (HMT)-FNGs, which carry one GlcNAc residue at the reducing end (GN1-FNGs), are ubiquitously found in developing plant cells. In a previous study, we found that HMT-FNGs assisted in protein folding and inhibited β-amyloid fibril formation, suggesting a possible biofunction of FNGs involved in the protein folding system. However, whether these HMT-FNGs occur in the ER, an organelle involved in protein folding, remained unclear. On the contrary, we also reported the presence of plant complex type (PCT)-GN1-FNGs, which carry the Lewisa epitope at the non-reducing end, indicating that these FNGs had been fully processed in the Golgi apparatus. Since plant ENGase was active toward HMT-N-glycans but not PCT-N-glycans that carry β1-2xylosyl and/or α1-3 fucosyl residue(s), these PCT-GN1-FNGs did not appear to be produced from fully processed glycoproteins that harbored PCT-N-glycans via ENGase activity. Interestingly, PCT-GN1-FNGs were found in the extracellular space, suggesting that HMT-GN1-FNGs formed in the cytosol might be transported back to the ER and processed in the Golgi apparatus through the protein secretion pathway. As the first step in elucidating the production mechanism of PCT-GN1-FNGs, we analyzed the structures of free oligosaccharides in plant microsomes and proved that HMT-FNGs (Man9-7GlcNAc1 and Man9-8GlcNAc2) could be found in microsomes, which almost consist of the ER compartments.
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Abstract
Folding of proteins is essential so that they can exert their functions. For proteins that transit the secretory pathway, folding occurs in the endoplasmic reticulum (ER) and various chaperone systems assist in acquiring their correct folding/subunit formation. N-glycosylation is one of the most conserved posttranslational modification for proteins, and in eukaryotes it occurs in the ER. Consequently, eukaryotic cells have developed various systems that utilize N-glycans to dictate and assist protein folding, or if they consistently fail to fold properly, to destroy proteins for quality control and the maintenance of homeostasis of proteins in the ER.
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13
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Yamasaki T, Kohda D. Uncoupling the hydrolysis of lipid-linked oligosaccharide from the oligosaccharyl transfer reaction by point mutations in yeast oligosaccharyltransferase. J Biol Chem 2020; 295:16072-16085. [PMID: 32938717 PMCID: PMC7681024 DOI: 10.1074/jbc.ra120.015013] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2020] [Revised: 09/12/2020] [Indexed: 11/06/2022] Open
Abstract
Oligosaccharyltransferase (OST) is responsible for the first step in the N-linked glycosylation, transferring an oligosaccharide chain onto asparagine residues to create glycoproteins. In the absence of an acceptor asparagine, OST hydrolyzes the oligosaccharide donor, releasing free N-glycans (FNGs) into the lumen of the endoplasmic reticulum (ER). Here, we established a purification method for mutated OSTs using a high-affinity epitope tag attached to the catalytic subunit Stt3, from yeast cells co-expressing the WT OST to support growth. The purified OST protein with mutations is useful for wide-ranging biochemical experiments. We assessed the effects of mutations in the Stt3 subunit on the two enzymatic activities in vitro, as well as their effects on the N-glycan attachment and FNG content levels in yeast cells. We found that mutations in the first DXD motif increased the FNG generation activity relative to the oligosaccharyl transfer activity, both in vitro and in vivo, whereas mutations in the DK motif had the opposite effect; the decoupling of the two activities may facilitate future deconvolution of the reaction mechanism. The isolation of the mutated OSTs also enabled us to identify different enzymatic properties in OST complexes containing either the Ost3 or Ost6 subunit and to find a 15-residue peptide as a better-quality substrate than shorter peptides. This toolbox of mutants, substrates, and methods will be useful for investigations of the molecular basis and physiological roles of the OST enzymes in yeast and other organisms.
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Affiliation(s)
- Takahiro Yamasaki
- Division of Structural Biology, Medical Institute of Bioregulation, Kyushu University, Fukuoka, Japan
| | - Daisuke Kohda
- Division of Structural Biology, Medical Institute of Bioregulation, Kyushu University, Fukuoka, Japan.
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14
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Global view of human protein glycosylation pathways and functions. Nat Rev Mol Cell Biol 2020; 21:729-749. [PMID: 33087899 DOI: 10.1038/s41580-020-00294-x] [Citation(s) in RCA: 506] [Impact Index Per Article: 126.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/24/2020] [Indexed: 02/07/2023]
Abstract
Glycosylation is the most abundant and diverse form of post-translational modification of proteins that is common to all eukaryotic cells. Enzymatic glycosylation of proteins involves a complex metabolic network and different types of glycosylation pathways that orchestrate enormous amplification of the proteome in producing diversity of proteoforms and its biological functions. The tremendous structural diversity of glycans attached to proteins poses analytical challenges that limit exploration of specific functions of glycosylation. Major advances in quantitative transcriptomics, proteomics and nuclease-based gene editing are now opening new global ways to explore protein glycosylation through analysing and targeting enzymes involved in glycosylation processes. In silico models predicting cellular glycosylation capacities and glycosylation outcomes are emerging, and refined maps of the glycosylation pathways facilitate genetic approaches to address functions of the vast glycoproteome. These approaches apply commonly available cell biology tools, and we predict that use of (single-cell) transcriptomics, genetic screens, genetic engineering of cellular glycosylation capacities and custom design of glycoprotein therapeutics are advancements that will ignite wider integration of glycosylation in general cell biology.
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15
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Miura N, Hanamatsu H, Yokota I, Okada K, Furukawa JI, Shinohara Y. Toolbox Accelerating Glycomics (TAG): Glycan Annotation from MALDI-TOF MS Spectra and Mapping Expression Variation to Biosynthetic Pathways. Biomolecules 2020; 10:biom10101383. [PMID: 32998456 PMCID: PMC7650810 DOI: 10.3390/biom10101383] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2020] [Revised: 09/23/2020] [Accepted: 09/26/2020] [Indexed: 11/16/2022] Open
Abstract
Glycans present extraordinary structural diversity commensurate with their involvement in numerous fundamental cellular processes including growth, differentiation, and morphogenesis. Unlike linear DNA and protein sequences, glycans have heterogeneous structures that differ in composition, branching, linkage, and anomericity. These differences pose a challenge to developing useful software for glycomic analysis. To overcome this problem, we developed the novel Toolbox Accelerating Glycomics (TAG) program. TAG consists of three units: ‘TAG List’ creates a glycan list that is used for database searching in TAG Expression; ‘TAG Expression’ automatically annotates and quantifies glycan signals and draws graphs; and ‘TAG Pathway’ maps the obtained expression information to biosynthetic pathways. Herein, we discuss the concepts, outline the TAG process, and demonstrate its potential using glycomic expression profile data from Chinese hamster ovary (CHO) cells and mutants lacking a functional Npc1 gene (Npc1 knockout (KO) CHO cells). TAG not only drastically reduced the amount of time and labor needed for glycomic analysis but also detected and quantified more glycans than manual analysis. Although this study was limited to the analysis of N-glycans and free oligosaccharides, the glycomic platform will be expanded to facilitate the analysis of O-glycans and glycans of glycosphingolipids.
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Affiliation(s)
- Nobuaki Miura
- Division of Bioinformatics, Niigata University Graduate School of Medical and Dental Sciences, 1-757 Asahimachi-dori, Chuo-ku, Niigata 951-8510, Japan
- Correspondence: (N.M.); (Y.S.)
| | - Hisatoshi Hanamatsu
- Department of Advanced Clinical Glycobiology, Faculty of Medicine and Graduate School of Medicine, Hokkaido University, Kita21, Nishi11, Kita-ku, Sapporo 001-0021, Japan; (H.H.); (I.Y.); (K.O.); (J.-I.F.)
| | - Ikuko Yokota
- Department of Advanced Clinical Glycobiology, Faculty of Medicine and Graduate School of Medicine, Hokkaido University, Kita21, Nishi11, Kita-ku, Sapporo 001-0021, Japan; (H.H.); (I.Y.); (K.O.); (J.-I.F.)
| | - Kazue Okada
- Department of Advanced Clinical Glycobiology, Faculty of Medicine and Graduate School of Medicine, Hokkaido University, Kita21, Nishi11, Kita-ku, Sapporo 001-0021, Japan; (H.H.); (I.Y.); (K.O.); (J.-I.F.)
| | - Jun-Ichi Furukawa
- Department of Advanced Clinical Glycobiology, Faculty of Medicine and Graduate School of Medicine, Hokkaido University, Kita21, Nishi11, Kita-ku, Sapporo 001-0021, Japan; (H.H.); (I.Y.); (K.O.); (J.-I.F.)
| | - Yasuro Shinohara
- Department of Pharmacy, Kinjo Gakuin University, Nagoya 463-8521, Japan
- Correspondence: (N.M.); (Y.S.)
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16
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Miyoshi E, Kamada Y, Suzuki T. Functional glycomics: Application to medical science and hepatology. Hepatol Res 2020; 50:153-164. [PMID: 31750967 DOI: 10.1111/hepr.13459] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/18/2019] [Revised: 10/20/2019] [Accepted: 10/29/2019] [Indexed: 02/08/2023]
Abstract
Glycomics refers to the comprehensive analysis of glycans. Recent progress in glycotechnology enables the determination of a variety of biological functions of glycans. Among different glycosylation patterns, certain types of aberrant glycosylation are linked to cancer and/or inflammation, and thus have biological importance. Glycotechnology has been applied to many fields of medical science, including hepatology. In particular, dramatic changes in glycosylation are observed in the progression of liver diseases. As the liver produces so many serum glycoproteins, changes in glycosylation of these proteins might provide useful disease biomarkers. Furthermore, many patients with genetic diseases of glycosylation who have liver dysfunction have been found as a result from whole genome sequencing, and various kinds of glycotherapy have been developed, especially in immunotherapy. In this review, we describe our basic knowledge of glycobiology and discuss the application of these data to medical science, especially hepatology.
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Affiliation(s)
- Eiji Miyoshi
- Department of Molecular Biochemistry & Clinical Investigation, Osaka University Graduate School of Medicine, Suita, Osaka, Japan
| | - Yoshihiro Kamada
- Department of Molecular Biochemistry & Clinical Investigation, Osaka University Graduate School of Medicine, Suita, Osaka, Japan
| | - Tadashi Suzuki
- Glycometabolic Biochemistry Laboratory, RIKEN Cluster for Pioneering Research (CPR), Wako, Saitama, Japan
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17
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Huang C, Suzuki T. The occurrence of nonglycosylated forms of
N
‐glycoprotein upon proteasome inhibition does not confirm cytosolic deglycosylation. FEBS Lett 2020; 594:1433-1442. [DOI: 10.1002/1873-3468.13734] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2019] [Revised: 12/20/2019] [Accepted: 01/06/2020] [Indexed: 11/07/2022]
Affiliation(s)
- Chengcheng Huang
- Glycometabolic Biochemistry Laboratory RIKEN Cluster for Pioneering Research Wako Japan
| | - Tadashi Suzuki
- Glycometabolic Biochemistry Laboratory RIKEN Cluster for Pioneering Research Wako Japan
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18
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Harada Y. New Developments on the Early Stage of the Biosynthesis of Asparagine-Linked Glycans. TRENDS GLYCOSCI GLYC 2019. [DOI: 10.4052/tigg.1945.2se] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Affiliation(s)
- Yoichiro Harada
- Department of Glyco-Oncology, Osaka International Cancer Institute
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19
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Harada Y. New Developments on the Early Stage of the Biosynthesis of Asparagine-Linked Glycans. TRENDS GLYCOSCI GLYC 2019. [DOI: 10.4052/tigg.1945.2sj] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Affiliation(s)
- Yoichiro Harada
- Department of Glyco-Oncology, Osaka International Cancer Institute
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20
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Hirayama H, Matsuda T, Tsuchiya Y, Oka R, Seino J, Huang C, Nakajima K, Noda Y, Shichino Y, Iwasaki S, Suzuki T. Free glycans derived from O-mannosylated glycoproteins suggest the presence of an O-glycoprotein degradation pathway in yeast. J Biol Chem 2019; 294:15900-15911. [PMID: 31311856 DOI: 10.1074/jbc.ra119.009491] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2019] [Revised: 07/04/2019] [Indexed: 11/06/2022] Open
Abstract
In eukaryotic cells, unconjugated oligosaccharides that are structurally related to N-glycans (i.e. free N-glycans) are generated either from misfolded N-glycoproteins destined for the endoplasmic reticulum-associated degradation or from lipid-linked oligosaccharides, donor substrates for N-glycosylation of proteins. The mechanism responsible for the generation of free N-glycans is now well-understood, but the issue of whether other types of free glycans are present remains unclear. Here, we report on the accumulation of free, O-mannosylated glycans in budding yeast that were cultured in medium containing mannose as the carbon source. A structural analysis of these glycans revealed that their structures are identical to those of O-mannosyl glycans that are attached to glycoproteins. Deletion of the cyc8 gene, which encodes for a general transcription repressor, resulted in the accumulation of excessive amounts of free O-glycans, concomitant with a severe growth defect, a reduction in the level of an O-mannosylated protein, and compromised cell wall integrity. Our findings provide evidence in support of a regulated pathway for the degradation of O-glycoproteins in yeast and offer critical insights into the catabolic mechanisms that control the fate of O-glycosylated proteins.
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Affiliation(s)
- Hiroto Hirayama
- Glycometabolic Biochemistry Laboratory, RIKEN Cluster for Pioneering Research, Wako, Saitama 351-0198, Japan
| | - Tsugiyo Matsuda
- Glycometabolic Biochemistry Laboratory, RIKEN Cluster for Pioneering Research, Wako, Saitama 351-0198, Japan
| | - Yae Tsuchiya
- Glycometabolic Biochemistry Laboratory, RIKEN Cluster for Pioneering Research, Wako, Saitama 351-0198, Japan
| | - Ritsuko Oka
- Glycometabolic Biochemistry Laboratory, RIKEN Cluster for Pioneering Research, Wako, Saitama 351-0198, Japan
| | - Junichi Seino
- Glycometabolic Biochemistry Laboratory, RIKEN Cluster for Pioneering Research, Wako, Saitama 351-0198, Japan
| | - Chengcheng Huang
- Glycometabolic Biochemistry Laboratory, RIKEN Cluster for Pioneering Research, Wako, Saitama 351-0198, Japan
| | - Kazuki Nakajima
- Department of Academic Research Support Promotion Facility, Center for Research Promotion and Support, Fujita Health University, Toyoake, Aichi 470-1192, Japan
| | - Yoichi Noda
- Collaborative Research Institute for Innovative Microbiology, Department of Biotechnology, Graduate School of Agricultural and Life Sciences, University of Tokyo, Tokyo 113-8657, Japan
| | - Yuichi Shichino
- RNA Systems Biochemistry Laboratory, RIKEN Cluster for Pioneering Research, Wako, Saitama 351-0198, Japan
| | - Shintaro Iwasaki
- RNA Systems Biochemistry Laboratory, RIKEN Cluster for Pioneering Research, Wako, Saitama 351-0198, Japan.,Department of Computational Biology and Medical Sciences, Graduate School of Frontier Sciences, University of Tokyo, Kashiwa, Chiba 277-8561, Japan
| | - Tadashi Suzuki
- Glycometabolic Biochemistry Laboratory, RIKEN Cluster for Pioneering Research, Wako, Saitama 351-0198, Japan
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Fermaintt CS, Sano K, Liu Z, Ishii N, Seino J, Dobbs N, Suzuki T, Fu YX, Lehrman MA, Matsuo I, Yan N. A bioactive mammalian disaccharide associated with autoimmunity activates STING-TBK1-dependent immune response. Nat Commun 2019; 10:2377. [PMID: 31147550 PMCID: PMC6542856 DOI: 10.1038/s41467-019-10319-5] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2018] [Accepted: 04/25/2019] [Indexed: 01/07/2023] Open
Abstract
Glycans from microbial pathogens are well known pathogen-associated molecular patterns that are recognized by the host immunity; however, little is known about whether and how mammalian self-glycans activate the host immune response, especially in the context of autoimmune disease. Using biochemical fractionation and two-dimensional HPLC, we identify an abundant and bioactive free glycan, the Manβ1-4GlcNAc disaccharide in TREX1-associated autoimmune diseases. We report that both monosaccharide residues and the β1-4 linkage are critical for bioactivity of this disaccharide. We also show that Manβ1-4GlcNAc is produced by oligosaccharyltransferase hydrolysis of lipid-linked oligosaccharides in the ER lumen, followed by ENGase and mannosidase processing in the cytosol and lysosomes. Furthermore, synthetic Manβ1-4GlcNAc disaccharide stimulates a broad immune response in vitro, which is in part dependent on the STING-TBK1 pathway, and enhances antibody response in vivo. Together, our data identify Manβ1-4GlcNAc as a novel innate immune modulator associated with chronic autoimmune diseases.
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Affiliation(s)
- Charles S Fermaintt
- Department of Immunology, University of Texas Southwestern Medical Center, Dallas, TX, 75390, USA
| | - Kanae Sano
- Division of Molecular Science, Gunma University, Maebashi, 371-8510, Japan
| | - Zhida Liu
- Department of Pathology, University of Texas Southwestern Medical Center, Dallas, TX, 75390, USA
| | - Nozomi Ishii
- Division of Molecular Science, Gunma University, Maebashi, 371-8510, Japan
| | - Junichi Seino
- Glycometabolic Biochemistry Laboratory, RIKEN Cluster for Pioneering Research, Wako, 351-0198, Japan
| | - Nicole Dobbs
- Department of Immunology, University of Texas Southwestern Medical Center, Dallas, TX, 75390, USA
| | - Tadashi Suzuki
- Glycometabolic Biochemistry Laboratory, RIKEN Cluster for Pioneering Research, Wako, 351-0198, Japan
| | - Yang-Xin Fu
- Department of Pathology, University of Texas Southwestern Medical Center, Dallas, TX, 75390, USA
| | - Mark A Lehrman
- Department of Pharmacology, Department of Microbiology, University of Texas Southwestern Medical Center, Dallas, TX, 75390, USA
| | - Ichiro Matsuo
- Division of Molecular Science, Gunma University, Maebashi, 371-8510, Japan
| | - Nan Yan
- Department of Immunology, University of Texas Southwestern Medical Center, Dallas, TX, 75390, USA. .,Department of Microbiology, University of Texas Southwestern Medical Center, Dallas, TX, 75390, USA.
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22
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Hirayama H. Biology of Free Oligosaccharides: Function and Metabolism of Free N-Glycans in Eukaryote. TRENDS GLYCOSCI GLYC 2018. [DOI: 10.4052/tigg.1761.1e] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Affiliation(s)
- Hiroto Hirayama
- Suzuki Project, T-CiRA Joint Program, Glycometabolic Biochemistry Laboratory, RIKEN
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23
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Hirayama H. Biology of Free Oligosaccharides: Function and Metabolism of Free N-Glycans in Eukaryote. TRENDS GLYCOSCI GLYC 2018. [DOI: 10.4052/tigg.1761.1j] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Affiliation(s)
- Hiroto Hirayama
- Suzuki Project, T-CiRA Joint Program, Glycometabolic Biochemistry Laboratory, RIKEN
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24
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Mammalian STT3A/B oligosaccharyltransferases segregate N-glycosylation at the translocon from lipid-linked oligosaccharide hydrolysis. Proc Natl Acad Sci U S A 2018; 115:9557-9562. [PMID: 30181269 DOI: 10.1073/pnas.1806034115] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
Oligosaccharyltransferases (OSTs) N-glycosylate proteins by transferring oligosaccharides from lipid-linked oligosaccharides (LLOs) to asparaginyl residues of Asn-Xaa-Ser/Thr acceptor sequons. Mammals have OST isoforms with STT3A or STT3B catalytic subunits for cotranslational or posttranslational N-glycosylation, respectively. OSTs also hydrolyze LLOs, forming free oligosaccharides (fOSs). It has been unclear whether hydrolysis is due to one or both OSTs, segregated from N-glycosylation, and/or regulated. Transfer and hydrolysis were assayed in permeabilized HEK293 kidney and Huh7.5.1 liver cells lacking STT3A or STT3B. Transfer by both STT3A-OST and STT3B-OST with synthetic acceptors was robust. LLO hydrolysis by STT3B-OST was readily detected and surprisingly modulated: Without acceptors, STT3B-OST hydrolyzed Glc3Man9GlcNAc2-LLO but not Man9GlcNAc2-LLO, yet it hydrolyzed both LLOs with acceptors present. In contrast, LLO hydrolysis by STT3A-OST was negligible. STT3A-OST however may be regulatory, because it suppressed STT3B-OST-dependent fOSs. TREX1, a negative innate immunity factor that diminishes immunogenic fOSs derived from LLOs, acted through STT3B-OST as well. In summary, only STT3B-OST hydrolyzes LLOs, depending upon LLO quality and acceptor site occupancy. TREX1 and STT3A suppress STT3B-OST-dependent fOSs. Without strict kinetic limitations during posttranslational N-glycosylation, STT3B-OST can thus moonlight for LLO hydrolysis. In contrast, the STT3A-OST/translocon complex preserves LLOs for temporally fastidious cotranslational N-glycosylation.
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25
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Harada Y. The Early Stages of Asparagine-Linked Glycosylation. TRENDS GLYCOSCI GLYC 2018. [DOI: 10.4052/tigg.1807.2e] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Affiliation(s)
- Yoichiro Harada
- Department of Systems Biology in Thromboregulation, Kagoshima University Graduate School of Medical and Dental Sciences
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26
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Harada Y. The Early Stages of Asparagine-Linked Glycosylation. TRENDS GLYCOSCI GLYC 2018. [DOI: 10.4052/tigg.1807.2j] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Affiliation(s)
- Yoichiro Harada
- Department of Systems Biology in Thromboregulation, Kagoshima University Graduate School of Medical and Dental Sciences
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27
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Ishii N, Sunaga C, Sano K, Huang C, Iino K, Matsuzaki Y, Suzuki T, Matsuo I. A New Fluorogenic Probe for the Detection of endo-β-N-Acetylglucosaminidase. Chembiochem 2018; 19:660-663. [PMID: 29323460 DOI: 10.1002/cbic.201700662] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2017] [Indexed: 01/31/2023]
Abstract
We developed a fluorescence-quenching-based assay system to determine the hydrolysis activity of endo-β-N-acetylglucosaminidases (ENGases). The pentasaccharide derivative 1 was labeled with an N-methylanthraniloyl group as a reporter dye at the non-reducing end and with a 2,4-dinitrophenyl group as a quencher molecule at the reducing end. This derivative is hydrolyzed by ENGase, resulting in an increase in fluorescence intensity. Thus, the fluorescence signal is directly proportional to the amount of the tetrasaccharide derivative, hence allowing ENGase activity to be evaluated easily and quantitatively. Using this system, we succeeded in measuring the hydrolysis activities of ENGases and thus the inhibitory activities of known inhibitors. We confirmed that this assay system is suitable for high-throughput screening for potential inhibitors of human ENGase that might serve as therapeutic agents for the treatment of N-glycanase 1 (NGLY1) deficiency.
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Affiliation(s)
- Nozomi Ishii
- Department Graduate School of Science and Technology, Gunma University, 1-5-1 Tenjin-cho, Kiryu, Gunma, 376-8515, Japan
| | - Chie Sunaga
- Department Graduate School of Science and Technology, Gunma University, 1-5-1 Tenjin-cho, Kiryu, Gunma, 376-8515, Japan
| | - Kanae Sano
- Department Graduate School of Science and Technology, Gunma University, 1-5-1 Tenjin-cho, Kiryu, Gunma, 376-8515, Japan
| | - Chengcheng Huang
- Glycometabolome Team, Systems Glycobiology Research Group, RIKEN-Max Planck Joint Research Center for Systems Chemical Biology, RIKEN Global Research Cluster, Wako, Saitama, 351-0198, Japan
| | - Kenta Iino
- Glyco Synthetic Lab., Tokyo Chemical Industry Co., Ltd., 6-15-9 Toshima, Kita-ku, Tokyo, 114-0003, Japan
| | - Yuji Matsuzaki
- Glyco Synthetic Lab., Tokyo Chemical Industry Co., Ltd., 6-15-9 Toshima, Kita-ku, Tokyo, 114-0003, Japan
| | - Tadashi Suzuki
- Glycometabolome Team, Systems Glycobiology Research Group, RIKEN-Max Planck Joint Research Center for Systems Chemical Biology, RIKEN Global Research Cluster, Wako, Saitama, 351-0198, Japan
| | - Ichiro Matsuo
- Department Graduate School of Science and Technology, Gunma University, 1-5-1 Tenjin-cho, Kiryu, Gunma, 376-8515, Japan
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28
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Deglycosylating enzymes acting on N- glycans in fungi: Insights from a genome survey. Biochim Biophys Acta Gen Subj 2017; 1861:2551-2558. [DOI: 10.1016/j.bbagen.2017.08.022] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2017] [Revised: 08/16/2017] [Accepted: 08/28/2017] [Indexed: 11/19/2022]
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29
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Fujihira H, Masahara-Negishi Y, Tamura M, Huang C, Harada Y, Wakana S, Takakura D, Kawasaki N, Taniguchi N, Kondoh G, Yamashita T, Funakoshi Y, Suzuki T. Lethality of mice bearing a knockout of the Ngly1-gene is partially rescued by the additional deletion of the Engase gene. PLoS Genet 2017; 13:e1006696. [PMID: 28426790 PMCID: PMC5398483 DOI: 10.1371/journal.pgen.1006696] [Citation(s) in RCA: 58] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2016] [Accepted: 03/15/2017] [Indexed: 11/25/2022] Open
Abstract
The cytoplasmic peptide:N-glycanase (Ngly1 in mammals) is a de-N-glycosylating enzyme that is highly conserved among eukaryotes. It was recently reported that subjects harboring mutations in the NGLY1 gene exhibited severe systemic symptoms (NGLY1-deficiency). While the enzyme obviously has a critical role in mammals, its precise function remains unclear. In this study, we analyzed Ngly1-deficient mice and found that they are embryonic lethal in C57BL/6 background. Surprisingly, the additional deletion of the gene encoding endo-β-N-acetylglucosaminidase (Engase), which is another de-N-glycosylating enzyme but leaves a single GlcNAc at glycosylated Asn residues, resulted in the partial rescue of the lethality of the Ngly1-deficient mice. Additionally, we also found that a change in the genetic background of C57BL/6 mice, produced by crossing the mice with an outbred mouse strain (ICR) could partially rescue the embryonic lethality of Ngly1-deficient mice. Viable Ngly1-deficient mice in a C57BL/6 and ICR mixed background, however, showed a very severe phenotype reminiscent of the symptoms of NGLY1-deficiency subjects. Again, many of those defects were strongly suppressed by the additional deletion of Engase in the C57BL/6 and ICR mixed background. The defects observed in Ngly1/Engase-deficient mice (C57BL/6 background) and Ngly1-deficient mice (C57BL/6 and ICR mixed background) closely resembled some of the symptoms of patients with an NGLY1-deficiency. These observations strongly suggest that the Ngly1- or Ngly1/Engase-deficient mice could serve as a valuable animal model for studies related to the pathogenesis of the NGLY1-deficiency, and that cytoplasmic ENGase represents one of the potential therapeutic targets for this genetic disorder. Ngly1 is a cytoplasmic de-N-glycosylating enzyme that is ubiquitously found in eukaryotes. This enzyme is involved in a process referred to as endoplasmic reticulum-associated degradation (ERAD), one of the quality control mechanisms for newly synthesized proteins. A genetic disorder, NGLY1-deficiency, caused by mutations in the NGLY1 gene has recently been discovered. However, the precise mechanism for the pathogenesis of this devastating disease continues to remain unclear. We report herein that Ngly1-deficient mice are embryonically lethal in a C57BL/6 background. Surprisingly, the lethality was suppressed by crossing the mice with an outbred mouse strain (ICR), suggesting that the phenotypic consequence of Ngly1 is greatly influenced by their genetic background. In both cases, the additional deletion of Engase in Ngly1-deficient mice could strongly mitigate the phenotypes. Interestingly, the remaining defects in Ngly1-deficient or Ngly1/Engase-deficient mice were reminiscent of the symptoms of subjects with an NGLY1-deficiency. Our results clearly point to the importance of Ngly1 in mammals and show that the inhibition of ENGase represents an effective therapy for treating an NGLY1-deficiency. Most importantly, the mice described herein could serve as valuable viable model mice for studies related to the pathophysiology of an NGLY1-deficiency.
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Affiliation(s)
- Haruhiko Fujihira
- Glycometabolome Team, Systems Glycobiology Research Group, RIKEN-Max Planck Joint Research Center, Global Research Cluster, RIKEN, Saitama, Japan
| | - Yuki Masahara-Negishi
- Glycometabolome Team, Systems Glycobiology Research Group, RIKEN-Max Planck Joint Research Center, Global Research Cluster, RIKEN, Saitama, Japan
| | - Masaru Tamura
- Technology and Development Team for Mouse Phenotype Analysis, Japan Mouse Clinic, BioResourse Center, RIKEN, Ibaraki, Japan
| | - Chengcheng Huang
- Glycometabolome Team, Systems Glycobiology Research Group, RIKEN-Max Planck Joint Research Center, Global Research Cluster, RIKEN, Saitama, Japan
| | - Yoichiro Harada
- Glycometabolome Team, Systems Glycobiology Research Group, RIKEN-Max Planck Joint Research Center, Global Research Cluster, RIKEN, Saitama, Japan
| | - Shigeharu Wakana
- Technology and Development Team for Mouse Phenotype Analysis, Japan Mouse Clinic, BioResourse Center, RIKEN, Ibaraki, Japan
| | - Daisuke Takakura
- Graduate School of Medical Life Science, Yokohama City University, Kanagawa, Japan
| | - Nana Kawasaki
- Graduate School of Medical Life Science, Yokohama City University, Kanagawa, Japan
| | - Naoyuki Taniguchi
- Disease Glycomics Team, Systems Glycobiology Research Group, RIKEN-Max Planck Joint Research Center, Global Research Cluster, RIKEN, Saitama, Japan
| | - Gen Kondoh
- Laboratory of Integrative Biological Science, Institute for Frontier Life and Medical Sciences, Kyoto University, Kyoto, Japan
| | - Tadashi Yamashita
- Laboratory of Biochemistry, School of Veterinary Medicine, Azabu University, Kanagawa, Japan
| | - Yoko Funakoshi
- Glycometabolome Team, Systems Glycobiology Research Group, RIKEN-Max Planck Joint Research Center, Global Research Cluster, RIKEN, Saitama, Japan
| | - Tadashi Suzuki
- Glycometabolome Team, Systems Glycobiology Research Group, RIKEN-Max Planck Joint Research Center, Global Research Cluster, RIKEN, Saitama, Japan
- * E-mail:
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Occurrence of complex type free N-glycans with a single GlcNAc residue at the reducing termini in the fresh-water plant, Egeria densa. Glycoconj J 2017; 34:229-240. [DOI: 10.1007/s10719-016-9758-z] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2016] [Revised: 11/26/2016] [Accepted: 12/22/2016] [Indexed: 10/20/2022]
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Li C, Zhu S, Tong X, Ou C, Wang LX. A facile synthesis of a complex type N-glycan thiazoline as an effective inhibitor against the antibody-deactivating endo-β-N-acetylglucosaminidases. J Carbohydr Chem 2017; 36:336-346. [PMID: 30930529 DOI: 10.1080/07328303.2017.1403616] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Endo-β-N-acetylglucosaminidases are a class of endoglycosidases that deglycosylate N-glycans from glycoproteins. We describe here a facile synthesis of a complex type N-glycan thiazoline as a new mechanism-based inhibitor for this class of enzymes. The synthesis started with the readily available sialoglycopeptide (SGP) and its conversion into the glycan thiazoline through several enzymatic and chemical reactions. The synthetic glycan thiazoline showed potent inhibitory activity against several endoglycosidases including the two antibody-deactivating enzymes, Endo-S and Endo-S2, from human pathogen Streptococcus pyogenes, which would be useful as tools for structural and functional studies of these enzymes.
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Affiliation(s)
- Chao Li
- Department of Chemistry and Biochemistry, University of Maryland, 8051 Regents Drive, College Park, Maryland 20742, USA
| | - Shilei Zhu
- Department of Chemistry and Biochemistry, University of Maryland, 8051 Regents Drive, College Park, Maryland 20742, USA
| | - Xin Tong
- Department of Chemistry and Biochemistry, University of Maryland, 8051 Regents Drive, College Park, Maryland 20742, USA
| | - Chong Ou
- Department of Chemistry and Biochemistry, University of Maryland, 8051 Regents Drive, College Park, Maryland 20742, USA
| | - Lai-Xi Wang
- Department of Chemistry and Biochemistry, University of Maryland, 8051 Regents Drive, College Park, Maryland 20742, USA
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Catabolism of N-glycoproteins in mammalian cells: Molecular mechanisms and genetic disorders related to the processes. Mol Aspects Med 2016; 51:89-103. [DOI: 10.1016/j.mam.2016.05.004] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2016] [Revised: 05/11/2016] [Accepted: 05/24/2016] [Indexed: 11/17/2022]
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Seino J, Fujihira H, Nakakita SI, Masahara-Negishi Y, Miyoshi E, Hirabayashi J, Suzuki T. Occurrence of free sialyl oligosaccharides related to N-glycans (sialyl free N-glycans) in animal sera. Glycobiology 2016; 26:1072-1085. [PMID: 27102284 DOI: 10.1093/glycob/cww048] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2015] [Revised: 04/01/2016] [Accepted: 04/13/2016] [Indexed: 12/23/2022] Open
Abstract
Free oligosaccharides that are structurally related to N-glycans [free N-glycans (FNGs)] are widely distributed in the cytosol of animal cells. The diverse molecular mechanisms responsible for the formation of these FNGs have been well clarified. In this study we demonstrate the wide occurrence of sialylated FNGs in sera of various animals. The features of these extracellular FNGs are quite distinct from the cytosolic FNGs, as they are Gn2-type glycans, bearing an N,N'-diacetylchitobiose unit at their reducing termini, while the cytosolic FNGs are predominantly Gn1-type, with a single GlcNAc at their reducing termini. The major structures observed varied from species to species, and the structures of the FNGs appear to be correlated with the major sialyl N-glycans on serum glycoproteins, suggesting that the serum FNGs are produced by hepatocytes. Interestingly, glycan-profiles of the FNGs indicated that they are altered in a developmental stage-dependent manner. Sialyl FNGs in the sera may not only be of biological relevance, in that they might reflect the functionality of the liver, but also can be attractive sources for obtaining uniform sialyl FNGs in the chemoenzymatic synthesis of glycoproteins.
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Affiliation(s)
- Junichi Seino
- Glycometabolome Team, RIKEN-Max Planck Institute Joint Research Center, RIKEN Global Research Cluster, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan
| | - Haruhiko Fujihira
- Glycometabolome Team, RIKEN-Max Planck Institute Joint Research Center, RIKEN Global Research Cluster, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan
| | - Shin-Ichi Nakakita
- Division of Functional Glycomics, Life Science Research Center, Institute of Research Promotion, Kagawa University, 1750-1 Ikenobe, Miki-cho, Kita-gun, Kagawa 761-0793, Japan
| | - Yuki Masahara-Negishi
- Glycometabolome Team, RIKEN-Max Planck Institute Joint Research Center, RIKEN Global Research Cluster, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan
| | - Eiji Miyoshi
- Department of Molecular Biochemistry and Clinical Investigation, Osaka University School of Medicine, 1-7 Yamada-oka, Suita, Osaka 565-0871, Japan
| | - Jun Hirabayashi
- Division of Functional Glycomics, Life Science Research Center, Institute of Research Promotion, Kagawa University, 1750-1 Ikenobe, Miki-cho, Kita-gun, Kagawa 761-0793, Japan
| | - Tadashi Suzuki
- Glycometabolome Team, RIKEN-Max Planck Institute Joint Research Center, RIKEN Global Research Cluster, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan
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Harada Y, Huang C, Yamaki S, Dohmae N, Suzuki T. Non-lysosomal Degradation of Singly Phosphorylated Oligosaccharides Initiated by the Action of a Cytosolic Endo-β-N-acetylglucosaminidase. J Biol Chem 2016; 291:8048-58. [PMID: 26858256 DOI: 10.1074/jbc.m115.685313] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2015] [Indexed: 01/29/2023] Open
Abstract
Phosphorylated oligosaccharides (POSs) are produced by the degradation of dolichol-linked oligosaccharides (DLOs) by an unclarified mechanism in mammalian cells. Although POSs are exclusively found in the cytosol, their intracellular fates remain unclear. Our findings indicate that POSs are catabolized via a non-lysosomal glycan degradation pathway that involves a cytosolic endo-β-N-acetylglucosaminidase (ENGase). Quantitative and structural analyses of POSs revealed that ablation of the ENGase results in the significant accumulation of POSs with a hexasaccharide structure composed of Manα1,2Manα1,3(Manα1,6)Manβ1,4GlcNAcβ1,4GlcNAc.In vitroENGase assays revealed that the presence of an α1,2-linked mannose residue facilitates the hydrolysis of POSs by the ENGase. Liquid chromatography-mass spectrometric analyses and fluorescent labeling experiments show that such POSs contain one phosphate group at the reducing end. These results indicate that ENGase efficiently hydrolyzes POSs that are larger than Man4GlcNAc2-P, generating GlcNAc-1-P and neutral Gn1-type free oligosaccharides. These results provide insight into important aspects of the generation and degradation of POSs.
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Affiliation(s)
- Yoichiro Harada
- From the Glycometabolome Team, Systems Glycobiology Research Group, RIKEN-Max Planck Joint Research Center, Global Research Cluster, RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198
| | - Chengcheng Huang
- From the Glycometabolome Team, Systems Glycobiology Research Group, RIKEN-Max Planck Joint Research Center, Global Research Cluster, RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198
| | - Satoshi Yamaki
- the Global Application Development Center, Analytical and Measuring Instruments Division, Shimadzu Corp., Hadano, Kanagawa 259-1304, and
| | - Naoshi Dohmae
- the Collaboration Promotion Unit, RIKEN Global Research Cluster, Wako, Saitama 351-0198, Japan
| | - Tadashi Suzuki
- From the Glycometabolome Team, Systems Glycobiology Research Group, RIKEN-Max Planck Joint Research Center, Global Research Cluster, RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198,
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35
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Harada Y. Biosynthesis and Degradation of Dolichol-Linked Oligosaccharides. TRENDS GLYCOSCI GLYC 2016. [DOI: 10.4052/tigg.1512.1j] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Affiliation(s)
- Yoichiro Harada
- Department of Systems Biology in Thromboregulation, Kagoshima University
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36
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Affiliation(s)
- Yoichiro Harada
- Department of Systems Biology in Thromboregulation, Kagoshima University
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37
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The cytoplasmic peptide:N-glycanase (NGLY1) - Structure, expression and cellular functions. Gene 2015; 577:1-7. [PMID: 26611529 DOI: 10.1016/j.gene.2015.11.021] [Citation(s) in RCA: 86] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2015] [Revised: 11/17/2015] [Accepted: 11/18/2015] [Indexed: 11/23/2022]
Abstract
NGLY1/Ngly1 is a cytosolic peptide:N-glycanase, i.e. de-N-glycosylating enzyme acting on N-glycoproteins in mammals, generating free, unconjugated N-glycans and deglycosylated peptides in which the N-glycosylated asparagine residues are converted to aspartates. This enzyme is known to be involved in the quality control system for the newly synthesized glycoproteins in the endoplasmic reticulum (ER). In this system, misfolded (glyco)proteins are retrotranslocated to the cytosol, where the 26S proteasomes play a central role in degrading the proteins: a process referred to as ER-associated degradation or ERAD in short. PNGase-mediated deglycosylation is believed to facilitate the efficient degradation of some misfolded glycoproteins. Human patients harboring mutations of NGLY1 gene (NGLY1-deficiency) have recently been discovered, clearly indicating the functional importance of this enzyme. This review summarizes the current state of our knowledge on NGLY1 and its gene product in mammalian cells.
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